Advances in Phycological Studies

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Author: Nadja Ognjanova-rumenova | Kalina Manoylov

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her current and former students, colleagues, collaborators, and friends over the years. This volume, in celebration of her 70th birthday, is a collection of 25 peer-reviewed research articles on different aspects of phycology and is intended to reflect her diverse academic interests and areas of expertise. The topics covered in this volume include: taxonomy, paleoecology, physiology, and ecology of different algal groups. Much of the work focuses on diatom research including new taxonomic descriptions (a new genus Hyalosigma, fourteen new diatom species, and one new combination), discussion of evolutionary patterns, ecology of freshwater species and the use of diatoms in bioassessment. However, the systematics and physiology of some other algal groups are also presented. This collection, a representation of the many ways algae contribute to our understanding of nature, will be of value to any true “phycologist” in the field as well as to any biological library.

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ADVANCES IN PHYCOLOGICAL STUDIES

Dobrina Temniskova-Topalova includes articles by some of

Festschrift in honour of Prof. Dobrina Temniskova-Topalova

Advances in Phycological Studies: Festshrift in honour of Prof.

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ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in honour of Prof. Dobrina Temniskova-Topalova

Editors Nadja Ognjanova-Rumenova & Kalina Manoylov

St. Kl. Ohridski University Publishing House

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ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova Editors Nadja Ognjanova-Rumenova & Kalina Manoylov

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ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova Editors Nadja Ognjanova-Rumenova & Kalina Manoylov

Pensoft Publishers St. Kliment Ohridski University Press Sofia–Moscow 2006 3

ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova

Editors Nadja Ognjanova-Rumenova & Kalina Manoylov

First published 2006 ISBN-10: 954-642-260-6 (Pensoft Publishers) ISBN-13: 978-954-642-260-6 (Pensoft Publishers) ISBN-10: 954-07-2354-X (St. Kliment Ohridski University Press) ISBN-13: 978-954-07-2354-9 (St. Kliment Ohridski University Press)

Cover photo: Pontodiscus baldjickianus Temniskova et Kozyrenko. Photo: Prof. D. Temniskova-Topalova.

©

PENSOFT Publishers

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the copyright owner.

Pensoft Publishers Geo Milev Str. 13a, 1111 Sofia, Bulgaria E-mail: [email protected] www.pensoft.net

Printed in Bulgaria, April 2006 4

CONTENTS

Preface

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Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students) Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan N. I. Strelnikova, J. P. Kociolek & E. Fourtanier

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Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia, Moldova, and Ukraine Tatyana F. Kozyrenko

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Comparison of seven species of Navicula sensu stricto. Six species described as new to science from Miocene lacustrine deposits in Bulgaria and Romania Horst Lange-Bertalot & Ditmar Metzeltin

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Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta) during the last eight million years in Lake Baikal Galina Khursevich

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A new Cymbella from the Neogene in Bulgaria and its stratigraphic significance Nadja Ognjanova-Rumenova & Ditmar Metzeltin

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Nitzschia toskalensis sp. nov. a new diatom (Bacillariophyceae) from the sediments of Toskaljavri, northwestern Finland Paul B. Hamilton & Jan Weckström

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Distribution of resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Bacillariophyta) in sediments of peat bogs from Mt. Central Sredna Gora, Bulgaria Rosalina Stancheva 5

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Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae) Ioanna Louvrou, Daniel Danielidis & Athena Economou-Amilli Staurosira incerta (Bacillariophyceae) a new fragilarioid taxon from freshwater systems in the United States with comments on the structure of girdle bands in Staurosira Ehrenberg and Staurosirella Williams et Round Eduardo A. Morales Achnanthidium temniskovae sp. nov., a new diatom from the Mesta River, Bulgaria Plamen Ivanov & Luc Ector A new Gyrosigma species from lakes Prespa and Ohrid Levkov Zlatko, Svetislav Krstic & Teofil Nakov

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Diatom species composition from the river Iskar in the Sofia region, Bulgaria Plamen Ivanov, Emilia Kirilova & Luc Ector

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Chara corfuensis J. Gr. ex Fil. 1937 (Characeae) – an endemic species of Balkan Peninsula, rare and globally endangered Jelena Blaženčiæ

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First record of the tropical invasive alga Compsopogon coeruleus (Balbis) Montagne (Rhodophyta) in Flanders (Belgium) Maya P. Stoyneva, Koenraad Vanhoutte & Wim Vyverman

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Initial observations on uniparental auxosporulation in Muelleria (Frenguelli) Frenguelli and Scoliopleura Grunow (Bacillariophyceae) Mark B. Edlund & Sarah A. Spaulding

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Effect of abscisic acid on host susceptibility during different ontogenetic phases of the host alga in the pathosystem Scenedesmus acutus – Phlyctidium scenenedesmi Irina D. Pouneva & Christo Christov

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Diatom succession in the Ferdynandovian Interglacial lacustrine deposits of Poland Barbara Marciniak

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Environment variation in the Black Sea region during the Late Quaternary based on fossil diatoms A. P. Olshtynskaya

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Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf Mariana Filipova-Marinova

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Diatoms as indicators of the influence of the Vistula river inflow on the Gulf of Gdańsk during the Holocene Katarzyna Stachura-Suchoples

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Diatom flora diversity in the strongly eutrophicated and α-mesosaprobic waters of the Szczecin Lagoon, NW Poland, southern Baltic Sea Ma³gorzata B¹k, Andrzej Witkowski & Horst Lange-Bertalot

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Use of nonparametric multiplicative regression for modeling diatom habitat: a case study of three Geissleria species from North America Marina G. Potapova & Diane M. Winter

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Density-dependent algal growth along N and P nutrient gradients in artificial streams Kalina M. Manoylov & R. Jan Stevenson

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Atypical Tabularia in Coastal Lake Erie, USA E. F. Stoermer & N. A. Andresen Refining diatom indicators for valued ecological attributes and development of water quality criteria R. Jan Stevenson

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List of Referees ALVERSON, Andrew 1 University Station (A6700), 311 Biological Laboratory, University of Texas at Austin, Austin, Texas 78712 ANDRESEN, Norman Andresen Consulting, LLC, 5742 Princeton Place, Ypsilanti, MI 48197 BERKMAN, Julie US Geological Survey, 6480 Doubletree Ave., Columbus, OH 43229 HEINLEIN, Juliane Department of Zoology, Michigan State University, 203 Natural Sciences Bldg. East Lansing, MI 48824 KHURSEVICH, Galina Institute of Geochemistry and Geophysics, National Academy of Sciences of Belarus, Kuprevich street 7, Minsk 220141, Republic of Belarus LEROY, Suzanne Department of Geography and Earth Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH, (West London), UK LANGE-BERTALOT, Horst Botanical Institute, J.-W. Goethe-University, Senckenberganlage 31–33, 60054 Frankfurt am Main, Germany LOWE, Rex Department of Biological Sciences, Bowling Green State University Bowling Green, OH 43403 MANOYLOV, Kalina Department of Zoology, Michigan State University, 203 Natural Sciences Bldg. East Lansing, MI 48824 MORALES, Eduardo Phycology Patrick Center for Environmental Research, The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103-1195 U.S.A. OGNJANOVA-RUMENOVA, Nadja Institute of Geology, Bulgarian Academy of Sciences, Acad. G. Bonchev str. 24, 1113 Sofia, Bulgaria

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PANAYOTOFF, Lara Kentucky Division of Water, 14 Reilly Road, Frankfort, KY 40601 POTAPOVA, Marina Phycology Patrick Center for Environmental Research, The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103-1195 U.S.A. ROLLINS, Scott Department of Zoology, Michigan State University, 203 Natural Sciences Bldg. East Lansing, MI 48824 SLAVCHOVA, Nadezda Environmental Sciences and Resources Portland State University PO Box 751 Portland, OR 97207 STACHURA-SUCHOPLES, Katarzyna Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, D-14473 Potsdam, Germany STANCHEVA, Rozalina Department of Botany, Faculty of Biology, St. Kliment Ohridski University of Sofia, D. Tsankov Blvd 8, 1164 Sofia, Bulgaria Current: Environmental Sciences and Resources Portland State University PO Box 751 Portland, OR 97207 STERRENBURG, Frithjof Stationsweg 158, 1852 LN Heiloo, The Netherlands STRELNIKOVA, Nina Department of Botany, Biological Faculty, St.Petersburg State University, Universitetskaya Emb. 7/ 9, St. Petersburg, 199034, Russia SWEETS, Roger P. University of Indianapolis, Biology Department, Indianapolis, IN 46227 TONCHEVA, Tonka Institute of Plant Physiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria, Georgi Bonchev Str., Block 21 URBANC-BERCIC, Olga Department of Aquatic and Terrestrial ecology, National Institute of Biology, Vecna pot 111, 1000 Ljubljana Slovenia WITKOWSKI, Andrzej Institute of Marine Sciences, University of Szczecin, Waska 13, PL-71-415 Szczecin, Poland WACHNICKA, Ania Southeast Environmental Research Center & Earth Sciences Department Florida International University, Miami, FL 33199

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Preface The Festschrift to honor Prof. Dobrina Temniskova-Topalova’s 70th birthday includes articles by some of her current and former students, colleagues, collaborators, and friends over the years. The volume is a collection of 25 research articles on different aspects of Phycology and is intended to reflect her versatile academic interests and areas of expertise. The topics covered by the papers include: taxonomy, palaeoecology, physiology, and ecology of different algal groups. Articles describe new taxa from fossil and recent materials of Europe, Asia and North America: a new genus Hyalosigma, fourteen new diatom species, and one new combination. Important patterns of the morphological evolution in extinct diatom genera of family Stephanodiscaceae in Lake Baikal are discussed. New floristic and taxonomic information for the distribution of the endemic Chara corfuensis J. Gr. ex Fil. and the tropical Compsopogon coeruleus (Balbis) Montagne is provided. Research on various biostratigraphical and palaeoecological marine and lacustrine basins, based on diatoms and dinoflagellate cysts, is presented. More specialized topics like uniparental auxosporulation are presented also. Careful analyses of the infection process in the green microalga pathosystem and an unicellular fungal parasite. A substantial group of articles focuses on the ecology of freshwater diatoms – redefinition of their importance in bioassessment, density and nutrient dependence of diatom, and the use of new analytical methods like Nonparametric multiplicative regression modeling. The editors would like to thank all colleagues that participated in the thorough review of every paper. We would also like to extend our gratitude to the people we were in contact in PENSOFT and St. Kliment Ohridski University Press, especially Dr. Lyubomir Penev (Managing Director of Pensoft) and Teodor Georgiev (Chief of Preprint Department) for meticulously working with the authors and editors in putting together the final touches of the book. Nadja Ognjanova-Rumenova & Kalina Manoylov

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Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 13-24) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Prof. Dr. Biol. Sc. DOBRINA N. TEMNISKOVA-TOPALOVA (A life dedicated to the students) Dimitar Vodenicharov1, Kalina Manoylov2 & Nadja Ognjanova3 Han Asparuh str. 88, Plovdiv, Bulgaria Michigan State University, Department of Zoology, 203 Natural Sciences Bldg. East Lansing, MI 48824, USA 3 Institute of Geology, Bulgarian Academy of Sciences, Acad. G. Bonchev str. 24, 1113 Sofia, Bulgaria 1 2

Unexpectedly for her active mentors and her students Prof. Temniskova jumped over a life long barrier that allowed her to celebrate her 70th Birthday anniversary. She managed to preserve the charm and temperament of her student years for most of her life. Maybe the biggest reasons for her energy are the beautiful algae she has studied for 40 years and still finds extremely exciting, the mornings around the pristine lakes of Pirin and Rila Mountains, and evenings around a camp fire full with intellectual conversations, endless funny stories and new project ideas for tomorrow. Happy anniversary Prof. Temniskova! We wish you health, continuous endless energy, drive and success in the future! Dobrina Nikolova Temniskova was born on November, 12 1934 in the historic and cultural center Veliko Turnovo. Veliko Turnovo brings pride in every Bulgarian as the capital of the Second Bulgarian Kingdom (1187–1396), and an energetic university town today. Prof. Temniskova still loves her birth town and in her academic speech in front of the Academic Board of the Sofia University. (21 January 2004) she said:… ‘for all my life, the beauty of my birthplace, its energizing atmosphere, together with my family, my friends and mentors gave me strength and inner vigor’. She completed her elementary and secondary education in V. Turnovo. Her favorite subjects were biology, science and Bulgarian language and literature. During her high school years she played violin in the school orchestra, participated in theatre and literature clubs. When she was in 11th grade she won second place for literature from the Ministry of Education of 13

Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

Bulgaria. In 1952 D. Temniskova graduated from High School and started her undergraduate studies in the Biology-Geology- Geography Faculty of the Sofia University ‘St. Kliment Ohridski’, Biology major. She specialized in the department of Plant Systematics and Plant Geography (today department of Botany) and in 1957 she graduated with honors. Prof. Temniskova is proud that she specialized (magistrate) in one of the oldest departments of Sofia University and the oldest in the Biology Faculty. The Botany department was established in 1891, three years after the establishment if the first school of Higher Education in Bulgaria, named Bulgarian University in 1904. This is the first University in Bulgaria after the 500 years under Turkish rule (1396–1878). In the Botany Department the beginning of Phycological studies began with Prof. St. Petkov (Doctor of Sciences from the University of Gent, Belgium) and chair of the Botany Department for many years. The University mentors of D. Temniskova were Prof. D. Vodenicharov, acad. Daki Yordanov, coresp.member BAS A. Vulkanov, Prof. K. Popov etc, most of whom graduated with Doctoral degrees from Western European Universities prior to Word War II. Prof. Temniskova many times had expressed her gratitude to her teachers and she didn’t forget them in her Academic speech when she was awarded the prestigious Blue Ribbon from Sofia University:…’I am immeasurably grateful to my mentors. They showed me what a university professor has to be – not only a great researcher, but an excellent and engaging teacher, with great professionalism, wide scientific and cultural knowledge, a person with decency, work ethics and energy.’ As a graduate student Prof. Temniskova showed great interest in algae. She participated in the Botany club, student scientific forums and in 1957 received Second place in science at the First Republican festival of student sciences in Bulgaria. After her graduation D. Temniskova was sent by the Government to work for 3 years at the town of Samokov (DIP“ Rilski Len”, 1957-1959), she worked for 2 years as a lab manager of the central factory lab and then for 2 years in DIP ’Uchtechprom’ department of Microscope slides. She organized the first factory production of permanent microscope slides with educational purposes in botany, zoology, and human anatomy (1960–1961).

Doing her dissertation research.

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Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students)

In 1962, D. Temniskova started as an adjunct assistant (free aspirant) in the Botany Department, Faculty of Biology, Sofia University ‘St. Kliment Ohridski’, where in 1964 she continued as a regular assistant. In 1972, as a free aspirant she defended her dissertation and became ‘Doctor of Sciences’, later in 1994 she completed a second (habilitation) dissertation and was awarded ‘Doctor of Biological Sciences’. In 1966, Dr. D. Temniskova had an opportunity to continue her studies in Germany with a Humbold stipend, but the political circumstances in Communist Bulgaria during this period were hard to overcome. Regardless of the political barriers and thanks to her love to her research, graduate students and teaching she continued her work at Sofia University. Luckily, later D. Temniskova had the opportunity to specialize at the St. Petersburg diatom lab at the Saint Petersburg University, the Botanical Institute of Academy of Sciences of USSR. She studied with Prof. D.Sc. V. S. Sheshukova-Poretzkaja, Prof. D.Sc. N. I. Strelnikova, Prof. Dr. T. F. Kozyrenko, Prof. D.Sc. I. V. Makarova, Prof. D.Sc. A. I. Moiseeva and many others (1968-1969). D. Temniskova specialized in the Harkov University ‘T. Shevchenko’ with Prof. D.Sc. A. M. Matvyenko, student of the great phycologist from Ukraine, Prof. Korshikov. From all her studies abroad and especially as gifts from her colleagues from St. Petersburg University and Athens University, Greece (Prof. Dr. K. Anagnostidis and Prof. Dr. A. Economou-Amilli) she collected extensive literature on diatoms for her research and her student’s research. D.

International Symposium: Biology and Taxonomy of blue-green algae, Smolenize Castle, Republic of Czechoslovakia (1987).

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Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

Temniskova had mentioned in many occasions that without the help and the scientific exchange with colleagues from abroad the development of Diatom analyses and Phycology in Bulgaria was never going to be successful. All teaching and research years of Prof. Temniskova were at the Sofia University, Biology Faculty, Department of Botany; 1962 – adjunct assistant, 1964 - regular assistant, 1982 - docent (Associate professor) and from 1995 – professor. She established and was a leader of the Laboratory of Diatom Analyses (1982–2002). From 1996-2002 she was Department Head of the Botany Department. After her retirement (2004) she remained engaged with the university as adjunct professor and mentor of doctoral students. She has been a member, for many years, of the Faculty Board of the Biology Faculty (1987–2002) and a member of the Academic board of Sofia University (1999–2003). She has been active on the Academic boards and her opinions and expertise were sought when decisions were made on the Botanical Garden of the Sofia University and other University events. She is tremendously respected among her academic peers and was deservingly elected as the first ombudsmen in the History of Sofia University (2004). Prof. Temniskova is an excellent teacher, lecturer, and a favorite professor. Her classes have been required classes in the Botany department and some specialized classes. She had laboratory and field practices in morphology and systematics of lower plants, phytogeography, and she lectured on systematics of algae and fungi; phycology with diatom analyses, taxonomy and evolution of algae, etc. Prof. Temniskova created a diverse collection of permanent diatom slides preserved algal and fungal specimens. Her extensive collection has been used in the educational laboratory practices, scientific observations and learning in the

International Diatom Symposium, Budapest, Hungary (1980)- from left to right Dr.G.Khursevich, Dr. B. Marciniak, Dr. D.Temniskova, Dr. R.Ross, Dr. I. Makarova, and Dr. L. Loginova).

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Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students)

Botany Department. She started a Herbarium collection of permanent diatom slide from hers and her student’s research. For the first time in Bulgaria she developed and taught a course in Diatom analyses (lectures and lab work). The slide collection, microscopes, and literature available in the lab contributed to the future studies and successes of her student working with recent and fossil diatoms (N. Ognjanova, M. Vuleva, S. Passy, K. Manoylova, R. Stancheva, P. Ivanov, R. Zidarova). She started, maintained and developed the only laboratory for Diatom Research in Bulgaria especially in the field of Paleodiatomology. Fossil studies with diatoms had been the most dynamic branch of studies in Bulgarian Phycology in the last decade. Many of Prof. Temniskova’s students, who graduated with M.Sc. degree, work in different fields of Botany (D. Ivanov – palinology, P. Robeva - embryology, K. Uzunova - anatomy, A. Uzunova – plant physiology, N. Misaleva – plant genetics etc) and many of her Masters students work in the pharmaceutical and food industries. As a mentor D. Temniskova left a shining trail of successful scientists, all touched and inspired by her scientific approach, enthusiasm, knowledge and personal conviction. D. Temniskova loved lecturing and teaching. She never considered working at other prestigious institutions like the Bulgarian Academy of Sciences, because of she couldn’t part with

Celebrating the Day of Slavic (24.May.2002) – from left to right Prof. B. Biolchev (Rector of Sofia University), prof. D. Temniskova, prof. V. Radeva and prof. O. Gerdzhikov (National Assembly Chairman).

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Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

her students. She confesses this: …‘I was unable to imagine living without the magic of teaching. I loved looking at excited student eyes when they understood a process or relationship, discovered a new species or got excited assigning a correct scientific name. In my priorities after my family, my teaching and work, I have close to my heart all my masters and doctoral students. They will be part of me forever. They are my pride and joy that energizes me’. That is why Prof. Temniskova left a memorable part of herself in all her students, grateful of their knowledgeable and inspiring mentor, and not daring even to dream to measure as colleagues with her one day in the future. As a token of her students’ appreciation, of the respect of the academic body of the Sofia University and the scientific community of the University, Prof. Temniskova had been warmly congratulated for her 70th year anniversary and awarded with many prestigious awards. She was awarded the Honorary Sign of Sofia University level 1, Honorary Sign of Sofia University with blue ribbon (2003) celebrating 40 years of the establishment of the Faculty of Biology and awarded the Icon of Saint Kliment Ohridski from the Rectorate of Sofia University (2004). Prof. Temniskova started her research as an undergraduate student. This resulted in her first publication (1961): Algal flora of the rivers Iskur and Palakarya in the man-made lake Iskar. In her paper she discussed representatives of Chlorophyta, Zygnemophyta, Cyanobacteria, Chrysophyta and Xanthophyta. From that time on algae become her favorite and main tool of research. For most of her career Prof. Temniskova addressed different Phycological questions, and her research can be divided into two major periods. In the first period of her research she studied algae from different groups and different water bodies, with major emphases on temporary water bodies. As a result she reported 632 species, varieties and forms from seven algal divisions: Chlorophyta, Euglenophyta, Bacillariophyta, Chrysophyta, Zantophyta, Dinophyta and Award ceremony when the Honorary Golden Sign of Sofia University with blue ribbon was awarded (2003) - Prof. B. Biolchev (Rector of Sofia University) and prof. D. Temniskova.

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Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students)

Cyanobacteria. From those, 239 taxa were reported for the first time in Bulgaria. She studied 748 temporary water bodies from 106 sites in Bulgaria, provided data on temperature, pH, chemical content of water, time period of existence, drying processes etc. She presented algal species composition, classification of the algal bodies and characteristics of the algal bodies first in Bulgaria. She presented her results with her first dissertation ‘Algal flora from temporary waters in Bulgaria’; she defended her work as a free aspirant and received a Ph.D. degree (1972). It is noteworthy to mention that for the Dissertation work of D. Temniskova there were official opinions from 14 European algologists: G. Deflandre, T. Hortobagyi, G. Jerkovic, M. M. Gollerbach, A.M. Matvyenko, V. S. Sheshukova-Poretzkaya, I. B. Makarova, Z. I. Asaul and others). They all gave high praise of her research as they were looking at it from different algal groups’ perspectives. We will site only Prof. G. Deflandre (honorary member of the French Academy of Sciences Paris, honorary member of the Austrian Academy of Sciences, member of the Royal Academy Belgium, fellow of the German Academy, Hale Germany) who in his opinion states:…’I have been studying algae for more than 10 years and I can attest for the enormous amount of work done by D. Temniskova to show this results. As far as the science in the work, many times I felt I am reading my own thoughts, taken from my unpublished manuscripts, results and interpretations I came as a result of shorter and way too shallow observation than those presented by D. Temniskova. With this review I want one more time to state that the presented work is in line with my own ideas and plans for Phycological research, what I have neglected in lately as I have been doing mostly micropaleontology. I agree with the presented classification of temporary waters presented by D. Temniskova, with the presentation of continuous historical perspective and a helpful discussion on the terminology of those waters’. During the first period of her research Prof. Temniskova did extensive research of floristic, taxonomic and horologic characteristics of some flagellate algal groups like Euglenophyta and Volvophyceae (Chlorophyta) from different waters. D. Temniskova was a coauthor of the first algal flora of Bulgaria –‘Flora of Bulgaria: algae’ (1971). During this time Prof. Temniskova promoted science for the general public with the publication of “Plantsdetectives’ (1964) and numerous educational papers in magazines and newspapers like ‘Plants-geologists’, ‘The extinct gentian’ etc. The second period of D. Temniskova’s scientific research has been dedicated to the diatoms (Bacillariophyceae) and the development of Diatom Analyses as a tool in Bulgaria. Today, the current accomplishments in the Bulgarian Diatom Analyses are determined by her research and the research of her students. In her diatom research there are several directions: As a result of taxonomic investigations D. Temniskova introduced a new genus, Pontodiscus, three species P. baldjickianus, Actinocyclus makarovae, Actinocyclus fungiformis and seven within species diatom taxa. There are 34 new taxonomic combinations. She uses biometric methodology for within species taxonomy of Aulacoseira granulata. She also studied variability in non-diatom populations like the variability within two species of Trachelomonas (Euglenophyta). She studied with SEM numerous recent and fossil diatoms, important in biostratigraphic and paleoecological research. The most prestigious and numerous are the contributions of Prof. Temniskova to the studies of fossil diatoms. Most of her work was summarized in the Dr.Sc. thesis 19

Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

(Dissertation): ‘Miocene diatom floras from Bulgaria-community composition, structure, evolution, paleoecology and biostratigraphy’ (in 3 parts: 1. 318 pp text, 2. 120 plates with 1236 LM and SEM original micrographs of fossil diatoms and 3. 4 maps, 30 tables and 111 graphs, diagrams, and dendograms). The major contributions of Prof. Temniskova in Paleodiatomology are in several areas: paleofloristic and taxonomy, biostratigraphy, paleoecology, paleobiogeography and evolution of diatoms. In those directions she characterized many florotypes: Chokrakian, Karaganian, Konkian, Volhynian, Bessarabian, Chersonian, Pontian and Pont-Pliocene. This encompasses a broad paleosuccession cycle for the Chokrakian-Chersonian stages and the narrower Pont-Pliocene stages. From the research on diatoms from Neogene marine-brackish and continental sediments, paleoflora of Bulgaria was enriched with 845 taxa (535 species, 268 varieties and 42 forms). For the first time 1 genus with 3 species of Archeomonada, 2 species and 2 varieties of Silicoflagellatae, representatives of type Poryfera (3 species) and one Phytolitaria were identified. Research on late glacial and Holocene sediments was performed (over 200 species and varieties) as a result of the first studies of Durankulak Lake and Beloslav Lake, Varna District. As contributions to the European paleoflora: there are 182 species, varieties and forms of diatoms new for the Miocene diatom floras from the Euxinian Basin. Three genera and 86 species, varieties and forms, new for the Miocene diatom flora of the Whole Paratethys were reported. Also reported for the first time, were archeomonads in East Paratethys. Based on these rich data sets Prof. Temniskova for the first time in Bulgaria divided and characterized diatom floras from the Chokrakian, Karaganian, Konkian, Volhynian, Bessarabian and Chersonian age. She followed changes in diatom flora for 5.5 million years (16-10.5 million years BC) in the Northwest part of the Euxinian Basin. She uncovered the florogenesis during the Middle-Late Miocene and proved that the Miocene flora played a significant part in the formation of the modern floras of the Black, Azov and Caspian Seas. Her largest contribution to the modern communities was her work from Chersonian flora in the Black Sea - Caspian Sea basin. She described a repeated sequence in the evolution of diatoms for this time period. During this geological interval most of the modern diatom genera evolved. She determined the speed of macro evolutionary processes for the Middle and Late Miocene diatoms. The highest speed of evolvement of new genera was during the Karaganian stage (century) of the Middle Miocene, 2.26 genera/ 1 million years. Prof. Temniskova completed the first, for our country, biostratigraphic subdivision of the Miocene sediments (Chocrakian, Karaganian and Konkian stages and Volhynian, Bessarabian and Chersonian substages of the Sarmatian stage in Northeast Bulgaria) based on diatoms. She separated and characterized 5 taxon acro zones, 3 taxon acro subzones, one interval zone, and one barren interval zone for marine-brackish sediments. Those are the first diatom zones for the Miocene sediments of the Eastern Paratethys paleobasin. Very important is the parallel correlation with other biostratigraphic zones, based on different fossils groups: mollusks, foraminifers and ostracods. For the first time Prof. Temniskova compared the Late Miocene diatom floras from the Eastern and Central Paratethys and Tethys. She completed the biostratigraphic, chronostratigraphic and magnitostratigraphic units in the Tethys, Eastern and Central Paratethys. 20

Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students)

Prof. Temniskova carefully researched the Neogene continental basins in South Bulgaria. She established two types of diatom floras during the Late Miocene (Pontian) and Early Pliocene (Dacian): type ‘Aulacoseira’ and type ‘Actinocyclus’. She underlined the specificity of the type ‘Actinocyclus’ and presented the hypothesis that during the Late Miocene, the SouthBulgarian continental basin was one of the world’s centers of evolution of the genus ‘Actinocyclus’. She introduced a novel hypothesis for the possible ways of distribution of diatoms during colonization of the Neogene nonmarine basins in Bulgaria. Based on the diatom analyses she established the age of South-Bulgarian Neogene sediments. With this she proved that in different basins, sediments were deposited at the same chronological interval Late Miocene (Pontian) - Early Pliocene (Dacian). For the nonmarine Upper Miocene - Lower Pliocene sediments of the Sofia Basin there were distinguished 4 diatom taxa acro zones. Her contributions to paleoecology continued with the establishment of the character, dynamics and sequences of paleoecological diatom spectra from different stratigraphic levels in the Middle and Upper Miocene in different paleobasins. She reported a well defined reconstruction of the paleoecological conditions in different stages and sub stages of the Middle-Late Miocene. Based on changes in the weighted mean value of every halobic diatom group she determined the cycles of increase and decrease of the salinity of the waters in the studied basins. The results of the paleoecological analyses of different types of floras are diverse, but they summarized the full ecological characteristics of biotopes in different consequent periods of development of the diatom paleofloras during the Miocene stage.

16th International Diatom Symposium, Greece 2000, from left to right Drs: Kalina M. Manoylova, Nadja Ognjanova-Rumenova, Prof. Dobrina Temniskova-Topalova and Sophia Passy.

21

Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

A complete reconstruction was presented of the paleoecological conditions of the Durankulak and Beloslav Lakes during Late Glacial and Holocene times. She presented that the Durankulak Lake was part of the littoral zone of the Black Sea and went through three periods of salinity in its development. During those periods the habitat was brackish – marine (modern salinity of this Lake is 4‰). Similarly 3 periods in the salinity of the Beloslav Lake in northern Bulgaria were determined. The introduction of Diatom analyses in the geological practices in Bulgaria has been very important in the understanding of the genesis of depositional rocks, and for the practical answering of biostratigraphic, correlational and paleoecological questions. Biostratigraphic and paleoecological results of Prof. Temniskova have been used in the publication of the geologic map of Bulgaria (M 1:100000), also in the assessment of different Neogene basins in Bulgaria. Using diatom species composition there have been several assessments of diatomite and diatomite sediments in different regions in Bulgaria. Those assessments are important for future exploitation of different sediments. Her work also contributed to the use of electronic paramagnetic resonance in diatomite research. Most of the scientific research of Prof. Temniskova also has application in student education. Most of the published research of Prof. Temniskova can be used in the understanding of applied ecological problems. Many publications have been on the anthropogenic pollution of water bodies and the use of diatoms as bioindicators. Those publicaProf Temniskova with a group of students leading practicum “Ecology of algae”, Kaliakra Cape, the Black Sea (2003)

22

Prof. Dr. Biol. Sc. Dobrina N. Temniskova-Topalova (A life dedicated to the students)

tions are an important contribution to the application and use of biomonitoring in ecosystem management. She contributed tremendously in the taxonomic variability of diatoms in recent lakes and rivers from different regions in Bulgaria (Rhodope Mountains, Strandza Mountains, Ograzhden Mountain etc). For the classification of freshwater basins ecomorphs of Aulacoseira granulata have been used. Prof. Temniskova pioneered research on benthic diatoms from the Bulgarian Black Sea shelf: taxonomic composition (reported over 250 species, varieties and forms), changes in biomass, dominant species, and mean density. Research was done over a 5 year period (May 1986- December 1990) immediately after the Chernobil accident in Ukraine. She studied the first cores from the deep Black Sea shelf. She described 15 complexes (communities) of diatoms in the shallow and deep shelf. Especially she related anthropogenic influence (increase in heavy metals and radionucleotides) and established an indicator species (Podosira pellucida Pr-Lavr.). Her research has been a model as the diatom composition and structure of marine benthic communities can be used in understanding the eutrophicaion relationships and changing ecological condition in marine ecosystems. Temniskova studied for the first time silicoflagellates and representatives of Ebridae from recent sediments in the Bulgarian Black Sea Shelf. She reported 2 new genera, 3 new species and 1 variety new for Bulgaria. For the first time for the modern Black Sea community she reported the living fossil Dictyocha triacantha Ehr. (Dictyophyta = Silicoflagellatae). In conclusion, through her research on recent algal flora from Bulgaria ranging from diatoms, green algae, euglenophytes, blue-green algae, and silicoflagellates, she contributed to the describing of algal biodiversity in Bulgaria. She reported for the first time 7 genera and 610 species, varieties and forms of algae. Prof. Temniskova contributed to the algal studies in Irak, for the territory of ancient Babylon, together with Prof. E. Blaženčiæ (University of Belgrade, Serbia) she reported 5 Charophyta species. In recent years the collaboration continued with a project on Charophyta from Serbia, Montenegro and Bulgaria. In the last decade Prof. Temniskova has been a part of a team study of Antarctic flora and fauna on Livingston Island where Sofia University has built a research Base named after St. Kliment Ohridski. She works on materials collected from Bulgarian Antarctic expeditions, with participation of Biologists, including a student of hers. Diatoms from continental water and terrestrial biotopes have been studied and 190 taxa have been reported. The species in this community are mainly cosmopolitan, where arcto-antarctic and northern alpine species were rare. Diatom communities were dominated by the cosmopolition and, typical for the Antarctic communities, Luticola muticopsis (V. H.) D. G. Mann. Preliminary data has been published on blue green algae and green algae, distributed mainly in water and terrestrial habitats in the Bulgarian and Spanish bases on Livingston Island. The identified representatives are mainly cosmopolitan. Prof. Temniskova reported that there was no difference between the species living in aquatic and terrestrial habitats. This conclusion was similar to that reported in the literature, that clear boundaries of aquatic and terrestrial habitats in extreme environments are hard to distinguish and the same species live in both habitats. 23

Dimitar Vodenicharov, Kalina Manoylov & Nadja Ognjanova

In Antarctic communities green algae (reported 33 species from 21 genera) were represented with typical cryophytes and aerophytes, peat-loving and rheophilous mountain species, as well as terrestrial algae. Of the habitats studied, the snow and glacier ones have a specific flora. Lake habitats manifest a greater variety of representatives of class Zygnemophyceae, and the streams – Ulothrix spp., Zygnema spp. and Prasiola calophyta (Corm.) Meneghini. As expected, Prasiola crispa (Lightf.) Meneghini grew abundantly on rocks close to the penguin colonies. The research on different algal groups from Antarctic is important contribution to Phycology of the vastly unknown habitats from this continent. Prof. Temniskova was a principle investigator and participant in many national and international projects (projects 25, 158B and 329 UNESCO, project on complex research on Livingston Island, Antarctica, etc). Prof. Temniskova has participated in many national and international conferences, symposia and congresses. She presented more than 50 papers and posters. Prof. Temniskova is a member of many Bulgarian Scientific societies including the Bulgarian Botanical Society since 1964, Union of the Sciences of Bulgaria from 1966, and the Society of the Bulgarian Ecologists since 1999. Since 1999 she has been the president of the Bulgarian Botanical Societies, where she has an active and supportive role bringing the Society to new and fruitful scientific levels. Dr. Temniskova is a member of the International Phycological Society, and the International Society for Diatom Research. Prof. Temniskova has been a member of many scientific boards and expert working groups in Bulgaria: Committee of Medico-biological sciences with the High Attestation Committee (VAK) at the Ministry Council of Bulgaria, Specialized Council in botany and Mycology at VAK (1995-present), Scientific council of the Central laboratory in General Ecology at the Bulgarian Academy of Sciences (1999-present), Science-coordination center for Global projects at the Bulgarian Academy of Sciences (2004-present). Prof. Temniskova is the editor of the Yearly Scientific Journal of Sofia University ‘St. Kliment Ohridski’. All scientific research publications of Prof. Temniskova are significant and essential contributions to the development of Phycology and especially Paleodiatomology in Bulgaria. She introduced the beginning of systematic and modern studies of diatoms in Bulgaria with recent and relict aquatic habitats. Prof. Temniskova has presented many original and applied scientific contributions. Results from her studies have nation, European and World importance, especially the original classification of temporary water bodies; the new taxa described; the biostratigraphic subdivision and correlation, based on diatoms from the Miocene sediments from the Northwest parts of the Eastearn Paratethys and the correlations of the biostratigraphic zones of the whole Eastearn and Central Paratethys and Tethys.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 25-42) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan N. I. Strelnikova1, J. P. Kociolek2 and E. Fourtanier2 Department of Botany, Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg, 199034, Russia, e-mail: [email protected] 2 Diatom Collection, California Academy of Sciences, 875 Howard St., San Francisco, CA 94103-3098, U.S.A. 1

ABSTRACT A new genus of sigmoid, naviculoid diatoms Hyalosigma gen. nov. and two new species H. temniskovae-topalovae sp.nov. and Gyrosigma kazachstanicum sp.nov. were studied with light and scanning electron microscopy and described from Lower Eocene-Early Middle Eocene diatomite quarry Kirgizskoe, Emba River basin, Kazakhstan. Gyrosigma kazachstanicum differs from other members of the genus by its convex valve and round external areaolar openings. Hyalosigma differs from Gyrosigma and Pleurosigma by having ornamentation of the striae interrupted by large hyaline areas on the valve face and acute angle of marginal and mantle striae. These records are the oldest known for the sigmoid group of naviculoid diatoms. Key words: Sigmoid, naviculoid diatoms, Hyalosigma gen. nov., Hyalosigma temniskovaetopalovae sp. nov., Gyrosigma kazachstanicum sp. nov., Paleogene sediments, Kazakhstan

INTRODUCTION Very little is known about pennate diatoms from the Cretaceous and Paleogene Epochs. Scattered descriptions of pennate diatoms from these geological epoch can be found in the literature (Weisse 1854, Witt 1886, Grove and Sturt 1886-1887a-c, Pantocsek 1903-1905, Schrader and Fenner 1976, Aphanassyeva and Gleser 1986, Harwood 1988, Desikachary and Sreelatha 1989, Fenner and Mikkelsen 1990, Edwards 1991, Fenner 1991, 1994, Strelnikova 1992). The most extensive study is that of H.J.Schrader (1969) who described pennate diatoms 25

N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

from the Upper Eocene/Lower Oligocene deposits of Oamaru, New Zealand. A total of 313 species from 52 genera of pennate diatoms are known from the Cretaceous and Paleogene sediments. Of those forms reported, araphid genera represented by the most species include Sceptroneis (21). Rhaphoneis (17), Synedra s. l. (11), while in the raphid group the genus Navicula s. l. is represented by the most taxa (69 species), followed by Amphora (26), Cocconeis (24), Diploneis (18), and Nitzschia (16). Of the raphid forms reported from Oamaru, only a few have been investigated with SEM (e.g.Novitski et al, in press). Of members of the sigmoid naviculoid, only two taxa have been reported: Donkinia antiqua Grove & Sturt (1887c) from the Oamaru (Eocene-Oligocene) and Gyrosigma ? sp. (Gleser et al. 1965) from the Late Eocene of Ukraina. In this report we describe two new sigmoid naviculoid diatoms and document their morphologies with light and scanning electron microscopy. MATERIALS AND METHODS Material observed herein is from a diatomite quarry in Kirghizskoe, Kazakhstan, from the Emba River basin. Samples were received by the senior author from the Geological Institute of Russian Academy of Scienses, Moscow, from Drs V.N.Beniamovski and E.P.Radionova. Samples examined have been accessioned in the Diatom Collection of the California Academy of Sciences as follows: Sample Number 19/422 22/425 23/434 29/440

CAS Diatom Accession Number 624811 624813 624814 624815

The diatomite belongs to the Ypresian stage and is dated as Lower Eocene, determined by stratigraphic position ( dates by V.N. Beniamovski) and confirmed by diatom analysis. Samples 19, 22 and 23 are from diatomite alternating with diatomitic clay and glauconitic sand and diatomite with sand lenses, belongs to the Pyxilla gracilis zone and sample 29 from silted clays with an admixture of sand, and belong to the Pyxilla oligocaenica var. tenuis zone. The sequence of Kirghizskoe was established by Gleser (1979) as a stratotype of Pyxilla gracilis and P. oligoceanica var. tenuis zones dated as Late Eocene. Later Gleser et al. (1997) dated these zones as Late Early Eocene - Middle Eocene. The age of these zones are under disscussion. Strelnikova (1992) believed the age of P. gracilis and P. oligocaenica var. tenuis zones to be Early Eocene. According to new dates (Radionova et al. 2003, Akhmetiev and Beniamovski 2004), the age of P. gracilis zone is Early Eocene and corresponds to the nannoplankton zone NP12 (CP10) while the P. oligocaenica var. tenuis zone is Early EoceneEarly Middle Eocene and corresponds NP13-NP14 (CP11-CP12) nannoplankton zones. Light microscope observations were made with a Leitz DMRB (CAS). For SEM observations, individual specimens were selected according to the procedures described by Nikolaev (1982). SEM observations were made on a Leo-1450VP (CAS). 26

Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

RESULTS AND DISCUSSION Pennate diatom assemblages. The samples investigated here have a rich, well-preserved flora of marine planktonic centric diatoms and several pennate forms. Well represented in the samples are Oestrupia powellii (Lewis) Heiden, Clavicula polymorpha Pantocsek, Navicula hennedy f. granulata Grun., Sceptroneis caducea Ehrenb. Amphora sp., Amphiprora sp., Nitzschia sp. and Rhaphoneis sp. The presence of these pennate diatoms and sand lenses indicate a near shore, shallow depositional environment. In addition to the forms listed above, we encountered two sigmoid, naviculoid diatoms that appear to be new to science, including a new genus. Descriptions of these two new forms are presented below. Class Bacillariophyceae Order Naviculales Family Naviculaceae Genus Gyrosigma Hassal Gyrosigma kazachstanicum, sp.nov. Strelnikova et Kociolek (Figs 1-25). Holotype: CAS slide number 581071 Type material: CAS Accession number 624815 Holotype is Figure 1. DESCRIPTION: Valves sigmoid, lanceolate, valve face slightly convex, valve margin with hyaline line. Length 144-270 µm, breadth 15-27 µm. Areolae in transverse rows 15-21/10 µm. Openings of the areolae are round both externally and internally. Raphe slightly sigmoid, excentric at the end but in the middle of the valve at the center. External raphe fissures are curved to opposite sides at the apices. External proximal raphe ends simple, straight, without deflections, located in a small central area. Internal proximal raphe ends are positioned on a hyaline ridge, which has a lunate form in the center. Internal distal raphe ends are helictoglossae. Girdle hyaline – structure not discerned. COMMENTS: The suite of features that assign this species to the genus Gyrosigma include sigmoid form of the valve, transverse striation pattern of the areolae, and striae pattern without a diagonal axis (Sterrenburg 1989, 1991, 1992, 1993, Stidolph 1988, 1992, 1994). It differs from other known species of the genus by the convex form of the valve and external openings of the areolae being round, instead of slit-like. The convex valve structure is reminiscient of Plagiotropis Pfitzer (Paddock 1988), but G. kazachstanicum differs from Plagiotropis species by the lack of a raised valve face with raphe and by its pronounced sigmoid outline of valve and raphe. This species was noted from all four samples examined in this study.

27

Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

2

1

3 Figs 1-3. Gyrosigma kazachstanicum Strelnikova & Kociolek, LM. Scale bars =10 µm. Fig. 1. Valve view, holotype. CAS 624815, slide 581071. Figs 2,3. Valve views showing structure of central area. CAS 624815, slide 581071 (Fig.2); CAS 624813, slide 581069 (Fig.3).

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

5

4

6

7 Figs 4-7. Gyrosigma kazachstanicum Strelnikova & Kociolek, LM, Scale bars = 10 µm. Figs 4, 5. View of frustule from girdle. CAS 624811, slide 581066. Figs 6,7. Valve views showing structure of central area. CAS 624815, slide 581071.

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

8

9

10

11

12

Figs 8-12. Gyrosigma kazachstanicum Strelnikova & Kociolek, SEM. Fig. 8. General aspect view. Figs 9, 10. External view of valve terminus. Fig. 11. External view of central area showing raphe. Fig. 12. Broken valve, showing locaular areolae and raphe structure. Figs 8-11. CAS 624814. Fig. 12. CAS 624815.

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

14

13

15

Figs 13-15. Gyrosigma kazachstanicum Strelnikova & Kociolek, SEM. View of valve from girdle view. Scale bars: 13 = 10 µm; 14, 15 = 3 µm. Fig. 13. General aspect view. Fig. 14. External valve margin with hyaline girdle element. Fig. 15. External view showing round areolae and curved distal raphe end. Internal view of valve end shows prominent helictoglossa. Figs 13-15. CAS 624813.

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

16

17

18

19

21 20

Figs 16-21. Gyrosigma kazachstanicum Strelnikova & Kociolek, SEM. Figs 16-18. Internal views showing rounded areolae. Fig. 19. Internal view showing elevated central nodule. Fig. 20. Broken valve showing locaular arrangement of areolae. Fig. 21. External view of central area showing narrow proximal raphe ends and central hyaline rib bordered by shallow grooves. Figs 16,19, 20. CAS 624814. Fig. 17. CAS 624815. Figs 18, 21. CAS 624811.

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

22

23

24

25

Figs 22-25. Gyrosigma kazachstanicum Strelnikova & Kociolek, SEM. Fig. 22. Whole frustule, general aspect. Fig. 23. External view of valve mantle and hyaline girdle element. Figs 24, 25. Terminus of frustule with rounded areolae and external distal raphe ends curving onto valve mantle. Figs 22, 24, 25. CAS 624811. Fig. 23. CAS 624814.

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

Class Bacillariophyceae Order Naviculales Family Naviculaceae Genus Hyalosigma, gen. nov. Strelnikova et Kociolek DESCRIPTION: Valves flat, in their apical axis sigmoid, linear-lanceolate in shape, with sigmoid raphe system and striae interrupted by large hyaline areas on the valve face. Marginal and mantle striae at acute angles. GENERITYPE: Hyalosigma temniskovae-topalovae, sp.nov. Strelnikova et Kociolek Hyalosigma temniskovae-topalovae sp.nov. Strelnikova et Kociolek Figures 26-51 Holotype: CAS slide number 581070 Type Material: CAS Accession number 624814 Holotype: Figs 26-29 DESCRIPTION: Valves flat, valve face curved smoothly into a very shallow mantle which is scarcely distinguishable. Valve linear-sigmoid with subacutae ends. Length 196-280 µm, breadth 11-23 µm. Proximal raphe ends located in the center of the valve within a small hyaline central area. Raphe ends only slightly deflected in the same direction, raphe branches highly sigmoid, curved along valve margin and towards the center of each apex. Internally, the distal raphe ends are helictoglossae. The raphe is contained in narrow axial area. Striae along the axial area are parallel to convergent, and number 18-23/10 µm. On the side of the valve opposite the raphe branch, beyond the striae comprising the axial area, there is a large hyaline area that extends to almost the apex of the valve and tapers to a point past the central nodule. This hyaline area is bordered along the margin by another group of striae that run the entire length of the valve, equal in density to the striae along the axial area. In the SEM, areolae of these striae are arranged in acute angles to the length of valve. The naviculoid organization of valve, sigmoid shape of the valve and sigmoid raphe suggest a close affinity of this new genus and species with Pleurosigma W.Smith or Gyrosigma Hassal. The interrupted striae on the valve face and acute angle of the marginal and mantle striae separate this form from either previously known genus. This taxon occurred in all four samples examined in this study. We dedicate this new species of diatom to Dr. Dobrina Temniskova-Topalova, on the occasion of her 70th Birthday. These observations extend the known geological range for Gyrosigma, which was previously known from the Late Eocene epoch (Gleser et al. 1965) and suggest the sigmoid diatoms were morphologically more diverse than previously understood. These new taxa underscore we still have a tremendous amount of work to do to understand the diversity and history of pennate diatoms, especially the earliest known raphid diatoms. 34

Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

26

27

29

28

Figs 26-29. Hyalosigma temniskovae-topalovae Strelnikova & Kociolek, LM, Scale bars = 10 µm. Fig. 26-29. Holotype. Fig.26. Valve view, plane of focus on the center of the valve. Figs 27, 28. Focus on the ends of the valve showing wide hyaline areas. Fig. 29. Valve center showing small external proximal raphe ends and axial area bordered by jagged-edged hyaline areas on either side. Figs 26-29. CAS 624814, slide 581070.

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

31

30

32

33

Figs 30-33. Hyalosigma temniskovae-topalovae Strelnikova & Kociolek, LM, Scale bars = 10 µm. Fig. 30. Valve view showing sigmoid nature of valve and raphe. Fig. 31. Valve terminus showing raphe in axial area and wide hyaline area. Fig. 32. Central area of valve. Fig. 33. Internal linear-shaped central nodule. Figs 30-33. CAS 624814, slide 581070.

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

35

34

36

37

38

39 Figs 34-39. Hyalosigma temniskovae-topalovae Strelnikova & Kociolek, SEM. Fig. 34. General aspect view. Figs 35, 37. Ends of valve with raphe along margin. Figs 36, 39. External view of valve center with small proximal raphe ends positioned close together. Fig. 38. Broken part of valve, showing external and internal surfaces of valves with raphe groove. Figs 34-39. CAS 624814.

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

40

41

42

44

43

45

46

Figs 40-46. Hyalosigma temniskovae-topalovae Strelnikova & Kociolek, SEM. Views showing whole frustule in different positions. Figs 40, 46. General aspect view. Figs 41, 43, 44, 45. Valve face, ends of valve with wide hyaline area. Acute angle of mantle striae is also visible. Fig. 42. View showing central area of valve and “shaped” nature of hyaline area. Figs 40-45. CAS 624813.

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

47

48

49

50

51

Figs 47-51. Hyalosigma temniskovae-topalovae Strelnikova & Kociolek, SEM. Views showing whole frustule in different positions. Fig. 47. General aspect view. Fig. 48. External distal raphe end curved onto valve mantle. Figs 50, 51. View of center of valve with raphe becoming more highly arched. Note highly acute angle of mantle striae. Fig. 49. Valve terminus showing internal view with helictoglossa evident. Figs 47,48, 50, 51. CAS624814. Fig. 49. CAS 624813.

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N. I. Strelnikova, J. P. Kociolek and E. Fourtanier

ACKNOWLEDGEMENTS We thank Dr. N.Ognjanova-Rumenova for the invitation to take part on the edition on the honor of Dr. D.Temniskova-Topalova. We also thank Drs V.N.Beniamovski and E.P.Radionova for the interesting material, masters student A.Schvezova for the cleaning material and J.Rubinstein and S.Serrata for the assistance with SEM photomicrographs. The Russian part of work was supported by Grant #03-04-48711 of Russian Fund of Fundamental Research. REFERENCES AKHMETIEV, M. A. and V. N. BENIAMOVSKI 2004. Paleocene and Eocene of Western Eurasia (Russian sector) – stratigraphy, paleogeography, climate. – N.Jb. Geol. Paläont. Abh., 234(1–3): 137-181. APHANASSYEVA, N. I. and Z. I. GLESER 1984. Paleocenovie diatomovie so schvom is Srednego Povoljya. in: Actualjnie voprosi sovremennoy paleontologii, Kiev, Naukova Dumka: 73–76. (in Russian) CLEVE, P.T. 1894. Synopsis of the Naviculoid Diatoms. – Kongl. Svenska Vetenskapsakademiens Handlingar, part I, 26(2): 194 pp. DESIKACHARY, T. V. and P. M. SREELATHA 1989. Oamaru Diatoms. – Bibliotheca Diatomologica, 19: 330 p., 145 pl. J.Cramer, Berlin-Stuttgart. EDWARDS, A. R. 1991. The Oamaru Diatomite. – New Zealand Geological Survey paleontological bulletin, 64: 260 p. FENNER, J. AND N. MIKKELSEN N. 1990. Eocene-Oligocene diatoms in the Western Indian ocean: taxonomy, stratigraphy, and paleoecology. in: Proceeding of the Ocean Drilling Program, Scientific Results, 115: 433–463. FENNER, J. 1991. Taxonomy, stratigraphy, and paleoceanographic implications of Paleocene diatoms. in: Proceeding of the Ocean Drilling Program, Scientific Results, 114: 123–154. FENNER, J. 1994. Diatoms of the Fur Formation, their taxonomy and biostratigraphic interpretation. Results from the Harre borehole, Denmark. – Aarhus Geosciece, 1: 99–164. GLESER, Z. I. 1979. Zonal dismemberment paleogene sediments by the diatoms. – Soviet Geology, 116:19–30. (in Russian) GLESER, Z. I., V. U. ZOSIMOVICH and M. N. KLUSHNIKOV 1965. Diatoms of paleogene deposits in the North Donez basin and their stratigraphic position. – Paleontologichesky sbornik, 2:73–87. (in Russian) GLESER, Z. I., L. A. PANOVA, I. P. TABACHNIKOVA and S. G. VJALOVA. 1997. Correlation marine Eocene of North-West Eurasia according to microphytofossiliens (West Siberia, Povolje). – Stratigraphy, Stratigraphic correlation, 5(4): 35–45. (in Russian)

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Two new sigmoid, naviculoid diatoms from the Eocene of Kazakhstan

GROVE, E. and G. STURT 1886. On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Part I. – Journ. Queckett Microscop. Club, ser.II, 16: 321–330. GROVE, E. and G. STURT 1887a. On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Part II. – Journ. Queckett Microscop. Club, ser.II, 17: 7–12. GROVE, E. and G. STURT. 1887b. On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Part III. – Journ. Queckett Microscop. Club, ser.II, 18: 63–78. GROVE, E. AND G. STURT 1887c. On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Appendix. – Journ. Queckett Microscop. Club, ser.II, 19: 131–148. HARWOOD, D. M. 1988. Upper Cretaceous and lower paleocene diatom and silicoflagellate biostratigraphy of Seymour Island, eastern Antarctic Peninsula. – Geological Society of America Memoir, 169: 55–129. NIKOLAEV, V. A. 1982. On the method of preparation of diatoms for studies by light and scanning electron microscopy. – Bot. Zurn. (Moscow&Leningrad), 67: 1677–1679. NOVITSKI, L., J. P. KOCIOLEK and E. FOURTANIER (in press) Preliminary light and scanning electron microscope observations of marine fossil Eunotia species with comments on the evolution of the genus Eunotia. – Diatom Research. PADDOCK, T. B. B. 1988. Plagiotropis Pfitzer and Tropidoneis Cleve, a summary account. – Bibliotheca Diatomologica, 16: 151 p. PANTOCSEK, J. 1903-1905. Beitrage zur Kenntinis der fossilen bacillarien Ungarns. – Berlin, Verlag von W. Junk (2 verbesserte Auflage). Teil 1 - 76 pp, 2 - 122 pp, 3 - 118 pp. RADIONOVA, E. P., V. N. BENIAMOVSKI, A. I. IAKOVLEVA, N. G. MIZYLÖV, V. ORESHKINA, E. A. SHERBININA and G. E. KOZLOVA 2003. Early Paleogene transgressions: stratigraphical and sedimentological evidence from the northern Peri-Tetis. – Geological Society of America. Special Paper, 369: 239–261. ROUND, F., R. CRAWFORD and D. G. MANN 1990. The Diatoms. Biology and morphology of the genera. – Cambridge Univ. Press, Cambridge: 747 pp. SCHRADER, H. J. 1969. Die pennaten Diatomeen aus dem obereozän von Oamaru Neuseeland. –Nova Hedwigia, Beih. 28:124 p. SCHRADER, H. J. and J. FENNER 1976. Norwegian Sea Cenozoic biostratigraphy and taxonomy. Part I. Norwegian Sea Cenozoic diatom biostratigraphy. – Initial reports of the Deep Sea Drilling Project, 38: 921-1099. STERRENBURG, F. A. S. 1989. Studies on tube-dwelling Gyrosigma . – Diatom Research, 4(1): 143-150. STERRENBURG, F. A. S. 1991. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae). Light microscopical critetia for taxonomy.– Diatom Research, 6(2): 367–389. STERRENBURG, F. A. S. 1992. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae). The type of the genus Gyrosigma and other attenuate sensu Perogallo. – Diatom Research, 7(1): 137–155. STERRENBURG, F. A. S. 1993. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae). Rules controlling raphe fissure morphogenesis in Gyrosigma. Diatom Research, 8(2): 457–463. 41

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STIDOLPH, S. R. 1988. Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassal and Pleurosigma W.Sm. – Nova Hedwigia, 47 (3–4): 377–388. STIDOLPH, S. R. 1992. Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassal and Pleurosigma W.Smith. III.Gyrosigma sterrenburgii sp.nov., and Pleurosigma amara sp.nov. – Diatom Research, 7(2): 345–366. STIDOLPH, S. R. 1994. Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassal and Pleurosigma W. Smith. IV. Gyrosigma fogedii sp. nov., and some diatoms similar to G. fasciiola (Ehrenb.) Griffith & Henfrey. – Diatom Research, 9(1): 213–224. STRELNIKOVA, N. I. 1992. Paleogenovye Diatomovye Vodorosli. – St.Petersburg University Press, St.Petersburg. 309 p. (in Russian) WEISSE, J. F. 1854: Mikroskopische Analyse eines organischen Polirschiefers aus dem Gouvernement Simbirsk – Melanges bioigiques. Bulletin de l”Academie Imperiale des Sciences de St.Petersburg, 2: 237–250. WITT O. N. 1886. Uber den Polierschifer von Archangelsk-Kuroedovo im Gouv. Simbirsk. – Verhandlungen der Russisch-kaiserlichen mineralogischen Geselschaft zu St.Petersburg. Serie II, 2: 137–177.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 43-54) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia, Moldova, and Ukraine Tatyana F. Kozyrenko Department of Botany, Biological Faculty, St. Petersburg State University, Universitetskaya Emb. 7/9, St. Petersburg 199034, Russia, e-mail: [email protected] ABSTRACT The frustular morphology of three Terpsinoë species from the Miocene deposits of Russia, Ukraine, and Moldova was studied with SEM. T. americana and T. solida both have poroid areolae, while T. intermedia has pseudolocular areolae. Heterovalvar frustules of T. intermedia (one valve with pseudolocular areolae and another with poroid areolae) have been observed in the past. The pseudolocular structure is might be absent in the earlier stages of cell cycle, in initial or post-initial cells. In this study such heterovalvy was not observed. The welldeveloped pseudolocular structure of the valve should be considered as a reason to maintain the species rank of T. intermedia as opposed to downgrading this taxon to a variety of T. musica, a species that does not have such a well-developed pseudolocular valve structure. Key words: Terpsinoë, pseudosepta, poroid areola, pseudolocula, Neogene, Russia INTRODUCTION The genus Terpsinoë and its type species T. misuca have been described by Ehrenberg (1843) from samples collected in Mexico at the seashore of Atotonilco El Grande and from marine macroalgae and sediments at the shore of Vera Cruz. Van Landingam (1978) listed seven species within this genus. Round et al. (1990) described this genus as an inhabitant of brackish and fresh waters. Luttenton et al. (1986) stated that Terpsinoë has a wide ecological range and lives in both marine and fresh waters.

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This paper describes the frustular morphology of three Terpsinoë species from the Miocene deposits from Russia, Ukraine, and Moldova. These species are T. americana (Bailey) Ralfs in Pritchard, T. intermedia Grunow, and T. solida Kozyrenko. MATERIALS AND METHODS The following Miocene deposits were studied (stratigraphic descriptions follow Iosifova 1977): 1. Russia, Oka-Don Plain a. Borehole 10 (Lamka Formation, Middle Miocene - Konkian stage) and borehole 92 (Gorelka Formation, Late Miocene - Sarmatian stage) near station Selezni, b. Boreholes 11 and 961 (Gorelka Formation, Late Miocene - Sarmatian stage) near town Komsomolets, c. Outcrop 15 near town Staroe Grayznoe (Gorelka Formation, Late Miocene -Sarmatian stage). 2. Russia, Volga-Khoper interfluvial a. Outcrop near town Gurovo (Ilovlinsko-Gurovskye layers, Middle MioceneKonkian stage). 3. Moldova a. Outcrop near town Naslavcha (Late Miocene - Early Sarmatian stage). 4. Ukraine, Lviv District a. Borehole near town Polyana (Late Miocene - Tortonian stage). Terminology follows Ross et al. (1979).

RESULTS Studied samples contained rich brackish-marine diatom flora where representatives of the genera Hyalodiscus Ehrenberg, Plagiogramma Grewille, Melosira Agardh, and Rhabdonema Kützing were especially abundant. These diatoms apparently inhabited a large shallow brackish lagoon. In Russian materials T. americana was most abundant among Terpsinoë species, in some samples T. solida was moderately abundant, and T. intermedia was rare. In materials from Moldova T. intermedia was found occasionally, and in Ukrainian materials T. solida was observed. Terpsinoë americana (Bailey) Ralfs in Pritchard (1861, p. 859). (Figs 1–27) The frustule is rectangular with rounded corners in girdle view, 20-24 µm high (Fig. 3). Valves are linear and linear-elliptical, triundulate, 35-90 µm long, 20-38 µm wide, with drawn-out ends and two pseudoseptae. Some valves have rounded-elliptical shape, 50-66 µm long, 40-50 µm wide. Pseudoseptae are straight, drop-shaped at free ends (Figs 1, 5, 11). Areolae are poroid, arranged 44

Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia

5

1 6

2 7 3

4

8 Figs 1-8. Terpsinoë americana, SEM. Fig. 1. External valve view. Scale bar = 10 µm. Fig. 2. external valve surface with granules. Scale bar = 1 µm. Fig. 3. Frustule in girdle view. Scale bar = 10 µm. Fig. 4. Detail of valve mantle, external view. Scale bar = 5 µm. Figs 5-8. Internal valve views. Fig. 5. Whole valve. Scale bar = 10 µm. Figs 6, 7. Central part of the valve. Fig. 6. Scale bar = 10 µm. Fig. 7. Scale bar = 5 µm. Fig. 8. View of a broken valve showing poroid areolae. Scale bar = 1.5 µm.

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Tatyana F. Kozyrenko

10

9 11

12

13

15

14

16

Figs 9-16. Terpsinoë americana, SEM. Fig. 9. Valve mantle and fragments of the girdle. Scale bar = 20 µm. Figs 9-16. Scale bars = 10 µm. Figs 9-12. External valve surface. Fig. 10. Valve mantle. Fig. 11. Whole frustule. Fig. 12. Apical view of the frustule. Figs 13, 14. Internal valve views. Fig. 13. Whole valve. Fig. 14. Valve with additional apically oriented pseudoseptae. Figs 15, 16. External views of the valve face.

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Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia

17

19

18

20

24

21

22

25

27

23 26

Figs 17-27. Terpsinoë americana. Scale bars = 10 µm. Figs 17-23. LM. Valves of different size and shape. Figs 24-27. SEM. Fig. 24. Internal valve view. Fig. 25. External view of whole frustule. Fig. 26. Detail of the girdle. Fig. 27. External view of the apical part of frustule.

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Tatyana F. Kozyrenko

in radial rows originating from the small round central area, which sometimes has irregular areolae (Figs 15, 16, 23). There are 11-15 rows of areolae in 10 µm, 13-16 areolae in 10 µm in a row. Pseudocelli are large, situated at the valve ends; they are usually bordered by narrow hyaline stripes. Pseudocelli have apically arranged rows of small pores, 18-20 rows in 10 µm, and 20-24 pores in 10 µm in a row (Figs 12, 15). The valve margin bears a row of irregularly spaced elongated granules, 13-20 in 10 µm (Figs 1, 2). Poroid areolae on the valve mantle are arranged in vertical rows, 14 rows in 10 µm (Fig. 4). The lower portion of the mantle is hyaline. No rimoportulae were found. The girdle has several copulae. T. americana was found in Russian materials, where it was usually quite abundant, but not in materials from Ukraine or Moldova. In studied samples this species was extremely variable in shape and size, but not in frustule structure. Besides frustules of typical size and shape, some rounded valves with one pseudoseptum circling middle part of the valve (Figs 19, 20) and valves with additional apically oriented pseudoseptae (Figs 14, 18) were found. Terpsinoë solida Kozyrenko in Kozyrenko et al. (1977, p. 130, pl. 30, figs 6 a, b). (Figs 28-43) The frustule is thick-walled, rectangular with rounded corners in girdle view, 24-36 µm high (Fig. 28). Valves are linear-elliptical, rarely elliptical, with rounded ends, 36-67 µm long, 18-20 µm wide. Valves have two robust straight or slightly bent pseudoseptae, thickened at their free ends (Fig. 28). Areolae are poroid with sunken volae which are more conspicuous from the internal surface of the valve (Figs 38, 40). Valve face has radial rows of areolae originating from a small round central area (Figs 29-31). At the valve ends rows of areolae become less distinct, there are some irregular pores amongst areolae (Figs 34, 43). In the middle part of the valve there are 6-8 rows of areolae in 10 µm, 6-9 areolae in 10 µm in a row. Pseudocelli are small, 7-9 µm in diameter, they are vaguely distinct at the valve ends and have pores in irregular apically oriented rows at the valve ends, 14-16 rows in 10 µm, 14-15 areolae in 10 µm in a row (Figs 34, 35). Valve mantle is 12-20 µm high with areolae in parallel vertical rows, 68 rows of areolae in 10 µm, 5-7 areolae in 10 µm in a row. Low portion of the valve mantle is hyaline (Figs 30, 41). Copulae have vertical rows of small areolae, 18-20 rows of areolae in 10 µm, 13-14 areolae in 10 µm in a row (Figs 42, 43). On the internal valve surface near pseudoseptum a rimoportula opening was found (Fig. 39). T. solida was sometimes quite abundant in Miocene deposits from the Oka-Don Plain, Russia and from Ukraine. Terpsinoë intermedia Grunow (1884, p. 59). (Figs 44-52). The frustule is thick-walled, rectangular with rounded corners in girdle view, 24-30 µm high (Fig. 44). Valves are linear-elliptical, triundulate, with drawn-out attenuate ends, 75-130 µm long, 20-25 µm wide (Fig. 45). Pseudoseptae are straight, with thickened ends which are curved towards valve center. Usually there are four well developed pseudoseptae per valve, 48

Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia

28

32

29

33

34

30

35

31

Figs 28-35. Terpsinoë solida. Figs 28, 29. LM. Scale bars = 10 µm. Fig. 28. Girdle view. Fig. 29. Valve view. Figs 30-35. SEM. External valve views. Figs. 30, 31. Whole valves. Scale bars = 10 µm. Figs 32, 33. Central part of the valve. Fig. 32. Scale bar = 10 µm. Fig. 33. Scale bar = 1 µm. Figs 34, 35. Apical part of the valve with pseudocellus. Small pores between regular-sized areolae. Fig. 34. Scale bar = 1 µm. Fig. 35. Scale bar = 10 µm.

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36

37

38

39 40

41 42

43 Figs 36-43. Terpsinoë solida. Figs 36-40. Internal valve surface. Fig. 36. Whole valve. Scale bar = 20 µm. Fig. 37. Central area. Scale bar = 2 µm. Figs 38-40. Scale bars = 1 µm. Fig. 38. Poroid areolae with sunken volae and two small pores. Fig. 39. Rimoportula. Fig. 40. Poroid areolae. Figs 41-43. External valve surface. Fig. 41. Valve mantle with vertical rows of areolae and hyaline edge. Scale bar = 10 µm. Figs. 42, 43. Valve mantle with remains of the valvocopula. Scale bars = 5 µm.

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Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia

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44 45

49

46

50

51 47 52

Figs 44-52. Terpsinoë intermedia. Figs 44, 45, 48. LM. Scale bar = 10 µm. Fig. 44. Whole frustule in the girdle view. Fig. 45. Whole frustule in valve view. Fig. 48. Detail of the valve in girdle view showing pseudlocular structure of the surface. Figs 46, 47, 49-52. SEM. Figs 46, 47. Scale bars = 10 µm. Fig. 46. External view of the apical part of the valve showing pseudocellus and pseudoloculi. Figs 49, 50. External valve views showing pseudoloculi. Scale bars = 10 µm. Figs 51, 52. Internal valve views. Fig. 51. Detail of internal valve surface. Scale bar = 1 µm. Fig. 52. Rimoportula. Scale bar = 10 µm.

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sometimes there four additional reduced pseudoseptae. Valve face and mantle bear a network of irregularly spaced pseudoloculi of variable size, 2.5-3, sometimes up to 5 in 10 µm (Figs 44-50). The bottoms of pseudoloculi are perforated by areolae (Fig. 49), areolae openings are clearly seen on the internal valve surface (Fig. 51); there are 10-15 areolae in 10 µm. Central area is absent. Pseudocelli situated at the valve ends are distinct, with large pores in parallel rows, 24-26 pores in 10 µm (Fig. 46). Valve mantle has a hyaline edge (Fig. 49). Copulae were not observed. An internal rimoportula opening was observed in the middle portion of the valve, slightly off the valve center (Fig. 52). T. intermedia was sometimes observed in studied materials from Russia and Moldova. DISCUSSION The pseudoseptae are the most stable character of the genus Terpsinoë, while the structure of the valve surface varies among species. The species studied here have either simple structure of poroid areolae (T. americana, T. solida) or have pseudoloculi in the basal layer (T. intermedia). The term “pseudoloculus” used here following Ross et al. (1979) corresponds to the term “poroid canals in depressions formed by anastomosing costae” of Nikolaev and Harwood (2002, p. 108). These two types of valve structure were illustrated by Round et al. (1990). Their figures a, i, and h (pp. 256, 257) show poroid areolae, while figures b, c, d, and e show pseudoloculi, but pseudoloculi were not mentioned in the genus description. Ehrlich (1995, p. 39, pl. 5, figs 6-9) describes the valve of T. musica as ”radially striate-punctate in its central part, apically striate-punctate towards the extremities, but her fig. 8 clearly illustrates pseudoloculi. Old authors, such as Ralfs (1861) regarded the structure of valve surface in Terpsinoë as an important diagnostic character, and Grunow (1884) used the presence of reticulate (“unregelmässigen Maschen”) structure to distinguish his new species T. intermedia. The taxonomic rank of Terpsinoë intermedia has been the subject of a discussion for a long time. Grunow (1884, p. 59) did not leave a formal text description of this species, but in the note to Biddulphia flos (Ehrenberg) Grunow discussed the genus Terpsinoë and noted that unlike T. musica and T. americana, T. intermedia has a reticulate valve surface structure. Pantocsek (1903), Peragallo and Peragallo (1987-1908), Boyer (1926), and Schmidt (1895) recognized T. intermedia as separate species, but later Hustedt (1930) downgraded it to a variety of T. musica. Hustedt argued that some cells have one valve with reticulate structure, but another valve does not have such a structure. This heterovalvy was documented by Schmidt (1895, Plate 199, Figs 1-8) who illustrated various stages of life cycle of T. intermedia. His fig. 4 shows a regular cell with reticulate structure of both valves and his fig. 1 shows an initial cell with one reticulate valve, and another with a simple structure of poroid areolae. Schmidt (1895) also wrote that T. musica has thin distinct rows of areolae, while T. intermedia in most cases has reticulate structure, but mentioned that Cleve did not distinguish these two species. In studied populations of T. intermedia from Miocene deposits from Russia and Moldova heterovalvar frustules were absent. It appears that such heterovalvar frustules 52

Species of the genus Terpsinoë Ehrenberg (Bacillariophyta) from the Miocene of Middle Russia

have been only observed in initial or post-initial cells, and therefore, the well-developed reticulate or pseudolocular structure is a character that allows distinguishing T. intermedia from T. musica. The pseudocellus clearly separated in T. intermedia is also a distinctive character of this species. ACKNOWLEDGEMENTS This work was supported by the grant 03-04-48711 of the Russian Foundation for Fundamental Research. Many thanks to N. Ognjanova for the invitation to participate in the volume honoring Prof. D. Temniskova-Topalova. I also thank A. Ulanova for several SEM photos; and N. I. Strelnikova and M. G. Potapova for their help in preparing this manuscript. REFERENCES BOYER, C. S. 1926. Synopsis of North American Diatomaceae. Part I. Proceedings of the Academy of Natural Sciences of Philadelphia, 78: 228 p. EHRENBERG, C. G. 1843. Verbreitung und Einfluß des mikroskopischen Lebens in Süd- und Nord-Amerika. Abhandl. der Königl. Academie der Wissenschaften zu Berlin: 291-446. EHRLICH, A. 1995. Atlas of the inland-water diatom flora of Israel. Flora Palestina. Jerusalem, The Israel Academy of Sciences and Humanities. GRUNOW, A. 1884. Die Diatomeen von Franz Josefs-Land. Denkschriften der matematisch-naturwissenschaftlichen Classe der kaiserlichen Akademie der Wissenschften, 48: 53-112. HUSTEDT, F. 1930. Die Kieselalgen Deutschlands, Österreichs und der Schweiz. Mit Berücksichtigung der übrigen Länder Europas sowie der angrenzenden Meeresgebiete. in: Rabenhorst’s Kryptogamen-Flora von Deutschland, Österreich und der Schweiz. Leipzig, Akadem. Verlag., 7(1): 1-920. IOSIFOVA, J. I. 1977. Geology of Miocene deposits of the Oka-Don Plain. Pages 6-53 in: Miocene of the Oka-Don Plain. Moscow, Nedra (in Russian). KOZYRENKO, T. F., A.P. JOUSÉ and KOSLOVA O. G. 1977. Diatom flora of Miocene deposits of the Oka-Don Plain. Pages 113-131 in: Miocene of the Oka-Don Plain. Moscow, Nedra. LUTTENTON, M. R., L. PFIESTER and P. TIMPANO 1986. Morphology and growth habit of Terpsino¸ musica Ehr. (Bacillariophyceae). – Castanea, 51: 175-182. NIKOLAEV, V. A. and D.M. HARWOOD 2002. Morphology, taxonomy and system classification of centric diatoms. St.Petersburg, Nauka (in Russian). PANTOCSEK, J. 1903. Beitrage zur Kentnis der fossilen Bacillarien Ungarns. I Teil. Marine Bacillarien. 2. verbesserte Auflage. Verlag von W.Junk, Berlin. PERAGALLO, M. H. and M. PERAGALLO 1897-1908. Diatomées marines de France et des districts maritimes voisins. Tempère, Grez-sur-Loing. 53

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RALFS, J. 1861. Sub-group Diatomeae or Diatomaceae. Pages 756-940 in Pritchard A. History of Infusoria including the Desmidiaceae and Diatomaceae, British and Foreign. Wittaker and Co., London. ROSS, R., E.J. COX , N.I. KARAYEVA , D.G. MANN, T.B.B. PADDOCK, R. SIMONSEN and P.A. SIMS 1979. An amended terminology for the siliceous components of the diatom cell. Nova Hedwigia, Beih. 64: 513-533. ROUND, F. E., R.M. CRAWFORD and D.G. MANN 1990. The diatoms. Biology and morphology of the genera. Cambridge University Press. Cambridge. SCHMIDT, A. 1895. Atlas der Diatomaceenkunde. R. Reisland, Leipzig. VAN LANDINGHAM, S. L. 1978. Catalogue of the fossil and recent genera and species of diatoms and their synonyms. Part VII. Rhoicosphenia through Zygoceros. J. Cramer, Vaduz.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 55-72) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Comparison of seven species of Navicula sensu stricto Six species described as new to science from Miocene lacustrine deposits in Bulgaria and Romania Horst Lange-Bertalot1 and Ditmar Metzeltin2 Botanical Institute, J.-W. Goethe-University, Senckenberganlage 31–33, 60054 Frankfurt am Main, Germany 2 Am Stegskreuz 3b, D-65719 Hofheim, Germany, E-mail: [email protected] 1

ABSTRACT Navicula bulgariarum, N. nadjae, N. peripontica, N. serdicensis, N. temniskovae are described as fossil freshwater species, new to science, from material of a core 1.50-50.00 m depth, located at 18 km North of Sofia, Bulgaria. N. superhasta is described from comparable Neogene material found near Köpecz in Transylvania, Romania. Both materials contain likewise Navicula hasta Pantocsek. The common but not quite clear species concept of this prominent taxon is critically discussed. Name of the new taxa is known to occur extant. Key words: Bacillariophyta, Navicula, new species, Sofia Neogene Basin, Bulgaria INTRODUCTION Late Alpine tectonic events in the central parts of the Balkan Peninsula differ from coeval tectonic events in the other parts of the Alpine orogens in Eurasia (Zagorchev 1996). The geodynamics of the realm had been changed by an intense compressional phase in earliest Neogene times. The long lasting peneplanation led to the formation of a large swells, separating graben complexes and rift valleys, surrounded and insulated by marine basins (Pannonian, Peri-Carpathian, Euxinian, Aegean, Adriatic). Neogene Sofia Basin is situated in South Bulgaria and its deposits fill the Sofia graben. Four lithostratigraphic units are described in the neogene from the basin: 1. Varriagated 55

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terrigenous formations (probably Meotian age); 2. Gniljane Formation (Pontian inf.); 3. Novi-Iskar Formation (Pontian, partly Dacian inf.) and 4. Lozenec Formation (DacianRomanian age, Kamenov and Kojumdgieva 1983, Angelova and Yaneva 1998). With the exception for Navicula superhasta, from Transylvania, all other new taxa and also the taxon here identified as Navicula hasta Pantocsek 1897 originate from the locality Goljanovci near Sofia. Diatomologically both materials have been investigated by several authors in the past. Generally they contain taxa that have survived from the Pliocene, Pleistocene and Holocene periods until recently (Temniskova-Topalova and Ognjanova-Rumenova 1997), whereas various other taxa are known exclusively as fossil records from the Neogene period, and from several locations in SE– or E– Europe or eastern central Europe. For a major part they can be found documented and depicted in form of line drawings or photographs, particularly by Pantocsek (1892-1905) and more recently e.g. by Ognjanova-Rumenova (1991) or Temniskova-Topalova and Ognjanova-Rumenova (1997). However, a critical study and comparison show that more than a few populations can be proved to be not identifiable as established taxa. Concerning Navicula s. str. Several obviously independent populations have been overlooked, neglected or lumped together under few prominent names like Navicula hasta or Navicula lacusbaicali. Symptomatically older species concepts turn out to appear much too broad. MATERIAL AND METHODS The sediments studied were collected from borehole C-1, village of Goljanovci, 18 km North of Sofia, 23o13’48’’ East and 42o51’00’’ North. The borehole penetrated through Novi Iskar Formation and is represented by irregular alternation of diatom clays (0-50.00 m), lignite and lignite clays (50.0-53.0 m), gray clays (53.0-68.0 m), lignite clays (68.0-76.70 m) and gray limestones (76.7-89.30 m). Diatom bearing sediments from borehole C-1 (1.50-48.80 m) were investigated. The other investigated material (containing Navicula superhasta) originates from Köpecz Neogene deposits, southern Carpathians, Transylvania, Romania. Slides containing that material are housed in the Hustedt Collection, Bremerhaven and were probably mounted by Pantocsek from the material collected during the last decades of the 19th century. The samples for the current study were prepared following standard laboratory procedures (Ognjanova-Rumenova 1991). RESULTS AND DISCUSSION Navicula hasta Pantocsek 1892, Icon. Beitrg. III, pl. 5, fig. 74 (pl. 1: Figs 1-3, pl. 2: Figs 1-4) Description: Pantocsek 1905, p. 69 To exclude from the diagnosis is: “Navicula hasta” Pantocsek 1892, Icon Beitrg. III, pl. 14, fig. 213. Pantocsek’s diagnosis, translated from Latin, reads:

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2

3 10 µm

1 Plate 1, Figs 1-3 Navicula hasta Pantocsek 1892. Scale bar 10 µm.

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4 3 2 1 10 µm Plate 2, Figs 1-4 Navicula hasta Pantocsek 1892. Scale bar 10 µm.

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Comparison of seven species of Navicula sensu stricto

Valves elongated lanceolate, 63-76 µm long, 14-18 µm broad, with produced obtuse poles. Raphe straight, encircled by a rather dilated axial area. Striae coarse, radiate, lineolated, 8-10 in 10 µm, in the centre longer and shorter. In Tertiary freshwater deposits of Bibarczfalva, Bodos and Köpecz in Transylvania. Icon: Beitrg. III, tab. 5, fig. 74, tab. 14, fig. 213.

From the two icons only fig. 5: 75 matches the diagnosis, whereas the specimen in fig. 14: 213 is approximately 108 µm long and 25 µm broad. This exceeds the maximum data considerably. The two depicted specimens originate from Köpecz. Recent observations on the type material displayed several “size classes” of Navicula hasta – like specimens (cf. Lange-Bertalot 2001, plates 58-60). Whilst the specimens in plates 58 and 59 – although not all matching the diagnosis – may be identified as N. hasta, the population represented in plate 60 can hardly belong to this taxon in a strict sense (see under N. superhasta). In the deposits of the Sofia region N. superhasta was not observed. However – like in Köpecz – occurrence of Navicula hasta sensu lato is represented by a smaller and a larger sized deme. The first one with specimens about 80 µm long and 14-15 µm broad, striae 77.5/10 µm (plate 2: Figs 2-4); the second one (plate 1: Figs1-3, plate 2: Fig.1) 95-120 µm long, 17-20 µm broad, 6-6.5 striae/10 µm proximally and 8-9/10 µm distally. Other features e.g. position of the striae, lineola density, axial and central area, raphe with position of the central pores are coincident. Therefore a broader concept of N. hasta than given in Pantocsek’s diagnosis seems to be more appropriate. However, a “catch–all” concept encom-passing all N. hasta–like populations may hardly reflect the taxonomic reality. Navicula superhasta nov. spec. (pl. 3: Figs 1-3) Navicula hasta sensu Pantocsek 1892, pl. 14, fig. 213 (non pl. 5, fig. 74 nec description 1905, p. 69) Navicula hasta sensu Hustedt in A. Schmidt Atlas partim (figs 395: 10-12) Navicula (?nov.) spec. Lange-Bertalot 2001, pl. 60: 1-4 Diagnosis differens versus Navicula hasta Pantocsek et Navicula temniskovae nov. spec. Valvae rhombico-lanceolatae ad apices plus minusve leniter protractae. Longitudo 105-160 µm, latitude 21-25 µm (id est conspicue plus quam N. hasta quoad diagnosem). Raphe lateralis poris centralibus conspicue sitis (quam N. temniskovae). Area axialis fere lata, sterno lato raphis distincte conturato (ita differ tab alteris speciebus). Area centralis aliquid indistincta vel variabiliter formata quia striae hic irregulariter abbreviatae. Striae transapicales radiantes fortiter omnino usque ad apices, 6 proximaliter, 8 distaliter (nec 8-10 in mediis partibus quam in N. hasta). Lineolae 23-25 (nec 16-18) in 10 µm (ita differt N. temniskovae).

Typus: Praep. 400/116 in Coll. Hustedt, Bremerhaven Locus typicus: Köpecz Neogene Deposits Etymology: “super–hasta” means dimensions larger and structures coarser than in N. hasta. 59

10 µm

10 µm

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Plate 3, Figs 1-3 Navicula superhasta nov. spec. Scale bar 10 µm.

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Differential diagnosis compared to Navicula hasta Pantocsek and Navicula temniskovae nov. spec. Valves rhombic-lanceolate tapering to the more or less distinctly protracted ends. Length 105-160 µm, breadth 21-25 µm (this is conspicuously more than in N. hasta where less than 100 and 14-20 respectively are indicated by Pantocsek). Raphe lateral, lying in a comparatively broad, strongly contoured sternum (different from both taxa in comparison). Central pores comparatively close, deflected to the secondary side. Axial area rather broad, central area somewhat indistinct or with variable shape, confined by some irregularly shortened striae. Other striae strongly radiate throughout (not subparallel at the ends) about 6 in 10 µm and 8 only at the ends (not 8-10 in all proximal parts). Lineolae 23-25 in 10 µm (not 16-18 as in N. temniskovae). Remarks: The complex of characters is much closer related to N. hasta than to N. temniskovae due to the arrangement of the striae, lineolae and the narrower standing central pores of the raphe. Nevertheless, the numerical dimensions, given in the protologue of N. hasta, differ so significantly that assumption of heterospecificity appears more likely than conspecificity in this case. Infraspecific offspring is not to exclude, but remains hypothetical just like supposing monophyletic sister species. Even the assumed conspecificity of various morphodemes in N. hasta with closer related numerical dimensions of cell sizes and striae densities is not out of question yet (see morphodeme 1 and 2 from Sofia and morphodeme with broader, more rhombic valve outlines from Dubravica shown in Lange-Bertalot 2001, figs 59: 1-7). Navicula serdicensis nov. spec. (pl. 4: Figs 1-6) Diagnosis differens specimem fossilem Navicula radians Héribaud 1903. Valvae simpliciter lanceolatae apicibus non protractis aliquid minus obtuse rotundatis. Longitudo 145-180 µm (nec 120-150), latitudo 23-30 µm (nec 20). Fissurae raphis distincte laterales sitae inter se poris centralibus comparate parvis ad latus secundum deflexis nec conspicue distanter nec dense sitis inter se. Area axialis fere lata irregulariter dilatata ad mediam versus (parum sed non conspicue latius formata unilateraliter). Area centralis variabilis ad instar (tamen numquam circularis) quia striae mediae irregulariter alternantes longae curtaeque (ita ut in N. radians). Striae transapicales radiantes omnino usque ad apices, constanter 6.5-7 in 10 µm (ut N. radians). Lineolae 23-26 in 10 µm (incognitae in N. radians).

Typus: Praep. Core 1/20, 30.0 m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia. Locus typicus: 18 km North of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; Borhole is 23o13’48’’ East and 42o51’00’’ North. Etymology: Serdica is the ancient name of the recent city of Sofia. Differential diagnosis compared to the fossil taxon Navicula radians Héribaud 1903. Valves simply lanceolate tapering to moderately acute (rather than somewhat more obtusely) rounded ends. Length 145-180 µm (not 120-150). Breadth 23-30 µm (not 20 as given in Héribaud’s protologue). Raphe fissures distinctly lateral with comparatively small 61

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Plate 4, Figs 1-6 Navicula serdicensis nov. spec. Scale bar 10 µm.

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central pores deflected to the secondary side, neither remarkably far nor close standing. Axial area moderately broad, gradually expanded towards the centre (not con-speciously broader unilaterally). Central area variable in shape (but never markedly circular) by irregularly alternately longer and shorter striae. Striae radiate throughout, very consistently 6.5-7 in 10 µm (as in N. radians). Lineolae 23-26 in 10 µm (unknown density in N. radians). Remarks: N. radians Héribaud 1903 non N. radians (Østrup 1899) Cleve-Euler 1922 is an almost forgotten taxon from the Neogene deposits of Ceyssac, Auvergne, France. Later on it was synonymized with Navicula radiosa var. acuta (W. Smith) Grunow 1860 by other authors. However, that fossil taxon appears by no means closely related to N. radiosa which is characterized by clearly convergent striae towards the ends instead of distinctly radiate striae throughout. Héribaud compares his taxon with N. vulpina Kützing which, however, resembles very little the two fossil taxa in question here. The other Navicula species from Neogene deposits are distinguished by other distinct complexes of characters. Comparable is also Navicula ajajensis Skabitschevsky 1936, recent from Lake Bajkal with a length of 95108 µm, breadth 14.4-16.2 µm, and 7.8-8.8 striae in 10 µm, only one of the central striae is shortened on either side. Navicula temniskovae nov. spec. (pl. 5: Figs 1-3) Diagnosis differens versus Navicula hasta Pantocsek. Valvae plus minusve rhombico-lanceolatae cuneatim attenuatae ad apices nec acute nec obtuse rotundatis omnino non protractis. Longitudo 70-140 µm, latitudo 22-31 µm (non 60-90 nec 1519 µm). Raphe lateralis poris centralibus distincte dilatatis, conspicue distanter sitis inter se et deflexis ad latus secundum. Area axialis modice lata ad mediam dilatata. Area centralis fere lata, variabilis ad instar plerumque plus minusve rhombice expansa. Striae transapicales radiantes in mediis partibus hic 5-6 in 10 µm tam usque ad apices paulatim subparallelae circiter 7 in 10 µm (nullo loco 8-10). Circum aream centralem complures striae abbreviatae irregulariter intermixtae (non una singula stria vel nulla). Item striae non conspicue distanter inter se. Lineolae 16-18 (nec circiter 26) in 10 µm. Alterae taxa similissimae adhuc non descriptae sed vide sub Navicula superhasta. Navicula peregrina sensu auct. nonnull satis differt.

Typus: Praep. Core 1/12, 18.0 m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia. Locus typicus: 18 km North of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; 23o13’48’’ East and 42o51’00’’ North. This species is dedicated to our colleague Prof. Dr. Dobrina Temniskova on the occasion of her 70 th birthday. Differential diagnosis compared to Navicula hasta Pantocsek. Valves more or less rhombic-lanceolate tapering to the non-protracted cuneately rounded ends. Length 70-140 µm, breadth 22-31 µm (not 60-90 and 15-19 µm respectively). 63

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3 2 10 µm

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Plate 5, Figs 1-3 Navicula temniskovae nov. spec. Scale bar 10 µm.

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Raphe fissures narrow-lateral, central pores expanded conspicuously wide-standing and deflected to the secondary side. Axial area moderately broad expanding to the centre. Central area variable in outlines, mostly more or less rhombically expanded. Striae radiate proximally, 5-6/10 µm becoming less radiate distally and finally subparallel, c. 7 in 10 µm (nowhere 8-10). Around the central area several striae shortened irregularly (not only a single pair and not distinctly wider spaced here). Lineolae 16-18 (not c. 26) in 10 µm. Other large-sized Navicula taxa will be hardly confused with the new taxon because the complexes of characters like e.g. Navicula peregrina (see also under N. superhasta) differ significantly. Navicula nadjae nov. spec. (pl. 6: Figs 1-6, ?7) Diagnosis differens versus Navicula hasta Pantocsek. Valvae anguste-lanceolatae ad apices fere acute rotundatos paulatim attenuatae apices non vel vix protracti. Longitudo (?70)115-165 µm, latitudo 12-18 µm (nec rhombico-lanceolatae). Raphe lateralis poris centralibus potius aliquid distanter quam dense sitis inter se deflexis ad latus secundum. Area axialis anguste-lanceolata. Area centralis aliquid indistincta et variabiliter formata. Striae transapicales fortiter radiantes usque sub apices sed una singula stria utrimque parallelae vel parum convergentes, 8-8.5 in 10 µm in mediis partibus, 9-10 sub polos. Lineolae circiter 24-25 in 10 µm. Similissima Navicula rakowskae Lange-Bertalot differt lineolis densius sitis inter se enim 30-31 in 10 µm etiam mediis striis distantius sitis inter se.

Typus: Praep. Core 1/19, 28.5m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia. Locus typicus: 18 km North of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; Borehole is 23o13’48’’ East and 42o51’00’’ North. Etymology: The new species is dedicated to Dr. Nadja Ognjanova-Rumenova, Sofia. Differential diagnosis compared to Navicula hasta Pantocsek. Valves narrowly lanceolate tapering to fairly acutely rounded apices that are not or barely protracted. Length (?70)115-165 µm, breadth 12-18 µm (not rhombic-lanceolate). Raphe fissures lateral, central pores moderately distant rather than close-standing, deflected to the secondary side. Axial area narrow-lanceolate. Central area somewhat indistinct or variable in shape. Striae strongly radiate up to the ends, only the apical pair of striae parallel to slightly convergent, 8-8.5/10 µm, except for the most distal ones becoming 9-10/10 µm. Lineolae 24-25/10 µm. Similar large-celled taxa e.g. the fossil Navicula radiosa var. dubravicensis Grunow or Navicula costei Héribaud differ by the numerous distinctly convergent stria–pairs distally and the broader valves. Most similar to the new taxon is the recent Navicula rakowskae Lange-Bertalot, it is distinguished by significantly more densely spaced lineolae, 30-31/10 µm. Moreover, in N. rakowskae the central striae are much more spaced than the others. Navicula lucida Pantocsek (syn. N. lucifica Pantocsek) 1882 fig. 18: 264, fossil from Bodos and Köpecz (non Navicula lucida O’Meara 1876) is longer, broader and with denser striae (15-16 striae/10 µm). 65

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Plate 6, Figs 1-6, ? 7 Navicula nadjae nov. spec. Scale bar 10 µm.

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Navicula peripontica nov. spec. (pl. 7: Figs 1-3) Diagnosis difference versus Navicula lacusbaicali Skvortzow & Meyer 1928 et Navicula perturbata Jurilj 1954 Species subsectionis Navisantiqua Lange-Bertalot 2001. Valvae simpliciter lanceolatae apicibus non protractis sed cuneatim attenuatis denique rotundatis. Longitudo 80-90 µm, latitudo 18.5-20 µm (nec 24-27). Fissurae raphis laterales poris centralibus (parvius dilatatis quam in N. perturbata) ad latus secundum deflexis. Area axialis fere angusta, dilatata ad mediam versus. Area centralis fere late rectangulata striis 5-6 abbreviatis formata. Striae transapicales, 7.5 in 10 µm, radiantes sed 5-7 striae sub apices utrimque distinctissime convergentes parum densius sitae inter se enim 8-8.5 in 10 µm (numquam radiantes omnino usque ad apices ut in N. lacusbaicali et N. perturbata). Lineolae circiter 26 in 10 µm (non circiter 40 nec minus quam 26).

Typus: Praep. Core 1/20, 30.0 m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia. Locus typicus: 18 km North of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; Borhole is 23o13’48’’ East and 42o51’00’’ North. Etymology: “peri–pontica” means the area around the Black Sea in a wide sense. Differential diagnosis compared to Navicula lacusbaicali Skvortzow & Meyer 1928 and to Navicula perturbata Jurilj 1954. Valves lanceolate with simply wedge-shaped ends (neither protracted nor markedly obtusely or acutely rounded). Length 80-90 µm, breadth 18.5-20 µm. Raphe fissures lateral, central pores (smaller than in N. perturbata) deflected to the secondary side. Axial area rather narrow, expanded only in their proximal parts. Central area broadly rectangular or tie-bowshaped, confined by 5-6 shortened striae on either side. Other striae, 7.5 in 10 µm, proximally radiate, but the distal 5-7 pairs of striae becoming progressively more strongly convergent (not radiate throughout). The subpolar striae are only slightly more densely spaced, c. 8 in 10 µm (not up to 10 as in N. perturbata). Lineolae around. 26 in 10 µm (not about 40 as in N. perturbata or less than 25 as in all varieties of N. lacusbaicali). Ecology: See under N. bulgariarum. Remarks: This species is one among fairly few known taxa belonging to the subsection Navisantiqua of the section Navicula in Navicula s. str. (see Lange-Bertalot 2001). Navicula haueri Grunow from Dubravica is another fossil species. It possesses also convergent striae distally - in contrast to the recent taxa - and very bluntly rounded ends. Probably more than a single taxon is included in the range of forms identified uniformly as N. haueri by different authors. Thus, two specimens of N. haueri sensu P.T. Cleve in A. Schmidt Atlas, figs 212: 32a, b from Jastraba deposits possess narrower, slightly protracted ends (i.e. more similar to N. peripontica) and a narrower, transversely rectangular central area with 2-3 shortened striae instead of the almost circular one of N. haueri from Dubravica.

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Plate 7, Figs 1-3 Navicula peripontica nov. spec. Scale bar 10 µm.

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Navicula bulgariarum nov. spec. (pl. 8: Figs 1-3) Diagnosis differens versus Navicula peripontica nov. spec. (vide supra). Valvae potius paene rhombico-lanceolatae (quam simpliciter lanceolatae) quia constanter fortius attenuatae ad apices versus. Longitudo 60-70 µm quoad pauca specimina adhuc cognita. Latitudo 15-20 µm. Altera signa generaliter aequalia speciebus ambabus tamen striae transapicales densius sitae inter se enim proximaliter 9 (non 7-8) in 10 µm, sub apices 10-11 (non 8-9) in 10 µm.

Typus: Praep. Core 1/20, 30.0 m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia. Locus typicus: 18 km North of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; Borhole is 23o13’48’’ East and 42o51’00’’ North. Etymology: The species is dedicated to our colleagues (so far ladies are concerned) working at the fossil diatom flora of Bulgaria. Differential diagnosis compared to Navicula peripontica (see above). Valves consistently rhombic-lanceolate (not simply lanceolate) since more strongly attenuated from the middle towards the slightly protracted ends. Poles almost acutely (rather than obtusely) rounded. Length 60-70 µm, obviously representing only a small part of variability in the cell cycle; width 15-20 µm. The peculiar pattern of the other characters generally conforming in both taxa. However, transapical striae spaced more densely, 9 (not 7-8) in 10 µm proximally, becoming 10-11 (not 8-9) near the ends. Ecology: The results of the palaeoecological analyses of the sediment deposition of the Novi Iskar Formation, from which Navicula bulgariarum and N. peripontica were determined, demonstrated that during the Late Middle Miocene period there was an increase of the percentage of the mesohalobous diatoms. In the beginning of the sediment formation the salt content ranged between 0.2-0.3‰, and later went up to 5‰. Therefore the brackish influence during the sediment genesis was established. However most of the species in taxonomical composition are non-marine – including numerous species of Aulacoseira, Diploneis, Surirella, and Campylodiscus. (Ognjanova-Rumenova 1997) ACKNOWLEDGEMENTS We gratefully acknowledge the help rendered to us by Dr. Nadja Ognjanova-Rumenova yielding the fossil material that contained five of the new taxa. Moreover she made translations of data from her Doctoral Thesis (written in Bulgarian language).

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10 µm Plate 8, Figs 1-3 Navicula bulgariarum nov. spec. Scale bar 10 µm.

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REFERENCES ANGELOVA, D. and M. YANEVA 1998. New lithostratigraphical data about Neogene of Sofia Basin. – Review of the Bulgarian Geological Society, 59(2): 37-40 (in Bulgarian). HÉRIBAUD, J. 1893-1908. Les diatomées d’Auvergne, Libr. des Sci. Nat. Paris. p. 1-233, 6 pl. (1893); premier mémoire, p. 1-79, 2 pl. (1902); deuxième memoire, p. 1-166, 4 pl. (1903); troisième memoire, p. 1-70, 2 pl. (1908). JURILJ, A. 1954. Flora I Vegetacija Dijatomeja Ohridskog Jezera. – Prirodosl. Istraz., 26: 99-110. KAMENOV, B. and E. KOJUMDGIEVA 1983. Stratigraphy of the Neogene in Sofia Basin. Palaeontology, stratigraphy and lithology. – Bulgarian Academy of Sciences, 18: 6985 (in Bulgarian). LANGE-BERTALOT, H. 2001. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats. (ed. Lange-Bertalot, H.) Vol. 2. Navicula sensu stricto - 10 Genera Separated from Navicula sensu lato - Frustulia. 526 p., 140 pl. – A.R.G. Gantner Verlag K.G. FL 9491 Ruggell. Distributed by Koeltz Scientific Books, Koenigstein. OGNJANOVA-RUMENOVA, N. 1991. Neogene diatoms from sediments of Sofia Valley and their stratigraphic significance. – Ph.D. Thesis, Geological Institute, Bulgarian Academy of Sciences, 330 pp. (in Bulgarian). OGNJANOVA-RUMENOVA, N. 1997. Lake trophic evolution determined by fossil diatoms, Chrysophycean stomatocysts and mollusca. - Annales Geologiques des Pays Helleniques, Athenes, premiere serie, 37, 1996-1997: 97-117. O’MEARA, E. 1876. Report on the Irish diatomaceae.- Proc. R. Irish Acad., second. Ser., 2: 235-425, 9 pl. ØSTRUP, E. 1899. Diatoméerne. in: Hartz, N. and E. Østrup, editors. Danske Diatoméjord-Aflejringer og deres Diatoméer. Danmarks geol. Undersogelse II. 9: 35-81, 2 pl. – Kjoebnhavn. PANTOCSEK, J. 1892. Beiträge zur Kenntnis der fossilen Bacillarien Ungarns. Teil 3. Süßwasser Bacillarien. Anhang: Analysen 15 neuer Depots von Bulgarien, Japan, Mähren, Rußlands und Ungarn, 42 pl. Nagy-Tapolcsany. PANTOCSEK, J. 1905. Beschreibung neuer Bacillarien, welche in der Pars III der “Beiträge zur Kenntnis der fossilen Bacillarien Ungarns” abgebildet wurden. 118 pp. – Pozsony. SCHMIDT, A. et al. 1874-1959. Atlas der Diatomaceen-Kunde. Heft 1-120, Tafeln 1-480 (Tafeln 1-216 A. Schmidt; 213-216 M. Schmidt; 217-240 F. Fricke; 241-244 H. Heiden; 245, 246 O. Müller; 247-256 F. Fricke; 257-264 H. Heiden; 265-268 F. Fricke; 269-472 F. Hustedt). – Aschersleben & Leipzig. SKABITSCHEVSKY, A.P. 1936. Neue und interessante Diatomeen aus dem nördlichen Baikalsee. – Bot. Zhurnal, 21: 705-719, 3 pl. (Russian).

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SKVORTZOW, B.W. and C.I. MEYER 1928. A contribution to the diatoms of Baikal Lake. – Proc. Sungare River Biol. Stat., 1/5: 1-55, 3 pl. TEMNISKOVA-TOPALOVA, D. and N. OGNJANOVA-RUMENOVA 1997. Description, comparison and biastratigraphy of the nonmarine Neogene diatom floras from South Bulgaria. – Geol. Balcan., 27 (1-2): 57-81. ZAGORCHEV, I. 1996. Late Alpine (Palaeogene-Early Miocene) tectonics and neotectonics in the central parts of the Balkan Peninsula. – Z. geol. Wiss., 24, 1/2: 91-112.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 73-89) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta) during the last eight million years in Lake Baikal Galina Khursevich Institute of Geochemistry and Geophysics, National Academy of Sciences of Belarus, Kuprevich street 7, Minsk 220141, Republic of Belarus, email: [email protected] ABSTRACT In the Upper Cenozoic (Upper Miocene – Holocene) sediments of Lake Baikal, recovered by the long continuous drill cores BDP-98 (600 m long), BDP-96-1 (200 m long) and BDP96-2 (100 m long) on the top of the underwater Academic Ridge, revealed a rich and diverse composition of planktonic centric diatoms from the family Stephanodiscaceae. The latter is represented by 60 species and 12 intraspecific taxa belonging to 9 genera. Among them, 6 genera (3 endemic for Lake Baikal and the Transbaikal area), 42 species (41 baikalian endemics) and 10 intraspecific taxa (8 baikalian endemics) are extinct. The extinct genera from the family Stephanodiscaceae (Concentrodiscus, Mesodictyon, Mesodictyopsis, Tertiariopsis, Stephanopsis and Tertiarius) replace each other from bottom to top along the studied sections of the BDP-98 and BDP-96-1 cores that allows to trace the evolution of some morphological characters in time. The pattern of morphological evolution in these genera in the ancient Baikal ecosystem can be described as follows: a) change of the cribrum position in areola; b) change of the stria morphology; c) change of the structure of marginal fultoportulae on the valve mantle; and d) change of the number of rimoportulae. Key words: diatoms, Stephanodiscaceae, extinct genera, evolution, Lake Baikal. INTRODUCTION Lake Baikal (situated in the southeastern part of Siberia, Russian Federation), is the world’s deepest (1637 m), largest (about 600 km long) and oldest (25–30 million years) extant 73

Galina Khursevich

freshwater lake. It is a natural laboratory for studing a wide variety of modern and ancient global change processes. Lake Baikal is very sensitive to orbitally forced climatic changes because it is located at high latitude (52º- 56º N) in the middle of a continent and surrounded by mountain ridges (Baikal Drilling Project, BDP-Members 1997). This lake occupies the deepest portion of the Baikal Rift Zone (BRZ), one of the most active continental rift zones of the world. This makes it possible to use Baikal deposits to study the development of sedimentary basins and the evolution of geographically isolated populations including freshwater diatoms. The high-resolution continuous sedimentary records from drill cores BDP-98 (600 m long), BDP-96-1 (200 m long) and BDP-96-2 (100 m long) spanning the last 8 Ma (BDPMembers 2000, Sapota et al. 2004), 5 Ma and 2.5 Ma (BDP-Members 1997), respectively are unique for the whole Eurasian continent. The profile of diatom abundance, generic and species composition change allowed to distinguished 58 biostratigraphic diatom zones in Lake Baikal deposits over the Late Miocene – Holocene interval from 8 Ma to 0 Ka BP. Among them, 9 diatom zones were indentified in the Upper Miocene sediments, 8 diatom zones in the Pliocene deposits, and 41 diatom zones in the Quaternary sediments (Khursevich et al. 2001a, b, c, 2003c, 2005). Dramatic changes in insolation during the Pleistocene (1.79– 0.01 Ma) produced surprisingly rapid diatom speciations and extinctions in the ancient basin. The orbitally-tuned age model allowed diatom assemblages to be compared with individual marine isotopic stages and substages, especially of the Brunhes chron (Khursevich et al. 2001a,c). Diatom succession studied in the Brunhes section of the BDP-96-2 core showed that most of the interglacial periods are characterized by explosive speciation and appearances of new pelagic planktonic species, especially within the Stephanodiscus genus many taxa of which are limited to narrow age ranges. In contrast, most of the glacial periods are distinguished by spectacular extinctions (Khursevich et al. 2001c). At least 30 new centric species and intraspecific taxa appeared in the Pleistocene record of Lake Baikal. Among them, 26 members of centric diatoms belong to extinct endemics (see Table 1). The evolution of planktonic centric diatoms within the ancient Baikal ecosystem during the Late Miocene and Pliocene yielded both new species and new genera. Main trends in the evolution of extinct genera from the family Stephanodiscaceae in the Lake Baikal for the last eight million years are described in this paper. MATERIALS AND METHODS Numerous samples collected from the long continuous drill cores BDP-96-1, BDP-96-2 and BDP-98 were analyzed for diatoms. Two parallel cores BDP-96-1 and BDP-96-2 were taken on the top of the underwater Academician Ridge of Lake Baikal at 53°412483 N and 108°212 063 E in water depth of 321 m (BDP-Members 1997). The drilling of the BDP-98 core was performed on this ridge at 53°442483 N and 108°242343 E in water depth of 333 m (BDP-Members 2000, 2001). The total core recovery was about 95%. Sediments consist of alternating biogenic diatomaceous ooze and terrigenous clay intervals. The BDP-96-1 and BDP-96-2 cores were sampled each 2 cm, the BDP-98 core was sampled each 10 cm. The age 74

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

Taxon

Age range

Endemic (+) or extinct endemic (++)

Extinct species

Extant species

Table 1. Systematic composition of fossil diatoms of the family Stephanodiscaceae from the Upper Cenozoic sediments of Lake Baikal.

1

2

3

4

5

Division Bacillariophyta Class Coscinodiscophyceae Round & Crawford Subclass Archaegladiopsophycidae Nikolaev & Harwood Order Thalassiosirales Gleser & Makarova Family Stephanodiscaceae Makarova Genus Concentrodiscus Khursevich, Moisseeva & Sukhova C. indigenus Khursevich & Fedenya C. kuzminii Khursevich & Fedenya C. proteus Khursevich & Fedenya C. subabnormis Khursevich & Fedenya Genus Mesodictyon Theriot & Bradbury M. nativus Khursevich & Fedenya Genus Mesodictyopsis Khursevich, Iwashita, Kociolek & Fedenya M. academicus Khursevich, Iwashita, Kociolek & Fedenya M. baicalensis Khursevich, Iwashita, Kociolek & Fedenya M. insolitus Khursevich & Fedenya M. medius Khursevich & Iwashita M. peculiaris Khursevich, Kociolek & Fedenya M. similis Khursevich & Fedenya M. singularis Khursevich, Iwashita & Fedenya Genus Tertiariopsis Khursevich & Kociolek T. imperseptus Khursevich, Fedenya & Kociolek T. makarovae Khursevich & Kociolek T. sibericus Khursevich, Fedenya & Kociolek Genus Stephanopsis Khursevich & Fedenya S. costatus Khursevich & Fedenya Genus Stephanodiscus Ehrenberg S. asteroides var. baicalensis Khursevich & Fedenya S. baicalensis Likhoshway & Pomazkina S. baicalensis var. concinnis Pomazkina & Likhoshway S. binderanoides Khursevich & Fedenya S. binderanus (Kützing) Krieger var. binderanus S. binderanus var. hyalinus Khursevich & Fedenya

75

lMi lMi lMi lMi

++ ++ ++ ++

lMi

++

lMi lMi - ePl lMi lMi lMi LMi – ePl lMi

++ ++ ++ ++ ++ ++ ++

ePl ePl ePl

++ ++ ++

ePl

++

mPlei lPlei mPlei – lPlei mPlei lMi – R lPl

++ ++ ++ ++ + ++

Galina Khursevich

Table 1. Continued 1

2

S. carconeiformis Khursevich & Loginova S. compactus Khursevich & Fedenya S. dissimilis Khursevich & Fedenya S. distinctus Khursevich var. distinctus S. distinctus var. excentricoides Khursevich S. exiguus Khursevich S. flabellatus Khursevich & Loginova S. formosus Khursevich & Loginova S. grandis Khursevich & Loginova var. grandis S. grandis var. entis Khursevich S. hantzschii Grunow S. imperpetuus Khursevich & Fedenya S. inconspicuus Makarova & Pomazkina S. invisitatus Hohn & Hellerman S. jucundus Khursevich & Fedenya S. khurseviczae Likhoshway S. majusculus Khursevich & Fedenya S. meyerii Genkal & Popovskaya S. minutulus (Kützing) Cleve & Möller S. cf. niagarae Ehrenberg S. notabilis Khursevich & Fedenya S. parvus Stoermer & Håkansson S. princeps Khursevich S. veneris Khursevich & Fedenya S. williamsii Khursevich S. yukonensis var. antiquus Khursevich Genus Tertiarius Håkansson & Khursevich T. baicalensis Khursevich & Fedenya Genus Cyclotella (Kützing) Brébisson C. andancensis Ehrlich C. baicalensis Skvortzow C. comtaeformica Khursevich var. comtaeformica C. comtaeformica var. spinata Khursevich C. distincta Khursevich C. distinguenda Hustedt C. foveolata Khursevich & Fedenya C. gracilis Nikiteeva & Likhoshway C. iris Brun & Héribaud var. iris C. iris var. charetoni (Héribaud) Serieyssol

mPlei – lPlei mPlei ePlei mPlei mPlei lPl – mPlei lPlei – Hol mPlei – lPlei mPlei – lPlei mPlei – lPlei Pl – R ePlei lPlei – R Hol – R ePlei lPlei ePlei Hol – R lMi – R Pl – R ePlei Plei – R mPlei mPlei ePlei ePlei

++ ++ ++ ++ ++ ++ ++ ++ ++ ++

lPl

++

lMi – Pl? lPlei – R ePlei ePlei lPl Pl – R lMi lPlei lMi – R lMi – R

76

3

4

5

+ ++ + + ++ ++ ++ + + + ++ + ++ ++ ++ ++

+ + ++ ++ ++ + ++ ++ + +

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

Table 1. Continued 1

2

C. iris var. combierensis Serieyssol C. iris var. insueta Khursevich C. iris var. integra Peragallo & Héribaud C. iris var. ovalis Brun & Héribaud C. krammeri Håkansson C. meneghiniana Kützing C. minuta (Skvortzow) Antipova C. ocellata Pantocsek C. ornata (Skvortzow) Flower C. praeminuta Khursevich C. pseudostelligera Hustedt C. tempereiformica Khursevich Genus Cyclostephanos Round C. dubius (Fricke) Round

lMi lMi - ePl lMi – Pl lMi – R Pl – R Pl – R mPlei – R Pl – R mPlei – R mPlei Pl – R lPl lPl – R

3

4

5

+ ++ + + + + + + + ++ + ++ +

Legend: lMi – late Miocene, Pl – Pliocene, ePl – early Pliocene, lPl – late Pliocene, Plei – Pleistocene, ePlei – early Pleistocene, mPlei – middle Pleistocene, lPlei – late Pleistocene, Hol – Holocene, R – Recent.

model for these cores is based on the identification of paleomagnetic event/reversal boundaries and the correlation with marine oxygen isotope curve (Williams et al. 1997), as well as on 10Be isotope geochronology for the BDP-98 drill core (Sapota et al. 2004). Permanent diatom slides were prepared with identical volumes of material according to the method described in Grachev et al. (1997). Diatom abundance (mln valves per gram of dry sediment) was calculated in each slide using quantitative method. Specimens were examined with Ergaval light microscope with an oil immersion objective (100x, NA=1.25). In order to precisely define taxonomic belonging of diatoms, the ultrastructure of their valves was studied using JEOL (JSM–35C) scanning electron microscope. The terminology is recommended by Anonymous (1975) and Ross et al. (1979). A system of diatoms proposed by Round et al. (1990) and refined for centric diatoms by Nikolaev and Harwood (2001) has been used in the paper. The information about the age range of species and intraspecific taxa of the family Stephanodiscaceae found in the Upper Cenozoic sediments of Lake Baikal was taken from numerous publications (Ehrlich 1966, Serieyssol 1981, 1984, Fourtanier and Gasse 1988, Khursevich 1989, 1999, Serieyssol and Gasse 1991, Gleser et al. 1992, Nikiteeva and Likhoshway 1994, Likhoshway 1996, Ognjanova-Rumenova 1996, 2001, Julius et al. 1997, Temniskova-Topalova and OgnjanovaRumenova 1997, Edlund and Stoermer 2000, Khursevich et al. 2000, 2001a, b, c, 2002a, b, 2003a, b, c, 2004, 2005, Rasskazov et al. 2001, Khursevich and Fedenya 2005).

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RESULTS AND DISCUSSION Upper Cenozoic (Upper Miocene – Holocene) sediments of Lake Baikal contain the diverse composition of centric diatoms from the family Stephanodiscaceae. The latter includes 60 species and 12 intraspecific taxa belonging to 9 genera. Among them, 6 genera (3 endemic for Lake Baikal and the Transbaikal area), 42 species (41 baikalian endemics) and 10 intraspecific taxa (8 baikalian endemics) are extinct (Table 1). Morphological peculiarities of some members of extinct genera from the family Stephanodiscaceae found in the Upper Miocene and Pliocene deposits from Lake Baikal have been illustrated in Plates 1 – 3 (Figs 1– 26). The extinct genus Concentrodiscus is known at present from the Paleo-Baikal and the ancient basins of the Transbaikal area. This genus and its type species Concentrodiscus abnormis Khursevich, Moisseeva and Sukhova were first described from the Middle-Upper Miocene diatomaceous rocks of the Upper-Sulbanian depression within the Transbaikal area (Khursevich et al. 1989). Later a new member of this genus, Concentrodiscus variabilis Khursevich & Chernyaeva, was defined in the Middle Miocene deposits within the Amalat plateau of the Transbaikal area (Khursevich and Chernyaeva 1994, Rasskazov et al. 2001). Four new representatives of Concentrodiscus were found in the Upper Miocene stratum from the BDP-98 drill core (Khursevich et al. 2002a, Khursevich and Fedenya 2005). Hence, the age range of this genus is from the Middle to Late Miocene. The genus Concentrodiscus is characterized by the following distinctive features: a) the presence of valves with one-two concentric convex and concave zones; b) the availability of internal flat cribra in areolae; c) the presence of marginal fultoportulae with 4 satellite pores; d) the various position of a single rimoportula on the valve surface (near the centre, in the submarginal zone of the valve face, at the valve face/mantle junction, on the mantle); e) the presence of valve face fultoportulae with 4 satellite pores in both isotopic and heterotopic position, rarely the absence of them. The age range of this genus in the ancient Baikal ecosystem is Late Miocene (ca. 8–7 Ma), according to the age model for the BDP-98 core (Sapota et al. 2004). However, this geological age may be extended because for the present the complete Miocene diatom record from Lake Baikal is absent. The genus Mesodictyon (Theriot and Bradbury 1987) is restricted mainly to the Late Miocene. It is widespread and diverse in lacustrine deposits of that time in the western regions of USA (Krebs et al. 1987, Theriot 1990, Krebs 1994, Khursevich and VanLandingham 1995), Ethiópia (Fourtanier and Gasse 1988), France (Serieyssol and Gasse 1991), northern Peru (Fortanier et al. 1993), southern Bulgaria (Temniskova-Topalova and Ognjanova-Rumenova 1997), Belarus (Rylova et al. 1999). The presence of the new fossil species Mesodictyon nativus in the Upper Miocene deposits of Lake Baikal (Khursevich et al. 2002a) is the first record of this genus within Asia. Thus, the genus Mesodictyon belongs to one of the important biochronological markers and can be used for cross-continental correlation of lacustrine sedimentary sections. The genus Mesodictyon is distinguished by the following morphological peculiarities: a) the presence of flat or concentrically undulate valves; b) the location of the areola cribrum inside of the loculus; c) the presence of marginal fultoportulae with 2 satellite pores; d) the position 78

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

2

1

3

4 6

5

7

8

Figs 1, 2, 5, 8. Concentrodiscus kuzminii Khursevich & Fedenya, SEM. Scale bars = 10 µm (Figs 1, 5) or 1 µm (Figs 2, 8). Fig. 1. External view of the valve surface with tubular extensions of marginal fultoportulae (arrows). Figs 2, 5. Fragments of the internal valve surface with flat cribra in areolae, a ring of marginal fultoportulae with four satellite pores (arrow in Fig. 2) and a single rimoportula on the valve face/mantle junction (arrow in Fig. 5). Fig. 8. Detail showing round external aperture of rimoportula (arrow). Figs 3, 4, 6, 7. Concentrodiscus indigenus Khursevich & Fedenya, SEM. Scale bars = 1 µm. Figs 3, 6. External view of the valve surface with a ring of small openings of valve face fultoportulae near the centre (arrow in Fig. 6). Fig. 4. Fragment of the internal valve surface with a single rimoportula on the mantle (black arrow) and a ring of marginal fultoportulae with four satellite pores (white arrows). Fig. 7. Detail showing a distinct opening of rimoportula on the mantle (arrow).

79

Galina Khursevich

of a single rimoportula on the valve mantle; e) the absence of valve face fultoportulae. The age range of this genus in the ancient Lake Baikal: Late Miocene (ca. 7.7–6.3 Ma). The genus Mesodictyopsis belongs to extinct endemics of the ancient lacustrine ecosystems of Lake Baikal and the Transbaikal area (Khursevich et al. 2004). At present it contains 8 species. Among them, 7 members of Mesodictyopsis are known from the Late Miocene–the beginning of Pliocene of Lake Baikal, and 1 taxon apparently from the Late Miocene of the Dzhilinda hollow (the Transbaikal area). The genus Mesodictyopsis is diagnosed by a combination of the following morphological features: a) the presence of medial velum (cribrum?) in areolae; b) the presence of marginal fultoportulae with 3 satellite pores; c) the various location of rimoportula(e) on the valve surface (near the centre, in the submarginal zone of the valve face, at the valve face/mantle junction, on the mantle); d) the presence of valve face fultoportulae mainly with 3 ( rarely 2 or 4) satellite pores. The age range of this genus in the ancient Lake Baikal is ca. 7–5.1 Ma. The extinct genus Tertiariopsis and its three species were described from the Lower Pliocene deposits of Lake Baikal (Khursevich et al. 2002b). This genus may include also two species described by Serieyssol et al. (1998) from the Upper Miocene sediments of France and Mexico. These species, originally placed in Thalassiosira, lack alveolae and appear to have a valve mantle dissected by hyaline strips. The genus Tertiariopsis possesses by the following characteristic peculiarities: a) the presence of internal raised cribra in areolae; b) the availability of a distinct break between the valve face areolae and those of the mantle; c) the breaking up of the valve mantle onto distinct areolar sections separated by hyaline strips; d) the presence of marginal fultoportulae with 3 satellite pores covered by a marginal lamina internally; e) the position of one-two rimoportulae mainly on the valve mantle; f) the presence of valve face fultoportulae with usually 3 (rarely 2) satellite pores. The age range of this genus in the ancient Lake Baikal: ca. 5.1- 4.6 Ma. The genus Stephanopsis has been found only in the Pliocene sediments from the BDP98 and BDP-96-1 drill cores and belongs to one of the extinct endemic genera of the ancient Lake Baikal (Khursevich et al. 2000). The type species of this genus, Stephanopsis costatus, is characterized by a great morphological variability (at least 5 morphotypes were revealed in the studied material). The genus Stephanopsis is distinguished by the following characters: a) the presence of internal raised cribra in areolae; b) the presence of thin radial costae crossing the valve mantle internally; c) the location of marginal fultoportulae with 3 satellite pores at the proximal ends of thin radial internal costae; e) the position of rimoportula(e) on the valve surface mainly at the proximal end of one or several thin radial internal costae, sometimes elsewhere on the valve face, but usually near the centre; f) the presence of valve face fultoportulae with 2 or 3 satellite pores. The age range of this genus in the ancient Lake Baikal is ca. 4.84 – 2.6 Ma, according to the age model for the BDP-96-1 and BDP-98 cores (Williams et al. 1997, Sapota et al. 2004). The genus Tertiarius was first proposed for three members of the genus Cyclotella occurred in the Pliocene material from Köpecz (Transylvania, Romania) in Pantocsek’s Collection and studied in SEM (Håkansson and Khursevich 1997). Later new species of 80

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

9

11

10

12

13

14

15

16

Figs 9 -11. Mesodictyon nativus Khursevich & Fedenya, SEM. Scale bars = 1 µm. Fig. 9. External view of the valve surface. Figs 10, 11. Internal view of the valve surface with a single sessile rimoportula on the mantle (arrow in Fig. 10) and a ring of marginal fultoportulae with two satellite pores (arrow in Fig. 11). Figs 12, 13. Mesodictyopsis singularis Khursevich, Iwashita & Frdenya, SEM. Scale bars= 1 µm. Fig. 12. Internal view of the valve surface with a single rimoportula on the valve face/mantle junction (arrow). Fig. 13. Detail showing medial velum within areolae (arrow). Fig. 14 – 16. Mesodictyopsis medius Khursevuch & Iwashita, SEM. Scale bars = 1 µm. Fig. 14. External view of the valve surface. Fig. 15. Internal view of the valve surface with a single rimoportula in the centre (arrow) and a ring of marginal fultoportulae with three satellite pores. Fig. 16. Detail showing medial velum within areolae (arrow).

81

Galina Khursevich

17

20

18

19

21

22

23

24

25

26

Figs 17-18. Tertiariopsis sibericus Khursevich, Fedenya & Kociolek, SEM. Scale bars = 1 µm. Fig. 17. External view of the valve surface with a ring of marginal fultoportulae openings (arrow). Fig. 18. Internal view of the valve surface with a single rimoportula on the mantle (arrow) and a ring of valve face fultoportulae with three satellite pores near the centre. Fig. 19. Tertiariopsis imperseptus Khursevich, Fedenya & Kociolek, SEM. Scale bar = 1 µm. Internal view of the valve surface with a single rimoportula on the mantle (arrow). Figs 20 – 22. Stephanopsis costatus Khursevich & Fedenya, SEM. Scale bars = 10 µm. Fig. 20. External view of the valve surface. Figs 21, 22. Internal view of the valve surface with the presence of thin radial costae crossing the mantle, three rimoportulae located near the centre (arrow in Fig. 21) or rimoportula positioned at the inner end of one of thin costae (white arrow in Fig. 22) and a ring of marginal fultoportulae with three satellite pores (black arrow in Fig. 22). Figs 23 – 26. Tertiarius baicalensis Khursevich & Fedenya, SEM. Scale bars = 1 µm. Figs 23, 25. External view of the valve surface. Figs 24, 26. Internal view of the valve surface with the marginal ring of alveolae and a single rimoportula (arrows).

82

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

Tertiarius have been identified in the Pliocene lacustrine sediments from the Former Yugoslavian Republic of Macedonia (Ognjanova-Rumenova 2001) and the Upper Miocene and Pliocene deposits from western USA (Khursevich and Kociolek 2002). The occurrence of Tertiarius baicalensis in the Upper Pliocene sediments from the ancient Lake Baikal is the first report of this genus in Asia (Khursevich et al. 2003a). Thus, the age range of this genus is restricted to the Late Miocene–Pliocene. The genus Tertiarius is diagnosed by a combination of the following morphological features: a) the presence of more or less flat valves; b) the availability of internal domed cribra in areolae on the valve face; c) the presence of alveolae on the valve mantle; d) the location of marginal fultoportulae with 2 or 3 satellite pores on the thick costae internally; d) the various position of rimoportula(e) on the valve surface (in the submarginal zone of the valve face, at the base of internal costa(e) or within the alveolar chamber(s); e) the presence of valve face fultoportulae with 2 or 3 satellite pores. The age range of this genus in the ancient Lake Baikal is ca. 2.7–2.5 Ma. The extinct genera from the family Stephanodiscaceae characterized above replace each other from the bottom to top along the long continuous sections of the BDP-98 (Fig. 1) and BDP-96-1 cores that allows to trace the evolution of some morphological characters in time. Pattern of morphological evolution in these genera in the ancient Baikal ecosystem can be described in the following ways: a) change of the cribrum position in areola from the internal flat cribrum (the genus Concentrodiscus) to the medial cribrum located within loculus (the genera of Mesodictyon and Mesodictyopsis), later again to the internal but slightly raised cribrum (the genera of Tertiariopsis and Stephanopsis), and lastly to the internal domed cribrum (the Tertiarius genus); b) change of the stria morphology from areolar stria (the genera of Concentrodiscus, Mesodictyon, Mesodictyopsis, Tertiariopsis, Stephanopsis) to areolar-alveolar stria (the genus Tertiarius); c) change of the structure of marginal fultoportulae on the valve mantle (the species of Concentrodiscus have marginal fultoportulae only with 4 satellite pores, whereas the members of Mesodictyon, Mesodictyopsis, Tertiariopsis, Stephanopsis and Tertiarius possess marginal fultoportulae with 2 or 3 satellite pores); d) change of the number of rimoportulae (if the more ancient genus Concentrodiscus has a single rimoportula on the valve surface, then the younger genera Mesodictyopsis, Tertiariopsis, Stephanopsis and Tertiarius have from one to several, sometimes up to seven rimopotulae forming a marginal ring). At the same time the extinct endemic genera of Concentrodiscus, Mesodictyopsis and Stephanopsis developed in the ancient Lake Baikal have some common inherited morphological features (such as the various placement of rimoportula on the valve surface including certain taxa with the location of rimoportula in or near the valve centre). Besides the inherited position of rimoportula in or near the centre of the valve is characteristic also of some ancient members of Stephanodiscus (S. dissimilis Khursevich and Fedenya, S. majusculus Khursevich and Fedenya and S. yukonensis var. antiquus Khursevich) which appeared and developed in Lake Baikal in early Pleistocene (Khursevich et al. 2001b, 2003a). Thus, the evolution of centric diatoms in the ancient Baikal ecosystem during the last 8 Ma is associated with the processes of extinction and neogeneration both of some genera and many species. Percentage of baikalian extinct endemics in the family Stephanodiscaceae makes up 70%. This diatom group has evolved in situ rapidly throughout the late 83

AGE

L.

M.

Early

Late

Early

Ma

9

8

7

6

5

4

3

2

1

0

MAG. POL.

8

7

6

5

C4A 9

C4

C3B

C3A

C3

C2A

C2

C1

CHRON Brunhes Matuyama Gauss Gilbert

Pleistocene

Pliocene

Miocene

84

Late

BDP96 depth, m BDP98 depth, m 600

550

500

450

400

350

300

250

200

150

100

50

0

600 1200 0

u A 500 1000 0

30

100 200 0

5

10 0

400 800 0

200 400 0

is ps n yo yo lla ct ct i i te od od lo s s c e e M Cy M

us sc

mln valves per gram of dry sediment

60 0

us di cl ro cy nt o e in nc ct Co A

300 600 0

o ol ve Al

a or ph

BDP96-1, BDP96-2 and BDP98 cores

0

s om at Di

ira se co la ti

is

400 800 0

no ha

us sc di

Concentrodiscus kuzminiiC. indigenusbenthic

Mesodictyon nativus

C.comtaeformica et var. spinata C.tempereiformicaC.distincta Tertiarius baicalensis Stephanopsis costatus Stephanopsis costatusAulacoseira sp. aff. A. islandica Tertiariopsis sibericusT. imperseptus Cyclotella iris group Cyclotella iris group -Mesodictyopsis similis Aulacoseira praegranulata -M. similis Mesodictyopsis baicalensisM.similis Cyclotella iris group -Mesodictyopsis baicalensis Mesodictyopsis singularis Mesodictyopsis academicus M. peculiaris Mesodictyopsis academicusMesodictyon nativus Mesodictyopsis insolitusM. medius Alveolophora baicalensisConcentrodiscus subabnormis -Actinocyclus immemoratus

* ** *** ****

Brunhes diatom zones

Diatom zones

Correction: 15 March 2005

600 1200

ep St

500 1000 0

s si s op an riu h ia rt ep St Te

500 1000 0

r Te

ps io ar

Galina Khursevich

Fig. 1. Diatom biostratigraphy of Lake Baikal sediments in BDP-96 and BDP-98 cores. The correlation of BDP-96 and BDP-98 cores with geomagnetic polarity time scale of Cande and Kent (1995) is given according to Williams et al. (1997), BDP-Members (2000) and Sapota et al. (2004). Diatom zones: * Stephanodiscus notabilis–S. binderanus–Synedra acus var. radians, ** Stephanodiscus jucundus– S. williamsii–Synedra ulna var. danica, *** Aulacoseira subarctica–Cyclotella ocellata, ****Stephanodiscus majusculus– Aulacoseira sp. aff. A. islandica

Evolution of the extinct genera belonged to the family Stephanodiscaceae (Bacillariophyta)

Miocene–Pleistocene, producing a number of short-ranging species. The ancient faultblock basin of Lake Baikal contains the endemic lineages within the centric genera of Concentrodiscus, Mesodictyopsis, Stephanodiscus and Cyclotella. Key for determination of the extinct genera belonged to the family Stephanodiscaceae from the Upper Cenozoic sediments of Lake Baikal Presence of loculate areolae with foramina on the external valve surface and cribra on the internal valve surface or within loculae. Striae areolate, areolate-alveolate or only alveolate. Marginal fultoportulae with two or three, rarely with four satellite pores. Rimoportulae from one to several have various position on the valve .............................. Stephanodiscaceae I. Striae areolate. 1. Areolae in no clear radial rows. Marginal fultoportulae with four satelliteores .......... ........................................................................................................ Concentrodiscus 2. Areolae in distinct radial rows. Marginal fultoportulae with two or three satellite pores. A. Presence of medial cribra in areolae. a. Marginal fultoportulae with two satellite pores. Valve face fultoportulae absent. The constant position of a single rimoportula on the mantle .... .............................................................................................................. Mesodictyon b. Marginal fultoportulae with three satellite pores. Valve face fultoportulae present. The various location of rimoportula(e) on the valve surface .... .......................................................................................................... Mesodictyopsis B. Presence of internal raised cribra in areolae. a. Marginal fultoportulae covered by a marginal lamina internally. The constant position of one-two rimoportulae on the mantle ... Tertiariopsis b. Marginal fultoportulae placed at the base of thin radial costae crossing valve mantle internally. The various location of one-several rimoportulae on the valve surface .................................................................. Stephanopsis II. Striae areolate-alveolate .................................................................................................. Tertiarius ACKNOWLEDGEMENTS This work was implemented as a part of Baikal Drilling Project supported by National Scientific Foundation of USA (NSF) grant EAR-96-14770, the Siberian Branch of Russian Academy of Sciences, the Russian Ministry of Geology, the Science and Technology Agency (STA) of Japan. Author thanks the entire NEDRA Scientific Drilling Team for the successful drilling effort. I am grateful to the scientists of the Institute of Geochemistry, Limnological Institute and the Institute of the Earth Crust (Irkutsk) who participated in primary description and sampling of the BDP-96-1 and BDP-98 drill cores, as well as in permanent slide preparation.

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REFERENCES ANONYMOUS 1975. Proposals for a standartization of diatom terminology and diagnoses. – Nova Hedwigia, Beih. 53: 325-354. BDP-Members 1997. Continuous paleoclimate record recovered for last 5 million years. – EOS American Geophysical Union, Transactions, 78(51): 597-604. BDP-MEMBERS 2000. Paleoclimatic record in the Late Cenozoic sediments of Lake Baikal (by 600 m deep-drilling data). – Russ. Geol. Geophys., 41(1): 3-32. (in Russian) BDP-MEMBERS 2001. The new BDP-98 600-m drill core from Lake Baikal: a key late Cenozoic sedimentary section in continental Asia. – Quatern. Intern., 80-81: 19-36. CANDE, S.C. and D.F. KENT 1995. Revised calibration of the geomagnetic polarity time scale for the Late Cretaceous and Cenozoic. – J. Geophys. Res., 100: 6093–6095. EDLUND, M.B. and E.F. STOERMER 2000. A 200,000-year, high-resolution record of diatom productivity and community makeup from Lake Baikal shows high correspondence to the marine oxygen-isotope record of climate change. – Limnol. Oceanogr., 45(4): 948-962. EHRLICH, A. 1966. Contributions à l’étude des gisements volcano-lacustres à Diatomées de la région de Rochessauve et de Saint Bauzile (Ardèche). – Bull. Soc. Géol. France, ser. 7 (7): 311-321. FOURTANIER, E. and F. GASSE 1988. Premiers jalons d’une biostratigraphie et évolution des diatomées lacustres d’Afrique depuis 11 Ma. - C. R. Acad. Sci. Paris, 306: 1401-1408. FOURTANIER, E., F. GASSE, O. BELLIER, M.G. BONHOMME and I. ROBLES 1993. Miocene non-marine diatoms from the western Cordillera basins of northern Peru. - Diatom Research, 8: 13-30. GLESER, Z.I., I. V. MAKAROVA, A.I. MOISSEEVA, and 6 OTHERS 1992. The diatoms of the USSR (fossil and recent). 2(2). Nauka, St.-Petersburg. (in Russian) GRACHEV, M.A., E.V. LIKHOSHWAY, S.S. VOROBYOVA, and 19 OTHERS 1997. Signals of the paleoclimates of the Upper Pleistocene in the sediments of Lake Baikal. – Russ. Geol. Geophys., 38: 957-980. (in Russian) HÅKANSSON, H. and G. KHURSEVICH 1997. Tertiarius gen. nov. – genus in the Bacillariophyceae, the transfer of some cyclotelloid species and a comparison to closely related genera. – Diatom Research, 12: 19-33. JULIUS, M.L., E.F. STOERMER, S.M. COLMAN and T.C. MOORE 1997. A preliminary investigations of siliceous microfossil succession in late Quaternary sediments from Lake Baikal, Siberia. – J. Paleolimnol., 18: 187-204. KHURSEVICH, G.K. 1989. Atlas of the species of Stephanodiscus and Cyslostephanos (Bacillarophyta) from the Upper Cenozoic sediments of the USSR. F. Ju. Velichkevich, editor. Nauka i tekhnika, Minsk. (in Russian) KHURSEVICH, G.K. 1999. Morphological peculiarities of some Stephanodiscus species from the bottom sediments of Lake Baikal. in: Mayama, Sh., M. Idei and I. Koizumi, editors. Proceedings of the 14th International Diatom Symposium: 603-612. Koeltz Scientific Books, Koenigstein. 86

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KHURSEVICH, G.K. and G.P. CHERNYAEVA 1994. A new species of the genus Concentrodiscus (Bacillariophyta) from the Miocene deposits of the Transbaikal area. – Botanichesky Zhurnal, 79(1): 107-109 (in Russian). KHURSEVICH, G.K. and S.A. FEDENYA 2005. Morphology of new fossil species of Concentrodiscus and Alveolophora (Bacillariophyta) from bottom sediments of Lake Baikal. – Algologia (accepted). KHURSEVICH, G.K., S.A. FEDENYA, E.B. KARABANOV, A.A. PROKOPENKO, D.F. WILLIAMS and M.I. KUZMIN 2001a. Late Cenozoic diatom record from Lake Baikal sediments. in: A. Economou-Amilli, editor. Proceedings of the 16th International Diatom Symposium: 451-460. University of Athens, Athens. KHURSEVICH, G.K., S.A. FEDENYA, E.B. KARABANOV, D.F. WILLIAMS and M.I. KUZMIN (2000): Stephanopsis Khursevich & Fedenya – new genus of class Centrophyceae (Bacillariophyta) from the Pliocene deposits of Lake Baikal (Russia). – Algologia, 10(1): 106-109. KHURSEVICH, G.K., S.A. FEDENYA, M.I. KUZMIN, E.B. KARABANOV, D.F. WILLIAMS and A.A. PROKOPENKO 2002a. Morphology of new species of Concentrodiscus and Mesodictyon (Bacillariophyta) from the Upper Miocene deposits of Lake Baikal. Algologia, 12(3): 361-370. KHURSEVICH, G.K., S.A. FEDENYA, M.I. KUZMIN, E.B. KARABANOV, D.F. WILLIAMS and A.A. PROKOPENKO 2003a. Morphology of new taxa of the class Centrophyceae (Bacillariophyta) from the Pliocene and Pleistocene deposits of Lake Baikal, Siberia. – Algologia, 13(3): 305-321. KHURSEVICH, G.K., S.A. FEDENYA, M.I. KUZMIN, E.B. KARABANOV, D.F. WILLIAMS and A.A. PROKOPENKO 2003b. New species of Stephanodiscus (Bacillariophyta) from the Pleistocene sediments of Lake Baikal. – Algologia, 13(4): 389-401. KHURSEVICH, G., E. KARABANOV, M. KUZMIN, D. WILLIAMS, A. PROKOPENKO and S. FEDENYA 2003c. Diatom succession in Upper Miocene sediments of Lake Baikal from BDP-98 drill core. in: K. Kashiwaya, editor. Long Continental Records from Lake Baikal: 271-282. Springer Verlag, Tokyo. KHURSEVICH, G.K., E.B. KARABANOV, A.A. PROKOPENKO, D.F. WILLIAMS, M.I. KUZMIN and S.A. FEDENYA 2001b. Biostratigraphic significance of new fossil species of the genera Stephanodiscus and Cyclotella from Upper Cenozoic deposits of Lake Baikal, Siberia. – Micropaleontology, 47(1): 47-71. KHURSEVICH, G.K., E.B. KARABANOV, A.A. PROKOPENKO, D.F. WILLIAMS, M.I. KUZMIN, S.A. FEDENYA and A. N. GVOZDKOV 2001c. Insolation regime in Siberia as a major factor controlling diatom production in Lake Baikal during the past 800,000 years. – Quatern. Intern., 80-81: 47-58. KHURSEVICH, G.K. and J. KOCIOLEK 2002. New Tertiarius (Bacillariophyta: Stephanodiscaceae) species from Western North America. in: J. John, editor. Proceedings of the 15th International Diatom Symposium: 331-349. Biopress Limited, Bristol. KHURSEVICH, G.K., J.P. KOCIOLEK and S.A. FEDENYA 2002b. A new genus of fossil freshwater diatoms (Bacillariophyta: Stephanodiscaceae) from the sediments of Lake Baikal. - Proceedings of the California Academy of Sciences, 53(1): 1–10. 87

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KHURSEVICH, G.K., J.P. KOCIOLEK, T. IWASHITA, S.A. FEDENYA, M.I. KUZMIN, T. KAWAI, D.F. WILLIAMS, E.B. KARABANOV, A.A. PROKOPENKO and K. MINOURA 2004. Mesodictyopsis Khursevich, Iwashita, Kociolek & Fedenya – new genus of class Centrophyceae (Bacillariophyta) from Upper Miocene sediments of Lake Baikal, Siberia. – Proceedings of the California Academy of Sciences, 55(15): 336–355. KHURSEVICH, G.K., A.I. MOISSEEVA and G.A. SUKHOVA 1989. New genus of diatom algae of the family Stephanodiscaceae. - Botanichesky Zhurnal, 74(11): 1600-1601. (in Russian) KHURSEVICH, G.K., A.A. PROKOPENKO, S.A. FEDENYA, L.I. TKACHENKO and D.F. WILLIAMS 2005. Diatom biostratigraphy of Lake Baikal during the past 1.25 Ma: new results from BDP-96-2 and BDP-99 drill cores. – Quatern. Intern., 136: 95-104. KHURSEVICH, G.K. and S.L. VANLANDINGHAM 1995. Morphology and stratigraphy of some Mesodictyon species (Bacillariophyta) from upper Miocene freshwater deposits of Idaho and Nevada, U.S.A. – Nova Hedwigia, 60(3-4): 467-478. KREBS, W.N. 1994. The biochronology of freshwater planktonic diatom communities in western North America. in: J.P. Kociolek, editor. Proceedings of the 11th International Diatom Symposium: 485-499. California Academy of Sciences, San Francisco. KREBS, W.N., J.P. BRADBURY and E. THERIOT 1987. Neogene and Quaternary lacustrine diatom biochronology, western USA. – Palaios, 2: 505—513. LIKHOSHWAY, YE.V. 1996. Stephanodiscus khurseviczae sp. nov. from Pleistocene sediments of Lake Baikal. – Diatom Research, 11(2): 273-281. NIKITEEVA, T.A. and YE.V. LIKHOSHWAY 1994. Cyclotella gracilis sp. nov. from Pleistocene material of Lake Baikal. – Diatom Research, 9(2): 349 – 353. NIKOLAEV, V.A. and D.M. HARWOOD 2001. Diversity and classification of centric diatoms. in: A. Economou-Amilli, editor. Proceedings of the 16th International Diatom Symposium: 127-152. University of Athens, Athens. OGNJANOVA–RUMENOVA, N.G. 1996. Cyclotella iris Brun & Héribaud – a group from the Upper Miocene sediments of the Sofia basin, Bulgaria. – Geologica Carpathica, 47(5): 301–310. OGNJANOVA–RUMENOVA, N.G. 2001. Neogene diatom assemblages from lacustrine sediments of F.Y.R.O.M. (Macedonia) and their distribution in correlative formations of south-western Bulgaria. in: A. Economou-Amilli, editor. Proceedings of the 16th International Diatom Symposium: 423-432. University of Athens, Athens. RASSKAZOV, S.V., N.A. LOGACHEV, A.V. IVANOV, V.A. MISHARINA, G.P. CHERNYAEVA, I.S. BRANDT, S.B. BRANDT, V.M. SKOBLO and N.A. LYAMINA 2001. Palynological and diatom analyses of sediments from the late Cenozoic Amalat valley. – Russ. Geol. Geophys., 42(5): 773-785. (in Russian) ROSS, R., E.J. COX, N.I. KARAYEVA, D.G. MANN, T.B.B. PADDOCK, R. SIMONSEN and P.A. SIMS 1979. An emended terminology for the siliceous component of the diatom cell. – Nova Hedwigia, 64: 513-533. ROUND, F.E., R.M. CRAWFORD and D.G. MANN 1990. The diatoms: biology and morphology of the genera. – Cambridge University Press, Cambridge. 88

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RYLOVA, T.B., T.V. YAKUBOVSKAYA and G.K. KHURSEVICH 1999. Palaeobotanical evidence for correlating the stratigraphy of the Neogene deposits of Belarus. – Acta Palaeobotanica, Suppl. 2.: 359-363. SAPOTA, T., A. ALDAHAN, G. POSSNERT, J. PECK, J. KING, A. PROKOPENKO and M. KUZMIN 2004. A late Cenozoic Earth’s crust and atmosphere dynamics record from an active continental rift system. – J. Paleolimnol., 32: 341-349. SERIEYSSOL, K. 1981. Cyclotella species of Late Miocene age from St. Bauzile, France. in: R. Ross, editor. Proceedings of the 6th Symposium on Recent and Fossil Diatoms: 27-42. O. Koeltz, Koenigstein. SERIEYSSOL, K. 1984. Cyclotella iris Brun & Héribaud. in: D.G. Mann, editor. Proceedings of the 7th International Diatom Symposium: 197-212. O. Koeltz, Koenigstein. SERIEYSSOL, K. and F. GASSE 1991. Diatomées néogènes du Massif Central Français: quelques faits biostratigraphiques. - C. R. Acad. Sci. Paris, 312: 957-964. SERIEYSSOL, K., I. ISRADE GARDUNO and F. GASSE 1998. Thalassiosira dispar comb. nov. and T. cuitzeonensis spec. nov. (Bacillariophyceae) found in Miocene sediments from France and Mexico. – Nova Hedwigia, 66 (1-2): 177-186. TEMNISKOVA-TOPALOVA, D. and N. OGNJANOVA-RUMENOVA 1997. Description, comparison and biostratigraphy of the nonmarine Neogene diatom floras from Southern Bulgaria. – Geologica Balcanica, 27(1-2): 57-81. THERIOT, E. 1990. New species of Mesodictyon (Bacillariophyta: Thalassiosiraceae) in Late Miocene lacustrine deposits of the Snake River basin, Idaho. - Proceedings of the Academy of Natural Sciences of Philadelphia, 142: 1-19. THERIOT, E. and J.P. BRADBURY 1987. Mesodictyon, a new fossil genus of the centric diatom family Thalassiosiraceae from the Miocene Chalk Hills Formation, western Snake River Plain, Idaho. – Micropaleontology, 33: 356-367. WILLIAMS, D.F., J. PECK., E.B. KARABANOV, A.A. PROKOPENKO, V.KRAVCHINSKY, J. KING and M.I. KUZMIN 1997. Lake Baikal record of continental climate response to orbital insolation during the past 5 million years. – Science, 278: 1114 –1117.

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A new Cymbella from the Neogene in Bulgaria and its stratigraphic significance Nadja Ognjanova-Rumenova1 and Ditmar Metzeltin2 Department of Palaeontology and Stratigraphy, Institute of Geology, Bulgarian Academy of Sciences, Acad. G.Bonchev str. 24, 1113 Sofia, Bulgaria E-mail: [email protected] 2 Am Stegskreuz 3b, D-65719 Hofheim, Germany 1

ABSTRACT A new species, Cymbella serdica is described and illustrated from the Upper Miocene Novi Iskar Formation of the Sofia Neogene Basin. Key words: Bacillariophyta, Cymbella serdica sp. nov., Sofia Neogene Basin, Bulgaria INTRODUCTION The Novi Iskar Formation consists of lacustrine sediments which were deposited in the Sofia Basin, South Bulgaria, in the Late Miocene – Early Pliocene, and contains very diverse diatom flora (Ognjanova-Rumenova 1991). The diatom flora includes 365 extinct and extant species, varieties and forms, which are significant from ecological and evolutional viewpoints. In previous studies of this material the biochronological scheme was based only on the development of the different planktonic genera of the Centrophyceae (Ognjanova-Rumenova and Popova 1992). In this scheme the most diverse group of the Pennatophyceae was neglected. Some of these pennatae species have a short stratigraphic range and even if benthic – they could be used as index species, for example the extinct species of the genera Fragilaria Lyngbye, Tetracyclus Ralfs, and Eunotia Ehrenberg. The objective of this study was to describe and illustrate a new species, of the genus Cymbella Ehr. from the Upper Miocene Novi Iskar Formation, Sofia Basin, and to determine its biostratigraphic significance.

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MATERIAL AND METHODS The sediments studied were collected from two boreholes C-1 and C-14, situated in the northern part of the Sofia Basin. The two boreholes cut across the Novi Iskar Formation (Kamenov and Kojumdgieva 1983). Borehole C-1, village of Goljanovci, 18 km northern of Sofia, 42o51’00'’ north and 23o13’48'’ east, is represented by irregular alternation of diatomaceous clays (0-48.8 m), lignite and lignite clays (48.8-57.1 m), chalk (57.1-67.4 m), lignite clays (67.4-76.7 m) and gray limestones (76.7-87.3 m). Borehole C-14, village of Katina, 15 km northern of Sofia, 42o50’01'’ north and 23o14’13'’ east, cuts across 10 m sands (not sampled), gray-bluish silty clays alternated by lignite, sands and sandy silty clays (10.0-110.0 m), gray clays with diatomacous clays (110.0-199.0 m), lignite with lignite clays (199.0-260.0 m), chalk (260.0-262.4). Diatom bearing sediments from boreholes C-1 (1.548.8 m) and C-14 (10.0-190.0 m) were investigated. (Fig. 1) The samples were prepared for diatom analyses following standard laboratory procedures (Ognjanova-Rumenova 1991), which combined parts of methods of Schrader (1973) and Hasle and Fryxell (1970). The relative abundance of the taxon was given according to Schrader’s scale (Schrader 1973). OBSERVATIONS AND DISCUSSION Cymbella serdica Metzeltin & Ognjanova-Rumenova nov. spec. (Pl. 1: Figs 1-3) Valvae valde dorsiventrales, semi-lanceolatae-ellipticae valvis maioribus fortiter lunatis, cum margine dorsali magis convexa et margine ventrali magis concava cum levi inflatione in medio, apicibus non protractis modice late rotundatis, 110-165 µm longae, 38-48 µm latae. Area axialis modice angusta, linearis. Area centralis fere parva. Raphe modice lateralis, ad aream centralem sensim filiformis. Stigmata nulla vel non bene aspectabilia. Striae transapicales modice radiatae, punctatae-lineolatae, 8-9 in 10 µm in parte dorsali, parte ventrali 6,5-7 in 10 µm, puncta 12 in 10 µm.

Typus: Praep. Core 1/20, 30.0 m depth in Coll. Ognjanova-Rumenova, Institute of Geology, Bulgarian Academy of Sciences, Sofia Locus typicus: 18 km in the north of Sofia, “Neogene Sofia basin”, near the village of Goljanovci; Borhole is 42o51'00'’ north and 23o13'48'’ east. Etymology: Serdica is the first recorded name of the modern town of Sofia. The Thracian Serdi tribe settled here in the 7th century BC and gave this name. Diagnosis difference in comparison with Cymbella aspera (Ehr.) Peragallo and C. neogena (Grunow) Krammer. (Krammer 2002) Valves much more strongly dorsiventral, crescent-shaped. Dorsal margin more convex than the ventral margin concave, the latter commonly slightly inflated in the middle. Ends bluntly rounded, not protracted. Length 110-165 µm, breadth 38-48 µm (not 26-35). Raphe 92

A new Cymbella from the Neogene in Bulgaria and its stratigraphic significance

Fig. 1. Biostratigraphic distribution of Cymbella serdica in the lacustrine sediments of Novi Iskar Formation, Sofia Neogene Basin, South Bulgaria.

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1

2

3 10 µm

Plate 1. Figs 1-3 Cymbella serdica sp. nov. Scale bar 10 µm.

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moderately lateral, becoming filiform proximally, central ends somewhat far-standing and very distinctly deflected (not weakly) to the ventral side (without large, somewhat round central pores). Axial area moderately narrow; central area comparatively small rather than large. Stigmata absent or at least not discernible in LM. Striae moderately radial becoming subparallel near the ends, 8-9 in 10 µm at the ventral side, 6.5-7 at the dorsal side (nowhere more than 10/10 µm. Areolae 12 in 10 µm. Biostratigraphic distribution: Cymbella serdica has been found as ‘’rare’’ in samples: C-1, village of Goljanovci, 4,5m, 9.0m, 12.0m, 30.0m and 31.5m; C-14, village of Katina, 140.0145.0m, 183.0-190.0m. (Fig. 1) These levels come from diatom zone Concentrodiscus sp. (Ognjanova-Rumenova and Popova 1992), the Middle Pontian stage of Late Miocene age, corresponds to mammal zone MN-13 (Kojumdgieva et al. 1984, Spassov 2000), about 6 MA B.P. (Steininger and Wessely 2000). According to the hypothesis for the palaeoecological development of the Sofia Neogene basin – this was the first stage of the deposition of sediments of Novi Iskar Formation – an oligotrophic phase (Ognjanova-Rumenova and Popova 1996). ACKNOWLEDGEMENTS Nadja Ognjanova-Rumenova dedicates this paper to Prof. Dobrina Temniskova, who inspired me to study fossil diatoms and to thank her for our fruitful cooperation for many years. The authors acknowledge the help our colleague and friend, Prof. Dr. Dr. h. c. Horst Lange-Bertalot for the latin description of this new species, and also our colleague and friend Dr. Kurt Krammer for the numerous discussions of Cymbella species. REFERENCES HASLE, G. and G. FRYXELL 1970. Diatoms: Cleaning and mounting for light and electron microscopy. – Transaction of the American Microscopical Society, 89, 4: 469-474. KAMENOV, B. and E. KOJUMDGIEVA 1983. Stratigraphy of the Neogene in Sofia Basin. Palaeontology, stratigraphy and lithology. – Bulgarian Academy of Sciences, 18: 6985 (in Bulgarian). KOJUMDGIEVA, E., I. NIKOLOV and P. MEIN 1984. Les associations de grands mamifères du Miocene superieur en Bulgarie et leur correlation avec l’echelle regionale de la Paratethys. – Comptes rendus de l’Academie bulgare des Sciences, 37, 3: 341-343. KRAMMER, K. 2002. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats. (ed. Lange-Bertalot, H.) Vol. 3. Cymbella. 584 p., 194 pl. A.R.G. Gantner Verlag K.G. FL 9491 Ruggell. Distributed by Koeltz Scientific Books, Koenigstein. OGNJANOVA-RUMENOVA, N. 1991. Neogene diatoms from sediments of Sofia Valley and their stratigraphic significance. Ph.D. Thesis, Geological Institute, Bulgarian Academy of Sciences, 330 pp. (in Bulgarian).

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OGNJANOVA-RUMENOVA, N. and E. POPOVA 1992. Diatom biostratigraphy and comparative core correlation within Sofia basin, Bulgaria. in: J. Eder-Kovar, editor. Palaeovegetational development in Europe and regions relevant to its palaeofloristic evolution, Proceedings of the 1st Pan-European Palaeobotanical Conference, Vienna, 1991: 197-203. OGNJANOVA-RUMENOVA, N. and E. POPOVA 1996. Palaeolimnological reconstruction of the Sofia Neogene Basin, Southern Bulgaria – a review of palaeoenvironmental diatom studies. – Phytologia Balcanica, 2, 2:43-53. SCHRADER, H-J. 1973. Proposal for a standardized method of cleaning diatom bearing deep-sea and land-exposes marine sediments. – Beihefte zur Nova Hedwigia, 45: 403-409. SPASSOV, N. 2000. The Turolian Hipparion-fauna and the character of the environment in the Late Miocene of West Bulgaria. – Review of the Bulgarian Geological Society, 61, 1-3: 47-61. STEININGER, F. and G. WESSELY 2000. From the Tethian ocean to the Paratethys sea: Oligocene to Neogene stratigraphy, palaeogeography and palaeobiogeography of the circum Mediterranean region and the Oligocene to Neogene Basin evolution in Austria. Aspects of geology in Austria. – Mitt. Österr. Geol. Ges., 92 (1999): 95-116.

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Nitzschia toskalensis sp. nov. a new diatom (Bacillariophyceae) from the sediments of Toskaljavri, northwestern Finland Paul B. Hamilton1 & Jan Weckström2 Phycology Section, Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4 Canada, e-mail: [email protected] 2 Environmental Change Research Unit (ECRU), Department of Biological and Environmental Sciences, P.O. Box 65 (Viikinkaari 1), FIN-00014, University of Helsinki, Finland, e-mail: [email protected] 1

ABSTRACT Nitzschia toskalensis Hamilton & Weckström sp. nov. is identified and described from the Holocene sediments of Lake Toskal, northwestern Finland. The new species was observed sporadically in the sediments from present to 6500 cal. yr BP. Nitzschia toskalensis is a rare taxon (<1% abundance) with maximum numbers observed between 2000 – 3500 cal. yr BP. Valves linear-lanceolate (length 26-50 µm), strongly silicified with a distinctly rounded keel and large areolae. Present analogues to this taxon are found in Nitzschia amphibia sensu lato, but differ in raphe structure, keel morphology and areolae structure. Based on cooccurrences with Staurosirella pinnata, Pseudostaurosira pseudoconstruens and Pseudostaurosira brevistriata and association with stenothermic chironomids, it appears that Nitzschia toskalensis is a cold water stenotherm taxon living in oligotrophic waters. Key words: Nitzschia toskalensis sp. nov., Paleolimnology, Lake Toskal, northwestern Finland INTRODUCTION Holocene climate conditions derived from a variety of proxies have been instrumental in studying present day changes in climate due to natural and anthropogenic factors (Smol et al. 2001). Ecosystems, especially freshwater aquatic systems, north of the arctic-circle are sensitive to changing climatic conditions and recent research clearly shows that circumpolar 97

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freshwaters have changed over the last 150 years due to warming trends (Smol et al. 2005). More detailed paleolimnological studies on a regional scale have further shown more significant changes over the last 50-80 years indicating links to anthropogenic activities (e.g. Gajewski et al. 1997). Through these studies it is evident that identifying the flora and fauna and understanding the autecological signals that these taxa present is essential in attempts to further develop predictive models based on biological diversity. Rare or poorly identified taxa are often eliminated from analyses due to elevated statistical errors, which regrettable eliminate some important biological indicators, the species most susceptible to change. Potapova and Charles (2004) have effectively used rare taxa counts from North American stream and rivers to show significant decreases in numbers and species loss of “native” benthic taxa along gradients of human impact. From a paleoclimate reconstruction perspective, the possibly extinct and rare diatom species Nitzschia pseudosinuata Hamilton & Laird was an important paleolimnological indicator of temporal changes in the saline Moon Lake, U.S.A. 1840-2220 cal. yr BP (Laird et al. 1996, Hamilton and Laird 2001). Nitzschia sensu lato comprises a large number of diatom taxa historically placed in the genus based on the presence of a single character, the fibula (Mann 1986). It is recognized that the fibulae play a key role in maintaining a keel that is separated from the valve while allowing the keel to be connected to the main body of the valve through portulae. The structure of the central fibulae is also determined by the proximal raphe fissures (present/ absent) and the associated central area. Taxa within the subgenus Lanceolatae are defined by lanceolate, linear-lanceolate or sometimes oval valve forms, containing an eccentric folded keel and fibulae not projecting far onto the valve face (Cleve and Grunow 1880). Most species are epipelic, many are adapted to unstable environments (e.g. rivers) or are pollution-tolerant (Lowe 2003). The current paper, presents the description of a new species of Nitzschia within the subgenus Lanceolatae, which is rare in the paleolimnological record of Lake Toskal, northwestern Finland, but present in selected periods during lake evolution and regional climatic events. MATERIAL AND METHODS Lake Toskal (Toskaljavri, 69° 12' N, 21° 28' W, elevation 704 m) covers an area of ca. 100 ha in the north-western part of Finland close to the connecting boundaries of Sweden, Norway and Finland (Seppä et al. 2002, Table 1). The lake is situated in a wide flat valley underlain by metamorphosed fjell schist, except in the north part of the lake with dolomite (Seppä et al. 2002). The climate is characterized as arctic alpine, with alpine meadow vegetation surrounding most of the lake. The lake is typically free of ice from late June to early October. Extrapolated temperatures based on altitude, distance from coast and the nearest meteorological station (ca. 40 km) to the southwest suggest a July mean temperature of 9.7°C and a mean January temperature of -13.9°C (Seppä et al. 2002). Lake Toskal is an oligotrophic clear water lake with relatively high buffering capacity, when compared with other lakes in the area (Table 1). The pH is circumneutral (7.2) with 98

Nitzschia toskalensis sp. nov. a new diatom (Bacillariophyceae) from the sediments of Toskaljavri

calcium bicarbonate representing the primary buffering ion complex. Dissolved organic carbon (DOC) concentrations are low, indicative of low lake productivity and colour (platinum cobalt L5) readings further indicate that allochtonous humic material inputs to the lake are minimal. Vegetation around the lake is typical for north Finland, meadows, peat lands and upland heath communities (Hustich 1948, Hämet-Ahti 1963). In the wet meadows around the lake, woody plants are predominately Salix L. and Betula L. Other prominent vascular plants in these meadows include the genera Carex L., Geranium L., Ranunculus L., Rumex L. and Solidago L. In the drier areas the family Ericaceae along with the genera Betula, Empetrum L., Juniperus L. and Vaccinium L. dominate the vegetation (Haapasaari 1988, Seppä et al. 2002). Forests are absent immediately around the lake. Throughout the region forests are sparse and present at slightly lower elevations (600 m. a.s.l., Seppä et al. 2002). Betula pubescens ssp. tortuosa (Ledeb.) Nyman and Pinus sylvestris L. are the predominant regional forest species. One benthic core, representing 161 cm of sediment, was collected in April 1999, while the lake was still covered with ice. The core was taken from the deepest part of the lake (21.5 m) using a rod-less piston corer (Chambers and Cameron 2001). The core was then sectioned at 1 cm intervals and stored in Minigrip plastic bags. Eight accelerator mass spectrometry (AMS) dates of plant macrofossil remains were used to construct core Table 1. Summary of physical and chemical parameters for Lake Toskal. Samples collected in July 1998. PARAMETER

UNITS

Latitude Longitude Altitude Area Perimeter Catchment area Catchment/Area Loss on Ignition (LOI) Sampling depth Secchi pH Conductance Alkalinity Ca2+ K+ Na2+ Mg2+ DOC Color

(°N) (°E) (m a.s.l) (ha) (km) (ha) (ratio) (%) (m) (m) (units) (µS/cm) (mmol/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg(l) (PT mg/l)

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MEASURE 69.19 21.45 704.30 100.35 4.10 1432.58 14.28 14.29 21.50 7.00 7.20 39.00 0.32 4.14 0.19 0.69 1.92 0.92 L5

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chronology with a basal date at 159 cm of 9470 ± 200 14C cal. yr BP. A complete description of AMS dating for the core sections is presented in Seppä et al. (2002). Sediment samples for diatom analysis were digested using H2O2 and HCl (37%) and subsequently washed following the protocol of Weckström (2001). Cleaned material was dried onto cover slips and mounted on microscope slides using Naphrax®. LM studies were conducted using an Olympus BX40 microscope with Phase and DIC optics at 1000x magnification. For the Holocene climate reconstruction research (Seppä et al. 2002), diatoms were counted at 1 cm sediment intervals through the first 10 cm sections and subsequently counted at 2-3 cm intervals for the remaining downcore sections. This counting strategy gives a resolution of ca. 60 years per interval for the first 10 cm and 120180 years per interval for the remaining core sections. From each sample at least 500 valves were counted. A modern diatom-water chemistry calibration set comprising 109 lakes in northern Fennoscandia (Weckström 2001) was used to reconstruct the pH history of Lake Toskal (Seppä et al. 2002). The model produced a root mean square error of prediction (RMSEP) of 0.31 pH units (r2 = 0.68) with a maximum bias of 0.34 pH units between measured and predicted values. For diatom analyses selected sediments containing the new species from sections 20-22 cm and 44-45 cm representing ca. 1100 cal. yr BP and 2600 cal. yr BP respectively, were digested using 50:50 nitric:sulfuric acid and subsequently washed following the protocol of Hamilton et al. (1990). Cleaned material was dried onto cover slips and mounted on microscope slides using Hyrax®. LM studies were conducted using a Leica DMR microscope with Phase, DIC and RIC optics: 40x: Plan Apo HCX 40/1.25 and 100x: Plan Apo HCX 100/1.35 objectives. Selected specimens from the Holotype and Isotype slides were circled using a Leica diamond scriber. The type material and slides are deposited in the Canadian Museum of Nature (CANA) and the Academy of Natural Sciences of Philadelphia (ANSP) diatom collections. Additional isotype slides are kept by J. Weckström at the Department of Biological and Environmental Sciences, University of Helsinki, Finland. Samples for SEM study were filtered on either 8.0 or 0.8 µm filter papers and mounted on aluminum stubs using double sided carbon tape. The stubs were coated with a 300-500 Å layer of gold and examined with an Environmental SEM (ESEM), FEI model 20 at 5-25 KV under high vacuum. A total of fifty-four valves of the new taxon were measured from LM and SEM observations. Terminology used to describe morphological structures follows Ross et al. (1979). RESULTS AND DISCUSSION Nitzschia toskalensis Hamilton & Weckström sp. nov. (Figs 1-37) Frustula solitarii. Valvae lineares-lanceolati cum attenuatis acute rotundatis apicibus. Valva superficies transapice undulata. Carina secus valvae marginem distincta, elevata et rotunda. Duo series aliquantum grandium rotundarum aerolarum in carina. Raphe in siliqua porca inter grandes areolas. Raphe filiformis, continua et terminales fissurae uncinâns circa apicem in mantello.

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Longitudo 29-51 µm, latitudo 4-5 µm, 16-18 striae/10 µm. Striae parallelae ad leviter radiatae ubique. Aerolae 11-14/10 µm, rotundi ad elliptici pori 0.17-0.25 µm in diametro. Hymenii positio in areola approximata ad internam valvae superficiem. Areolae in margine oppositae carinae, locatae in ellipticis depressiibus. Valvae margo oppositus canalis raphis cum angusta porca. Fibulae graviter siliceae; fibula singulares costa vel saepe duo costae connatae simul in media formare “x”. Portula rotunda. Chloroplasti forma ignota. Comparâ cum Nitzschia amphibia Grunow 1982.

Frustules solitary. Valves linear-lanceolate with attenuated acutely rounded apices. Valve surface transapically undulate. Keel along valve margin distinct, elevated and round. Two rows of somewhat large round areolae on keel. Raphe on silica ridge between large areolae. Raphe filiform, continuous and terminal fissures hooking around the apex on

1

2

3

4

Figs 1-4. Nitzschia toskalensis nov. sp. Triple circled Holotype specimen, Lake Toskal, sediment from lake bottom, 20-22 cm below sediment surface, CANA 77895. Fig. 1. Bright field image of whole valve. Keel distinct with expanded portulae opening at apex. Fig. 2. Phase contrast showing large areolae, sometimes interrupted. Fig. 3. Reflective interference contrast showing the smaller internal openings of the areolae. Fig. 4. Defractive interference contrast (DIC) optics showing a series of costae-like thickenings on the opposite side of the valve away from the keel. Magnification 2000X. Scale bar = 10 µm.

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mantle. Valves 26-50 µm long, 3.5-5 µm wide, 15-18 striae/10 µm. Striae parallel to slightly radiate throughout. Areolae 11-14/10 µm, round to elliptical pores 0.17-0.25 µm in diameter. Hymen positioned in areolae close to internal valve face. Areolae on margin opposite keel, located in elliptical depressions. Valve margin opposite canal raphe with 5

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9 10

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Figs 5-18. Nitzschia toskalensis nov. sp. Selected Isotype specimens circled, Lake Toskal, sediment from lake bottom, 20-22 cm below sediment surface, CANA 77895. Size diminution series for valves using bright field, phase contrast and DIC optics. Figs 13, 17. Fibula thick and often appears in a “X” pattern (arrow). Magnification 1500X. Scale bar = 10 µm.

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Nitzschia toskalensis sp. nov. a new diatom (Bacillariophyceae) from the sediments of Toskaljavri

narrow ridge. Fibulae heavily silicified; fibula a single rib or frequently two ribs fused together in the middle to form an “X”. Portulae round. Chloroplast shape unknown. Compare with Nitzschia amphibia Grunow 1862. Holotype: CANA slide 77895, triple circled around valve (Figs 1-4). Isotype: CANA slide 77895, circled valves (see Figs 5-18). ANSP slide ANSP G.C. 14442, 4 circled valves. Locus typicus: Lake Toskal, northern Finland (69° 12' N, 21° 28' W). Type material: dry sediments from sediment core depth 20-21 cm, (CANA 77895). Collectors: J. Weckström, A. Korhola, M. Rautio, S. Sorvari and C. Dalton. Collection Date: August 1999. Nitzschia toskalensis is a member of the subgenus Lanceolatae. The linear-lanceolate valve form of N. toskalensis represents the dominant shape for taxa within the family and has created much confusion in identifications. The presence or absence of proximal raphe fissures and widely spaced central fibulae significantly helps in LM studies to separate taxonomic groups. Nitzschia toskalensis is similar to taxa within the Nitzschia amphibia complex, but is easily distinguished by a continuous raphe (i.e. no proximal raphe fissures and no widely space central fibulae). In SEM, N. amphibia has two rows of areolae adjacent to the raphe, but the areolae are not rimmed and have a cribra (Lange-Bertalot 1993, pl. 124, Fig. 1). The fibulae of N. amphibia are forked and extend well onto the internal valve face (Lange-Bertalot 1993, pl. 124, Fig. 2). Nitzschia frauenfeldii (Grunow) Grunow in Cleve & Grunow (= N. amphibia f. frauenfeldii (Grunow) Lange-Bertalot in Lange-Bertalot and Krammer is the most similar in valve form, surface relief, apparent marginal ridge opposite the keel and fibulae construction (i.e. the “X” formation), but the more linear shape, presence of widely spaced central fibulae and higher areolae density (see Lange-Bertalot and Krammer 1987, plate 37, Figs 17, 18, Grunow collection # 617 Tahiti, Lake Wahiria type preparation) separates this taxon from N. toskalensis. Also compare with N. amphibioides Hustedt from Lake Matano and Lake Towuti (Sulawesi, Indonesia), with continuous raphe and enlarged areolae (Simonsen 1987). Nitzschia toskalensis is separated from N. amphibioides by valve shape, size and fibulae forming extensions onto the valve face. Nitzschia dealpina Lange-Bertalot & Hofmann is not similar in shape, but has a continuous raphe and two rows of large areolae on the keel (Lange-Bertalot 1993, pl. 115, Figs 1-4). In SEM, the round keel of N. toskalensis is elevated from the valve face with enlarged rimmed areolae adjacent to the raphe (Figs 23-26). The raphe is positioned on a thickened ridge on the keel (Figs 20, 23, 28). The thickened ridge terminates just prior to the apex (Figs 24, 28). The ridge on the opposite margin to the keel (Figs 23, 25, 27) is narrow with a rounded upper surface. Areolae adjacent to this margin are situated in linear depressions between costae-like ridges (Figs 19, 24, 25, 26). In LM using DIC optics, these depressions can also be observed (Fig. 4). Areolae on the valve face are unevenly spaced sometimes creating interruptions in the striae pattern (Figs 10-11, 14-15). Each areola contains a hymen which is approximately ½ way between the outer and inner foramina (Figs 25, 26, 31, 34, 37). The hymens are fine poroid plates (Figs 25, 26, 37 arrow). Internally the fibulae of N. toskalensis can vary from one rib (Figs 32, 33) to two ribs that merge in the middle to form the “X” mentioned earlier (Figs 2, 8, 31-34). When fibular ribs merge, the areolae between the ribs on the mantle appear to become isolated from the 103

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19

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21 23

24

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28 27

29 Figs 19-29. Nitzschia toskalensis nov. sp. SEM, external valve views. Type material, Lake Toskal, sediment from lake bottom, 20-22 cm below sediment surface, CANA 77895. Figs 19-22. Whole valves showing flat and tilted projections. Fig. 23. Tilted specimen showing the undulating valve surface with well developed round keel on one margin and thickened ridge on the opposite margin. The raphe is continuous (no proximal raphe fissures) and positioned on a siliceous ridge. Fig. 24. Apex, slightly capitate to rounded, keel with a single row of large rimmed areolae on either side of the raphe (arrow). Figs 25-26. Valve surface. Areolae with a recessed hymen plate, some broken (arrow). Areolae on the opposite side of the valve from the keel are positioned with an elongated depression with costae-like ridges. (double arrow). Fig. 27. Apex showing the silica ridge on the margin opposite the keel. Figs 28, 29. Apex. Terminal raphe fissure extends down onto the mantle and runs across the apex, deflecting up at the termination point. Figs 19-22, scale bars = 10 µm. Figs 23-24, scale bars = 2 µm. Figs 25-29, scale bars = 1 µm.

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areolae aligned with the portulae (Figs 31-34). The areolae within the striae are simple pores positioned between thickened costae (Fig. 35). Areolae on the valve face close to the keel are sloped towards the portulae (Figs 32, 33), giving the appearance in non-tilted view to be linked to the portulae (Fig. 31). The apex is enclosed by silica creating an internal circular opening (Figs 4, 6, 36). The helictoglossa is small, positioned on the upper edge of the mantle and difficult to discern (Fig. 36). 30

32

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35 Figs 30-37. Nitzschia toskalensis nov. sp. SEM, internal valve views. Type material, Lake Toskal, sediment from the lake bottom, 20-22 cm below sediment surface, CANA 77895. Fig. 30. Whole valve. Figs 3134. Internal views (flat and tilted projections) showing the “X” pattern of the fibulae (arrow), a simple fibula (double arrow). Each fibula merges onto two, sometimes three interstriae. Fig. 35. Valve fracture showing poroid areolae (not chambered) positioned between interstriae (arrow). Fig. 36. Apex with a small almost indistinct helictoglossa. Fig. 37. Hymen positioned within areola (arrow). Fig. 30, scale bar = 10 µm. Fig. 31, scale bar = 2 µm. Figs 32-37, scale bars = 1 µm.

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Loss on ignition (LOI) data suggests that the organic input to the lake has varied between 12 and 16% throughout the Holocene [except for a short-term drop to ca. 5 % around 4800 cal. yr BP] most probably due to a strong avalanche or a slush flow from the catchment area (Seppä et al. 2002) indicating a relatively stable sedimentation environment. A total of 248 taxa representing 38 genera were identified in the Holocene core of Lake Toskal. Nitzschia toskalensis was found in low numbers (<1% abundance) from present day to approximately 6500 cal. yr BP and was absent from the early Holocene record (Fig. 38). The maximum numbers observed were ca. 2500 cal. yr BP. When N. toskalensis was most abundant, the dominant taxa were Staurosirella pinnata (Ehrenberg) Williams & Round, Pseudostaurosira pseudoconstruens (Marciniak) Williams & Round, Pseudostaurosira brevistriata (Grunow in Van Heurck) Williams & Round and Aulacoseira subarctica (O. Müller) Haworth (type 1/long form). Less abundant but common species include Cyclotella schumanni (Grunow) Håkansson, Achnanthidium minutissimum (Kützing) Czarnecki and Achnanthes suchlandtii Hustedt. The dominant diatom species S. pinnata, P. pseudoconstruens and P. brevistriata are often associated with cooler climate conditions (e.g. Smol 1988, Joint and

Fig 38. Relative occurrence of Nitzschia toskalensis in the sediments of Lake Toskal throughout the Holocene.

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Wolfe 2001). These taxa were also found to be dominant during 2000-3500 cal. yr BP in a tundra high Arctic Canadian lake (LeBlanc et al. 2004). LeBlanc et al. (2004) and Wolfe (2000) have also discerned that this was one of the colder periods during the Holocene. The diatom inferred pH in Lake Toskal at the time of peak abundance was slightly above 7. When N. toskalensis first appears (ca. 6500 cal. yr BP), Pinus sylvestris and Betula spp. were declining from peak periods of growth (7000 and 9500 cal. yr BP) and Ericaceae meadow influxes were peaking (Seppä et al. 2002). At the time when N. toskalensis was most abundant (ca. 2700 cal. yr BP), P. sylvestris and Betula spp. were again in decline with influx rates less than 200 pollen grains cm-2 yr-1 compared to peak pollen influx levels of 600-900 grains cm-2 yr-1 during the early Holocene. The terrestrial vegetation at 2700 cal. yr BP can be described as dry oligotrophic heaths (Ericaceae-type), which was slowly changing to present day moister alpine vegetation characterized by Salix spp., Carex spp. and Sphagnum spp. (Seppä and Birks 2002, Seppä et al. 2002). Throughout the lake sediment core the chironomid record was dominated by cold stenotherms (e.g. Constempellina brevicosta (Edwards), Sergentia Kieffer spp., Heterotrissocladius brundini Saether & Schnell, Micropsectra insignilobus Kieffer and Corynocera oliveri Lindeberg (Seppä et al. 2002). At the time when N. toskalensis was most abundant, the chironomid fauna and the diatom flora both indicate cooler climatic conditions similar to alpine and circumpolar arctic conditions (Walker et al. 1991, Joint and Wolfe 2001, Bouchard et al. 2004). Thus, the recent declines in the dominant diatom taxa along with lower numbers of N. toskalensis are likely a reflection of changing regional weather patterns. ACKNOWLEDGMENTS We would like to thank Catherine Dalton, Atte Korhola, Milla Rautio and Sanna Sorvari for help in the field sampling. The financial support for JW was provided by the EC Environment and Climate Research Programme; Contract ENV4-CT97-0642 and The Academy of Finland, Contract 204291. This research was also funded by a Biological Sciences RAC-2004 grant to PBH from the Canadian Museum of Nature. REFERENCES BOUCHARD, G.K., K. GAJEWSKI and P.B. HAMILTON 2004. Freshwater diatom biogeography in the Canadian Arctic Archipelago. - J. Biogeogr., 31: 1955-1973. CHAMBERS, J.W. and N. CAMERON 2001. A rod-less piston corer for lake sediments: an improved rope-operated percussion corer. - J. Paleolim., 25: 117-122. CLEVE, P.T. and A. GRUNOW 1880. Beiträge zur Kenntnis der arktischen Diatomeen. Kongl. Svenska Vetensk. Acad. Handl., 17: 1-121, 7 pls. GAJEWSKI, K., P.B. HAMILTON and R. MCNEELY 1997. A high resolution proxy-climate record from an arctic lake with annually-laminated sediments on Devon Island, Nunavut, Canada. - J. Paleolim., 17: 215-225. 107

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HAAPASAARI, M. 1988. The oligotrophic heath vegetation of northern Fennoscandia and its zonation. - Acta Bot. Fenn., 135: 1-219. HÄMET-AHTI, L. 1963. Zonation of the mountain birch forests in northern Fennoscandia. Ann. Bot. Soc. “Vanamo”, 34: 1-127. HAMILTON, P.B. and K.R. LAIRD 2001. Nitzschia pseudosinuata sp. nov., a new Holocene diatom from the sediment of Moon Lake, North Dakota, U.S.A. – Diatom Res., 16: 317-324. HAMILTON, P.B., M. POULIN and M.C. TAYLOR 1990. Neidium alpinum var. quadripunctatum (Hustedt) comb. nov., an important acidobiontic taxon from northeastern North America. - Diatom Res., 5: 289-299. HUSTICH, I. 1948. The scotch pine in northern Finland and its dependence on the climate in the last decades. - Acta Bot. Fenn., 42: 1-75. JOINT, E.H. and A.P. WOLFE 2001. Paleoenvironmental inference models from sediment diatom assemblages in Baffin Island lakes (Nunavut, Canada) and reconstruction of summer water temperature. - Can. J. Fish. Aquat. Sci., 58: 1222- 1243. LAIRD, K.R., C.S. FRITZ, K.A.MAASCH and B.F. CUMMING 1996. Greater drought intensity and frequency before AD 1200 in the Northern Great Plains, USA. – Nature, 384: 552-554. LANGE-BERTALOT, H. 1993. 85 Neue Taxa und über 100 weitere neu definierte Taxa ergänzend zur Süßwasserflora von Mitteleuropa Vol. 2/1-4. – Biblioth. Diatomol., 27: 1- 454. LANGE-BERTALOT, H. and K. KRAMMER 1987. Bacillariaceae Epithemiaceae Surirellaceae Neue und wenig bekannte Taxa, neue kombinationen und synonyme sowie Bemerkungen und Ergänzungen zu den Naviculaceae. – Biblioth. Diatomol., 15: 1-289. LEBLANC, M., G. GAJEWSKI and P.B. HAMILTON 2004. A diatom-based Holocene paleoenvironmental record from a mid-arctic lake on Boothia Peninsula, Nunavut, Canada. – The Holocene, 14: 423-431. LOWE, R.L. 2003. Keeled and canalled raphe diatoms. in: J.D.Wehr and R.G. Sheath, editors. Freshwater Algae of North America: 669-683. - Academic Press, New York. MANN, D.G. 1986. Nitzschia Subgenus Nitzschia (notes for a monograph of the Bacillariaceae, 2). in: M.Richard, editor. Proceedings of the 8th International Diatom Symposium: 215-226. Koeltz Scientific Books, Koeningstein. POTAPOVA, M. and D.F. CHARLES 2004. Potental use of rare diatoms as environmental indicators in U.S.A. rivers. in: M.Poulin, editor. Proceedings of the 17th International Diatom Symposium: 281-295. Biopress Limited, Bristol. ROSS, R., E.J.COX, N.I. KARAYEVA, D.G.MANN, T.B.B. PADDOCK, R. SIMONSEN and P.A. SIMS 1979. An amended terminology for the siliceous components of the diatom cell. Nova Hedwigia, Beih. 64: 513-533. SEPPÄ, H. and H.J.B. BIRKS 2002. Holocene climate reconstructions from the Fennoscandian tree-line area based on pollen data from Toskaljavri. - Quarternary Res., 57: 191-199.

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SEPPÄ, H., M. NYMAN, A. KORHOLA and J. WECKSTRÖM 2002. Changes of treelines and alpine vegetation in relation to post-glacial climate dynamics in northern Fennoscandia based on pollen and chironomid records. - J. Quarternary. Sci., 17: 287-301. SIMONSEN, R. 1987. Atlas and catalogue of the diatom types of Friedrich Hustedt. Vol. l: Catalogue. p. 1-525. Vol. 2: Atlas, pls. 1-395. Vol. 3: Atlas, pls. 396-772. - J. Cramer, Stuttgart, Germany. SMOL, J.P. 1988. Paleoclimate proxy data from freshwater arctic diatoms. - Verh. Int. Ver. Limnol., 23: 837-844. SMOL, J.P., J. BIRKS and W.M. LAST 2001. Tracking Environmental Change Using Lake Sediments: Biological Techniques and Indicators (Volume 2), - Kluwer Academic Publishers, Dordrecht. 300 pp. SMOL, J.P., A.P. WOLFE, H.J.BIRKS, M.S.V.DOUGLAS, V.J.JONES, A.KORHOLA, R.PIENITZ, K.RÜLAND, S. SORVARI, D. ANTONIADES, S.J. BROOKS, M.-A. FALLU, M. HUGHES, B.E.KEATLEY, T.E. LAING, N. MICHELUTTI, L. NAZAROVA, M. NYMAN, A.M. PATERSON, B. PERREN, R. QUINLAN, M. RAUTIO, E.SAULINER-TALBOT, S. SIITONEN, N. SOLOVIEVA and J. WECKSTRÖM 2005. Climate regime shifts in the biological communities of arctic lakes. - Proc. Natl. Acad. U.S.A., 102: 4397-4402. WALKER, I.R., J.P. SMOL, D.L. ENGSTROM and H.J.B. BIRKS 1991. An assessment of Chironomidae as quantitative indicators of past climatic change. - Can J. Fish. Aquat. Sci., 48: 975-987. WECKSTRÖM, J. 2001. Assessment of diatoms as markers of environmental change in northern Fennoscandia. Ph.D. thesis, University of Helsinki. 66 pp. + app. WOLFE, A.P. 2000. A 6500-year diatom record from southwest Fosheim Peninsula, Ellesmere Island, Canadian High Arctic. in: M. Garneau and B.T. Alt, editors. Environmental response to climate change in the Canadian High Arctic. Geological Survey of Canada Bulletin, 529: 249-256.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 111-121) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Distribution of resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Bacillariophyta) in sediments of peat bogs from Mt. Central Sredna Gora, Bulgaria Rosalina Stancheva Department of Botany, Faculty of Biology, St. Kliment Ohridski University of Sofia, D. Tsankov Blvd 8, 1164 Sofia, Bulgaria Present address: Environmental Science and Resources, Portland State University, 1719 SW 10th Ave., Portland, OR 97207, U.S.A. E-mail: [email protected] ABSTRACT Resting spores of Eunotia soleirolii and Meridion circulare var. constrictum were found in the Holocene sediments from peat bogs, located in Mt. Central Sredna Gora (Bulgaria). Scanning electron microscopy observations of the resting spores of M. circulare var. constrictum are presented here. Distribution and paleoecological significance of the resting spores of E. soleirolii and M. circulare var. constrictum are discussed. Key words: Diatoms, resting spores, peat bogs, paleoecology, Holocene INTRODUCTION Resting spores, also called “hypnospores”, “double valves”, “inner septae”, “inner thecae”, or “double thecae” (Krammer and Lange-Bertalot 1986) are heavily silicified stages in the cycles for many diatoms. In most taxa, the formation of resting spores is vegetative (Round et al. 1990). They provide survival mechanisms during periods of environmental extreme and are common in many marine neritic centric diatoms (Hargraves and French 1983). The occurrence of diatom resting spores in fresh water is limited to a few centric and pennate taxa (von Stosch and Fecher 1979). The centric species belong to Urosolenia Round 111

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& Crawford, Acanthoceras Honigmann (Edlund and Stoermer 1993), Aulacoseira Thwaites (Edlund et al. 1996), and inland Chaetoceros Ehrenberg (Rushforth and Johansen 1986). Spore formation as a perennation strategy may have a role in the annual cycle of these planktonic species in some lakes (Lund 1954, Edlund and Stoermer 1993, Edlund et al. 1996). The resting spores of Chaetoceros are commonly preserved in saline lacustrine sediments and have proven to be excellent paleolimnologic indicators of higher lake salinity levels (Fritz and Battarbee 1988). The observed freshwater pennate diatoms that form resting spores are restricted to Achnanthes taeniata Grunow, Diatoma anceps (Ehrenberg) Kirchner, Meridion circulare (Greville) Agardh, Eunotia faba Ehrenberg, E. pectinalis (Dillwyn) Rabenhorst, E. soleirolii (Kützing) Rabenhorst, Nitzschia grunowii (Cleve) Hasle (Hargraves and French 1983, Round et al. 1990, McQuoid and Hobson 1996). Most of the freshwater species forming resting spores are widely distributed in temperate latitudes (Hargraves and French 1983) and especially those whose natural habitats are soil and rock can survive desiccation for a long time (Round et al. 1990). This study is focused on the resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Ralfs) Van Heurck, which were identified in the Holocene sediments of mountain peat bogs. Literature data on the forming of the resting stages of M. circulare var. constrictum are completely missing, and information for distribution of E. soleirolii and M. circulare resting spores is scarce (Hustedt 1930, Cleve-Euler 1953, Geitler 1971). According to Hustedt (1930) finding resting spores of those two diatoms in natural habitats is very rare. Geitler (1953, 1963) investigated the development of the “Innenschalen” in E. soleirolii and M. circulare cytologically. Von Stosch and Fecher (1979) studied in vivo events leading up to spore formation and subsequent spore germination in E. soleirolii and considered that conditions for forming resting spores are generally unfavorable for growth. The resting spores are able to survive years of dormancy and have greater viability than vegetative cells under conditions of darkness, temperature extreme and desiccation. The investigations on diatom record of Holocene sediments from peat bogs, located in Mt. Central Sredna Gora (Stancheva 2001 a, b, 2003, Stancheva and Slavchova 2002, Stancheva and Temniskova 2003, 2004) led to finding in some of them of resting spores of E. soleirolii and M. circulare var. constrictum. The purpose of this paper is to describe the distribution and paleoecological significance of the resting spores of E. soleirolii and M. circulare var. constrictum in the Holocene sediments of the investigated mountain peat bogs. MATERIALS AND METHODS Material was obtained from 150-0 cm cores at Bogdan-3; 80-0 cm cores at Bogdan-6; 70-0 cm cores at Shiligarka; 100-0 cm cores at Koznitsa-2 and 70-0 cm cores at Barierata. Five investigated peat bogs are located in Mt. Central Sredna Gora at an altitude between 10001550 m (Stancheva and Temniskova 2004). Mt. Sredna Gora is south of the Balkan Range and Rearbalkan valleys, with a predominantly West-East orientation. It is in the European Deciduous Forests Zone, the Balkan (Illyrian) Province (Bondev 2002). 112

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The cores were taken with a Dachnowsky-type corer, with camera diameter of 2 cm. The absolute age of the sediments from Bogdan-6 was 10025±225 BP (80-70 cm); Bogdan3 was 8115±100 BP (135-125 cm) and Shiligarka was 5285±180 BP (60-55 cm). Radiocarbon dating of the sediments was carried out at the 14C und 3H Laboratorium, Niedersächisches Landesamt für Bodenforschung in Hannover, Germany (Filipovitch et al. 1998). The cores from Barierata and Koznitsa-2 were of Subboreal/Subatlantic age in accordance with the data from pollen analysis (Filipovitch et al. 1998). The samples for diatom analysis were collected at 1-2 cm intervals. Laboratory processing followed the technique of Hasle and Fryxell (1970), as modified by OgnjanovaRumenova (1991). Microscopic slides for LM were prepared according to Gleser et al. (1974). For SEM investigation, the material was covered with a 50 nm gold coating. An “Amplival” photomicroscope with oil immersion objective 100 x and Jeol JSM–5510 scanning electron microscope were used. Quantitative analysis followed the standard percentage counting technique of Battarbee (1986), with 500 valves counted for each slide. Resting spores were counted together with the valves of the normal vegetative cells. pH reconstruction is based on Index B of Renberg and Hellberg (1982). Nomenclature followed mainly Krammer and Lange-Bertalot (1986 - 1991) and Round et al. (1990). Nonmetric multidimensional scaling (NMDS) was used to ordinate the samples from peat bog sediments, and to show the distributional patterns of E. soleirolii, M. circulare var. constrictum in the sediment cores. The NMDS includes all diatoms with relative abundance greater than 0.2% in three or more samples (a total 161 species, varieties, and forms). NMDS analysis was used to ordinate the diatoms with relative abundance above 10% in at least one sample (a total 25 species and varieties) too. The NMDS analysis was performed with the computer program PRIMER v. 5 (Clarke and Warwick 2001). RESULTS Meridion circulare var. constrictum was widely distributed in different levels of all five cores in the range of 0.2-37% relative abundance. In those cores, diatom-inferred pH values ranged from 5.2 to 6.4. Meridion circulare was found in the sediments of Koznitsa-2 only. In the initial stage of development of Koznitsa-2 peat bog (50-100 cm) M. circulare and M. circulare var. constrictum had maximum relative abundance of 12% and 37% respectively. Both taxa have biostratigraphic importance for distinguishing diatom assemblage zones in the core Koznitsa-2. During the latest stages of Koznitsa-2 peat bog, abundance of M. circulare continuously decreased, and in the upper 12 cm, was completely absent. M. circulare var. constrictum dominated in the upper 17 cm of the sediments. Resting spores of M. circulare var. constrictum were present in a few samples (0, 4, 6, 9, 12, 15, 17 cm) in the range of 0.6-2.8% relative abundance and were count together with normal vegetative valves. A single resting spore of M. circulare var. constrictum was also indentified in core Bogdan-6 (40 cm). E. soleirolii was distributed in the sediments of two peat bogs, Shiligarka and Barierata. The relative abundance of E. soleirolii was highest (16%) and resting spores were present in the bottom layers of the sediment core from Shiligarka peat bog (60-53 cm, age 5285 BP). 113

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The initial stage of development of this peat bog displayed a rich and diverse diatom flora. For the sediment levels with E. soleirolii diatom-inferred pH values ranged from 5.6 to 6.2. Later, at the end of the Atlantic and at the beginning of Subboreal climatic period (50 – 20 cm), the abundance of diatoms gradually decreased as did the number of taxa. At the last stage of the development of Shiligarka peat bog, E. soleirolii appeared only as several vegetative cells in few samples. In the core of Barierata, E. soleirolii was distributed in whole depth sediments with relative abundance 0.4 - 6.2%. In the upper 16 cm of the sediments (4, 10, 12, 15, 16 cm), both normal vegetative cells and resting spores were present. Figures 1 and 2 presented NMDS ordination diagram of the sediment samples. Minimum stress of 0.12 corresponds to a good ordination with 2-dimensional plot. The first ordination axis separated clearly samples from the five cores. The samples from Bogdan-3 and Bogdan-6 cores were located to the left on Axis I while samples from Koznitsa-2 core were located to the right on Axis I. Samples from the Barierata and Shiligarka cores were clustered in the middle of Axis I. Relative abundance of M. circulare var. constrictum, were positively correlated with Axis I (Fig. 1). The relative abundance of E. soleirolii was positively correlated with Axis II (Fig. 2). These data are in good agreement with ordination of the most frequently diatoms showed on Fig. 3. M. circulare var. constrictum was positively correlated with Axis I again. While E. soleirolii together with other diatoms, widely distributed in all cores were positively correlated with Axis II. In LM, diatom resting spores are easily distinguished from vegetative cells by their thickened, modified siliceous frustule. The spores of E. soleirolii and M. circulare var. constrictum are endogenous: the mature spore is completely enclosed within the parent cell. The fossilisation process led to separation of the external parent valves. Therefore, one or two of them can be absent, and the E. soleirolii resting spore appeared oval (Figs 6, 7). In the investigated sediments, resting spores of M. circulare var. constrictum (Figs 9, 13) were well preserved, but rare. Because of scanty of the material, the scanning electron microscopy investigations are incomplete. However, initial observations showed some specifics in the M. circulare var. constrictum resting spores. Thickened costae were absent on the internal valve surface of the resting spore, and there were only slight transversal undulations (Fig. 16). One normal rimoportula is present (Figs 16, 17). Areolae are simple, circular, and without vela, the same as normal vegetative thecae (Figs 14, 15). DISCUSSION While only relatively small morphological differences in the ultrastructure of resting spores, physiologically they have highly dissimilar to normal vegetative cells (Hargraves and French 1983). The resting spore is considered to be a cell with reduced metabolism, a reduced contact with the environment compared to the vegetative cell, and with the capability to survive conditions unfavourable to the vegetative cell (Hoban et al. 1980). Von Stosch and Fecher (1979) found that the resting spores of E. soleirolii differed in five respects from the vegetative cells: they are product of a distinctive and standardized development; the thecal morphology is different; the spores are rich in storage products, 114

Distribution of resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Bacillariophyta)

Figs 1-3. NMDS ordination diagrams. Fig. 1. Ordination of the samples from peat bog cores with relative abundance of Meridion circulare var. constrictum (Ralfs) Van Heurck. Fig. 2. Ordination of the samples from peat bog cores with relative abundance of Eunotia soleirolii (Kützing) Rabenhorst. Fig. 3. Ordination of the most frequently diatoms from peat bog cores. Legend: bt – core Bogdan-3; bs – core Bogdan-6; s - core Shiligarka; b - core Barieraia; k - core Koznitsa-2; Circles represent relative abundance of M. circulare var. constrictum and E. soleirolii, respectively; Aul – Aulacoseira; Cym - Cymbella; Eun - Eunotia; Frag - Fragilaria; Gom – Gomphonema; Hant – Hantzschia; Mer – Meridion; Pin – Pinnularia; Tab – Tabellaria.

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mainly oils; they are unable to germinate without a cold treatment. They are able to survive for at least three years as spores. According to Von Stosch and Fecher (1979) a number of external factors have been found to induce spore formation of E. soleirolii. These include high or low pH, high temperature (but not above 24ºC), and nutrient deficiencies (N, P, Fe, Si). E. soleirolii in nature thrives in the colder seasons and is induced to form resting spores by rising temperatures and perhaps N and P deficiencies. A similar seasonal cycle with spring spore formation occurs in cold-stenothermal species Meridion circulare.

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Figs 4-13. LM micrographs. Figs 4 - 8. Eunotia soleirolii (Kützing) Rabenhorst: Figs 4, 8. Valve face. Fig. 5. Girdle view of thecae of normal vegetative cell. Figs 6, 7. Girdle view of thecae with internal resting spore. Figs 9-13. Maridion circulare var. constrictum (Ralfs) Van Heurck: Figs 10, 11. Valve face. Fig. 12. Girdle view of thecae of normal vegetative cell. Figs 9, 13. Girdle view of thecae with internal resting spore. Scale bar=10 µm.

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This information can be facilitate paleoecological reconstruction of the local Holocene environmental conditions in the investigated peat bogs. The first record of the E. soleirolii and M. circulare var. constrictum resting spores were found in the sediments of age 5285 BP and 5060 BP, respectively. This period of the Bogdan-6 and Shiligarka peat bogs history was characterized by diverse diatom assemblages, which is related to the higher water level and good trophic conditions. In the diatom flora prevailed oligohalobous (indifferent and halophobous), acidophilous, ologotrophic, and oligo-mesotrophic species. 14

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Figs 14-17. SEM micrographs of Maridion circulare var. constrictum (Ralfs) Van Heurck. Fig. 14. External valve surface. Fig. 15. Internal valve surface of vegetative cell thecae with thickened costae. Fig. 16. Internal valve surface of resting spore thecae without thickened costae. Fig. 17. Same specimen as Fig. 16. Detail of the internal surface of resting spore thecae with rimoportula.

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North-alpine diatoms increase up to 25%, indicating relatively low water temperature. The ecological conditions favorable for this diatom community declined, and the appearance of E. soleirolii and M. circulare var. constrictum resting spores signal this event. The unfavorable conditions in the peat bogs, probably increased temperature and particular desiccation of the surface led to dormancy stage of those two cold-stenothermal diatoms (Von Stosch and Fecher 1979). The climatic change is reflected throughout the entire diatom community, and its development was gradually abated. In the sediments from this unfavorable period only single, fragmented valves of few benthic diatoms were preserved. The formation of the resting spores of E. soleirolii and M. circulare var. constrictum in the superficial sediments of Koznitsa-2 and Barierata peat bogs may indicate worsened local hydrological and trophic conditions at the latest stage of existing of both wetlands. Koznitsa-2 and Barierata peat bogs emerged about 4000 BP as a result of intensive seepage of underground water. Palynological data has shown a rise in humidity between 4000 and 2000 BP, which led to formation of many peat bogs in the Sredna Gora Mountain. (Filipovitch 1996). The entire Late Holocene history of these two peat bogs is characterized by a rich and specific diatom flora. For the initial stage of Koznitza-2 peat bogs, M. circulare and M. circulare var. constrictum were dominant in the diatom assemblage. M. circulare and M. circulare var. constrictum are epiphytic forms, characteristic of pure running waters in mountainous regions, which suggests that there was a flowing water in the peat-bog complex (Temniskova-Topalova and Ognjanova-Rumenova 1983). Later it leads to watercovered patches in the peat bog, with open water surfaces where the epiphytic and tychoplanktonic diatoms thrive. In these conditions tychoplanktonic species Fragilaria virescens Ralfs dominates with maximal relative abundance of 34%, M. circulare disappeared, and M. circulare var. constrictum decreased quantitatively. Fragilaria virescens and M. circulare var. constrictum are most important dominants only in the sediments of core Koznitza-2 that explain positively correlation of both taxa with Axis I on NMDS ordination diagram (Fig. 3). According to Van Dam et al. (1994), the only difference between ecological indicator values of M. circulare and M. circulare var. constrictum is in moisture preferences. Meridion circulare “never, or only very rarely, occurring outside water bodies”, while M. circulare var. constrictum “mainly occurring in water bodies, sometimes on wet places”. At the latest stage of development of Koznitsa-2 peat bog, M. circulare var. constrictum formed resting spores, which indicates drying and probably poor water trophic content. In the same starigraphic level increased presence of aerophilous diatoms and representatives of genus Caloneis Cleve, developing on mosses in highalpine swamps - C. lauta Carter & Bailey-Watts, C. pulchra Messikommer, C. tenuis (Gregory) Krammer (Krammer and Lange-Bertalot 1986). The latest stage of history of Barierata peat bog is characterized by resting spores of E. soleirolii. According to Round et al. (1990) the resting spores ability to withstand periods of drought redundant, is a prerequisite for terrestrial life. The presence of E. soleirolii resting spores is in good agreement with the finding of a high abundance of aerophilous diatoms (20 – 22% of diatom flora), which suggests particular desiccation of the peat bog surface. On the other hand, in the same level of sediments, the last maximum of development of the tychoplanctonic species Aulacoseira alpigena (Grunow) Krammer, A. tenuior (Grunow) Krammer and Tabellaria flocculosa (Roth) Kützing that inhabit patches of 118

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open surface water, were found. Wetlands are ecosystem in which the soil, despite periodic fluctuations in water level, is more or less continuously saturated (Goldsborough and Robinson 1996) and their mosaic structure provided different ecological conditions for algal assemblages. The formation of the resting spores of E. soleirolii is a common phenomenon, linked with seasonal cycles (Hustedt 1930, Von Stosch and Fecher 1979). This conclusion is supported by this study, where vegetative cells and resting spores of E. soleirolii are found simultaneously in two of five sediment cores. Forming resting spores in M. circulare var. constrictum can be considered more likely as a response to unfavourable hydrological conditions rather than a seasonal effect in paleoecological analysis. The mountain wetland ecosystems are very sensitive to local climatic changes, and the sediment record of diatom resting spores can be applied as an indicator in water level reconstructions. ACKNOWLEDGEMENTS I am very grateful to Dr. Y. Pan from Environmental Science and Resources, Portland State University for valuable consultations in data analysis. I wish to thank to Nikola Dimitrov from the Scanning Electron Microscopy Laboratory, Chemical Faculty of St. Kliment Ohridski University of Sofia for his assistance in the course of investigations. REFERENCES BATTARBEE, R. 1986. Diatom analysis. in: B. Berglund, editor. Handbook of Holocene Palaeoecology and Palaeohydrology: 527-570. John Wiley Sons, London. BONDEV, I. 2002. Vegetation – Geobotanic regioning. in: M. Yordanova and D. Donchev, editors. Geography of Bulgaria. Physical and socio-economic geography: 336-352. ForCom, Sofia. (in Bulgarian). CLARKE, K. and R. WARWICK 2001. Change in marine communities: an approach to statistical analysis and interpretation, Plymouth Marine Laboratory, PRIMER-E: Plymouth. CLEVE-EULER, A. 1953. Die Diatomeen von Schweden und Finnland. - Konglica Svenska Vetenskapsakademiens Handlingar, Serie 4/1: 1-158. Almqvist & Wiksells, Stockholm. EDLUND, M. and E. STOERMER 1993. Resting spores of the freshwater diatoms Acanthoceras and Urosolenia. – J. Paleolimnol., 9:55-61. EDLUND, M., E. STOERMER and M. TAYLOR 1996. Aulacoseira skvortzowii sp. nov. (Bacillariophyta), a poorly understood diatom from Lake Baikal, Russia. – J. Phycol., 32: 165-175. FILIPOVITCH, L. 1996. Type region Bg–d, Stara planina and Sredna Gora Mountains. in: Berglund B., H. J. B. Birks, M. Ralska-Jasieviczowa and H. E Wrigth, editors.

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Palaeoecological Events during the Last 15 000 Years: 715-718. John Wiley Sons, Chichester. FILIPOVITCH, L., M. LAZAROVA, I. STEFANOVA and M. PETROVA 1998. Development of vegetation in Mt. Sredna Gora during the Holocene. – Phytol. Balc., 4(3): 13-29. FRITZ, S. and R. BATTARBEE 1988. Sedimentary diatom assemblages in freshwater and saline lakes of Northern Great Plains, North America: Preliminary results. in: F. Round, editor. Proceedings of the Ninth International Diatom Symposium. Biopress, Ltd., Bristol, Koeltz, Koenigstein: 265-271. GEITLER, L. 1971. Die inäquale Teilung bei der Bildung der Innenshalen bei Meridion circulare. - Österr. Bot. Z., 119: 442-446. GLESER, S, A. JOUSE, I. MAKAROVA, A. PROSCHKINA-LAVRENKO and V. SHESHUKOVAPORETZKAJA 1974. The diatoms of the USSR. Fossil and recent. I. - Nauka, Leningrad. (in Russian) GOLDSBOROUGH, G. and G. ROBINSON 1996. Pattern in Wetlands. in: R. Stevenson, M. Bothwell and R. Lowe, editors. Algal Ecology. Freshwater Benthic Ecosystems: 78109. Academic Press, Inc., San Diego. HARGRAVES, P. and F. FRENCH 1983. Diatom resting spores: significance and strategies. in: G. Fryxell, editor. Survival Strategies of the Algae: 49-58. Cambridge University Press, New York. HASLE, G. and G. FRYXELL 1970. Diatoms: Cleaning and mounting for ligth and electron microscopy. – Trans. Amer. Microscop. Soc., 89( 4): 469-474. HOBAN, M., G. FRYXELL and K. BUCK 1980. Biddulphioid diatoms: resting spores in antarctic Eucampia and Odontella. – J. Phycol., 16: 591-602. HUSTEDT, F. 1930. Die Kieselalgen Deutschlands, Österreichs und der Schweiz. – Rabenhorst Kryptogamen-Flor von Deutschlands, Österreichs und der Schweiz. Band VII/1: 1-920. Reprinted by Koeltz Science Publishers, Koenigstein. KRAMMER, K. and H. LANGE-BERTALOT 1986-1991. Bacillariophyceae. in: H. Ettl, J. Gerloff, H. Heyning and D. Mollenhauer, editors. Süsswasserflora von Mitteleuropa. 1986, 2/1, 1 Teil: 876 s; 1988, 2/2, 2 Teil: 596 s; 1991, 2/3, 3 Teil: 576 s; 1991, 2/4, 4 Teil: 437 s., G. Fischer Verlag, Stuttgart. LUND, J. 1954. The seasonal cycle of the plankton diatom, Melosira italica (Ehr.) Kütz. subsp. subarctica O. Müll. – J. Ecol., 42: 90-102. MCQUOID, M. and L. HOBSON 1996. Review: Diatom resting stages. – J. Phycol., 32: 889-902. OGNJANOVA-RUMENOVA, N. 1991. Neogene diatoms from sediments of Sofia Valley and its stratigraphic significance. — Ph D Thesis, Geological institute, Bulgarian Acad. Sci.: 330 pp. (in Bulgarian). RENBERG, I. and T. HELLBERG 1982. The pH history of lakes in southwestern Sweden, as calculated from the subfossil diatom flora of the sediments. – Ambio, 11: 30-33. ROUND, F., R. CRAWFORD and D. MANN 1990. The Diatoms. Biology and Morphology of the Genera. - Cambridge University Press, Cambridge. RUSHFORTH, F. and J. JOHANSEN 1986. The inland Chaetoceros (Bacillariophyceae) species of North America. – J. Phycol., 22: 441-448. 120

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STANCHEVA, R. 2001a. Diatoms in Holocene sediments from Mt Sredna Gora. I. – Phytol. Balc.,7(1): 85-99. STANCHEVA, R. 2001b. Diatoms from Holocene sediments of Mt Sredna Gora. II. – Phytol. Balc., 7(3) :313-326. STANCHEVA, R. 2003. Diatom-based pH reconstruction studies of Holocene sediments of peat bogs in Central Sredna Gora Mountains. in: B. Rossnev, editor. Proceedings of scientific papers, International scientific conference “75 years of the forest research institute of BAS”, Sofia 1-5 october 2003, vol. I: 271-276. (in Bulgarian) STANCHEVA, R. and N. SLAVCHOVA 2002. Siliceous microfossils in Holocene sediments from two peat bogs in Sredna gora Mt. (Bulgaria). in: V. Ranđelović, editor. Proceeding of Seventh Symposium on the Flora of Southeastern Serbia and Neighbourimg Regions, Dimitrovgrad, June 6-8, 2002: 39-43. STANCHEVA, R. and D. TEMNISKOVA 2003. Diatom flora from Holocene sediments in Mt Sredna Gora. Species composition and taxonomic structure. – Phytol. Balc., 9(2): 293-306. STANCHEVA, R. and D. TEMNISKOVA 2004. Paleoecology of Holocene diatoms from sphagnum peat bogs in the Central Sredna Gora Mountains (Bulgaria). – Geol. Carp., 55(1): 65-76. TEMNISKOVA-TOPALOVA, D. and N. OGNJANOVA-RUMENOVA 1983. Diatoms of Freshwater Neogenic Diatomites in the Gotse Delèev Region. – Fitologija, 22: 29-45. (in Bulgarian). VAN DAM, H., A. MERTENS and J. SINKELDAM 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. - Netherlands Journal of Aquatic Ecology, 28 (1): 117- 133. VON STOSCH, H. and K. FECHNER 1979. “Internal thecae” of Eunotia soleirolii (Bacillariophyceae): Development, structure and function as resting spores. – J. Phycol., 15: 233-243.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 123-131) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae) Ioanna Louvrou, Daniel Danielidis and Athena Economou-Amilli University of Athens, Faculty of Biology, Department of Ecology and Systematics, Panepistimiopolis, Athens 15784, Greece, email: [email protected] ABSTRACT Detonia Frenguelli is a monotypic genus with one established species, D. superba (Janisch) Frenguelli (1949), which is poorly known and has been misinterpreted on various occasions. The presence of this species in surface marine sediments of hydrothermal vents at Milos Island (Cyclades, Greece) offered us the opportunity for a review of the taxonomic status of the genus and revealed the existence, in literature, of another much larger and coarsely striated species that was up to now neglected. The proposed name for the new taxon is Detonia dobrinae sp. nov. (lectotype designated here) in honor of Prof. Dobrina TemniskovaTolalova. An emended description and a lectotype (here designated) for Detonia superba (Janisch) Frenguelli is also offered. Key words: Taxonomy, Detonia, Detonia dobrinae sp. nov. INTRODUCTION The genus Detonia was first established by Frenguelli (1949) as Detonia superba (Janisch) Frenguelli including Rhaphoneis superba (Janisch) Grunow (1862). This taxon was first described by Janisch (1861) as Cocconeis superba and it was soon after transferred to Rhaphoneis by Grunow (1862). Under the names Cocconeis superba or Rhaphoneis superba, this taxon has been reported by various workers (Schmidt 1894, Frenguelli 1949, Hustedt 1952, Cholnoky 1963, Giffen 1966, Foged 1975, 1978, 1979, Ehrlich 1975, VanLandingham 1969, 1978), but not always in the same context as the original species (see discussion). Ehrlich (1975, as Detonia superba) and Foged (1975, as R. superba) provided the most thorough characterization of this taxon that closely follows the original description provided by Janisch. On the other hand, Frenguelli 123

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(1949) while establishing the genus Detonia based his arguments on the work of Janisch, but the illustration he provides is clearly of a much larger and coarser diatom with only a general resemblance to Cocconeis superba Janisch (1861). More recently, Blazé (1984) and Scherer (1997), establishing the genera Diplomenora Blazé and Dickensoniaforma Scherer, provided extensive discussion on the taxonomy of Detonia genus with comparisons to the related genera of Rhaphoneis Ehrenberg (1844), Psammodiscus Round & Mann (1980) and Adonis Andrews & Rivera (1987). It is also interesting that in the publication of Round et al. (1990), Detonia is not included as a valid genus. Nevertheless, some of their illustrations for Diplomenora Blazé show considerable resemblance to Detonia Frenguelli as this is depicted by Janisch (1861), Frenguelli (1949), Foged (1975) and Ehrlich (1975, SEM photos pl. 1, figs 1 & 2). It seems that Detonia was omitted from this key publication due to the lack of material and adequate data on the fine structure and it is otherwise probably a valid genus (D.G. Mann, personal communication). The diatom found in Milos Island has all the characteristic features of Detonia, giving us the opportunity to reexamine the taxonomy of the genus. The specimens of Milos closely resemble the original Cocconeis superba Janish (1861) in valve dimensions and striae counts (see Table I). On the contrary, Detonia superba (Janisch) Frenguelli (1949) that was previously presented in Schmidt (1894, as C. superba) and in Schmidt et al. (1874-1959) is clearly a different taxon needing a new name. Detonia dobrinae sp. nov. closely resembles D. superba in the general valve appearance but it can easily be distinguished from the later by having much larger valves and coarser striae. MATERIAL AND METHODS Sediment samples were collected from hydrothermal vents in Paleochori Bay on Milos Island during two field expeditions in June 1996 and 1997. Each vent is surrounded by three characteristic concentric zones of distinctive color: yellow, white, and brown. Samples containing Detonia speciments were found in the white zone at a water depth of 7 m. Collected samples were preserved in formaldehyde. Material was oxidized and slides were prepared for diatom analyses according to standard procedures (Simonsen 1962). Observations were made using Zeiss Axiolab microscope equipped with a Sony DSC-S85 digital camera and Jeol-35 scanning electron microscope. Photographs were made on Agfapan APx100 b/w film. The Taxonomic History of Detonia Frenguelli (1949) Janisch (1861) in his description of Cocconeis superba described a diatom with an ovateelliptic outline, 23 µm long, with fine striation (Janisch, 1861 in Blazé, 1984) and ocelli present near the apices. Based on this morphology and on the absence of a raphe, Grunow (1862) transferred this species into the genus Rhaphoneis. This species was later reported in literature by Rabenhorst 1864 and De Toni 1892 (in VanLandingham, 1978), and illustrated 124

125

Janisch, 1861-62 Foged, 1975 Ehrlich, 1975 Present study Schmidt, 1894 Frenguelli, 1949

Cocc. superba Janisch Rh. superba (Janisch) Grunow Det. superba (Janisch) Frenguelli

Det. superba (Janisch) Frenguelli Cocc. superba Janisch Det. superba (Janisch) Frenguelli.

Dipl. cocconeiformis (Schmidt) Blazé Blazé, 1984 Dipl. cocconeiformis (Schmidt) Blazé Round et al., 1990

Reference

Taxon

Dipl. cocconeiformis (Schmidt) Blazé Dipl. cocconeiformis (Schmidt) Blazé

Det. superba (Janisch) Frenguelli Det. dobrinae sp. nov. Det. dobrinae sp. nov.

Det. superba (Janisch) Frenguelli Det. superba (Janisch) Frenguelli Det. superba (Janisch) Frenguelli

Current name

round round-elliptic

elliptic elliptic-round elliptic

elliptic elliptic-round elliptic

Valve shape

Table I. Comparative data for Detonia superba, D. dobrinae and Diplomenora cocconeiformis

16-17 38-82 63

21 19-30 12-20

17-18 7-8 5-6

18 13-14 12-20

2, stalkless unknown unknown

unknown 2-4 2, stalkless

20-50 (diameter) 4-8 2-10 with stalk unknown unknown unknown 1-10, stalkless

20-21 50-96 73

23 20-34 15-25

Valve Valve width, Striae Number of length, µm µm in 10 µm rimoportulae

Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae)

Ioanna Louvrou, Daniel Danielidis and Athena Economou-Amilli

in Schmidt et al. (1874-1959, pl. 193, figs 9-11) where both elliptical and circular forms were presented exhibiting considerable variation in size (elliptic forms: 58-96 µm long, 38-82 µm wide, 7-8 striae in 10 µm, see Fig. 3). Later Frenguelli (1949) pointed out that the presence of ocelli excludes this taxon from both Cocconeis and Rhaphoneis and established the genus Detonia with D. superba as the type species. Hustedt (1952), on the other hand, commented extensively on the structure of these ocelli and concluded that Detonia should be rejected as a valid genus. This characteristic can be observed in older drawings (Janisch 1861, Schmidt 1894; see also Figs 3-4 of the present study) as a hyaline, more or less round to ovate area near the poles. The photograph of Frenguelli (pl. XI, fig. 8) and those of other authors (Foged 1975, pl. IX, figs 7-9; Ehrlich, 1975 pl. 1, figs 1-3) revealed the lack of ocelli in Detonia, and rather the presence of finer areolae with a characteristic bifurcate arrangement on either side of the axial area at the poles. This arrangement differs considerably from the apical pore field of Rhaphoneis Ehrenberg and resembles that of Diplomenora Blazé and perhaps Adonis Andrews & Rivera. Blazé (1984) in establishing Diplomenora [based on Coscinodiscus cocconeiformis Schmidt (1878) in Schmidt et al. (1874-1959)] differentiated this genus from Detonia based on the shape of the valve and the number and position of the rimoportulae. In particular, Diplomenora is characterized by constantly circular valves with 2-10 rimoportulae located around the valve margin but never in or near the apical area of finer areolae. The rimoportulae closer to the pole are at an angle of about 15° and always out of the apical, finer area. Detonia, on the other hand, has mainly elliptical valves, and the circular outline seems to be the exception. This was verified by Blazé (1984) after examination of D. superba from Tasmania presented in Foged (1975) where the majority of valves were elliptical and only a small fraction was circular. Furthermore, the rimoportulae were constantly located somewhat inside or at the boundary of the valve’s face towards the finer apical area. Although no evidence exists in the earlier records of Detonia (Janisch 1861, Grunow 1862, Schmidt 1894, Frenguelli 1949) about the number and location of rimoportulae, it is clear from Foged’s (1975) photographs (as ‘prominent tubuli’, p. 51, pl. IX, figs 7-9) that there are 1 or 2 rimopostulae per apex which are always located at the boundary of the finer areolated apical area. The same observations can be made for the Detonia superba presented by Ehrlich (1975) where only one rimoportula per apex is visible. Additionally, in Diplomenora the rimoportulae are stalked, while in Detonia these are sessile on the internal wall (see Ehrlich, 1975 and specimens of the present study). Circular and coarser valves have been reported erroneously on some occasions as Rhaphoneis superba. In particular, Foged’s (1978, 1979) illustrations of R. superba probably represent specimens belonging to Diplomenora, a view that is shared by Foged himself (in Blazé, 1984, p. 223). Furthermore, the combination Detonia superba (Janisch) Frenguelli has also been incorrectly used by some authors (Giffen 1966, Cholnoky 1963) for a coarse, round species with a ring of rimoportulae, which according to Blazé (1984) also belongs to the genus Diplomenora. The fine structure of the areolae in Detonia is not clear. The only data come from Ehrlich (1975) for D. superba, showing externally circular areolae with raised periphery and depressed center, much like a crater. The exact morphology of the rotae is not visible. 126

Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae)

Internally, the areolae openings look like simple holes sunken in the silica wall and the valve structure seems to be costate. This structure is generally similar to that of Diplomenora as presented by Blazé (1984) but no clear details are offered. Recently, Round et al. (1990) seem to expand the description of Diplomenora including the ovate-elliptic valves and a more variable number and location of rimoportulae. Additionally, some of the published photographs clearly resemble Detonia as was originally described by Janisch (as Cocconeis superba). Especially some of the SEM photographs are very similar to those of Ehrlich (1975) showing elliptic valves with only one stalkless rimoportula per apex, located at the boundary of the finer apical area. Nevertheless, Round et al. (1990) did not state explicitly that these two genera are the same, which further complicates the distinction between them. If these two genera indeed represent the same genus, then this genus should be called Detonia since it is the oldest name and should therefore have priority. Although only the examination of the original material, if this exists, can resolve the true relationship of Detonia and Diplomenora with absolute certainty, we prefer to accept the distinction of the two genera based on the valve shape and the arrangement and morphology of the rimoportulae. Detonia superba (Janisch) Frenguelli (1949) Although the above taxonomic history and discussion seem to justify Frenguelli in his distinction of Detonia as a separate genus, there are some interesting differences between the species he illustrates and the one described by Janisch. The original Janisch’s description (in Blazé 1984) refers to a rather small diatom, 23 µm long that agrees to the scale of the reproduced drawing (Fig. 13, in Blazé 1984 and Fig. 4 here). As it is also obvious from the illustration, Janisch’s species has fine striae (up to 18 in 10 µm). In contrast, the Frenguelli’s specimen (Fig. 5) is much larger (73 µm long and 63 µm wide) and coarser, with 5-6 striae in 10 µm. These dimensions and densities are in accordance with all of Schmidt’s drawings of Cocconeis superba (=Detonia superba) especially the elliptic forms (1894, pl. 193, figs 9, 11) that are 58-96 µm long and 38-82 µm wide, with 7-8 striae in 10 µm (Fig. 3). Based on those observations we believe that it is unlikely that Frenguelli’s Detonia superba and Janisch’s Cocconeis superba represent the same taxon. The recent report of Foged (1975) of small individuals, 2034 µm long, agree with the scales of the published photographs but his measurements of 1012 striae in 10 µm seem to be incorrect. In particular, all the depicted specimens have rather finer striae (13-14 in 10 µm), thus having a closer resemblance to Janisch’s species. The individuals from Milos Island (Figs 1-2) also closely resemble the specimens presented by Janisch based on their size and striae density and should be identified as D. superba (Janisch) Frenguelli; these are also identical in fine structure to the specimens of Ehrlich (1975) and show considerable agreement to Foged’s illustrations from Tasmania with the exception of the number of rimoportulae (for comparisons see Table I). Thus, when Frenguelli created Detonia based on Janisch’s C. superba he was correct in his argument for the establishment of a new genus but the offered illustration was of a different species (not D. superba) that was left unidentified. This species is the same as the 127

Ioanna Louvrou, Daniel Danielidis and Athena Economou-Amilli

one presented in Schmidt (1894, as C. superba), it has larger and coarser valves than D. superba (Janisch) Frenguelli (1949) and should be given a new name. The name Detonia superba (Janisch) Frenguelli should be preserved since Frenguelli (1949) was the first who published this combination, but the description must be emended. Detonia dobrinae sp. nov. (Figs 3, 5) Lectotype here designated: Frenguelli, 1949, pl. XI, fig. 8 [as Detonia superba (Janisch) Frenguelli] and reproduced here in fig. 5 Additional illustrations: Schmidt Atlas, 1894, pl. 193, figs 9-11. Etymology: This name was given in honor of Prof. Dobrina Temniskova-Tolalova in recognition of her work on diatom research. Type locality: Tiltil y Mejillones, Chili (Frenguelli, 1949). Latin diagnosis Valvis late ovato-ellipticis, 50-96 µm longis et 38-82 µm latis. Areolae 5-8 per 10 µm in arcibus circum areolarum parviorum quae ad polos. Valves ovate-elliptic in outline, rarely circular, 50-96 µm long and 38-82 µm wide, with a narrow, linear axial area. Valve face with coarse striae of areolae, 5-8 in 10 µm, perpendicular to the axial area along the apical axis but arched when reaching the margins, especially towards the apices where they become finer with a characteristic bifurcated arrangement on either side of the main axis. Detonia superba (Janisch) Frenguelli (1949) emend. Figs 1-2, 4 non Detonia superba (Janisch) Frenguelli 1949, pl. XI, fig. 8 = Detonia dobrinae Louvrou, Danielidis & Economou-Amilli sp. nov.

1

2

Figs 1-2: Specimens of Detonia superba from Milos Island. Scale bars = 10 µm. Fig. 1: View of the valve under the light microscope showing the apical hyaline areas and the arrangement of areolae. Fig. 2: Internal view of the valve showing the position and morphology of the rimoportulae. The “hyaline” apical areas are composed of finer areolae with characteristic bifurcate arrangement.

128

Taxonomic Status of Detonia Frenguelli and the Establishment of Detonia dobrinae sp. nov. (Bacillariophyceae)

3

4

5 Figs 3-5: Scale bars = 10 µm. Fig. 3: Detonia dobrinae sp. nov., reproduction of Schmidt’s drawings (as Cocconeis superba) showing valves with round-elliptic outline and coarse striae. Fig. 4: Janisch’s original drawing of Cocconeis superba (=lectotype of D. superba) as reproduced in Blazé (1984) showing the hyaline apical areas and the fine striation of the valve. Fig. 5: Lectotype of Detonia dobrinae sp. nov. Reproduction of Frenguelli’s (1949) original photograph (as Detonia superba). The apical area is clearly composed of finer areolae; striae density is coarse.

Basionym: Cocconeis supeba Janisch (1861). Lectotype here designated: Janisch (1861), fig. 13 and reproduced here Fig. 4. Synonyms: Cocconeis superba Janisch 1861, Rhaphoneis superba (Janisch) Grunow 1862. Previous records: Janisch, 1861 as Cocconeis supeba; Hustedt, 1952 & Foged, 1975 as Raphoneis superba; Ehrlich, 1975 as D. superba. Type locality: Guano de Angamos (Janisch, 1861). Valves more or less flat with a rather shallow mantle, ovate-elliptic in outline, 15-25 µm long and 12-20 µm wide, with a narrow, almost linear axial area, slightly swollen in the middle and tapering towards the poles. Valve face with fine striae, 12-18 in 10 µm, perpedicular to the axial area but arched when reaching the margins, where they become much finer with a characteristic bifurcated arrangement on either side of the main axis. Areolae almost invisible at the poles under the light microscope, giving the impression of hyaline areas. Two to four rimoportulae present, one on each apex, placed either on the same side or diagonally to the axial area. Rimoportulae located between the finer polar area and the main valve face; their orientation is that of the neighboring areolae. No stalk is visible and the rimoportulae seem to emerge directly from the interior surface of the cell wall. Each rimoportula seems to be composed of one pair of labia.

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ACKNOWLEDGMENTS This work was partly supported by EU project ‘Hydrothermal fluxes and Biological Production in the Aegean’ contract no: MAST3-CT95-0021. REFERENCES BLAZÉ, K. L. 1984. Morphology of Diplomenora gen. nov. (Bacillariophyta). – Br. phycol. J., 19: 217-225. CHOLNOKY, B. J. 1963. Beitrage zur Kenntnis des marinen Litorals von Südafrika. – Bot. Mar., 5: 28-83. EHRLICH, A. 1975. The Diatoms from the Surface Sediments of the Bardawil Lagoon (Northern Sinai) – Paleoecological Significance. in: R. Simonsen, editor. Third Symposium on Recent and Fossil Marine Diatoms. Nova Hedwigia, Beih. 53: 253271. J. Cramer. Vaduz. FOGED, N. 1975. Some littoral diatoms from the coast of Tanzania. – Bibliotheca Phycologica, 16: 1-127. J. Cramer, Vaduz. FOGED, N. 1978. Diatoms in eastern Australia. – Bibliotheca Phycologica, 41: 1-243. J. Cramer, Vaduz. FOGED, N. 1979. Diatoms in New Zealand, the north Island. – Bibliotheca Phycologica, 47: 1-225. J. Cramer, Vaduz. FRENGUELLI, J. 1949. Diatomeas fòsiles de los Yacimientos Chileanos de Tiltil y Mejillones. Darwiniana, 9: 97-157. GIFFEN, M. H. 1966. Contributions to the diatom flora of South Africa. III. Diatoms of the marine littoral regions at Kidd’s Beach near East London, Cape Province, South Africa. – Nova Hedwigia, 13: 245-292. GRUNOW, A. 1862. Die österreichischen Diatomeen nebst Anschluss einiger neuen Atren von anderen Lokalitäten und einer kritischen Übersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Surirelleae, Meridioneae, Diatomeae, Entophyleae, Surirelleae, Amphipleureae. – Verh. zool.- bot. Ges. Wien, 12: 315-472. HUSTEDT, F. 1952. Neue und wenig bekannte Diatomeen. II. – Ber. Dtsch. Bot. Gers., 64: 305-315. JANISCH, C. 1861. Zur Charakteristik des Guanos von verschiedenen Fundorten. – Jahr. Ber. Schles. Ges., Naturw.-med. II.: 149-164. ROUND, F. E., R. CRAWFORD. and D. MANN 1990. The diatoms. Biology and Morphology of the Genera. –747 pp. Cambridge University Press, Cambridge, U.K. SCHMIDT, A. et al. 1874-1959. Atlas der Diatomaceeen-Kunde. pl. 193 – R. Reisland, Leipzig. SCHERER, R. P. 1997. Dickensoniaforma: A new diatom genus in the family Rhaphoneidaceae, with two new fossil species from the Norwegian - Greenland Sea. – Diatom Research, 12: 83-94. 130

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SIMONSEN, R. 1962. Vegetation und Vegetationsbedingungen in der westlichen Ostsee (Kieler Bucht). – Kieler Meeresforschungen, 20:157-168. VANLANDINGHAM, S. L. 1969. Catalogue of the fossil and recent genera and species of diatoms and their synonyms. Part III. Coscinophaena through Fibula. 1087-1756. J. Cramer. Vaduz. VANLANDINGHAM, S. L. 1978. Catalogue of the fossil and recent genera and species of diatoms and their synonyms. Part VI. Neidium through Rhoicosigma. 2964-3605. J. Cramer. Vaduz.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 133-145) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Staurosira incerta (Bacillariophyceae) a new fragilarioid taxon from freshwater systems in the United States with comments on the structure of girdle bands in Staurosira Ehrenberg and Staurosirella Williams et Round Eduardo A. Morales Patrick Center for Environmental Research, The Academy of Natural Sciences, Philadelphia, PA 19103-1195, E-mail: [email protected] ABSTRACT A new fragilarioid diatom, Staurosira incerta, is described based on light microscopy (LM) and scanning electron microscopy (SEM) data from samples collected from streams in the United States of America. This taxon has valves with strongly inflated central area and may have been misidentified as Staurosira construens Ehrenberg in past ecological and taxonomic works. The striae are parallel and the apical pore fields are located on the mantle and appear almost hidden in valve view. Many valves present an additional band of silica that is located on the abvalvar side of the mantle. This band is relatively thick and has perforations present at the sites where there is an areola underneath the band. This band is not always present in both valves of a frustule. Ecological aspects together with a discussion of the taxonomy of the new taxon presented here in the light of published information are also included. Additionally, some details of the cingulum of S. construens and Staurosirella leptostauron (Ehrenberg) Williams et Round are presented herein together with a discussion of girdle band structure in these fragilarioid taxa based on material from North America and published literature. Key words: Bacillariophyceae, Staurosira, Staurosirella, NAWQA, North America

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Eduardo A. Morales

INTRODUCTION Our understanding of fragilarioid diatom diversity and taxonomy has been greatly affected by the use of the electron microscope, particularly SEM. Exploration of wider geographical regions has produced many new taxa and allowed for a better circumscription of already described taxa. However, detailed analysis of geographical areas that have historically received considerable attention from diatomists can also yield new taxa. For example, many new fragilarioid taxa have been described recently from different parts of the United States (e.g., Manoylov et al. 2003, Morales 2002, 2003a, Morales and Edlund 2003), and some of them from well studied areas such as Florida and Pennsylvania. This is evidence that detailed studies incorporating LM and SEM may still yield improved estimations of diatom diversity. These estimations, in turn, have a direct impact on ecological assessment programs, which heavily rely on taxonomic accuracy. Most of the recent taxonomic reviews of North American fragilarioid diatoms have been based on material collected by the NAWQA Program (National Water Quality Assessment dependent from the U. S. Geological Survey), which concentrates on the study of periphytic algae –among other groups of organisms - from streams and rivers in the continental U.S. and Hawaii (http://water.usgs.gov/nawqa/). NAWQA has a sampling program, which spans the continent and provides an opportunity to estimate distributions of organisms and touch on taxonomic and other ecological aspects. The present study represents an effort in the taxonomic and ecological characterization of fragilarioid diatom taxa, which are important components of NAWQA samples. A new species, Staurosira incerta, is presented here alongside a discussion regarding the taxonomy and ecology of this taxon based on newly collected data. One of the common shortcomings in fragilarioid diatom taxonomy is the lack of sufficient characters to distinguish morphologically related taxa at the species or even genus levels. In the case of the genera Staurosira (Ehrenberg) and Staurosirella Williams et Round the protologues make both taxa distinguishable from each other (Williams and Round 1987), but the tremendous variability and intergradations of some diagnostic features make the placement of certain species in either genus an intimidating task. Thus, it is necessary to find additional characters that clearly separate these two genera. One potential structure that might yield a number of diagnostic features is the cingulum or girdle, which in fragilarioid diatoms is composed of a valvocopula that attaches directly to the valve interior and several copulae. These girdle bands can be either closed (continuous) or open (discontinuous at one of the valve apices) and have a series of ornamentations such as row(s) of areolae, valvocopular fimbriae (finger-like projections that attach the valvocopula to the costae of the valve’s interior surface), ligulae (projections located toward the valve apex), and blister like deposits of silica on the outer surface of the band (see Von Stosch [1975] and Round et al. [1990] for a more detailed discussion on girdle band structure). In spite of the existence of a considerable amount of literature on fragilarioid diatoms from throughout the world, very few investigators make reference to the structure of the girdle, and in many cases, many protologues of new species give the impression that they 134

A new fragilarioid diatom from the USA

simply follow the description of the cingulum of the corresponding genus, with no extra effort devoted to the study of girdle bands in those particular species. Therefore, it is difficult to assess the suitability of girdle bands as potential sources of diagnostic features from the literature. In addition to this lack of interest on the structure of the girdle, the latter has often been assumed to be a relatively simple structure with no variability within or across species (as denoted by revisions of genera presented by Williams and Round [1986, 1987] among others). Thus, entire genera are characterized as having either a closed or an open cingulum, with or without fimbriae, etc. More recently, however, it has been shown that species within Staurosirella and Pseudostaurosira Williams et Round vary in the open/closed nature of their cingula (Morales and Edlund 2003). Thus, it is evident that more studies are needed to assess patterns of variability in girdle band structure of the different fragilarioid genera. Here, some preliminary details of the structure of the girdle in one species within Staurosira and another in the genus Staurosirella are presented. Detailed observations of the cingulum of Staurosira construens reveal a cingulum composed of closed and open girdle elements, which may represent the first report of this kind for fragilarioid diatoms. MATERIAL AND METHODS Periphyton material from three streams in the states of Wisconsin and Washington (Table 1) was investigated as part of NAWQA through a Cooperative Agreement between the U.S. Geological Survey and ANSP (The Academy of Natural Sciences of Philadelphia). Samples were collected in 1993 and 2003 using methodology outlined in Fitzpatrick et al. (1998) and Moulton et al. (2002). For LM analysis of NAWQA material, sub-samples of samples fixed with formaldehyde (4% final concentration) were digested with nitric acid using the microwave method, washed by decanting using distilled water, and air-dried aliquots mounted on glass slides using Naphrax (Charles et al. 2002). A Zeiss Axioscope was used to measure valve dimensions of 50 specimens from the type population found in Dry Creek, Washington (Table 1). A Nikon Microphot-FXA microscope equipped with a Spot Insight QE Model 4.2 Color Digital Camera was used to capture images of selected specimens. For SEM studies, aliquots of clean material were air dried onto 15 X 15 cm pieces of aluminum foil. Smaller pieces were trimmed and mounted on aluminum stubs with doublesided tape. The stubs were then coated with gold-palladium using a Polaron Sputter Coater for ca. 1.5 min at 1.8 kV. A Leo-Zeiss 982-DSM electron microscope was used for SEM analysis. Digital images were directly captured and plates were assembled using Adobe Photoshop v. 7.0. Morphological terminology follows Anonymous (1975), Ross et al. (1979), and Round et al. (1990). Ecological information for the NAWQA samples was downloaded from the NAWQA website: http://water.usgs.gov/nawqa/. Methods of collection of environmental parameters can be found in: http://water.usgs.gov/nawqa/protocols methodprotocols.html.

135

Lawrence Creek Dry Creek Dry Creek Red Rock Coulee

River

ANSP ANSP ANSP ANSP

G.C. 100041aRichest-targeted-habitat G.C. 106549a Richest-targeted-habitat G.C. 106550aDepositional-targeted-habitat G.C. 106547aRichest-targeted-habitat

Sample Id./Type of sample

Table 1. U.S. NAWQA samples used in the present study.

Adams, Wisconsin Yakima, Washington Yakima, Washington Grant, Washington

County/State

WMIC CCYK CCYK CCYK

1993 2003 2003 2003

NAWQA Study Unit/Year

43.898 46.254 46.254 46.874

Latitude

89.601 120.407 120.407 119.597

Longitude

Eduardo A. Morales

136

A new fragilarioid diatom from the USA

RESULTS AND DISCUSSION Staurosira incerta Morales sp. nov. (Figs. 1-12 [LM], Figs. 13-24 [SEM])

10 µm

Holotype: Academy of Natural Sciences General Collection G.C.106549a. Type locality: Dry Creek, Yakima County, Washington, USA. Latitude: 46.254 N, Longitude: 120.407 W. Latin description: Frustula aspectu cingulari rectangularia in catenis cum marginibus spiniferis. Valvae isopolares extremiis rostratis. Sternum angustum et lanceolatum. Striae parallelae aliquantulae radiatae ad apices versus. Areolae rima-similis. Spinae cavae, spatulatae super costas transapicales. Area porellarum ad apices pro parte maxima deiecta. Rimoportulae nullae. Cingulum cum valvocopola maxima et copulis minores non-areolatae. Valvocopulae clausaris cum fimbriae. Longitudo 8-17 µm, latitudo 4-6 µm, striae 13-16 per 10 µm. English description: Frustules rectangular in girdle view forming chains by means of marginal spines (Fig. 9). Valves isopolar with rostrate apices (Figs 1-8). The central sternum

10 µm

1-8

9-12 Figs 1-12. LM photographs of Staurosira incerta from the type population. Dry Creek, Clay County, Washington, ANSP G.C. 106549a. 1-8. Valve views of several specimens. 9. Small chain in girdle view. 10-12. Valvocopulae, notice closed feature and short fimbriae in Fig. 11 (not noticeable in other two Figs due to focal plane).

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is narrow and lanceolate (Figs 1-8). The striae are parallel or slightly radial toward the poles (Figs 1-8), they are composed of slit like areolae (Figs 13-18, and 24), which bear delicate vola (Fig. 17). Spines are hollow, spatulate and located on the costae (Figs 15, 18, 19-21, and

Figs 13-18. SEM pictures of Staurosira incerta, type population. Dry Creek, Clay County, Washington, ANSP G.C. 106549a. 13 and 14. Valve view of two valves with lanceolate to slightly cruciate valve outline, narrow lanceolate central sternum, striae composed of wide elliptical areolae, spines located on the interstriae, and apical pore fields located on the mantle. 15. View of tilted valve showing hollow spines and extra band of silica on valve mantle. 16. Internal view showing central sternum, striae, and apical pore field characteristics. 17. Close up on an internal view of the striae showing the minute volae. 18. Close up on the valve apex. Apical pore field is barely visible in this specimen.

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24). Apical pore fields well developed and located on the valve mantle (Fig. 19). No rimoportulae are present. Several non-areolate bands compose the cingulum and the valvocopula is much wider than the rest of the elements (Figs 19 and 21). The valvocopula

Figs 19-24. SEM pictures of Staurosira incerta. 19. Detail of linking spines, and apical pore fields located on an almost vertical valve mantle. Red Rock Coulee, Bee County, Washington, ANSP G.C. 106547a. 20 and 21. Side views of valves showing linking spines and girdle bands. 22. Top view of valvocopula with fimbriae. 23. Valvocopula with fimbriae still attached to one of the valves. 24. Close up on valve face/mantle junction showing extra siliceous band. Notice perforations at the sites where there are areolae underneath the band. Also hollow spines can be seen here. 20-24. Dry Creek, Clay County, Washington, ANSP G.C. 106549a.

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is closed and has fimbriae that attach to the costae at the valve interior (Figs 22 and 23). Length 8-17 µm, width 4-6 µm, transapical striae 13-16 in 10 µm. Etymology: The species epithet refers to the fact that the valves of this taxon sometimes present a ribbon-like siliceous deposit on the abvalvar margin of the mantle. Comments: This taxon resembles other Staurosira species in many regards. The characteristics of the spines, the apical pore fields, and the areolae with fine volae are all found on other species of Staurosira. Staurosira incerta may have been confused with Staurosira construens due to their morphological similarity. Both taxa have cruciform valve outlines and both form chains that persist in acid-digested preparations. When only these chains are observed under the LM, separation of both taxa is practically impossible. Specimens lying in valve view are easier to separate. The central inflation in S. incerta is much smoother and the ends subrostrate, and thus the valves approach a more lanceolate shape (especially larger specimens) than S. construens in which the central inflations are much more acute and the apices more subcapitate. There are also a number of differences between these taxa at the SEM level. The areolae are commonly much elongated in S. incerta and the apical pore fields in this taxon are located on the mantle (Fig. 19). In contrast, S. contruens has apical pore fields located on the transition between valve face and valve mantle (Fig. 25). The most conspicuous difference between S. incerta and S. construens is the presence of a well-developed ribbon-like siliceous deposit on the abvalvar margin of the mantle of valves of S. incerta (Figs 15 and 24) This feature has only been observed in S. contruens var. binodis (Morales 2005, Fig. 90), but not in other species within the genus. The formation of this siliceous deposit is not consistent from valve to valve and analysis of chains in type material reveals that at least one of the valves of a frustule has this feature. One must be careful with the interpretation of the open or closed nature of the girdle bands in S. incerta. Many of the valvocopulae observed under both LM and SEM were open and many others were closed, giving the impression that both kinds were produced by this organism. However, upon closer examination of material under SEM it became evident that the valvocopulae’s weakest point is at one of the apices and that many of these structures were in fact broken (broken apices were irregularly split and showed signs of breakage). This tendency to break may be accentuated with the sample treatment and as valvocopulae become detached from the valves. The copulae have not been observed under SEM; thus it was not possible to determine whether they were open or closed. Many copulae appear to be open in LM permanent preparations, but this could be an artifact such as that observed with the valvocopulae. Two types of samples collected from the same site at Dry Creek, Washington presented the largest populations of S. incerta. The first sample is a Richest-targeted-habitat sample (composite sample from riffle or woody snags, see Moulton et al., 2002) in which the relative abundance of the new taxon (in a 600 valve count of the total periphytic diatom community) was ca. 24%. Among the most abundant diatoms in this sample were Epithemia sorex Kützing (ca. 15 %), Nitzschia frustulum (Kützing) Grunow (ca. 11%), Staurosira construens var. venter (Ehrenberg) Hamilton (ca. 5%), Achnanthidium minutissimum (Kützing) Czarnecki (ca. 4%), and Nitzschia inconspicua Grunow (ca. 4%). This is the sample from which the type 140

A new fragilarioid diatom from the USA

Figs 25-30. SEM images of Staurosira construens from Red Rock Coulee, Bee County, Washington, ANSP G.C. 106547a. 25. Valve view depicting features of the valve face. Notice small elliptical to round areolae, wide central sternum, hollow (barely visible) spines located between the striae, and apical pore fields located on the transition between valve face and mantle. 26. Whole cingulum showing all elements still attached to each other. Arrows depict open copulae, which are not clearly seen at this magnification. Notice continuous valvocopula on top of whole structure. 27. Top view of several copulae still attached to each other and giving the impression of being closed. 28. Open copula. 29. Close up on frustule. Arrows depict end of a copula. 30. Close up on frustule showing additional open copulae.

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specimen was selected. The second sample was a Depositional-targeted-habitat sample (composite sample of fine sediment deposits) and presented a higher relative abundance of S. incerta (ca. 41%). Other dominant taxa in this sample were Nitzschia frustulum (ca. 10%), Planothidium lanceolatum (Brébisson ex Kützing) Lange-Bertalot (ca. 6%), and Nitzschia fonticola Grunow (ca. 5%). The pH at the collection site was 8.5, while the conductivity was 159 µS/cm, and P (orthophosphate) and nitrates plus nitrates were 0.02 mg/L and 0.06 mg/L, respectively. Based on the high abundance of the taxon, these conditions are probably near the optimal conditions for growth of the organism. The new taxon was also observed in a Richest-targeted-habitat sample from Red Rock Coulee, Washington, but the relative abundance was only ca. 2%. This sample also contained Cymbella affinis Kützing (ca. 29%), Achnanthidium minutissimum (ca. 19%) and Staurosira construens (ca. 11%). The pH at this site was 8.9, the conductivity 377 µS/cm, the nitrates and nitrites concentration 1.97 mg/L, and the concentrations of phosphorus (orthophosphate) 0.026 mg/L. It is worth noticing that although the concentrations of phosphorus are almost the same as those present in Dry Creek, the rest of the parameters measured from Red Rock Coulee present higher values, which may favor the development of S. construens. Support for this observation can be found in Van Dam et al. (1994), who characterized S. construens as an alkaliphilous and meso-eutraphentic taxon (as opposed to alkaliphilous and oligotraphentic as is the case of S. incerta). Comment on the structure of girdle bands in the genera Staurosira and Staurosirella The revised description of the genus Staurosira states that the cingulum is open (Williams and Round 1987). However, detailed studies of this structure under SEM are lacking. In general, it appears that statements about the characteristics of the girdle bands of fragilarioid genera are derived from observations of girdle bands that are still attached to the valves of the mother cell. Although it is evident that this is the safest way to ensure that the proper girdle bands are observed, the open/closed character of the bands can be misinterpreted from elements that are still tightly packed in the original frustule. Thus, the most appropriate way to discern between open and closed girdle elements is by comparison of attached and detached girdle bands. This is the method used during the present study, which yielded a much more precise appreciation of girdle band structure. The valvocopulae of S. contruens were consistently closed (Figs 26 and 27) except when broken pieces were found. Breakage always occurred at places other than the valvocopular apices so that the closed character of these elements is unmistakable. The copulae, on the other hand, were open (Figs 28-30). Many copulae were observed detached from the mother cell (Fig. 28). Because some Staurosira taxa seem to have girdle bands with the weakest point located at the element’s apex (see the case of S. incerta presented in this paper), copulae in S. construens also had to be observed when they were still attached to the valves. Figures 26, 29 and 30 show that the copulae are incomplete and end right before 142

A new fragilarioid diatom from the USA

they reach the apex of the girdle (see arrows), thus confirming that these elements are in fact open. One must be careful when copulae are still attached to each other, since they might give the impression that they are closed (Fig. 27). It is recommended that several observations be made in lateral view rather than top view.

Figs 31-36. SEM images of Staurosirella leptostauron from Lawrence Creek, Adams County, Wisconsin, ANSP G.C. 100041a. 31. Valve view showing details of valve face. Notice slit-like areolae, flat solid spines located on the costae, lanceolate central sternum and apical pore fields located on the transition between valve face and mantle. 32. Cingulum with broken valvocopula on top. 33. Valvocopula and copula. 34. Closed copula. 35. Closed valvocopula, notice incompletely broken apex on lower left portion of figure. 36. Closed copula.

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This seems to be the first report of fragilarioid diatoms having girdle bands with open and closed elements. A similar pattern has been preliminarily observed in S. construens var. venter, although the observation has been only made from girdle bands that were still attached to the valves (Morales, pers. obs.). The structure of girdle bands of Staurosirella leptostauron was also observed in the present study following the same methodology employed for the observation of girdle elements in Staurosira construens. In this case, the valvocopulae were closed (Figs 33 and 35), except in cases in which large portions of this element were missing (Fig. 32). The copulae were also closed as demonstrated by Figures 34 and 36 Morales (2003b) and Morales and Edlund (2003) reported that the open/closed character of the girdle elements in Staurosirella seems to be very variable. The girdle bands of S. berolinensis (Lemmermann) Bukhtiyarova, for example are open, whereas those of S. minuta Morales et Edlund are closed. Preliminary observations of the girdle band structure of S. lapponica (the type of the genus Staurosirella) suggest a closed girdle structure. So far, none of the species that have been studied in some detail under SEM seem to possess girdle bands in which some of the elements are closed while others are open, and perhaps this could be a distinguishing feature between Staurosira and Staurosirella, although any conclusive assertions are still premature. The observations on girdle band structure reported here seem to be in conflict with the current view expressed in the literature (Williams and Round 1987). Additional research is needed in order to establish patterns of variation and existence of additional cingulum characters so the taxonomic inconsistencies surrounding genera such as Staurosirella and Staurosira are clarified. ACKNOWLEDGEMENTS This paper is dedicated to Dr. D. Temniskova-Topalova for her contributions to phycology and diatom research. I thank M. Cantino and J. Romanow from the University of Connecticut Electron Microscopy Laboratory (Storrs Campus) for their help and support during SEM analyses. I acknowledge and thank the support provided by Dr. D. Charles (ANSP). All NAWQA samples were collected by NAWQA biologists. REFERENCES ANONYMOUS 1975. Proposals for the standardization of diatom terminology and diagnoses. - Nova Hedwigia, Beih. 53: 323-354. CHARLES, D. F., C. KNOWLES and R. S. DAVIS, editors 2002. Protocols for the Analysis of Algal Samples Collected as Part of the U.S. Geological Survey National Water-Quality Assessment Program. Patrick Center for Environmental ResearchPhycology Section, - The Academy of Natural Sciences of Philadelphia. Report No. 02-06. 124 pp. 144

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FITZPATRICK, F.A., I.R. WAITE, P.J. D’ARCONTE, M.R. MEADOR, M.A. MAUPLIN and M. E. GURTZ 1998. Revised Methods for Characterizing Stream Habitat in the National Water-Quality Assessment Program. - U.S. Geological Survey Water Resources Investigations Report 98-4052. Raleigh, North Carolina. 67 pp. MANOYLOVA, K.M., E.A. MORALES and E.F. STOERMER 2003. Staurosira stevensonii (Bacillariophyta) a new species from Florida, USA. - European Journal of Phycology, 38: 65-71. MORALES, E.A. 2002. Studies in selected fragilarioid diatoms of potential indicator value from Florida (USA) with notes on the genus Opephora Petit (Bacillariophyceae). – Limnologica, 32:102-113. MORALES, E.A. 2003a. Fragilaria pennsylvanica, a new diatom (Bacillariophyceae) species from the United States of America with comments on the taxonomy of the genus Synedra Ehrenberg. - Proceedings of the Academy of Natural Sciences of Philadelphia, 153: 155-166. MORALES, E.A. 2003b. On the taxonomic position of the Belonastrum and Synedrella, two new fragilarioid genera described by Round and Maidana (2001). - Cryptogamie Algologie, 24: 277-288. MORALES, E.A. 2005. Observations of the morphology of some known and new fragilarioid diatoms (Bacillariophyceae) from rivers in the United States. Phycological Research, 53: 113-133. MORALES, E.A. and M.B. EDLUND 2003. Studies in selected fragilarioid diatoms (Bacillariophyceae) from Lake Hovsgol, Mongolia. - Phycological Research, 51: 225-239. MOULTON, S.R. II, J.G. KENNEN, R.M. GOLDSTEIN and J.A. HAMBROOK 2002. Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program. - Open-File Report 02-150. Reston, Virginia. 75 pp. ROSS, R., E.J. COX, N.I. KARAYEVA, D.G. MANN, T.B. PADDOCK, R. SIMONSEN and P.A. SIMS 1979. An amended terminology for the siliceous components of the diatom cell. - Nova Hedwigia, Beih. 64: 513-533. ROUND, F.E., R.M. CRAWFORD and D.G. MANN 1990. The Diatoms. Biology and Morphology of the Genera. - Cambridge University Press, UK. 747 pp. VAN DAM, H., A. MERTENS and J. SINKELDAM 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. – Netherlands Journal of Aquatic Ecology, 28: 117-133. VON STOSCH, H.A. 1975. An amended terminology of the diatom girdle. - Nova Hedwigia, Beih. 53: 1-36. WILLIAMS, D. M. and F.E. ROUND 1986. Revision of the genus Synedra Ehrenb. - Diatom Research, 1: 313-339. WILLIAMS, D.M. and F.E. ROUND 1987. Revision of the genus Fragilaria. - Diatom Research, 2: 267-288.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 147-154) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Achnanthidium temniskovae sp. nov., a new diatom from the Mesta River, Bulgaria Plamen Ivanov1 and Luc Ector2 1

Sofia University “St. Kliment Ohridsky”, Faculty of Biology, Department of Botany, 8 Dragan Tzankov blvd., 1164, Sofia, Bulgaria, e-mail: [email protected]

2

Centre de Recherche Public-Gabriel Lippmann, CREBS, 41 rue du Brill, L-4422 Belvaux, Grand-duchy of Luxembourg, e-mail: [email protected] ABSTRACT

Achnanthidium temniskovae Ivanov et Ector, a new species of the family Achnanthidiaceae D.G. Mann is described on the basis of light and scanning electron microscopy from the Mesta River, Bulgaria. The new species is distributed in the epilithon of a restricted part of the river. It is closely related and compared to some other species from the genus Achnanthidium: A. atomoides Monnier, Lange-Bertalot et Ector, A. atomus (Hustedt) Monnier, Lange-Bertalot et Ector, A. minutissimum (Kützing) Czarnecki, A. pyrenaicum (Hustedt) Kobayasi, A. subatomus (Hustedt) Lange-Bertalot, A. eutrophilum (Lange-Bertalot) LangeBertalot and A. saprophilum (Kobayasi et Mayama) Round & Bukhtiyarova. Light and scanning electron micrographs of the new species and some other Achnanthidium species found in the Mesta River: A. minutissimum (Kützing) Czarnecki, A. pyrenaicum (Hustedt) Kobayasi, A. subatomus (Hustedt) Lange-Bertalot, A. eutrophilum (Lange-Bertalot) LangeBertalot, A. saprophilum (Kobayasi et Mayama) Round & Bukhtiyarova are given. Key words: Bacillariophyta, Achnanthidium temniskovae sp. nov., river, Bulgaria INTRODUCTION The studies of the diatom flora of Bulgarian rivers are limited and include data for few rivers (Ivanov and Kirilova in press). One of these is the Mesta River, situated in the southwestern part of the country. The diatom flora of the Mesta River from the period 1989 – 1991 was studied by Passy-Tolar and Lowe (1994, 1995) and Passy-Tolar et al. (1999). The latest investigation of the epilithic diatom flora of the Mesta River started in 2000 and 147

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shows some changes in the taxonomic composition and environmental conditions of the river during the last decade (unpublished data). In the investigated samples some species new to the Mesta River and to Bulgaria have been found. Among them were some species belonging to the former genus Achnanthes Bory, but recently split from it and moved from the subgenus to genus level as Achnanthidium by Mann (Round et al. 1990). These are A. pyrenaicum (Hustedt) Kobayasi, A. subatomus (Hustedt) Lange-Bertalot, A. eutrophilum (Lange-Bertalot) Lange-Bertalot and A. saprophilum (Kobayasi et Mayama) Round & Bukhtiyarova. The Achnanthidium taxa found in the Mesta River were taxonomically investigated leading to the description of a new Achnanthidium species. Under the light microscope it most closely resembles Achnanthidium atomoides Monnier, Lange-Bertalot et Ector and A. atomus (Hustedt) Monnier, Lange-Bertalot et Ector, both of them not yet found in the Mesta River (Monnier et al. 2004). MATERIALS AND METHODS Epilithic samples from the Mesta River, Bulgaria, were collected during the period July – September 2003. The samples were laboratory processed following the method of Hasle and Fryxell (1970). For light microscopy, the cleaned materials were mounted on permanent slides with Naphrax. Light microscopy was performed with a Leica DMRB with a 100x oilimmersion objective. For scanning electron microscopy, the clean material was air dried on stubs and sputtered with gold (40 nm). Scanning electron microscopy was performed with a Leica Stereoscan 430i, operated at 20 kV. The diatom identification followed: Krammer and Lange-Bertalot (1986-1991), Lange-Bertalot (1993, 2001), and Lange-Bertalot and Krammer (1989). Fifty valves from six samples were used to measure the morphometric features of the new species. Five hundred valves were counted in each sample to assess the relative abundance of the diatoms. Temperature, conductivity and pH, were measured at the time of sample collection to characterize the environmental conditions. RESULTS Achnanthidium temniskovae Ivanov et Ector spec. nov. (Figs 1-26, 27-43). Diagnosis: Achnanthidio atomoide et A. atomo affinis sed, in microscopio electronico, projecturis rotundatis pleurarum ad extremitates valvarum in limbo extensis et extremitatibus distalibus raphis in directionem unam externe uncatis differt; in microscopio optico valvis leviter subrostratis, centralibus extremitatibus raphis distantioribus et majore area centrali differt. Valvae lineares ellipticae, leviter subrostratae, 8,8-13,2 µm longae, 2,8-3,8 µm latae. Striae uniseriatae, in raphovalva 22-27 in 10 µm, valde radiatae in centrali parte, radiatae densioresque ad extremitates, in areovalva 19-26 in 10 µm, parallelae in majore parte valvae, leviter radiatae densioresque ad extremitates. Proximales extremitates raphis 0,7-1,0 µm distantes, bene visibiles; distales extremitates raphis externe in directionem unam uncatae.

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1-11

12-14

15-18

19-26

Figs 1-26. Achnanthidium temniskovae (type material from the Mesta River, Bulgaria), LM. Scale bar = 10 µm. Figs 1-11: raphe valves. Figs 12-14: rapheless valves. Figs 15-18: girdle views. Figs 19-26: two valves of the same individual.

Description: Valves linear-elliptic, slightly subrostrate. Length 8.8 to 13.2 µm, width 2.8 to 3.8 µm. Length/ width ratio 2.9 to 4.3. Raphe valve concave (Figs 15-18, 31), rapheless convex (Figs 15-18, 32, 34 ) along the transapical axis. Valves in girdle view narrow – 2.0 to 3.0 µm, slightly bent along the apical axis, central nodule visible in LM (Figs 15-18). Striae always uniseriate. Outside foramen of the areolae small and mostly circular, elongate only toward the ends of the rapheless valve. Internally the areolae are expanded, elliptical and closed by hymens (Figs 37-43). Raphe valve striae between 22 to 27 in 10 µm, denser at the valve ends, curved, radiate near the center, strongly radiate toward the ends. Striae interrupted at the valve face/mantle junction by a hyaline area, forming a single row of circular areolae on the mantle (Fig. 31). No striae in the central area. Rapheless valve striae very different, between 19 to 26 in 10 µm, parallel trough almost the whole valve length, to slightly radial and denser at the valve ends. Striae interrupted at the valve face/ mantle junction by a hyaline area, forming a single raw of elongated areolae on the mantle (Fig. 32). Areolae denser on the raphe valve (approximately 46 in 10 µm, externally) than on the rapheless valve (approximately 41 in 10 µm, externally). Axial area on raphe valve and pseudoraphe on rapheless valve very narrow and linear. Raphe valve central area rectangular. Raphe branches straight. Central raphe ends externally straight, drop shaped (Figs 27-31), internally slightly deflected to opposite directions (Figs 37-40). Distance between central raphe ends between 0.6 and 1.0 µm. Distal raphe ends externally hooked to one direction (Figs 27-30), internally slightly deflected to one direction (Figs 37-40). Girdle bands near the valve ends with rounded projections, extended to the valve faces and covering the mantle (Figs 31, 34). 149

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Figs 27-43. Achnanthidium temniskovae (type material from the Mesta River, Bulgaria), SEM. Scale bar = 1 µm. Figs 27-30: raphe valves, outside view. Fig. 31: raphe valve and girdle, outside view. Figs 32, 33: rapheless valves, outside view. Fig. 34: frustule, rapheless valve and girdle, outside view. Figs 35, 36: frustule, girdle view. Figs 37-40: raphe valves, inside view. Figs 41-43: rapheless valves, inside view.

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The species is named in honor of Prof. Doc. Dobrina Temniskova in celebration of her 70 year anniversary. Holotype: Sofia University “St. Kliment Ohridsky”, Faculty of Biology, Department of Botany, Collection of Plamen Ivanov, # 1/190903. Isotype: Centre de Recherche Public-Gabriel Lippmann, CREBS, Luxembourg. Type locality: Bulgaria, in the epilithon of the Mesta River, between 41° 54.073' N, 23° 31.632' E and 41° 42.583' N, 23° 42.138' E. Distribution and ecology: Achnanthidium temniskovae was found in all six epilithic samples of a 40 km stretch of the Mesta River, between General Kovatchev (41° 54.073’ N, 23° 31.632’ E) and Koupena (41° 42.583’ N, 23° 42.138’ E), Bulgaria, and neither upstream nor downstream of the river (Fig. 44). The relief of the area is mountainous, the altitude is between 770 and 605 m a.s.l., and the width of the river is approximately six meters. The temperature varied from 10 to 20 °C, pH from 9.0 to 10.0, and conductivity from 611 to 730 µS/cm. Achnanthidium temniskovae was rare in the observed sites. Its frequency of occurrence in the samples varied from 0.5 to 2%. The most frequently accompanying and abundant taxa were Achnanthidium subatomus (Hustedt) Lange-Bertalot, Cocconeis placentula var. euglypta (Ehrenberg) Grunow, Diatoma vulgaris Bory, Encyonema minutum (Hilse) D.G. Mann, Fistulifera saprophila (Lange-Bertalot & Bonik) Lange-Bertalot, Navicula capitatoradiata Germain, N. cryptotenella Lange-Bertalot, N.

Fig. 44. Distribution of Achnanthidium temniskovae in the Mesta River, Bulgaria. The stretch of the river where Achnanthidium temniskovae was found is marked with asterisks.

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subminuscula Manguin, Nitzschia amphibia Grunow, N. fonticola Grunow, N. paleacea Grunow, Reimeria sinuata (Gregory) Kociolek et Stoermer. DISCUSSION According to its morphological features the new taxon belongs to the genus Achnanthidium within the family Achnanthidiaceae. When compared to the other representatives of the genus, Achnanthidium temniskovae most closely resembles Achnanthidium atomoides Monnier, Lange-Bertalot et Ector and A. atomus (Hustedt) Monnier, Lange-Bertalot et Ector (Monnier et al. 2004). Under SEM it differs from them by the rounded projections of the

45-54

63-66

55-62

67-75

76-85 Figs 45-85. Some other close Achnanthidium species from the Mesta River, LM. Scale bar = 10 µm. Figs 45-54. A. minutissimum. Figs. 55-62. A. pyrenaicum. Figs 63-66. A. saprophilum. Figs 67-75. A. eutrophilum. Figs 76-85. A. subatomus.

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Table 1. Comparison of morphometric features of the type material of Achnanthidium temniskovae and A. atomoides, and the original material from the type locality of A. atomus. The data concerning the last two taxa are according to Monnier et al. (2004). The first and the last numbers are minimal and maximal values, bold numbers are averages. Achnanthidium Achnanthidium Achnanthidium temniskovae atomoides atomus (Bulgaria) (Luxembourg) (Java) Length (µm) Width (µm) Length/width ratio Distance between central raphe ends (µm) Number of stria in 10 µm on raphe valve Number of stria in 10 µm on rapheless valve Number of areolae in 10 µm on raphe valve, externally Number of areolae in 10 µm on raphe valve, internally

8.8-11.1-13.2 2.8-3.1-3.8

4.3-7.1-9.7 2.2-2.6-3.2

6.6-9.1-13.4 2.7-3.1-3.7

2.9-3.7-4.3 0.6-0.8-1.0 22-24-27

1.8-2.6-3.1 0.4-0.6 25.3-29.0-32.0

2.2-3.0-4.0 0.5-0.9 21.6-23.6-26.2

19-21-26 42-46-50 40-44-45

22.8-25.8-28.1 60-65-69 60-62-65

18.5-19.9-21.2 42-45-46 51-54-65

46-50-55 55-58-60

37 37-44-46

Number of areolae in 10 µm on rapheless valve, externally 40-41-43 Number of areolae in 10 µm on rapheless valve, internally 35-36-37

girdle bands near the valve ends, extending to the valve faces (Figs 31, 34), distal raphe endings externally hooked to one direction (Figs 27-30), and the single raw of elongated areolae on the mantle (Figs 32, 34, 36). Under LM it differs mainly by some morphological features: a slightly subrostrate shape of the valve; a visibly greater distance between central raphe ends (up to 1.0µm); and a larger central area (Table 1). A. atomoides and A. atomus were not found in the investigated samples. Some other close Achnanthidium species found in the Mesta River were A. subatomus (Hustedt) Lange-Bertalot (more elliptic, not subrostrate, not such large central area - Figs 7685); A. minutissimum (Kützing) Czarnecki (very variable but shaped differently with denser stria - Figs 45-54); A. pyrenaicum (Hustedt) Kobayasi (valve shape different, with smaller central area - Figs 55-62); A. eutrophilum (Lange-Bertalot) Lange-Bertalot (lanceolate valve shape - Figs 6775); A. saprophilum (Kobayasi et Mayama) Round & Bukhtiyarova (different valve shape, not so linear, more elliptical and not with such a large central area - Figs 63-66). ACKNOWLEDGMENTS We express our gratitude to O. Monnier, F. Rimet and C. Bouillon (Centre de Recherche Public-Gabriel Lippmann, Luxembourg) for the critical notes, advice and technical support, and to P. Compere (National Botanical Garden, Meise, Belgium) for the Latin translation and corrections. Funding of this research was provided by Sofia University “St. Kliment Ohridsky”, Bulgaria and Centre de Recherche Public - Gabriel Lippmann, Luxembourg.

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REFERENCES HASLE, G. and G. FRYXELL 1970. Diatoms: Cleaning and mounting for light and electron microscopy. - Transactions of the American Microscopical Society, 89(4): 469-474. IVANOV, P. and E. KIRILOVA in press. Benthic diatom assemblages from different substrates of the Iskar River, Bulgaria. in: A. Witkowski, editor. Proceedings of the 18th International Diatom Symposium. Miendzyzdroje, Poland, 2-7 September. KRAMMER, K. and H. LANGE-BERTALOT 1986-1991. Süßwasser flora von Mitteleuropa. H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Vol. 2: Parts 1-4. Bacillariophiceae. Gustav Fisher Verlag, Stuttgart, N. York. LANGE-BERTALOT, H. 1993. 85 Neue Taxa und über 100 weitere neu definierte Taxa ergänzend zur Sübwasserflora von Mitteleuropa Vol. 2/1-4. in: Bibliotheca Diatomologica, 27, 454 pp. J. Cramer, Berlin. Stuttgart. LANGE-BERTALOT, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. in: H. Lange-Bertalot, editor. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats, 2, 526 pp. A.R.G. Gantner Verlag K.G. LANGE-BERTALOT, H. and K. KRAMMER 1989. Achnanthes eine Monographie der Gattung mit Definition der Gattung Cocconeis und Nachtragen zu den Naviculaceae. in: Bibliotheca Diatomologica, 18, 393 pp. J. Cramer, Berlin. Stuttgart. MONNIER, O., H. LANGE-BERTALOT, F. RIMET, L. HOFFMAN and L. ECTOR 2004. Achnanthidium atomoides sp. nov., a new diatom from the Grand-duchy of Luxembourg. – Vie et Milieu, 2004, 54 (2-3): 127-136. PASSY-TOLAR, S. and R. LOWE 1994. Taxonomy and ultrastructure of Gomphoneis mesta sp. nov. (Bacillariophyta), a new epilithic diatom from the Mesta River, Bulgaria. Journal of Phycology, 30: 885-891. PASSY-TOLAR, S. and R. LOWE 1995. Gomphoneis mesta (Bacillariophyta). II. Morphology of the initial frustules and perizonium ultrastructure with some inferences about diatom evolution. - Journal of Phycology, 31: 447-456. PASSY-TOLAR, S., Y. PAN and R. LOWE 1999. Ecology of the major periphytic diatom communities from the Mesta River, Bulgaria. - International Review of Hydrobiology, 84(2): 129-174. ROUND F., R. CRAWFORD and D. MANN 1990. The diatoms. Biology and morphology of the genera. Cambridge University Press, Cambridge, 747 p.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 155-165) © PENSOFT Publishers & University Publishing House Sofia–Moscow

A new Gyrosigma species from lakes Prespa and Ohrid Zlatko Levkov, Svetislav Krstic and Teofil Nakov Institute of Biology, Faculty of Natural Sciences, Gazi Baba bb 1000 Skopje, Republic of Macedonia, email: [email protected] ABSTRACT A new diatom species, G. macedonicum Levkov, Krstic & Nakov, is described from Lakes Prespa and Ohrid, Macedonia. The species belongs to the group Acuminati sensu Peragallo with approximately equally fine longitudinal and transverse striae. The most distinct feature of the new species is double curvature of the raphe system. A comparison with other Gyrosigma species found in both lakes is also performed. Key words: Gyrosigma, new species, Lakes Ohrid and Prespa. INTRODUCTION Lakes Ohrid and Prespa belong to a group of ancient lakes, with age of cca. 3 million years. Lake Ohrid is well known for the endemic occurrence of taxa from the genera Campylodiscus Ehrenberg (Jurilj 1949, 1954, 1956, Jerkovic 1971), and Navicula sensu lato (Hustedt 1945, Lange-Bertalot 2001). In the past two decades, additional diatom studies have been made in Lake Ohrid (Lange-Bertalot et al. 1991, Krammer 1997, 2002, Levkov et al 2005a), resulting in the description of several new diatom species. In two floristic studies (Hustedt 1945, Jurilj 1954) four Gyrosigma Hassall species were listed, with short notes on their distribution in Lake Ohrid. Only Jurilj (1954) supplied a drawing of two species: G. attenuatum (Kützing) Rabenhorst (Figs 53a,b) and Gyrosigma distortum var. parkeri Harrison (Fig. 53c). The latter is drawn as 114 µm long and 15 µm wide with equally fine longitudinal and transverse striation. In more recent studies (Sterrenburg 1994) on Gyrosigma species it has been shown that “G. distortum var. parkeri” is, in fact, an additionally established synonym for G. wormleyi and it is a markedly different species from the marine species G. distortum (W. Smith) Cleve. In personal studies on Lakes Prespa and Ohrid, many Gyrosigma specimens that superficially 155

Zlatko Levkov, Svetislav Krstic and Teofil Nakov

resemble G. wormleyi have been observed and may have previously been identified as “G. distortum var. parkeri” (e.g. Jurilj 1954, Fig. 53c). However, these specimens differ essentially from G. wormleyi, and description of new species is required. MATERIAL AND METHODS Lake Ohrid is the largest lake of the Dessaret group of lakes (Cvijic 1906). It is located in the south-western part of Macedonia (40o54' N and 20o40' E) between the mountains Mokra Gora and Galicica (Fig. 1) at 695.8 m above sea level (Kolchakovski 2004). The total surface area is 348.8 km2, (229.9 km2 of which belongs to Macedonia and 118.9 km2 to Albania) and the maximum depth is 285.7 m. The largest springs, sublacustric and above ground, are located in the south-eastern part of the lake. A large quantity of water in these springs originates from Lake Prespa (Anovski et al. 2001), due to the natural underground connection between the two lakes and differences in altitude. Lake Prespa is the second largest lake of the Dessaret group of lakes. It is located in the south-western part of Macedonia (40o50' N and 19o43' E), in a tectonic valley between

Fig 1. Map of investigated area with sampling sites.

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A new Gyrosigma species from lakes Prespa and Ohrid

the mountains Galicica and Baba at 853 m above sea level (Chavkalovski 1997). It is mountainous and relatively deep (c. 60 m) with a total surface area of 274 km2. The total area of the watershed is 1095 km2 (Chavkalovski 1997). Samples from Prespa and Ohrid were collected in the period June 2002 to July 2004. From Lake Prespa materials such as macrophytes, sediment, and epilithon were collected from 12 sampling sites. Samples from Lake Ohrid were collected along two transects from 0.5-150 m depth, on contours of 5-10 m depth. The sediment was collected using a Van Veen bottom sampler at different depths. Collected samples were preserved with 4% formaldehyde and deposited in the Diatom Collection at the Institute of Biology, Faculty of Natural Sciences in Skopje (DCIBS). Samples were cleaned using the acid digestion method (Krammer and Lange-Bertalot 1986), and mounted in Naphrax®. Slides were deposited at the Diatom Collection at Institute of Biology in Skopje (DCIBS) and the Friedrich Hustedt Diatom Collection. Light microscope photographs were made using a Nikon Eclipse 800 and plates were prepared according to Bayer et al. (2001). SEM analyses were performed with a JEOL JSM 6480 at 20 kV. The relative abundance of the species was estimated by counting of 200 valves per slide (Levkov 2005). OBSERVATIONS In personal studies on Gyrosigma species in Lakes Prespa and Ohrid four different species were observed (Table 1). One of these has different numerical and morphological features than the already described species and should be described as a new species. Gyrosigma macedonicum sp. nov. Figs 2-13 Synonym: Gyrosigma distortum var. parkeri Harrison sensu Jurilj 1954 Fig. 53c. Diagnosis: Valva lanceolata, distincte gracilior apices versus, 110-142 µm longa, 14-19 µm lata. Striae longitudinales 18-20 in 10 µm, transversae 19-21 in 10 µm. Sternum raphis bicurvatum, fissurae raphis centrales sensu contrario curvatae. Area centralis elongata vel leniter obliqua. A Gyrosigma acuminatum (Kützing) Rabenhorst et Gyrosigma wormleyi (Sullivant) Boyer satis differt. Description: Valves lanceolate, 110-142 µm long, 14-19 µm wide, with clearly narrower apical portions. Longitudinal striae 18-20 in 10 µm, transverse striae 19-21 in 10 µm. The raphe sternum shows a clearly double curvature, the central raphe fissures are oppositely deflected towards the convex side of the raphe sternum on both valves of a frustule. The central area is elongated or slightly oblique. Holotype: Slide 000862, Diatom Collection at Institute of Biology, Faculty of Natural Sciences in Skopje, Macedonia. Isotype: Slide No. ZU5/100, Friedrich Hustedt Diatom Collection. Type locality: Lake Prespa, Oteševo, Macedonia, 200 56' 14" E - 400 58' 50" N. Type material: sediment 4 m deep, Oteševo, Lake Prespa, collection date: 25.04.2003. Accession No. DCIBS 000530. 157

Zlatko Levkov, Svetislav Krstic and Teofil Nakov

6

7

5 4 2

3

Figs 2-7. Light Microscopy (LM). Gyrosigma macedonicum sp. nov. Figs 2-5. Diminution series. Fig. 6. Valve apex. Fig. 7. Central area with proximal raphe fissures oppositely deflected. Scale bar 10 µm.

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A new Gyrosigma species from lakes Prespa and Ohrid

8

9

10

Figs 8-10. Gyrosigma macedonicum sp. nov. Scanning Electron Micrographs (SEM). Fig. 8. General valve outline. Figs 9,10. External valve view - middle portion of the valve with proximal “crookshaped” raphe ends. Arrow on Fig. 10 showing the slightly expanded raphe ends.

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11

12

13

14

Figs 11-14. Gyrosigma macedonicum sp. nov. SEM internal valve view. Figs 11, 12. middle portion of the valve with central area. Figs 13, 14. valve ends. Arrow on Fig. 14 showing the small apical foramina.

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A new Gyrosigma species from lakes Prespa and Ohrid

Etymology: The species name refers to country name (Macedonia), where this species was found. Distribution: This species has 1% abundance in the type material and is also present with 0.5-5% abundance in several additional samples from the studied area. On the SEM, externally, the acuminati-type striation was confirmed (Figs 8-11). Areolae are slit-like as in other Gyrosigma species (Fig. 10). The central area is narrow and slightly oblique in shape (Figs 9, 10). The central raphe fissures are oppositely deflected, “crook shaped”, do not cross the areolar rows as in G. acuminatum, and are slightly expanded at the ends (Fig. 10, arrow). Internally, the central area is elongated to slightly oblique (Figs 11, 12), opposite to G. acuminatum which has an oval and not rotated central area (Sterrenburg 1995). Central pores are small and slightly expanded as in other Gyrosigma species (Fig. 12). Terminal raphe fissures end with small helictoglossae (Figs 13, 14). Areolae are absent around the apex, while small apical foramina are present (Fig. 14, arrow), unlike G. rautenbachiae Cholnoky. DISCUSSION In valve outline, G. macedonicum closely resembles G. wormleyi (Sullivant) Boyer (also named Gyrosigma distortum var. parkeri, e.g. in Hustedt 1955), but it differs from that species because the transverse and longitudinal striae are equally fine. In G. wormleyi the transverse striae are clearly coarser. Also, the raphe sternum in G. macedonicum shows marked double curvature, while in G. wormleyi there is single curvature. The raphe fissures in G. macedonicum are oppositely deflected, unlike G. wormleyi where one raphe fissure of a pair is almost straight. Regarding striation, the new species somewhat resembles G. acuminatum, but it clearly differs since the raphe sternum branches show double curvature, while G. acuminatum has single curvature. Also, the valve becomes markedly narrower towards the apices, oppositely to gradually narrow valves in G. acuminatum. The raphe fissures in G. macedonicum show the same type of deflection to the convex side of the raphe sternum on both valves of a frustule, while in G. acuminatum the raphe fissures deflect to the concave side of the raphe sternum on one valve (Sterrenburg 1995). Another species that has double curvature is G. tubicolum Sterrenburg & Tiffany (Sterrenburg and Tiffany 2004), but the species belongs to the group of Attenuati sensu Peragallo with longitudinal striae coarser than the transverse, different valve outline and also a different ecology (tropical marine species). G. kützingii (Grunow) Cleve, a species that belongs to the group of Strigiles sensu Peragallo, has an asymmetric curvature of the raphe sternum and differently shaped valve ends that gradually narrow (Sterrenburg 1997). An important feature that was noted during observations of the Gyrosigma species from Lakes Ohrid and Prespa was that the observed G. attenuatum valves (Figs 16, 17) show a greater length and width than those reported in the literature (Table 1). This feature was also noticed in several other taxa from both lakes, that generally have a wider distribution, such as Navicula tripunctata Bory or Cymbella lange-bertalotii Krammer (Levkov 2005). Observations of populations of these species from the polluted River Vardar (Krstic 1995, Krstic et al. 1997) and oligotrophic lakes on Shara Mountain (Levkov et al. 2005b) show the 161

Zlatko Levkov, Svetislav Krstic and Teofil Nakov

19

16

15

18

20

17 Figs 15-20. Light micrographs of Gyrosigma attenuatum, G. sciotoense and G. obtusatum. Figs 15, 16. G. attenuatum. Figs 17, 18. G. sciotoense. Figs 19, 20. G. obtusatum. Scale bar for Figs 15,16 is 20 µm, scale bar for Figs 17-20 is 10 µm.

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A new Gyrosigma species from lakes Prespa and Ohrid

Table 1. Numerical data for different Gyrosigma species Species

Source

Length Width Transverse Longitudinal (µm) (µm) striae striae (in 10 µm) (in 10 µm)

G. attenuatum (Kützing) Rabenhorst

Krammer & 60-180 Lange-Bertalot 1986

11-18

14-16

10-12

G. acuminatum (Kützing) Rabenhorst G. sciotoense (Sullivant et Wormley) Cleve G. obtusatum (Sullivant et Wormley) Boyer

Sterrenburg 1995 Sterrenburg 1994 Sterrenburg 1994

70-180 70-175 45-110

12-24 12-20 10-16

18-23 18-22 22-26

19-24 21-25 28-35

G. wormleyi (Sullivant) Boyer G. kutzingii (Grunow) Cleve G. peisonis (Grunow) Cleve

Sterrenburg 1994 Sterrenburg 1997 Sterrenburg 1997

90-150 90-150 65-125

16-22 12-15 8-13

20-23 21-23 21-23

23-27 24-27 25-28

G. macedonicum n.sp. G. attenuatum (Kützing) Rabenhorst G. sciotoense (Sullivant et Wormley) Cleve

this study this study this study

110-142 14-19 200-350 25-35 105-175 12-15

19-21 12-14 17-20

18-20 9-10 21-26

27-28

30-33

G. obtusatum (Sullivant et Wormley) Boyer this study

45-70

8-10

presence of smaller cells than the populations in Lakes Ohrid and Prespa. According to Edlund et al. (2003) there are three possible explanations for larger cells occurring in ancient lakes: (i) larger gametangial and initial cell cardinal point size during sexual reproduction; (ii) oligotrophic conditions and (iii) evolutionary processes. It is hypothesized that an evolutionary mechanism, in combination with oligotrophic conditions, is important in the production of large-celled populations (Levkov 2005). In any case, molecular and reproductional analyses could help in resolving this hypothesis (Edlund et al. 2003). ACKNOWLEDGEMENTS The authors wish to express their gratitude to Dr. Frithjof Sterrenburg, National Natural History Museum, Leiden, The Netherlands, for his great help identification and Latin description of the new species and to Dr. Mario Langourov, BAN for his help in making SEM microphotographs. REFERENCES ANOVSKI, T., M. KOLANECI, J. MILEVSKI, P. RISTEVSKI and A. STAMOS 2001. Hydrological aspects and water balance of Prespa Lakes. in: T. Anovski, editor. Progress in study of Prespa Lake using nuclear and related techniques. 55-66, Skopje. BAYER, MM., S.J.M. DROOP and D.G. MANN 2001. Digital microscopy in phycological research, with special reference to microalgae. - Phycological Research, 49: 263-274. 163

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CHAVKALOVSKI, I. 1997. Hydrology of Prespa Lake. in: L. Gjiknuri, A. Miho and S. Shumka, editors. Proceedings of International Symposium: Towards Integrated Conservation and Sustainable Development of Transboundry Macro and Micro Prespa Lakes, 9-14. Korca. CVIJIC, J. 1906. Basis of the Geography and Geology of Macedonia and Old Serbia. Serbian Academy of Sciences, 1: 689-1271, Beograd. EDLUND, M.B., R.M. WILLIAMS and N. SONINKHISHIG 2003. The planktonic diatom diversity of ancient Lake Hövsgöl, Mongolia. – Phycologia, 42: 232-260. HUSTEDT, F. 1945. Diatomeen aus Seen und Quellgebieten der Balkan-Halbinsel. Archiv für Hydrobiologie, 40: 867-973. HUSTEDT, F. 1955. Marine littoral diatoms of Beaufort, North Carolina. - Duke University Marine Station Bulletin, 6: 3-67. JERKOVIC, L. 1971. Two new relic Campylodiscus species (diatoms) of Ochrid Lake (Yugoslavia). - Phycologia, 10: 227-280. JURILJ, A. 1949. New diatoms - Surirellaceae- of Ochrida Lake in Yugoslavia and their phylogenetic significance. - Prirodoslovna Istrazivanja, 24: 1-94, Zagreb. JURILJ, A. 1954. Flora and vegetation of diatoms from Ohrid Lake. - Prirodoslovna Istrazivanja, 26: 99-190, Zagreb. JURILJ, A. 1956. La phylogenese spécifique d’un groupe de diatomées Campylodiscoideae - et sa cause. - Hydrobiologia, 8: 1-15. KOLCHAKOVSKI, D. 2004. Physical geography of Republic of Macedonia. - “St. Cyrilus and Methodius” University Press. Skopje. 273 pp. KRAMMER, K. 1997. Die cymbelloiden Diatomeen. Teil 1. Allgemeines und Encyonema part. - Bibliotheca Diatomologica, 36: 1-382. KRAMMER, K. 2002. Cymbella. in: H. Lange-Bertalot, editor. Diatoms of Europe 3: 1-584. A.R.G. Gantner-Verlag, Ruggell, Liechtenstein. KRAMMER, K. and H. LANGE-BERTALOT 1986. Bacillariophyceae 2: Naviculaceae. in: H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Süsswasserflora von Mitteleuropa 2/1: 1-596. Gustav Fischer Verlag, Stuttgart. KRSTIC, S. 1995. Saprobiological characteristics of River Vardar microflora as indicator of anthropogenic influence. - PhD Thesis, 402 pp. Faculty of Natural Sciences, Skopje. KRSTIC, S., Z. LEVKOV and P. STOJANOVSKI 1997. Saprobiological characteristics of diatom microflora in river ecosystems in Macedonia as a parameter for determination of the intensity of anthropogenic influence. in: J. Prygiel, B.A. Whitton and J. Bukowska, editors. Use of Algae for Monitoring Rivers 3: 145-153. LANGE-BERTALOT, H. 2001. Navicula sensu stricto and 10 genera separated from Navicula sensu lato, Frustulia. in: H. Lange-Bertalot, editor.: Diatoms of Europe 2: 1526. A.R.G. Gantner-Verlag, Ruggell, Liechtenstein. LANGE-BERTALOT, H., U. RUMRICH and G. HOFMANN 1991. Zur Revision der Gattung Diatoma Bory (Subgenus Diatoma, Bacillariophyceae) Identifikation ökologisch wichtiger, aber taxonomisch problematischer Arten. - Acta Biologica Benrodis, 3: 115-130.

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LEVKOV, Z. 2005. Taxonomy and ecology of diatom flora from Lake Prespa and St. Naum Springs. - PhD Thesis, Faculty of Natural Sciences, Skopje, 482 pp. LEVKOV, Z., D. METZELTIN and S. KRSTIC 2005a. New and rare diatoms from Lakes Ohrid and Prespa. in: A. Witkowski, editor. Proceeding of 18th International Diatom Symposium. (in press). LEVKOV, Z., S. KRSTIC, T. NAKOV and L. MELOVSKI 2005b. Diatom assemblages on Shara and Nidze Mountains, Macedonia. - Nova Hedwigia, 81. (in press). STERRENBURG, F.A.S. 1994. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae). The species of Sullivant & Wormley 1859, synonymy and differentiation from other Gyrosigma taxa. - Proceedings Academy of Natural Sciences of Philadelphia, 145: 217-236. NOTE: subtitle inadvertently omitted in print. STERRENBURG, F.A.S. 1995. Studies on the Genera Gyrosigma and Pleurosigma (Bacillariophyceae): Gyrosigma acuminatum (Kützing) Rabenhorst, G. spenceri (Quekett) Griffith, and G. rautenbachiae Cholonoky. - Proceedings Academy of Natural Sciences of Philadelphia, 146: 467-480. STERRENBURG, F.A.S. 1997. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae): Gyrosigma kützingii (Grunow) Cleve and G. peisonis (Grunow) Hustedt. - Proceedings of the Academy of Natural Sciences of Philadelphia, 148: 157-163. STERRENBURG, F.A.S. and M.A. TIFFANY 2004. Studies on the genera Gyrosigma and Pleurosigma (Bacillariophyceae): Two new species from the Red Sea: Gyrosigma schmidianum nov.sp. and Gyrosigma tubicolum nov. sp. - Diatom Research, 19: 275-281.

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Diatom species composition from the River Iskar in the Sofia region, Bulgaria Plamen Ivanov1, Emilia Kirilova2 and Luc Ector3 Sofia University “St. Kliment Ohridsky”, Faculty of Biology, Department of Botany, 8 Dragan Tzankov blvd., 1164, Sofia, Bulgaria, e-mail: [email protected] 2 Laboratory of Palaeobotany and Palynology. Utrecht University, Budapestlaan 4, CD – 3584 Utrecht, the Netherlands, e-mail: [email protected] 3 Centre de Recherche Public - Gabriel Lippmann, CREBS (Cellule de Recherche en Environnement et Biotechnologies), 41, rue du Brill, L-4422 Belvaux, Grand-duchy of Luxembourg, e-mail: [email protected] 1

ABSTRACT This paper is a summary of the floristic data of the diatoms found in the river Iskar within the limits of the Sofia region in Bulgaria. A full list of the species composition is presented, together with some light micrographs of the periphytic diatoms, their distribution on different substrata, and sampling points. There were 329 diatom species, varieties and forms identified, from 70 genera. 184 taxa are presented in 324 light microscope photographs. The community was dominated by pennate diatoms. The most abundant genera were: Nitzschia (55 taxa), Navicula (41 taxa), Gomphonema (25 taxa), Pinnularia (17 taxa), Cymbella (14 taxa) and Fragilaria (11 taxa). Key words: diatoms, periphyton, the river Iskar, Bulgaria INTRODUCTION The ecology and distribution of diatoms in Bulgarian rivers are poorly investigated. Periphyton is an ecologically important component of rivers, but it is not included in the environmental assessment of river ecosystems in Bulgaria because of the lack of floristic data. The only rivers studied in Bulgaria in detail are Iskar (Kawecka 1974, Ivanov et al. 2003 a, b, Ivanov and Kirilova in press), and Mesta - from its springs to the Greece border (Passy et al. 1999). The taxonomic composition of the diatoms of the river Iskar is important to know, not only because Iskar is the longest Bulgarian river (368 km), but also 167

Plamen Ivanov, Emilia Kirilova and Luc Ector

because it crosses the city of Sofia, which strongly affects the aquatic biota. The diatom flora of the upper Iskar River and its tributaries Maljovica and Cerni Iskar (in the Rila mountain) was studied by Kawecka (1974), who found 136 diatom species. Later some particular aspects of the diatom flora (abundance in different sites and substrates, species diversity, etc.) and the ecological conditions (physicochemical data, etc.) of the river Iskar (in the Sofia region) were studied by Ivanov et al. (2003 a, b) and Ivanov and Kirilova (in press). Changes of the diatom species composition were observed along the river due to the high level of human activities in the region. Nevertheless, the full list of observed diatoms has not been published untill now, only the taxa with a relative abundance of more than 1% in a sample have been reported (Ivanov and Kirilova in press). This paper is a summary of the floristic data on the diatoms in the river Iskar. A full list of diatom species, varieties and forms is presented. Some light microphotographs of the periphytic diatoms, found, their distribution on different substrata, and sampling points are reported also. The most recent taxonomy from the latest monographs and articles on diatoms of Europe was used. The main goal of this paper is to serve as a future taxonomic reference for diatoms reported from lotic environmenments in Bulgaria. MATERIALS AND METHODS A total amount of 177 samples from: the epipelon (29), epiphyton on nonvascular plants (28), epiphyton on vascular plants (37), epipsammon (24), and epilithon (59) were analysed. Samples from 5 points were collected from the part of the river Iskar within the limits of the city of Sofia (the capital of Bulgaria and the city with highest population and industry) and the town of Svoge, Bulgaria (Fig. 1) during the period 1998 – 2002 (for details see Ivanov and Kirilova in press). Epilithic samples were collected by scrapping 5 to 6 pebbles and boulders from a site with a toothbrush. For collecting the epiphyton from nonvascular and vascular plants the whole plants or parts of them were shaked, rinsed and squeezed in a sample container. Epipelon was sampled by dragging a vial parallel to the bottom where brown flocculent materials were forming a mud. Epipsammon was collected by inserting spatula under inverted petri dish over sand sediments. Laboratory processing of the samples was carried out after Hasle and Fryxell (1970). For light microscopy, cleaned material was mounted on permanent slides with Naphrax. 500 valves were counted in each sample. Light micrographs were taken with a Leica DMRB under a 100X oil-immersion objective. The taxonomic determination of the diatoms was made primary according to Krammer (2000, 2002), Krammer and Lange-Bertalot (1986-1991), Lange-Bertalot (1993, 2001), and LangeBertalot and Krammer (1989), with some additions according to Round et al. (1990). RESULTS There were 329 identified diatom taxa of species, variety and forma level, from 70 genera in the periphyton of the studied part of the Iskar River (Table 1). 184 taxa are presented in 168

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Fig. 1. Study area and sample points along the river Iskar (filled triangles), with outline of Sofia area and the smaller urban areas (filled dots).

324 LM photographs in 10 plates. Pennate species predominated - 95%. The most abundant genera were: Nitzschia (55 taxa), Navicula (41 taxa), Gomphonema (25 taxa), Pinnularia (17 taxa), Cymbella (14 taxa) and Fragilaria (11 taxa). The largest number of species was observed in site1 and on epipelon substrate. DISCUSSION Typical, cosmopolitan, mesotrophic and eutrophic diatom taxa predominated in the sampled flora. The number of species in the studied part of the river (329) was more than two times higher than this of the upper part of the river and its tributaries (136), as reported by Kawecka (1974). The number of taxa in the richest genera - Navicula (senso lato) and Nitzschia was much higher comparing to the number found by Kawecka (1974) in the upper part of the river. This corresponds with the differences in ecological conditions between the upper (less human impact) and lower parts (with more human impact) of the river. The diatom composition found in our study was more similar to that found by Passy et al. (1999) for the river Mesta, except the absence of some oligotrophic species such as Psammothidium subatomoides (Hustedt) Bukhtiyarova et Round. It should be noted that the 169

Plamen Ivanov, Emilia Kirilova and Luc Ector

Table 1. List of the periphytic diatoms, found in river Iskar in Sofia region. Species names are listed in alphabetical order. Abbreviations: for sites - 1 to 5; for substrate - L – epilithon, S - epipsammon, P - epipelon, N - epiphyton from nonvascular plants, V - epiphyton from vascular plants; for the light microphotographs – number of the plate in arabic figures, followed by the number of the photograph; ‘+’ – presence, ‘-‘ – absence. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Achnanthes clevei var. bottnica Cleve 1891 Achnanthes exigua Grunow in Cleve et Grunow 1880

+ - - + - - - + - + + - - - - - - + - -

Photograph

III4-4a

Achnanthidium eutrophilum (Lange-Bertalot) Lange-Bertalot 1999 - + + - - + - - + Achnanthidium minutissimum (Kützing) Czarnecki 1994 + + + + + + + + + + Achnanthidium pyrenaicum (Hustedt) Kobayasi 1997 + - - - - - + - - -

II32-34 II28-31 II38, 38a

Achnanthidium saprophilum (Kobayasi et Mayama) Round et Bukhtiyarova 1984 Achnanthidium subatomus (Hustedt) Lange-Bertalot 1999

III1-3

+ - - - + - - - - -

II35-37a

Adlafia minuscula (Grunow) Lange-Bertalot 1986 Amphora commutata Grunow 1880 Amphora copulata (Kützing) Schoeman et Archibald

- + - - - - - - - + + - - - - - - + - + - + - - + + + + +

IV22, 23

Amphora fogediana Krammer 1985 Amphora inariensis Krammer 1980 Amphora montana Krasske 1932

+ + + + - + + + + + + - - - - + - - + - + + - - + + + + -

VI2 V31, 32

Amphora ovalis (Kützing) Kützing 1844 Amphora pediculus (Kützing) Grunow 1880 Amphora veneta Kützing 1844

+ + + - - + + + + + + + + + + + + + + + + + + - - - + + - +

VI1 V28-30 V33-35

Aneumastus stroesei (Ostrup) D. G. Mann 1990 Anomoeoneis sphaerophora (Ehrenberg) Pfitzer 1871 Asterionella formosa Hassall 1850

- - - - + - - - - + - - - + + - - + - + + + + + + + + + + +

II19

Aulacoseira ambigua (Grunow) Simonsen 1979 Aulacoseira granulata (Ehrenberg) Simonsen1979 Aulacoseira islandica (O. F. Müller) Simonsen 1979

+ + + + + - + + + + + + + + + + + + + + - + + - - + - + - -

Aulacoseira italica (Ehrenberg) Simonsen 1979 Aulacoseira subarctica (O. F. Müller) Haworth1988 Bacillaria paradoxa Gmelin 1791 Brachysira brebissonii Ross in Hartley 1986

+ +

Caloneis bacillum (Grunow) Cleve 1894 Caloneis branderii (Hustedt) Krammer 1985 Caloneis molaris (Grunow) Krammer 1985

+ - - - + + - + - + + - - - - + - - - + + + - - + + + - -

V22

Caloneis silicula (Ehrenberg) Cleve 1894 Ceratoneis arcus (Ehrenberg) Kützing 1844 Ceratonies recta (Skvortzow et Meyer) Iwohashi 1936

+ - + - - + - + - + + - + + + + + + + - + - - - - - + - -

V25 II15, 16

Cocconeis disculus (Schumann) Cleve in Cleve et Jentzsch 1882 Cocconeis neodiminuta Krammer 1991

+ - - - - - - + - + + - - + + + + + -

170

- - + - - + - - - -

+ + -

+ + + -

+ + -

+ + -

+ + +

+ -

+ + -

+ + -

+ + -

V26, 27

I5-6

I1-4

V23, 24

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Cocconeis pediculus Ehrenberg 1838

+ + + + + + + + + +

III16, 16a

Cocconeis placentula var. euglypta (Ehrenberg) Grunow 1884 Cocconeis placentula var. lineata (Ehrenberg) Van Heurck 1880 Cocconeis placentula var. pseudolineata Geitler 1927

+ + + + + + + + + + + + + + + + + + + + + - + + - + + + + +

III17-18a III19, 20 III21, 22

Craticula accomoda (Hustedt) D. G. Mann 1990 Craticula buderi (Hustedt) Lange-Bertalot 2000 Craticula cuspidata (Kützing) D. G. Mann 1990

+ - - + + + - + + + + + + + + + + + + + + - - + + - - + - +

V20

Cyclostephanos dubius (Fricke) Round 1982 Cyclostephanos invisitatus (Hohn et Hellerman) Theriot, Stoermer et Hakansson 1987

- + + + + + + + + - + + - - + - + + -

I22-24 I20, 21

Cyclotella meneghiniana Kützing 1844 Cyclotella ocellata Pantocsek 1902 Cymatopleura elliptica var. hibernica (W. Smith) Van Heurck 1896

- + + + + + + + + + + + + + + + + + + + + + + - - + - + - +

I28, 29 I25-27 X1

Cymatopleura solea var. apiculata (W. M. Smith) Ralfs 1861 + + + + Cymatopleura solea var. solea (Brebisson) W. M. Smith 1851 + + + + Cymbella affinis var. affinis Kützing 1844 (sensu Krammer 2002) + + + + Cymbella amphicephala Naegeli 1849 - - + -

+ + +

+ + + +

+ + + -

+ + + +

+ + + -

+ + + -

Cymbella aspera (Ehrenberg) H. Peragallo 1889 Cymbella cistula (Ehrenberg) Kirchner 1878 Cymbella compacta Ostrup 1910

+ + + - - + - + + + + + + + + + + + + + + - + - + + + + + +

Cymbella cymbiformis Agardh 1830 Cymbella excisa var. excisa Kützing 1844 Cymbella hustedtii var. hustedtii Krasske 1923

- + + - - + - - + - - + - - + - - - - - + - - - - + - -

Cymbella hybrida (Grunow) Cleve 1878 Cymbella laevis var. laevis Naegeli in Kützing 1849 Cymbella lanceolata var. lanceolata (Agardh?) Agardh 1830

+ - - - - - - - - + + - - - - - - + - + + + - + + + + + +

X2

VI17, 18 VI12, 13

X7

Cymbella similis Krasske 1932 + - - - + - + + - Cymbella tumida (Brebisson) Van Heurck 1880 + + + + + + + + + + Cymbella turgidula var. turgidula Grunow in A. Schmidt et al. 1875 - + - - + + + + - -

VI16

Cymbopleura cuspidata (Kützing) Krammer + + - - - - - + - + Denticula tenuis Kützing 1844 - - + - - - + - - Diadesmis perpusilla (Grunow) D. G. Mann in Round et al. 1990 + - - - + + + - - +

VI10 VIII24 V13, 14

Diatoma ehrenbergii Kützing 1844 Diatoma hyemalis (Roth) Heiberg 1863 Diatoma mesodon (Ehrenberg) Kützing 1844

+ + - + + + + + + + + - - - - - - + - + - - + + + - + - -

II25, 26 II22, 23 II20, 21

Diatoma moniliformis Kützing 1833 Diatoma tenuis Agardh 1812 Diatoma vulgaris Bory 1824

+ - - + + + + + + + - + + + - + - - - + + + + + + + + + +

II24

Diploneis elliptica (Kützing) Cleve 1891

- + - - - + - + - -

171

II27

Plamen Ivanov, Emilia Kirilova and Luc Ector

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Diploneis oblongella (Naegeli) Cleve-Euler 1922

- + - - - - + - - -

Diploneis ovalis (Hilse) Cleve 1891 Diploneis parma Cleve 1891 Encyonema caespitosum Kützing 1849

+ - - - - - + - - - + - - - - - + - + - - - + - + + -

V8 V7 VI11

Encyonema elginense (Krammer) D. G. Mann 1990 Encyonema minutum (Hilse in Rabenhorst) D. G. Mann 1990 Encyonema muelleri (Hustedt) D. G. Mann 1990

- + - - - - - + - + + + + + + + + + + - + - - - - - + - -

VI7, 8

Encyonema neogracile Krammer 1997 - - - - + - - + - Encyonema prostratum (Berkeley) Kützing 1844 + + + - - + - + + + Encyonema reichardtii (Krammer) D. G. Mann in Round et al. 1990 + - - - - - + - - Encyonema silesiacum (Bleisch in Rabenhorst) D. G. Mann 1990 + + + + + + + + + + Encyonema ventricosum (Agardh) Grunow in A. Schmidt et al. 1885 + + + + + + + + + + Encyonopsis falaisensis (Grunow) Krammer 1997 + - - - - - + - - + + + +

+

+ -

+ +

-

+ +

+ + + -

-

VI3, 4 VI5, 6

Encyonopsis microcephala (Grunow) Krammer1997 Encyonopsis subminuta Krammer et Reichardt 1997 Eolimna minima (Grunow) Lange-Bertalot 1998 Eolimna subminuscula (Manguin) Moser, Lange-Bertalot

+ -

et Metzeltin 1998 Epithemia sorex Kützing 1844 Eucocconeis laevis (Oestrup) Lange-Bertalot 1999

+ - - - - - - - - + + - - + - - + + - -

Eunotia bilunaris var. bilunaris (Ehrenberg) Mills 1934 Eunotia incisa var. incisa Gregory 1854 Eunotia paludosa var. paludosa Grunow in Van Heurck 1881

- - - - + - - - + + - - - - + - - - + - - + - + - + - -

Eunotia soleirolii (Kützing) Rabenhorst 1864 Fallacia helensis (Schulz) D. G. Mann 1990 Fallacia insociabilis (Krasske) D. G. Mann 1990

+ - - - - + - + - - - + - - - - + - - - - - + - - + - -

Fallacia monoculata (Hustedt) D. G. Mann 1990 Fallacia pygmaea (Kützing) Stickle et D. G. Mann 1990 Fistulifera saprophyla (Lange-Bertalot et Bonic)

- + - - - - - + - - + - + + - + + + + + + + + + + + - - -

Lange-Bertalot 1997 Fragilaria capucina var. amphicephala (Grunow) Lange-Bertalot 1991

- - - - + - - + - -

Fragilaria capucina var. austriaca (Grunow) Lange-Bertalot 1981 Fragilaria capucina var. capitellata (Grunow) Lange-Bertalot 1990 Fragilaria capucina var. capucina Desmazieres 1825

- + - - - - - - + + - - + - + + - + + + - + - + + - - - +

II10-12

Fragilaria capucina var. rumpens (Kützing) Lange-Bertalot ex Bukhtiyarova 1991 Fragilaria capucina var. vaucheriae (Kützing) Lange-Bertalot 1980

+ - - - + + + + + +

II5, 6

+ + + + + + + + + +

II7-9

Fragilaria crotonensis Kitton 1869

- + - - - + + + - -

II18

172

+ -

VI15 VI9

14 IV26, 27 III24, 25

III12

V6 V4, 5

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Fragilaria gracilis Oestrup 1910

+ - - - + - - + - -

Fragilaria henryi Lange-Bertalot 1999 Fragilaria neoproducta Lange-Bertalot 1991 Fragilaria ulna var. acus (Kützing) Lange-Bertalot 1980

- - - + + - - + - - + - + - - - + - + + + - + + + + + +

Frustulia vulgaris (Thwaites) De Toni 1891 Geissleria acceptata (Hustedt) Lange-Bertalot et Metzeltin 1996 Geissleria decussis (Oestrup) Lange-Bertalot et Mitzeltin 1996

+ + + + - + + + + + + - - - - - - + - + - + + + + + + + +

Photograph

V21 V12

Geissleria schoenfeldii (Hustedt) Lange-Bertalot et Metzeltin 1996 - - - + - - - + - Gomphonema acuminatum Ehrenberg 1832 + + - + + + - + + + Gomphonema affine Kützing 1844 - - - + + - - + + + Gomphonema amoenum Lange-Bertalot 1985 Gomphonema angustatum (Kützing) Rabenhorst 1864 Gomphonema angustum Agardh 1831

- - - + + - - + - + + + + + + + + + + + + + + + + + + + +

Gomphonema Gomphonema Gomphonema Gomphonema

+ + -

augur Ehrenberg 1840 calcifugum Lange-Bertalot et Reichardt 1999 carolinense Hagelstein 1975 gracile Ehrenberg 1838

+ +

+

+ +

+ + +

+ +

+

+ + + +

+ + +

+ +

Gomphonema micropus Kützing 1844 + - - - - - + + - Gomphonema minutum (Agardh) Agardh 1831 + + + + + + + + + + Gomphonema minutum f. pachypus Lange-Bertalot et Reichardt 1993 - + - - - + - - - Gomphonema neonasutum Lange-Bertalot et Reichardt 1998 - - - + - - - + - Gomphonema olivaceum var. calcarea (Cleve) Cleve 1894 - + + + - - - + + + Gomphonema olivaceum var. olivaceum (Hornemann) Brébisson 1838 + + + + + + + + + + Gomphonema olivaceum var. staurophorum Pantocsek 1889 Gomphonema parvulum (Kützing) Kützing 1849 Gomphonema parvulum var. parvulum f. saprophilum

- - + - - - - - - + + + + + + + + + + + - + - - - - - + - -

Lange-Bertalot et Reichardt 1993 Gomphonema pseudoaugur Lange-Bertalot 1979 - + - + + + - + + + Gomphonema pumilum var. elegans Reichardt et Lange-Bertalot 1997 + + - - - - + + + + Gomphonema pumilum var. rigidum Reichardt et Lange-Bertalot 1997 Gomphonema rosenstockianum Lange-Bertalot et Reichardt 1993

+ + + - - - - + + + - - - - - + + - -

VII15, 16 VII19, 20 VI23-26

VI27, 28 VII11-14

VI29-31 VI32, 33 VII1-3

Gomphonema subclavatum (Grunow) Grunow in Van Heurck 1885 + - + - + + + + + + Gomphonema tergestinum Fricke 1902 + - - - - - - - - + Gomphonema truncatum Ehrenberg 1832 + + - + + + - + + +

VII17, 18 VII4-6a VII7, 8

Gyrosigma acuminatum (Kützing) Rabenhorst 1853 Gyrosigma attenuatum (Kützing) Rabenhorst 1853 Gyrosigma nodiferum (Grunow) Reimer 1966

+ + + + + + + + + + + + + - - - + - + + + - + - - + + + - +

X10 X11, 11a X8

Gyrosigma scalproides (Rabenhorst) Cleve 1994

- + - - - + - + - +

X9

173

Plamen Ivanov, Emilia Kirilova and Luc Ector

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Gyrosigma spencerii (Quekett) Griffit et Henfrey 1856

+ + + - - + - + - +

Hantzschia amphioxys (Ehrenberg) Grunow 1880 Hippodonta capitata (Ehrenberg) Lange-Bertalot, Mtzeltin et Witkowski 1996

+ - + - + + + + + + + + + - - + + + - +

VIII25 V3

Hippodonta costulata (Grunow) Lange-Bertalot, Metzeltin et Witkowski 1996 Hippodonta lueneburgensis (Grunow) Lange-Bertalot,

+ - - - - - - + - -

V1, 2

+ - - - - + - - - -

Metzeltin et Witkowski 1996 Karayevia laterostrata (Hustedt) Kingston 2000 Lemnicola hungarica (Grunow) Round et Basson 1997

+ - - - - - - + - - + - - - - - + - -

Luticola goeppertiana (Bleisch in Rabenhorst) D. G. Mann 1990 Luticola monita (Hustedt) D. G. Mann 1990 Luticola mutica (Kützing) D. G. Mann 1990

+ + + + + + + + + + - - - - + - - - - + - - - + - - - + - -

Luticola muticopsis (Van Heurck) D. G. Mann 1990 Luticola nivalis (Ehrenberg) D. G. Mann 1990 Mayamaea atomus var. permitis (Hustedt) Lange-Bertalot 1997 Melosira varians Agardh 1827

+ + +

Meridion circulare var. circulare (Greville) Agardh 1831 Meridion constrictum Ralfs 1843 Navicula aff. arctotenelloides Lange-Bertalot et Metzeltin 1996

+ + + + + + + + + + + + - - + + + + - - + - - - - - - + -

IV19

Navicula amphiceropsis Lange-Bertalot et Rumrich 2000 Navicula capitatoradiata Germain 1981 Navicula cari Ehrenberg 1836

- - + - - - - - + + + + + + + + + + + + - + - - - - + - +

IV6 IV36 IV28

Navicula cariocincta Lange-Bertalot 1993 Navicula catalanogermanica Lange-Bertalot et Hofmann 1993 Navicula cincta (Ehrenberg) Ralfs in Pritchard 1861

+ - - - - - - + - + - - - - - + - - + + - - + - + + - +

IV10 IV32

Navicula concentrica Carter 1981 Navicula cryptocephala Kützing 1844 Navicula cryptotenella Lange-Bertalot 1985

+ + - - - + + - - + + + + + + + + + + + + + + + + + + + +

Navicula detenta Hustedt 1943 Navicula digitoradiata (Gregory) Ralfs in Pritchard 1861 Navicula erifuga Lange-Bertalot 1985

- + - - - - - - + - - - - + - - + - + - + - - + - - - -

IV15

Navicula exilis Kützing 1844 Navicula germainii Wallace 1960 Navicula gregaria Donkin 1861

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

IV18, 28 IV16 IV35

Navicula hambergii Hustedt 1924 Navicula heimansii Van Dam et Kooyman 1982 Navicula joubaudii Germain 1981

+ - - - - - + - - - - + - - - - - + + + - - - + + + - -

IV14 IV31

Navicula lanceolata (Agardh) Ehrenberg 1838

+ + + + + + + + + +

IV7

174

+ + +

+ +

+ +

+

+ +

+ + +

+ + +

+

+

III15, 15a V10

V11 IV24, 25 I7 I38-41

IV17 IV11-13

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Navicula medioconvexa Hustedt 1961

+ - - - - - + - - -

Navicula menisculus var. menisculus Schumann 1867 Navicula novaesiberica Lange-Bertalot 1993 Navicula opportuna Hustedt 1950

+ + + + + + + + + + + - - - - - - + - + - - - + - - + - -

IV3, 4

Navicula phyllepta Kützing 1845 Navicula radiosa Kützing 1844 Navicula recens (Lange-Bertalot) Lange-Bertalot 1985

+ + + + + + + + + + + + + + + + + + + + + + + - + + + + + +

III23

Navicula reichardtiana Lange-Bertalot 1989 Navicula reinhardtii (Grunow) Grunow in Cleve et Möller 1877 Navicula rhynchocephala Kützing 1844

- + + - - - + - + + - - - - - - - - + + - - + + - - + - +

Navicula rostellata Kützing 1844 Navicula salinicola Hustedt 1939 Navicula schroeteri var. schroeteri Meister 1932

+ + + + + + + + + + + - - - - - - + - - - - + - - - + - -

Navicula Navicula Navicula Navicula

+ + + +

subplacentula Hustedt in A. Schmidt et al. 1930 tripunctata (O. F. Müller) Bory 1822 trivialis var. trivialis Lange-Bertalot 1980 upsaliensis (Grunow) Peragallo 1903

+ + -

+ + -

+ + +

+ + +

+ + + +

+ + +

+ + +

+ + -

+ + -

IV30 IV38 IV5 IV8 IV1 IV37

Navicula vandamii var. vandamii Schoeman et Archibald 1987 Navicula veneta Kützing 1844 Navicula vilaplanii (Lange-Bertalot et Sabater)

+ - - - - - - + - + + + + + - + + + + + + - - - - - - - +

IV33, 34 IV29 IV20, 21

Lange-Bertalot et Sabater 2000 Navicula viridula (Kützing) Ehrenberg 1836 Neidium affine (Ehrenberg) Pfitzer 1871

+ + + - + + + + + + + + - - - + - - - +

IV2 V17

Neidium ampliatum (Ehrenberg) Krammer 1985 Neidium binodis (Ehrenberg) Hustedt1945 Neidium dubium (Ehrenberg) Cleve 1894

+ + - - - - - - - + + - - - - - + - - + - + - - + - + + +

V18 V19 V36

Nitzschia acidoclinata Lange-Bertalot 1976 Nitzschia acula Hantzsch in Rabenhorst 1862 Nitzschia aequorea Hustedt 1939

- + - - - - - + - - + - - - - - + - + - - + + - - + - +

VIII21

Nitzschia aff. paleaeformis Hustedt 1950 Nitzschia agnita Hustedt 1957 Nitzschia amphibia Grunow 1862

- + - - - - + - - + + - - - - - + - + + + + + + + + + + -

Nitzschia amplectens Hustedt 1957 Nitzschia angustata (W. Smith) Grunow 1880 Nitzschia archibaldii Lange-Bertalot 1980

- - - + + - - + - - - - + + + - + - + + + + + - + + - +

Nitzschia bacillum Hustedt 1922 Nitzschia brunoi Lange-Bertalot 1996 Nitzschia bulnheimiana (Rabenhorst) H. L.Smith 1862

- - + - - - - - + - + + + - + + + + + - - + - - - + + - -

VIII20 IX17

Nitzschia calida Grunow in Cleve et Grunow 1880

- + + - + + - + + +

VIII28

175

VIII31, 32 VIII14, 15

Plamen Ivanov, Emilia Kirilova and Luc Ector

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Nitzschia capitellata Hustedt in A. Schmidt et al. 1922

+ + + + + + - + + +

VIII8-10

Nitzschia clausii Hantzsch 1860 Nitzschia commutata Grunow in Cleve et Grunow1880 Nitzschia debilis (Arnott) Grunow in Cleve et Grunow 1880

- + - - - - - - - + - - - + - - - - - + - + - - - - - + - -

VIII26, 27

Nitzschia dissipata var. dissipata (Kützing) Grunow 1862 Nitzschia dissipata var. media (Hantzsch) Grunow 1881 Nitzschia dubiiformis Hustedt 1939

+ + + + + + + + + + + + + + + + + + + + - - - + - - - + - -

VIII3, 4

Nitzschia filiformis var. filiformis (W. Smith) Van Heurck 1896 Nitzschia flexoides Geitler 1968 Nitzschia fonticola Grunow in Cleve et Möller 1879

- - + - - + - - - + - + - - - - + - + + + + + + + + + + +

VIII11, 12

Nitzschia frustulum var. frustulum (Kützing) Grunow 1880 Nitzschia gracilis Hantzsch 1860 Nitzschia heufleriana Grunow 1862

+ + + + + + + + + + + + + + + - + + + + + + + + - + + + + +

VIII30 IX8, 9

Nitzschia Nitzschia Nitzschia Nitzschia

+ + + -

hungarica Grunow 1862 inconspicua Grunow 1862 intermedia Hantzsch ex Cleve et Grunow 1880 lacuum Lange-Bertalot 1980

+ + + -

+ +

+ + + -

+ + + -

+ + + -

+ + -

+ + + -

+ + +

+ + -

IX10

VIII29 VIII37-41

Nitzschia liebetruthii var. liebetruthii Rabenhorst 1864 Nitzschia linearis var. linearis (Agardh) W. Smith 1853 Nitzschia linearis var. subtilis (Grunow) Hustedt 1923

+ - - + - - - + + - + + - - + + - - + + - + + + + + - +

IX16, 16a

Nitzschia linearis var. tenuis (W. M. Smith) Grunow 1880 Nitzschia palea (Kützing) W. M. Smith 1856 Nitzschia palea var. debilis (Kützing) Grunow 1880

+ + - - + + - + - + + + + + + + + + + + + + + + + + + + + +

IX15 VIII5, 6 VIII7

Nitzschia paleacea (Grunow) Grunow in Van Heurck 1881 Nitzschia pellucida Cleve et Grunow 1880 Nitzschia perminuta (Grunow) M. Peragallo 1903

+ + + + + + + + + + - - + + - - + - + - + + - - + - + - +

VIII33-36

Nitzschia pseudofonticola Hustedt 1942 Nitzschia pura Hustedt 1954 Nitzschia pusilla (Kützing) Grunow 1862

- - + - - - - + - + + - - + - - + - + + + + + + + + + - -

Nitzschia recta Hantzsch in Rabenhorst 1861 Nitzschia rosenstockii Lange-Bertalot 1980 Nitzschia scalpelliformis (Grunow) Grunow in

+ + + + - + + + + + + - - - - - - + - - - - + - - - + - -

Cleve et Grunow 1880 Nitzschia sigma (Kützing) W. M. Smith 1853 Nitzschia sigmoidea (Nitzsch) W. Smith 1853

- + - - - - + - - + + + + + + + + + + +

VIII16-19 IX12, 13 VIII1, 2

X4

Nitzschia sinuata var. tabellaria (Grunow) Grunow in Van Heurck 1881 Nitzschia solgensis Cleve-Euler 1952

- + - - - + + + - - - + - - + - - - -

VIII22, 23

Nitzschia sublinearis Hustedt 1930

+ + + + + + + + + +

IX14

176

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Nitzschia supralitorea Lange-Bertalot 1979

- - - + - - - + - -

Nitzschia tubicola Grunow in Cleve et Grunow 1880 Nitzschia umbonata (Ehrenberg) Lange-Bertalot 1978 Nitzschia vermicularis (Kützing) Hantzsch 1860

+ - + + - - - + - + + - + + + + + + + + + + - + + + + + - +

IX11 IX6, 7 VIII13

Nitzschia vermicularis f. angustior Grunow in Van Heurck 1860 Opephora mutabilis (Grunow) Sabbe et Vyverman 1995 Orthoseira roeseana (Rabenhorst) O’Meara 1876

- - - + - - - + - + + + + + + + + - + - - - - - - + - -

I36

Parlibellus crucicula (Brockmann) Witkowski, Lange-Bertalot et Metzelin 2000 Pinnularia biceps Gregory 1856

+ - - + - - - + - + - - - - - - + - +

VII25

Pinnularia brandelii Cleve 1891 Pinnularia gibba Ehrenberg 1843 Pinnularia isselana Krammer 2000

+ + - - - + - - - + - - + + + - + - + + - - - - - + - -

VII26, 27

Pinnularia major (Kützing) Rabenhorst 1853 Pinnularia marchica var. marchica Ilka Schönfelder 2000 Pinnularia microstauron (Ehrenberg) Cleve 1891 Pinnularia parvulissima Krammer 2000

+ + -

Pinnularia rupestris Hantzsch in Rabenhorst 1861 Pinnularia sinistra Krammer 1992 Pinnularia subcapitata var. subcapitata Gregory 1856

+ - - - - + - - - + - - - - - - + - + - - - + + - + + +

Pinnularia subcommutata var. subcommutata Krammer 1992 Pinnularia subrostrata (Cleve) Cleve-Euler 1955 Pinnularia subrupestris var. cuneata Krammer 2000

+ - - - - - - + - - - - + - - - - - + + - - - - - + - - -

Pinnularia tirolensis var. julma (Metzeltin et Krammer) Krammer 2000 Pinnularia viridiformis var. viridiformis Krammer 1992

- + - - - + - - - + - - - - - - + - -

VII29, X3

Pinnularia viridis var. viridis (Nitzsch) Ehrenberg 1843 Placoneis elginensis (Gregory) Cox 1987 Placoneis gastrum (Ehrenberg) Mereschkowsky 1987

- + - - - + - - - + + - + - + + + - + - - - + - - - + - -

IV9

+ +

+ -

+ -

+ -

+ -

+ -

+ +

+ -

+ + -

VII21 VII23 VII22 VII28 VII24

Placoneis placentula (Ehrenberg) Heinzerling 1908 + - - - - + - + - Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot 1999 + + + + + + + + + + Planothidium granum (Hohn et Hellerman) Lange-Bertalot 1999 - - - + - - - + - -

V9 III7-11

Planothidium lanceolatum (Brébisson) Round et Bukhtiyarova 1999 + + + + + + + + + + Psammodictyon constrictum (Gregory) D. G. Mann 1990 - - - + + - - + - Psammothidium bioretii (Germain) Bukhtiyarova et Round 1996 + - - - - - - + - +

III13-14a III5-6a

Psammothidium helveticum (Hustedt) Bukhtiyarova et Round 1996 - - - - + - - - - + Pseudostaurosira brevistriata (Grunow) Williams et Round 1987 + + + + - - - + + + Puncticulata bodanica (Grunow in Schneider) Hakansson 2002 - + + - - - + - - +

II1-2a

Puncticulata radiosa (Lemmermann) Håkansson 2002

I30-35

- + - + - - - + + -

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Table 1. Continued. Taxon

Site Substrate 1 2 3 4 5 L S P N V

Photograph

Reimeria sinuata (Gregory) Kociolek et Stoermer 1987

+ + + + + + + + + +

VI22

Reimeria uniseriata Sala Guerrero et Ferrario 1993 Rhoicosphenia abbreviata (Agardh) Lange-Bertalot 1980 Rhopalodia acuminata var. acuminata Krammer in

+ + + - + + + + + + + + + + + + + + + + + - - - - - - + - -

VI19-21a VII9, 10

Lange-Bertalot et Krammer 1987 Rhopalodia gibba var. gibba (Ehrenberg) O. F. Müller 1895 Rhopalodia gibba var. minuta Krammer 1987

+ - + - + + - + - + - - - - - - + - -

Sellaphora bacillum (Ehrenberg) D. G. Mann 1989 Sellaphora pupula (Kützing) Mereschkowksy 1902 Sellaphora seminulum (Grunow) D. G. Mann 1989

+ + + - - + + + + + + + + + + + + + + + - + - - + + - + - +

V16 V15 III26-28

Simonsenia delognei Lange-Bertalot 1979 Stauroneis obtusa Langerstedt 1873 Stauroneis phoenicenteron (Nitzsch) Ehrenberg 1843

- + - - - - - + - - + - - - - - + - + - - - - - - + - -

X5

Stauroneis Staurosira Staurosira Staurosira

+ + + +

smithii Grunow 1860 construens (Ehrenberg) Williams et Round 1987 construens f. venter (Ehrenberg) Bukhtiyarova 1995 construens var. binodis (Ehrenberg) Hamilton 1992

+ +

+ + +

+ -

+ -

+ + + +

+ + -

+ -

+ +

+

Staurosira pinnata Ehrenberg 1843 Stephanodiscus hantzschii Grunow in Cleve in Grunow 1880 Stephanodiscus medius Hakansson 1986

- + + + + + - + - - + + - - - + - - - - - - + - - + - -

II13, 14 I8-9a

Stephanodiscus minutulus (Kützing) Cleve et Möller 1878 Stephanodiscus parvus Stoermer et Hakansson 1984 Stephanodiscus tenuis Hustedt

- - + - - - + - - - + + - - + - + + + - + - + - + - + - -

I16-19 I12-15 I10, 11

Surirella angusta Kützing 1844 Surirella biseriata Brebisson et Godey 1836 Surirella brebissonii Krammer et Lange-Bertalot 1987

+ + + + + + + + + + + + + - - + - - - + + + + + + + + + + +

IX5 IX1

Surirella brebissonii var. kuetzingii Krammer et Lange-Bertalot 1987 + + + + + + + + + + Surirella elegans Ehrenberg 1843 - - + - - - - - + + Surirella linearis W. M. Smith 1853 - + - - - + - - - -

IX2, 3

Surirella minuta Brebisson 1849 Surirella ovalis Brebisson 1838 Surirella tenera Gregory 1856

+ + + - - + + + - + + + - + + + + + - + + + - - + + + - -

IX4

Synedra fasciculata Kützing 1844 Synedrella parasitica (W. Smith) Round et Maidana 2001 Synedrella subconstricta (Grunow in Van Heurck)

- - - + - - - + - - + + - - + + + + + - + + - + + + + + +

Round et Maidana 2001 Thalassiosira weissflogii (Grunow) Fryxell et Hasle 1977 Tryblionella victoriae Grunow 1862

- + - - - - - - - + - - + - - - - - + -

I37

Ulnaria ulna (Nitzsch) Compère 2001

+ + + + + + + + + +

II17

178

II4 II3

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Plate I. 1-4 - Aulacoseira subarctica; 5,6 - A. granulata; 7 - Melosira varians; 8-9a - Stephanodiscus hantzschii; 10,11- S. tenuis; 12-15 – S. parvus; 16-19 – S. minutulus; 20, 21 - Cyclostephanos invisitatus; 22-24 – C. dubius; 25-27 - Cyclotella ocellata; 28, 29 – C. meneghiniana; 30-35 - Puncticulata radiosa; 36 - Orthoseira roeseana; 37 - Thalassiosira weissflogii; 38-41 – Meridion circulare var. circulare. Scale bar = 10 µm.

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Plate II. 1-2a - Pseudostaurosira brevistriata; 3 - Synedrella subconstricta; 4 – S. parasitica; 5, 6 - Fragilaria capucina var. rumpens; 7-9 – F. capucina var. vaucheriae; 10-12 – F. capucina var. capitellata; 13, 14 - Staurosira pinnata; 15, 16 – Ceratoneis arcus; 17 – Ulnaria ulna; 18 – Fragilaria crotonensis; 19 - Asterionella formosa; 20, 21 - Diatoma mesodon; 22, 23 – D. hyemalis; 24 – D. moniliformis; 25, 26 – D. ehrenbergii; 27 – D. vulgaris; 28-31 - Achnanthidium minutissimum; 32-34 – A. eutrophilum; 35-37a – A. subatomus; 38, 38a – A. pyrenaicum. Scale bar = 10 µm.

180

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Plate III. 1-3 - Achnanthidium saprophilum; 4, 4a - Achnanthes exigua; 5-6a - Psammothidium bioretii; 7-11 Planothidium frequentissimum; 12 - Eucocconeis laevis; 13-14a - Planothidium lanceolatum; 15, 15a - Lemnicola hungarica; 16, 16a -Cocconeis pediculus; 17-18a – C. placentula var. euglypta; 19-20 – C. placentula var. lineata; 21, 22 – C. placentula var. pseudolineata; 23 – Navicula radiosa; 24, 25 - Eolimna subminuscula; 26-28 – Sellaphora seminulum. Scale bar = 10 µm.

181

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Plate IV. 1 - Navicula tripunctata; 2 – N. viridula; 3, 4 – N. novaesiberica; 5 - N. rostellata; 6 – N. amphiceropsis; 7 – N. lanceolata; 8 – N. schroeteri var. schroeteri; 9 - Placoneis elginensis; 10 - Navicula cariocincta; 11-13 – N. cryptotenella; 14 – N. hambergii; 15 – N. detenta; 16 – N. germainii; 17 – N. cryptocephala; 18 – N. exilis; 19 – N. aff. arctotenelloides; 20, 21 – N. vilaplanii; 22, 23 - Adlafia minuscula; 24, 25 - Mayamaea atomus var. permitis; 26, 27 - Eolimna minima; 28 - Navicula cf. cari; 29 – N. veneta; 30 – N. reichardtiana; 31 – N. joubaudii; 32 – N. catalanogermanica; 33-34 - N. vandamii var. vandamii; 35 – N. gregaria; 36 – N. capitatoradiata; 37 – N. trivialis var. trivialis; 38 – N. rhynchocephala. Scale bar = 10 µm.

182

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Plate V. 1, 2 - Hippodonta costulata; 3 – H. capitata; 4,5 - Fallacia pygmaea; 6 – F. monoculata; 7 - Diploneis parma; 8 – D. ovalis; 9 - Placoneis placentula; 10 - Luticola goeppertiana; 11 – L. nivalis; 12 - Geissleria decussis; 13, 14 - Diadesmis perpusilla; 15 - Sellaphora pupula; 16 – S. bacillum; 17 - Neidium affine; 18 – N. ampliatum; 19 – N. binodis; 20 - Craticula accomoda; 21 – Frustulia vulgaris; 22 – Caloneis bacillum; 23, 24 – C. molaris; 25 – C. silicula; 26, 27 - Amphora copulata; 28-30 – A. pediculus; 31, 32 – A. montana; 33-35 - Amphora veneta 36 - Neidium dubium. Scale bar = 10 µm.

183

Plamen Ivanov, Emilia Kirilova and Luc Ector

Plate VI. 1 - Amphora ovalis; 2 – A. inariensis; 3, 4 - Encyonema silesiacum; 5, 6 – E. ventricosum; 7, 8 – E. minutum; 9 – E. reichardtii; 10 - Cymbopleura cuspidata; 11 - Encyonema caespitosum; 12, 13 – Cymbella excisa var. excisa; 14 - Encyonopsis subminuta; 15 - Encyonema prostratum; 16 - Cymbella tumida; 17, 18 – C. compacta; 19-21a - Reimeria uniseriata; 22 – R. sinuata; 23-26 - Gomphonema minutum; 27, 28 – G. olivaceum var. olivaceum; 29-31 – G. pumilum var. elegans; 32, 33 – G. pumilum var. rigidum. Scale bar = 10 µm.

184

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Plate VII. 1-3 - Gomphonema rosenstockianum; 4-6a – G. tergestinum; 7, 8 – G. truncatum; 9-10 - Rhoicosphenia abbreviata; 11-14 - Gomphonema parvulum; 15, 16 – G. gracile; 17, 18 – G. subclavatum; 19, 20 – G. micropus; 21 - Pinnularia marchica var. marchica; 22 – P. sinistra; 23 – P. parvulissima; 24 – P. subrupestris var. cuneata; 25 – P. biceps; 26, 27 – P. isselana; 28 – P. subcommutata; 29 – P. viridiformis var. viridiformis. Scale bar = 10 µm.

185

Plamen Ivanov, Emilia Kirilova and Luc Ector

Plate VIII. 1, 2 - Nitzschia recta; 3, 4 – N. dissipata var. dissipata; 5, 6 – N. palea; 7 - N. palea var. debilis; 8-10 – N. capitellata; 11, 12 – N. fonticola; 13 – N. vermicularis; 14, 15 – N. amphibia; 16-19 – N. perminuta 20 – N. bacillum; 21 - N. acidoclinata; 22, 23 – N. solgensis; 24 – Denticula tenuis; 25 - Hantzschia amphioxys; 26, 27 - Nitzschia clausii; 28 – N. calida; 29 – N. hungarica; 30 – N. gracilis; 31-32 – N. agnita; 33-36 – N. paleacea; 37-41 – N. inconspicua. Scale bar = 10 µm.

186

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

Plate IX. 1 - Surirella brebissonii; 2, 3 – S. brebissonii var. kuetzingii; 4 – S. minuta; 5 – S. angusta; 6, 7 – Nitzschia umbonata; 8, 9 – N. heufleriana; 10 – N. debilis; 11 – N. tubicola; 12, 13 – N. pura; 14 – N. sublinearis; 15 – N. linearis var. tenuis; 16, 16a – N. linearis var. linearis; 17 – N. brunoi. Scale bar = 10 µm.

187

Plamen Ivanov, Emilia Kirilova and Luc Ector

Plate X. 1 - Cymatopleura elliptica var. hibernica; 2 – C. solea var. apiculata; 3 - Pinnularia viridiformis var. viridiformis; 4 - Nitzschia sigmoidea; 5 - Stauroneis phoenicenteron; 6, 6a – Nitzschia sp.; 7 - Cymbella lanceolata var. lanceolata; 8 – Gyrosigma nodiferum; 9 – G. scalproides; 10 – G. acuminatum; 11, 11a – G. attenuatum. Scale bar = 10 µm.

188

Diatom species composition from the River Iskar in the Sofia region, Bulgaria

presence of typical planktonic species such as Asterionella formosa in the benthos of the studied part of the river was a result of drift from the three dams situated upstream. ACKNOWLEDGMENTS We express our acknowledgments to O. Monnier, F. Rimet and C. Bouillon (Centre de Recherche Public-Gabriel Lippmann, Luxembourg) for the critical notes, advises and technical support. Funding of this research was provided by Sofia University, Bulgaria and CRP - Gabriel Lippmann, Luxembourg. REFERENCES HASLE, G. and G. FRYXELL 1970. Diatoms: Cleaning and mounting for light and electron microscopy. - Transactions of the American Microscopical Society, 89(4): 469-474. IVANOV, P., N. CHIPEV and D. TEMNISKOVA 2003 a. Diatoms of the river Iskar (Sofia Plain) and their implication for water quality assessment, Part 1. The diatom flora, ecology and community structure. – Journal of Environmental Protection and Ecology, 2(4): 288 – 300. IVANOV, P., N. CHIPEV and D. TEMNISKOVA 2003 b. Diatoms of the river Iskar (Sofia Plain) and their implication for water quality assessment, Part 2. Diatom indices and their implication for water quality monitoring. – Journal of Environmental Protection and Ecology, 2(4): 301 - 310. IVANOV, P. and E. KIRILOVA (in press). Benthic diatom assemblages from different substrates of the Iskar River, Bulgaria. in: A. Witkowski, editor. Proceedings of the 18th International Diatom Symposium. Miendzyzdroje, Poland, 2-7 September. KAWECKA, B. 1974. Vertical distribution of algae communities in Maljovica Stream (Rila Bulgaria). – Polskie Archiwum Hydrobiologii, 21(1): 211-228. KRAMMER, K. 2000. The genus Pinnularia. in: H. Lange-Bertalot, editor. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats. 1, 703 pp. A.R.G. Gantner Verlag K.G. KRAMMER, K. (2002): Cymbella. in: H. Lange-Bertalot, editor. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats. 3, 584 pp. A.R.G. Gantner Verlag K.G. KRAMMER, K. and H. LANGE-BERTALOT 1986-1991. Sübwasser flora von Mitteleuropa. H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Vol. 2: Parts 1-4. Bacillariophiceae. Gustav Fisher Verlag, Stuttgart, N. York. LANGE-BERTALOT, H. 1993. 85 Neue Taxa und über 100 weitere neu definierte Taxa ergänzend zur Sübwasserflora von Mitteleuropa Vol. 2/1-4. in: Bibliotheca Diatomologica, 27, 454 pp. J. Cramer, Berlin. Stuttgart.

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LANGE-BERTALOT, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. in: H. Lange-Bertalot, editor. Diatoms of the European Inland Waters and Comparable Habitats. 2, 526 pp. A. R. G. Gantner Verlag K. G. LANGE-BERTALOT, H. and K. KRAMMER 1989. Achnanthes eine Monographie der Gattung mit Definition der Gattung Cocconeis und Nachtragen zu den Naviculaceae. in: Bibliotheca Diatomologica, 18, 393 pp. J. Cramer, Berlin. Stuttgart. PASSY-TOLAR, S., Y. PAN and R. LOWE 1999. Ecology of the major periphytic diatom communities from the Mesta River, Bulgaria. - International Review of Hydrobiology, 84(2): 129-174. ROUND F., R. CRAWFORD and D. MANN 1990. The diatoms. Biology and morphology of the genera. Cambridge University Press, Cambridge, 747 p.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 191-202) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Chara corfuensis J. Gr. ex Fil. 1937 (Characeae) – an endemic species of Balkan Peninsula, rare and globally endangered Jelena Blaženčić Institute of Botany and Botanical Garden “Jevremovac”, Faculty of Biology, University of Belgrade, Takovska 43, 11000 Belgrade, Serbia and Montenegro, e-mail: [email protected] ABSTRACT During the floristic, taxonomic, phytocoenological and ecological studies of Baćinska Lakes and Lake Desne (Croatia), a new locality for the Chara corfuensis, endemic species of Balkan was discovered, species previously identified only on several localities in Greece. In the literature only the incomplete description of this species can be found. This paper presents the overview of morphological, ecological and phytocoenological characteristics of this species, based on material collected at these new localities. Key words: Chara corfuensis, Endemic species, Croatia. INTRODUCTION In the swirl of technical and technological achievements of modern civilization and the new directions in research, matched with researchers’ curiosity on one hand and the needs of the humankind on the other, studies of flora and fauna represent a never diminishing challenge. The studies of flora are a constant need and the infinite source of data on plant diversity and the conditions that apply to certain species at the moment of study. In the future these data may become a valuable testimony that can be used to estimate changes of flora in function of time and living conditions. As a botanist who has been studied charophytes for quite a number of years, especially in areas of Central and Western Balkan Peninsula, I have noticed that data on charophytes from these regions are either completely missing or very sparsely noted, even in important monographs (Wood and Imahori 1964, 1965, Corillion 1957, 1975, Krause 1997, Schubert and Blindow 2003). That led us to make a survey and analysis of present state in the floristic 191

Jelena Blaženčić

diversity of charophytes from the Balkan Peninsula, and to estimate the level at which they have been studied and their threat status. We concluded that there are 47 recorded species of charophytes in Balkan Peninsula, including the following endemic species Chara rohlenae Vilh., Ch. corfuensis J.Gr. ex Fil., Ch. ohridana Kostić, Ch. visianii J. Blaz. & V. Randj. (Blaženčić and Blaženčić 2003). The analysis of threat status, based on principles and criteria of IUCN (2001), showed that the species Chara rohlenae is most probably extinct, while the other three endemic species belong to the “globally critically endangered” category (Blaženčić and Blaženčić 2002, Blaženčić et al. 2005 in press). As an endemic species Chara corfuensis deserves the attention and comprehensive modern studies by charologists. However, there is a lack of complete morphometric study for this species. A description of this species, made based on small number of incomplete or immature specimens can be found in literature (Wood and Imahori 1964, 1965) but without the definition of comparative alternative characteristics, causing great difficulties in recognition of the species and its inclusion in identification keys. While studying flora and ecology of charophytes in Western and Central Balkan Peninsula, in the vegetation of Baćinska Lakes and in the Lake Desne (Croatia), we have recorded a significant presence of species Chara corfuensis. Keeping in mind the limited amount of data, this paper has a goal to improve the knowledge on morphology, ecology and chorology of this endemic species, with a wish to help determine its place in the identification keys of charophytes. MATERIAL AND METHODS During the summer, the samples of Chara corfuensis were collected from Baćinska Lakes: Crniševo, Vrbnik, Oćuša, Sladinac, Podgora and the neighboring Lake Desne. At the sampling locations, standard methods were used to determine the basic ecological factors. They included temperature and transparency of water, physical characteristics of the bottom of the lake, pH and the depth at which material was collected. Research on flora and vegetation was made by observation from the shore and from the boat, by the method of transects and longitudinal profiles. At each lake, the samples were taken in “dots”, in as many places as it was needed in order to get a complete picture of the floristic diversity of vegetation and the distribution of population of recorded species. The samples were collected with a hook- and rake-type device, designed by the authors themselves (Blaženćić and Blaženčić 1991) and immediately fixated in 4 % formaldehyde. The laboratory processing of the samples was done in the Institute of Botany, University of Belgrade. The material is currently kept in the collection at the same place. In order to study the morphological characteristics important for taxon identification, the crust of calcium carbonate from the surface of the plants needed to be removed. Certain samples were immersed into 5 % hydrochloric acid (HCl) and after rinsing with water they were observed under the magnifying glass. The identification of Chara corfuensis was done by using the key and iconograph by Wood and Imahori (1964, 1965), while other charophytes were identified by using the keys 192

Chara corfuensis J. Gr. ex Fil. 1937 (Characeae) – an endemic species of Balkan Peninsula

of Corillion (1957, 1975), Gollerbah and Krasavina (1983), Krause (1997) and Schubert and Blindow (2003). The vascular plants were identified by using following literature: Flora SSSR I (Komarov and Ilin, editors 1934), Flora von Mitteleuropa, Bd.I (Hegi 1965), Flora SR Srbije 1-8 (Josifović, editor 1970-1977), Flora Europaea, Vol. 5 (Dandy and Valentine 1980), Martinčič and Sušnik, (1984). The categorization of endangered status of Chara corfuensis was done on the basis of the assessment of the threat degree by the application of new IUCN criteria (2001). RESULTS Habitat Baćinska Lakes and Lake Desne, where the samples of Chara corfuensis were collected, are interesting and specific habitats not only for their origin, but also position, hydrographical and hydrological characteristics. Six small, typically karst, fresh water lakes: Crniševo, Vrbnik, Oćuša, Podgora, Sladinac and Plitko, connected to each other by channels, form Baćinska Lakes. This lake complex is situated in the Croatian coast area, in Dinaric karst, SW from the delta of River Neretva into the Adriatic Sea and 1 km away from the port Ploče (Fig. 1), at the altitude not greater than 1 m. The lakes are positioned on limestone lacking any tributaries or effluents. A few springs of fresh water are located on the margins of the lakes. The lake area belongs to the semiarid Mediterranean zone, which has all the characteristics of a subtropical climate. In a span of a single year, four to five months show features of an arid climate, while the other months belong to humid and perhumid climate (Živković 1972) With the exception of the lake Plitko, the species Chara corfuensis was recorded in all other lakes, as well as in the channels connecting the lakes Oćuša and Crniševo, and Sladinac and Oćuša. The water of Baćinska Lakes is highly transparent. The transparency of water varies from 1.5 m (Vrbnik) to 7.0 m (Crniševo). The lakes receive their water from the precipitation and from surface and sublacustrine springs. The yearly fluctuation in water level often reaches 2.5 m. The basins of the deepest lakes – Crniševo (27.0 m), Oćuša (22.5 m) and Sladinac (10.0 m) are positioned below the sea level and are denoted as cryptodepressions. According to the chemical content, waters of Baćinska Lakes are clean and belong to calcium carbonate type (Živković 1972). Crniševo is to some extent different from the other lakes, because a larger quantity of chlorine occasionally appears in the lower layers of water. This is explained by existence of salty underwater lakes or occasional influx of seawater through the porous limestone substrate. Therefore, in contrast to the other lakes, which are clearly freshwater, Crniševo may in certain times be included in freshwater lakes, and in the other times, when the chloride content varies from 0.5 to 1.0 g/l, it is limnetic B (mixo) oligohaline or oligohaline-brackish (Živković 1972). However, in the zone where Chara corfuensis was recorded, only fresh water is present. Waters of Baćinska Lakes show neutral to slightly alkaline reaction (pH 7.2-8.4). 193

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The greatest part of the bottom of Baćinska Lakes is covered with mud. In the coastal part of some lakes, mud is mixed with sand. In Lake Crniševo, the coastal part of the bottom is composed of hard white sand, which turns into a fine powder when it dries up. When this powder is mixed with 5% hydrochloric acid (HCl), it completely dissolves showing us that the surface layer of the bottom of this lake is composed of pure calcium carbonate. The relief of the bottom of lakes, as well as parts of the same lake, varies from very steep in the coastal area (Sladinac), to steep (Crniševo) to light inclination in most other lakes. Although the quality of the water of Baćinska Lakes is generally good, the coastal parts of the lakes are exposed to negative anthropological influences (camps, cultivated areas, settlements). Lake Desne is located to the east from Baćinska Lakes, at the distance of 9 km (Fig. 1). Lake is surrounded by karst ridges from three sides and the shores of the lake are covered with marsh vegetation Schoenus nigricans - Phragmites communis. Lake Desne gets its water from the precipitation, from large spring Modro oko, as well as from numerous sublacustrine springs located at the sides of the lake. Through the channel called rivulet Desanka, it is connected to the River Neretva (Fig. Oćuša Crniševo

Baćinska Lakes Podgora Podkušinac Klokun Spring

Vrbnik

Plitko Desne Lake Ploče Harbour Modro oko Spring

Neretva River

Adriatic Sea

M = 1 : 50 000 Fig. 1. Baćinska Lakes and Desne Lake - new habitat of Chara corfuensis

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1). The lake is shallow, the deepest point is at 4.0 m and for the most of the lake the depth is 1.01.5 m. The water is clear, with neutral to weakly alkaline reaction (pH 7.2-8.0). Description of the species Chara corfuensis J.Gr. ex Fil. (Syn.: Chara hispida f. corfuensis (J.gr. ex Fil.) Wood & Imahori, 1964, Icon 37; 1965, p 138-139) is monoecious plant, grayish green, robust, “spiny” charophyte (Figs 2, 3). Plants are encrusted with calcium carbonate, especially those from shallow water. Axes are strong, brittle, more or less encrusted, with strong spines, 20-50 (-70) cm long, 0.9-1.5 mm wide. Long lateral branches often grow from the base. Plant is well rooted in the a

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substrate with its rhizoids, upon which the small tubers are formed. Internodes are equal in length or two (to four) times longer than branchlets. Cortex is diplostichous, tylacanthous, but sometimes is irregular, triplostichous (Fig. 3d). Spine-cells are in clusters of 2-5, rarely solitary, very well developed, stiff, acuminate (Fig. 2), equal or twice the diameter of axes (0.9-2.6 mm in length and 150-350 µm in width). Stipulodes are present in 2 tiers, both well developed, 2 sets per branchlet. Cells have thick walls, are irregular in length, 640-1200 µm long and 100-171 µm wide. Branchlets 10 (9) are in a whorl, are stout, from 0.8 to 2.2 cm long and from 575 to 690 µm wide with (6) 7 segments. All the segments are with cortex, except one or two distal, which are ecorticate (Figs 2d, 3c). The terminal segment has one or two cells and has no node. The terminal cell is tapering-acute, acuminate. Bract-cells 5-6 are elongated, acuminate, adaxials and abaxials and longer than oogonium. Anterior and lateral bract-cells are longer (2.2-3.6 mm / 160300 µm) than the posterior ones (1.4-2.6 cm / 200-300 µm). Bracteoles 2 are similar in length as bract-cells, longer than oogonia, and almost the same length as segments in branchlets. The plants are monoecious. Gametangia are conjoined at 1-4 lowest branchlet nodes (Figs 2c, 3b). Oogonium is solitary up to 800-1000 µm long (excl. coronula) and 550-650 µm wide, with 11-12

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convolutions (Figs 2e, 3e). Coronula is 100–170 µm high and 260-300 µm wide at base and cells are ovate-erect. Oospores are darkish brown or dark brown, granulate, 800-900 µm high, 410480 µm wide, with 11-12 blunt ridges terminating with basal cage. Fossa is 60-80 µm across. Antheridia are reddish-yellow, solitary, 450 do 610 µm in diameter, octoscutate. Ecology of the species Chara corfuensis is a freshwater charophyte, present in Baćinska Lakes in various depths from 0.2 to 8.0 m. In the shallow water it is spread in a mosaic distribution, in a form of low bushes, while in deeper water it forms the underwater meadows. The plants from shallow water are strongly encrusted with calcium carbonate. Encrustation decreases with the depth and the plants become clearly grayish green. Chara corfuensis is very well represented in Lake Crniševo, and especially in small Lake Vrbnik, where it forms a wide belt around the whole lake at the depth of 1.0-6.0 m. In that lake it is the only submersed macrophyte. Besides these lakes, Chara corfuensis is also present in coastal parts of lakes Sladinac, Oćuša and Perast, at the places where reeds have been cut down and in the shallow water of the channels connecting the lakes Oćuša and Crniševo, and Sladinac and Oćuša. Chara corfuensis develops in all types of substrate in the studied lakes – in mud, mixture of mud and sand, and on almost pure calcium carbonate sand. The temperature of the water where Chara corfuensis is found, varies from 10°C to 26°C during the year (Živković 1972, Štambuk-Giljanović 1998, Mišetić et al. 2000). This alga is adapted to weak light intensity, and is therefore present even at greater depths. At the smaller depths, in water with abundance of sunlight, the plants are encrusted to reduce the effect of strong light. Chara corfuensis, in the same manner as most other charophytes, inhabits the hard waters of calcium carbonate type, of neutral to weakly alkaline reaction (pH 7.2-8.4). In Lakes Sladinac and Oćuša, the recorded medium yearly values of total hardness are 9 in German ° and values of carbonate hardness of 6.2 and 7.8 German ° (Štambuk-Giljanović 1998). Chara corfuensis in Baćinska Lakes and in Lake Desne was recorded in pure and mixed populations. Pure populations are rare and they develop more often in a fragmented fashion at greater depths (in Lake Crniševo from 4.5 to 8.0 m). Within that same lake, they are also recorded in shallow water (1.5 m), but they are typically developed at the depths of 5-8 m. In Lake Vrbnik, Chara corfuensis is the only submersed plant, and stretches in a continuous belt at the depth between 1.0 and 6.0 m. Chara corfuensis is found in mixed populations in the shallow parts of Baćinska Lakes, in channels that connect them, and in Lake Desne, at depths of 0.2-2.0 m, and only occasionally in deeper water. Within that vegetation, it is present in various combinations with species Phragmites australis (Cav.) Trin., Schoenoplectus triquetrus (L .) Palla, Typha angustifolia L., Nymphaea alba L., Potamogeton natans L., P. pectinatus L., P. pusillus L., P. perfoliatus L., P. trichoides Cham. et Schld., Myriophyllum spicatum L., M. verticillatum L., Najas marina L., Nitella tenuissima (Desv.) Ag., N. confervacea (Bréb) A.Br. ex Leonh., Nitellopsis obtusa (Desv. in Loisel.) J. Groves, and 197

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Chara globularis Thuill. Each of this species can group with any other, while the dominance of present species in these microgroups is subject to variations. Chara corfuensis is most often present in submersed vegetation, however sometimes it also enters the zone of emerged or floating plants, at places where the vegetation is thin. Distribution of the species Locus classicus of Chara corfuensis is on the island Corfu, between Moraitik and Braganiotik (Wood and Imahori 1965). The localities in Croatia (Baćinska Lake and Lake Desne) are important, because at present moment, together with several new localities in Greece (record

Fig. 4. Distribution of Chara corfuensis recorded in Balkan Peninsula

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from the collection Lemonia Koumpli-Sovantzi, No 2357, 3090 b) these are rare known localities for this endemic species in Balkan Peninsula (Fig. 4). Threat status The endemic species of Balkan Peninsula, Chara corfuensis has been recorded in several localities in Croatia and Greece. It forms fragmented populations that are threatened by pollution due to extensive tourism, surrounding industry and the use of chemicals in agriculture. Therefore, under the criteria of IUCN (2001), Chara corfuensis is placed in the category of globally critically endangered species, CRB1-A1e (Blaženčić et al. 2005 in press). DISCUSSION When the morphological characteristics of Chara corfuensis from Baćinska Lakes and Lake Desne were compared to those cited in species description by Wood and Imahori (1964, 1965), certain differences were found: length of axes, internodes, length of cells of stipulodes, but also the dimensions of morphologically more stable characters, such as size of oogonia. Some of them, such as length of main axis, internodes and branchlets, can be understood as individual reaction of plants that develop under diverse environmental conditions, and which used to be unknown as the description of the species was made according to a small number of incompletely developed specimens from only one locality (Wood and Imahori 1964, 1965). It is known that size of thallus and its parts are very variable characters, greatly influenced by ecological factors on a location. The differences recorded in characteristics of oogonia are a consequence of analysis of immature (Wood and Imahori 1964, 1965) and completely developed oogonia from the plants from Baćinska Lakes and Lake Desne. Besides the data complimenting the present knowledge on morphology and morphometry of species Chara corfuensis, this paper also presents data on color, structure and dimensions of oospores, as well as the structure of their wall, which were never previously recorded in literature. R i s k o f c o n f u s i o n. Chara corfuensis is a robust charophyte with clearly visible spines at the nodes. Based on this and several other characteristics, on first glance it may be wrongly identified as Chara hispida (L.) Hartm., Ch. polyacantha A.Br. in A.Br., Rabenh. & Stizenb or Ch. intermedia A.Br. in A.Br., Rabenh. & Stizenb. (Gollerbah and Krasavina 1983, Krause 1997, Mannschreck 2003). The best obvious difference between the species Chara hispida and Ch. corfuensis is the structure of cortex. The cortex of Ch. corfuensis is diplostichous but on some places becomes irregular - tylacanthous, while the cortex of Ch. hispida is diplostichous but on some places irregular - isostichous-aulacanthous. There are also differences in structure of branchlets, size and structure of oogonia, oospores and antheridia. The species Chara polyacantha and Ch. intermedia have certain structural similarities with Ch. corfuensis, but with the careful morphological analysis and good knowledge of ecological characteristics the differences that point out to their special taxonomic position can be observed 199

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When compared with Chara polyacantha, Ch. corfuensis differs in the structure of the apical segment of the branchlet, the length of posterior bract-cells on the sterile nodes, the number of spiral convolutions on an oogonium (11-12), size, color and structure of oospores (form and height of the crown). Regarding the morphological characteristics, Chara corfuensis is the most similar to the species Ch. intermedia. However, Ch. intermedia is clearly distinct because of its ecology, as it primarily inhabits brackish waters, and only rarely is it found in freshwater, while Ch. corfuensis is a freshwater charophyte. With these two species, the ecological factor is one of the important differential characters for their distinction. Besides this factor, there are also some morphological differences in number and size of branchlets, size and structure of bractcells and oogonia (Krause 1997, Schneider 2003). CONCLUSION During the floristic, taxonomic, phytocoenological and ecological studies of Baćinska Lakes and Lake Desne, the first locality for Chara corfuensis in Croatia was recorded. This is an important set of data on its very sparse presence in Balkan Peninsula in general. As the literature contains only its incomplete description, without definitions of comparative alternative features, ecological and phytocoenological characteristics, this paper presents the processing and discussion of the material from Baćinska Lakes and Lake Desne from these aspects. The morphological analysis was performed on the completely developed and mature specimens that were in the phase of fructification. The results gathered in this study improve the present picture on morphology and morphometric values of certain taxonomically important characters of species Chara corfuensis. In addition, there are better-expressed limits of variability of a species due to ecological factors, as alternative characters used to distinguish between this and similar species. The species Chara corfuensis, an endemite of Balkan Peninsula, has so far been recorded on island Corfu in Greece, in karst Baćinska Lakes and in Lake Desne in Croatia. All known localities are situated in the Mediterranean region, in the conditions of subtropical climate. Chara corfuensis inhabits hard, calcium carbonate rich waters, of neutral to weakly alkaline reaction. It colonizes muddy and muddy-sandy substrate rich in calcium carbonate (CaCO3). Most often it is found in the form of fragmented populations within the mixed associations of submersed vegetation at the depth down to 2.0 m. Pure populations of this species have been recorded in deeper lakes, most often at the depths between 4.0 and 8.0 m. Although the quality of the water of Baćinska Lakes is generally good, the coastal parts of the lakes are exposed to negative anthropological influences. Extensive tourism, surrounding industry complexes and use of chemicals in agriculture pose a pollution threat to the natural stability of Chara corfuensis habitats, and therefore the survival of the species. After the analysis of threat degree, according to principles and criteria of IUCN (2001), it was found that Chara corfuensis belongs to the category of globally critically endangered species (CR B1-A1e). 200

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ACKNOWLEDGEMENTS The author owes infinite gratefulness for all the nice moments during the work, understanding, human and collegial support, to her husband Dr. Živojin Blaženčić, Professor at the Faculty of Veterinary Medicine, University of Belgrade. Thanks goes to Dr. Branka Stevanović, Professor at the Faculty of Biology, University of Belgrade, for useful suggestions during the writing of this paper, and to my colleagues M. Sci. Milica Ljaljević-Grbić, assistant at Faculty of Biology, and Milica Petrović-Djurić, B. Sci. in Biology, for the help in processing the samples and technical setting of the paper. The present work was supported by the Ministry of Science and Technology of the Republic of Serbia (Grant No. 1538). REFERENCES ˇ ˇ BLAZENČIĆ , J. and Ž. BLAZENČIĆ 1991. Makrofite Vlasinskog jezera. - Glasnik Prirodnjačkog muzeja u Beogradu, B 46: 71-85. ˇ ˇ , J. and Ž. BLAZENČIĆ 2002. Rare and threatened species of charophytes BLAZENČIĆ (Charophyta) in Southeast Europe. - Phytologia Balcanica, 8: 315-326. ˇ ˇ BLAZENČIĆ , J. and Ž. BLAZENČIĆ 2003. An overview of the existing data on living charophytes (Charales) of the Balkan peninsula. - Acta Micropalaeontologica Sinica, 20: 103-110. ˇ ˇ BLAZENČIĆ , J., B. STEVANOVIĆ, Ž. BLAZENČIĆ and V. STEVANOVIĆ in press. Red Data List of charophytes in the Balkans. – Biodiversity and Conservation. CORILLION, R. 1957. Les Charophycées de France et d’Europe occidentale. Bull. Soc. Sci. Bretagne, 32, fasc.h.-s. CORILLION, R. 1975. Flore des Charophytes (Characées) du Massif Armoricain et des contrées voisines d’Europe occidentale. Flore et vegetation du Massif Armoricain, IV. Jouve Editeurs, Paris. DANDY, J. E. and D.H. VALENTINE 1980. Potamogetonaceae. in : T.G. Tutin, editor. Flora Europaea, 5: 7-11. Cambridge University press. GOLLERBAH, M.M. and L.K. KRASAVINA 1983. Key of freshwater algae of the USSR 14 – harovie vodorosli – Charophyta. -”Nauka”, Leningrad. HEGI, D.G. 1965. Illustrierte Flora von Mitteleuropa. Bd.I. Carl Hanser verlag. IUCN 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge. JOSIFOVIČ, M. (editor) 1970-1977. Flora SR Srbije 1-8. SANU. Beograd. KOMAROV, V.L. and M.M. ILIN (editors) 1934. Flora SSSR, Tom. I, Izd. ANSSSR. Leningrad. KRAUSE, W. 1997. Charales (Charophyceae). in: H. Ettl, G. Gärtner, G., H. Heynig and D. Mollenhauer, editors. Süâwasserflora von Mitteleuropa 18, Fischer, Jena.

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MANNSCHRECK, B. 2003. Chara hispida (L.) Hartm. 1820. in: H. Schubert and I. Blindow, editors. Charophytes of the Baaltic Sea: 107- 112. Marine Biologists Publication No. 19, A.R.G. Gantner Verlag, K.-G. Ruggell. MARTINČIČ, A. and F. SUŠNIK 1984. Mala flora Slovenije praprotnice in semenke.- Državna založba Slovenije, Ljubljana. MIŠETIĆ, S., D. ŠURMANOVIĆ and M. MRAKOVČIĆ 2000. Sastav mrežnog planktona u Baćinskim jezerima.- Ekološke monografije, 5: 169-174. BIOKOVO 2. SCHUBERT, H. and I. BLINDOW (editors) 2003. Charophytes of the Baltic Sea. The Baltic Marine Biologists Publication No 19, A.R.G. Gantner Verlag, K.-G. Ruggell. SCHNEIDER, S. 2003. Chara intermedia A. Br. in A.Br., Rabenh. & Stizenb., 1859. in: H. Schubert and I. Blindow, editors. Charophytes of the Baaltic Sea.: 107- 112. Marine Biologists Publication No. 19, A.R.G. Gantner Verlag, K.-G. Ruggell. ŠTAMBUK-GILJANOVIĆ, N. 1998. Vode Neretve i njezina područja. Hrvatske vode, Zagreb. WOOD, R.D. and K. IMAHORI 1964. A Revision of the Characeae. II. Iconography of the Characeae. - J. Cramer, Weinheim. I-XV+Icon 1-395. WOOD, R.D. and K. IMAHORI 1965. A Revision of the Characeae. I. Monograph of the Characeae. - J. Cramer, Weinheim. ŽIVKOVIĆ, A. 1972. Zooplankton of Baćinska lakes.- Arh. biol. nauka, Beograd 24 (3-4): 141-164.

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First record of the tropical invasive alga Compsopogon coeruleus (Balbis) Montagne (Rhodophyta) in Flanders (Belgium) Maya P. Stoyneva1, Koenraad Vanhoutte2 and Wim Vyverman2 Department of Botany, Faculty of Biology, Sofia University “St Kliment Ohridski”, 8 bld. Dr. Zankov, BG-1164, Sofia, Bulgaria, e-mail: [email protected] 2 Ghent University, Department Biology, Laboratory of Protistology and Aquatic Ecology, Krijgslaan 281-S8, B-9000, Gent, Belgium 1

ABSTRACT Compsopogon coeruleus (Balbis) Montagne (Compsopogonales, Rhodophyta) develops worldwide in various natural tropical and subtropical waters, but also occurred as a weedy or nuisance taxon in garden ponds, aquaria, thermal house effluents and irrigation ditches. After the first description of the species from Algeria it was found several times in several European countries in various aquaria types and in a few natural sites. The presence of Compsopogon coeruleus had not been officially registered in Belgium until January 2005 when the peculiar greyish-blue filaments of this alga were noted in Ghent, in an Amazonian biotope aquarium. Responses to questionnaires amongst specialized aquarium associations revealed that this alga has already spread to aquaria in fifteen towns of four provinces in Flanders (Belgium). From the present situation it could easily be inferred that this invasive taxon will be released and settle in natural habitats of the country. The environmental data obtained during this study coincided with the previously published temperature preferences of Compsopogon coeruleus (ca. 26oC) but revealed its development under slightly lower pH conditions (pH values mainly of 6-6.5). The observations of the preference of this rhodophyte for stronger water current suggest that the velocity-control may be a good tool for eventual managing the development of this nuisance alga in contained environments. Conversely, this also suggests that streams and rivulets are the first natural habitats to look for this invasive taxon. Key words: Compsopogon coeruleus, red algae, invasive species

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INTRODUCTION Recent advances in the understanding of algal dispersal have shown that simultaneously with the worldwide increased exchange of goods, animals and plants, the risk of dispersal of alien algae has equally grown (Kristiansen 1996a, b). The potential harmful impact of invasive taxa is widely accepted as one of the greater contemporary menaces to local diversity (Le Maitre 2004). Also the socio-economic importance of invasive species, and the threat they pose for indigenous fauna and flora, has nowadays been widely recognized (Wilcove et al. 1998, Powell 2004). New theoretical developments and practice have revealed that the spatial distribution of invasive species is a much more complex process than was hitherto assumed (Hastings et al. 2005). Therefore a more detailed understanding of the dispersal mechanisms of algae is required in order to take effective preventive, as well as counter-measures, against these invasive taxa. For example, it still remains unclear whether dominant nonindigenous species are driving the community change or whether they are merely passengers, going along for the environmental ride (MacDougall and Turkington 2005). However, there are sufficient “good” examples from temperate regions that confirm the serious and long-lasting effects of the introduction of tropical exotic species on local communities (Provan et al. 2005). A typical symptom of such disruptive effect on an aquatic community is the appearance of harmful algal blooms (e.g. Hackett et al. 2004, Hamilton et al. 2005). Compsopogon Montagne 1846 was described first from Algeria with the species Compsopogon coeruleus (Balbis) Montagne. Since then, the understanding of the infrageneric diversity in Compsopogon has evolved with time (e.g. Vis et al. 1992, Rintoul et al. 1999, Sheath 2003). According to the most recent phylogenetic and taxonomic conclusions of Rintoul et al. (1999) C. coeruleus is the single representative of the monotypic family Compsopogonaceae of the rhodophycean order Compsopogonales. These conclusions are based on comparative analyses of morphology and of sequence data for the chloroplasts (rbCl) and nuclear (18S rRNA, 5.8S rRNA) genes, as well as on internally transcribed spacer regions (ITS1 and ITS2). This red alga develops worldwide in various natural tropical and subtropical waters (e.g. Sheath et al. 1995, Branco and Necchi 1996, Necchi et al. 1999, South and Skelton 2002, Sheath 2003, Vis et al. 2004), but has been described also as a weedy or nuisance taxon in garden ponds, aquaria, thermal house effluents and irrigation ditches (Leghari et al. 1997, Rintoul et al. 1999). In 1981, the dense growth of C. coeruleus on the leaves of Vallisneria sp. was noted in an aquarium in Tyrol by Gärtner (1987), who compiled and discussed the widely dispersed data on the distribution of this species in Europe and Asia, its dispersal paths through Europe and its invasion hotspots (Great Britain, Malta, Sicily, Spain, Germany, as well as former CSSR and USSR). Ironically, the most up to date information on the spread and auto-ecology of Compsopogon in Europe is to be found in various publications for aquarium keepers (e.g. Etscheidt 1997). The most recent scientific data on its occurrence in the British Isles were published by Sheath and Sherwood (2002). 204

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The presence of Compsopogon coeruleus had not been officially registered in Belgium until January 2005 when the peculiar greyish-blue filaments of this alga were noted in Ghent, in an Amazonian biotope aquarium. Responses to questionnaires amongst specialized aquarium associations revealed that this alga has already spread to aquaria in fourteen more towns of four provinces of Flanders. Therefore it could be expected that this invasive taxon will be released and settle in natural habitats throughout the region. MATERIALS AND METHODS The material was collected from the leaves and stems of Vallisneria spp. and Hydrocotyle leucocephala Chamisso et Schlechtendahl. These plants were grown in a biotope aquarium simulating Amazonian flooded forests. Water temperature was 26°C, pH at approximately 6.5 and the water colour was darkish-russet due to the presence of humic substances. The alga grew most lavishly where the water current was highest. The microscopic observations were done on non-permanent slides from living material on a Leitz Diaplan microscope, equipped with Differential Interference Contrast at a magnification of 1000x. Digital photographs were taken with an Olympus DP 50 camera. The identification procedure and terminology used followed Rintoul et al. (1999) and Sheath (2003). For comparison of our specimens with one of the last findings of Compsopogon in Europe (Gärtner 1987) material from the collection of the Innsbruck University (Figs 1-4) was kindly provided by Univ.-Doz. Dr. G. Gärtner. RESULTS The material studied consisted of well developed branching filaments with pronounced cortex in the basal parts (Figs 11-16) and rhizoids restricted to the thallus base. The main axis reached in diameter 210-220 µm (Fig. 16), while uniseriate branch diameter was 7.121.4 µm (Figs 5-12). The cortex consisted of one layer (Figs 13-15). Cortical cells varied in diameter from 23 to 38 (-55) µm and each cell contained several discoid chloroplasts (Figs 13-15, 16). Monospores were (7)-13-16-(18) µm long with ellipsoidal or irregular shape (Figs 18-21). Some minor morphological differences were found between the material from Innsbruck and Ghent. These differences concerned mainly the thickness of the cell walls of the uniseriate branches. In the material from Innsbruck aquarium the cell walls were thicker (up to 2.85-3 µm - Figs 2, 4 and also Fig. 1b in Gärtner 1987), while in the material from Ghent they were generally thinner (0.7-0.9 µm - Figs 9-12). According to the questionnaires, the peculiar greyish-blue filaments of Compsopogon coeruleus were noticed in fourteen more towns in four Belgian provinces (Fig. 22). Generally, the species was reported to be attached to the surface of the leaves of Vallisneria spiralis L. 205

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2 1

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Figs 1-4. Compsopogon coeruleus (Balbis) Montagne from the collection of the Innsbruck University (orig.): 1 – General view; 2-3 – Branching parts of the thalli with developed cortex layer and uniseriate filaments; 4 – Uniseriate filament. Scale bar - 100 µm.

but could also be found on other aquatic macrophytes with strong leaves (e.g. Hydrocotyle spp., Anubias spp.). Initial colonisation mostly started on the edges of the host leaves and increased inward onto the leaf surface. In the majority of the cases it developed epiphytically in Amazone aquaria with pH 6-6.5 (relatively rarer 6.5-7.5), at water temperatures from 24-27°C and always preferred hosts exposed to increased water current. This was mostly near the outlet of the filtering apparatus with maximum output between 1892 and 1900 liters per hour. After decreasing the current velocity by more than 60% a degradation of cells and their content was observed (Figs 5-8). In contrast to other algae, 206

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Figs 5-17. Compsopogon coeruleus (Balbis) Montagne from the Amazonian aquarium in Ghent (orig.): 58 – Uniseriate branches exposed to almost standing-water conditions, 9-12 – Uniseriate and young branching filaments exposed to strong current (Lugol staining); 13-15 – Cortex layer at different parts of the thallus; 16 – Branching near to the thallus base with pronounced cortex layer (Lugol staining); 17 – Discoid peripheral chloroplasts in the cells of the cortex layer. Scale bars - 100 µm (figs 5, 10-14, 16), 50 µm (figs 6-9, 15) and 10 µm (fig. 17).

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Figs 18-21. Monospores of Compsopogon coeruleus (Balbis) Montagne from the Amazonian aquarium in Ghent (orig.). Scale bars - 100 µm (fig. 18), 50 µm (fig. 19) and 10 µm (figs 20-21).

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Fig. 22. Distribution map of Compsopogon coeruleus (Balbis) Montagne in Flanders (Belgium); shading indicates the invaded provinces (The province Flemish Brabant surrounds completely the Brussels Capital Region).

only a limited number of fish were reported to actively graze on this alga, most notably Sturisoma panamense (Eigenmann et Eigenmann, 1889) and Ameca splendens (Miller et Fitzsimons, 1971). Typical algae controllers such as Otocinclus spp. or Hypostomus plecostomus (Linnaeus, 1758) do not appear to find this species very palatable. DISCUSSION Following Rintoul et al. (1999) and Sheath (2003) both the macroscopic habitus and microscopic features observed were sufficient to identify the studied specimens as Compsopogon coeruleus. The comparison between the Compsopogon material from Austria and Belgium, in spite of an overall conformity, showed some slight morphological differences in the organization of the cell walls of uniseriate filaments. According to Rintoul et al. (1999) these minor deviations in morphology are not sufficient for a systematic separation at species level. 209

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However, we tentatively suggest that this may indicate different sources of the introduction of this red alga in Europe. The environmental data obtained during this study coincide only in part with the published ecological requirements of Compsopogon coeruleus. The water temperature preferences (ca. 26oC) were basically similar with the previously published (13-27oC - Etscheidt 1997, Sheath 2003). However, the specimens from Amazonian aquaria in Belgium generally grow in conditions of relatively lower pH (ca. 6-6.5 and rarer 6.5-7.5) while previously more neutral to alkaline conditions (pH values of 6.9-7.3-8.6) were outlined (Etscheidt 1997, Sheath 2003). This seems not unlikely considering the wide ecological tolerance already reported for the species (e.g. from freshwater to brackish water - Gärtner 1987, specific conductance of 46-1880 µS cm-1 - Sheath 2003). According to Sheath (2003) this red alga appears mainly in streams. In the aquarium under observation in Ghent Compsopogon coeruleus clearly preferred a strong current. The species seemed unable to initiate a successful colonization in slow current or standing-water conditions. It could however endure such conditions for relatively long periods. This preference for stronger currents was confirmed from the other aquaria in Belgium from which it was reported. Therefore, in our opinion, changes in the current velocity could be used for controlling of the growth of this alga and even for its elimination from aquaria. This approach in combination with efficient grazers, such as Ameca splendens, may prove to be quite successful. This is of course not only virtually impossible but also quite unethical in natural habitats. Prevention of distribution of this taxon to wild habitats through waste water is the crucial point. As yet it has not been observed in streams or rivulets. Effective sterilization of waste water from aquaria should be encouraged to stop this and other invasive species. CONCLUSION In accordance with the present systematical view of this group, the material studied from the Amazonian aquarium in Ghent belongs to the species Compsopogon coeruleus. Based on the questionnaires this red algal species occurs at least in four provinces in Flanders. Therefore its appearance in natural habitats of Belgium might be more a matter of time rather than of conditions. The observations of the preference of Compsopogon coeruleus for stronger water current suggest that the velocity-control may be a good tool for eventual managing the development of this nuisance alga in contained environments. Conversely, this also suggests that streams and rivulets are the first natural habitats to look for this invasive taxon. ACKNOWLEDGMENTS We would like to thank Univ.-Doz. Dr. G. Gärtner for providing material and relevant literature and Mieke Sterken for making the distribution map. We thank the Zoetwateraquariumforum for hosting the questionnaire on Compsopogon coeruleus and all the people who responded to it and provided further data on the ecology of the species. 210

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REFERENCES BRANCO C. C. Z. and O. NECCHI 1996. Distribution of stream macroalgae in the eastern Atlantic rainforest of Sao Paulo state, southeastern Brazil. – Hydrobiologia, 333 (3): 139-150. ETSCHEIDT, J. 1997. Compleet Handboek. Zoetwater Aquarium. – Zuidnederlandse Uitgeverji N. V., Aartselaar, België. GÄRTNER, G. 1987. Compsopogon coeruleus (Balbis) Montagne (Rhodophyta, Bangiophycidae) erstmals in Tirol als Aquarienbewohner nachgewiesen. – Ber. nat.-med. Verein Innsbruck, 74: 41-47. HACKETT J. D., D. M. ANDERSON, D. L. ERDNER and D. BHATTARAYA 2004. Dinoflagellates: a remarkable evolutionary experiment. – Amer. J. Bot., 91 (10): 1523-1534. HAMILTON, P., L. M. LEY, S. DEAN and F. R. PICK 2005. The occurrence of the cyanobacterium Cylindrospermopsis raciborskii in Constance Lake: an exotic cyanoprokaryote new to Canada. – Phycologia, 44 (1): 17-25. HASTINGS, A., K. CUDDINGTON, K. F. DAVIES, C. J. DUGAW, S. ELMENDORF, A. FREESTONE, S. HARRISON, M. HOLLAND, J. LAMBRINOS, U. MALVADKAR, B. A. MELBOURNE, K. MOORE, C. TAYLOR and D. THOMSON 2005. The spatial spread of invasions: new developments in theory and evidence. – Ecology Letters, 8 (1): 91-101. KRISTIANSEN, J. 1996a. Biogeography of freshwater algae – conclusions and perspectives. – Hydrobiologia, 336: 159-161. KRISTIANSEN, J. 1996b. Dispersal of freshwater algae – a review. – Hydrobiologia, 336: 151-157. LEGHARI, S. M., G. N. SAHITO, A. HAYEEMEMON, M. Y. KHUHAWAR and G. M. MASTOI 1997. Freshwater red algae in water effluents of thermal power house at Jamshoro, Sindh, Pakistan. - Pakistan Journ. Bot., 29 (1): 151-160. LE MAITRE, D. C. 2004. Predicting invasive species impacts on hydrological processes: The consequences of plant physiology for landscape processes. – Weed Technology, 18: 1408-1410. MACDOUGALL, A. C. and R. TURKINGTON 2005. Are invasive species the drivers or passengers of change in degraded ecosystems? – Ecology, 86 (1): 42-55. MONTAGNE, C. 1846. Phyceae. in: Bory de St. Vincent, J. B. and M. Durieaux, editors. Flore d’Algerie, 1: 154. NECCHI, O., C. C. Z. BRANCO and R. R. V. GOMEZ 1999. Microhabitat and plant structure of Compsopogon coeruleus (Compsopogonales, Rhodophyta) populations in streams from Sao Paulo state, Southeastern Brazil. – Cryptogam. Algol., 20 (2): 75-87. POWELL, M. R. 2004. Risk assessment for invasive plant species. – Weed Technology, 18: 1305-1308. PROVAN, J., S. MURPHY and C. A. MAGGS 2005. Tracking the invasive history of the green alga Codium fragile ssp tomentosoides. – Molecular Ecology 14, (1): 189-194.

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RINTOUL, T. L., R. G. SHEATH and M. L. VIS 1999. Systematics and biogeography of the Compsopogonales (Rhodophyta) with emphasis on the freshwater families in North America. – Phycologia, 38 (6): 517-527. SHEATH, R. G. 2003. Red Algae. in: Wehr, J. D. and R. G. Sheath, editors. Freshwater Algae of North America. Ecology and Classification: 197-224. Academic Press, Amsterdam. SHEATH, R. G. and A. R. SHERWOOD 2002. Phyllum Rhodophyta (Red Algae). in: John, D. M., B. A. Whitton and A. J. Brook, editors. The Freshwater Algal Flora of the British Isles: 123-143. Cambridge University Press, Cambridge. SHEATH, R. G., K. M. MÜLLER, D. J. LARSON and K. M. COLE 1995. Incorporation of freshwater rhodophyta into the cases of caddislies (Trichoptera) from North America. – J. Phycol., 31 (6): 889-896. SOUTH G. R. and P. A. SKELTON 2002. Occurrence and use of Compsopogon coeruleus (Rhodophyta: Compsopogonaceae) in Fiji, South Pacific. – New Zealand J. Mar. Freshwat. Res., 36 (4): 879-881. VIS, M. L., R. G. SHEATH and K. M. COLE 1992. Systematics of the freshwater red algal family Compsopogonales in North America. – Phycologia, 31 (6): 564-575. VIS, M. L., R. G. SHEATH and W. B. CHIASSON 2004. A survey of the Rhodophyta and associated macroalgae from coastal streams in French Guiana. – Cryptogam. Algol., 25 (2): 161-174. WILCOVE, D. S., D. ROTHSTEIN, J. DUBOW, A. PHILLIPS and E. LOSOS 1998. Quantifying threats to imperiled species in the United States. – Bioscience, 48: 607-615.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 213-225) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Initial observations on uniparental auxosporulation in Muelleria (Frenguelli) Frenguelli and Scoliopleura Grunow (Bacillariophyceae) Mark B. Edlund1 and Sarah A. Spaulding2 St. Croix Watershed Research Station, Science Museum of Minnesota, 16910 152nd Street North Marine on St. Croix, Minnesota 55047, U.S.A. e-mail: [email protected] 2 Institute of Arctic and Alpine Research, Campus Box 450, University of Colorado, Boulder, Colorado 80309, U.S.A. 1

ABSTRACT Antarctic material containing Muelleria peraustralis (West and West) Spaulding and Stoermer and cultured material of Scoliopleura peisonis Grunow were examined and found undergoing uniparental auxosporulation to regain maximum valve size. Single unpaired parental cells produced a single bipolar expanding auxospore within the parent frustule. The auxospore split into two end caps and expansion was controlled by a banded perizonium. Similar to Neidium affine, the perizonium consisted of 18-22 split bands, a central closed band, and persistent siliceous endcaps on the expanding auxospore. A single longitudinal perizonium element was present in Scoliopleura. A single example of paired gametangia that produced two initial cells was noted in M. peraustralis; it provided initial evidence that both sexual (Geitler’s Type IA1) and uniparental modes of auxosporulation may be utilized by Muelleria peraustralis. Key words: diatoms, sexual reproduction, perizonium, automixis, selfing INTRODUCTION Diatoms (Class Bacillariophyceae) are characterized by a diplontic life cycle, in which vegetative cells are diploid, and the only haploid phase occurs in gametes. The generalized diatom life cycle consists of a long phase of vegetative growth, in which cells produce successively smaller cells with each mitotic division, and a relatively rapid phase of sexual 213

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reproduction, in which cell size is restored (reviewed in Edlund and Stoermer 1997). During the sexual phase for raphid pennate diatoms, gametangial cells become paired and divide meiotically to form haploid gametes (centric diatoms undergo oogamy). Following exchange of gametes between parental cells, gametes fuse to form the zygote. The resulting zygote expands as an auxospore and shortly before, after, or during expansion of the auxospore, the two haploid nuclei merge (karyogamy). This process, termed auxosporulation, gives rise to an “initial cell,” which is a cell of near maximum possible size of the population. The sexual phase is considered imperative for the continuation of the life cycle and for restoration of cell size and shape in diatoms (Pickett-Heaps et al. 1990, Mann 1994b). In an apparent modification of oogamic or allogamic reproduction (Round et al. 1990, Mann 1993), a number of centric and pennate diatom species have been shown to restore cell size via uniparental auxosporulation (automixis and apomixis). Following Geitler’s (1932) terminology, automixis and apomixis constitute the two main categories of sexual reproduction that do not involve gametangial pairing and/or gametic exchange. Automixis is also known as Type III, Reduced type B reproduction and can be further divided into paedogamy and autogamy. In paedogamy, a single gametangium, or parent cell, forms two gametes following the first meiotic division and cytokinesis. The two haploid gametes fuse and, following karyogamy, form a diploid zygote, which enlarges as an auxospore. In autogamy, a single gametangium forms a single binucleate haploid gamete in the absence of cytokinesis. The two haploid nuclei fuse with one another to form a diploid zygote, which expands as an auxospore. Apomixis, or parthenogenesis, similarly involves the formation of an auxospore from a single diploid gametangium. However, instead of the two steps of meiosis and subsequent fusion of haploid gametes, a single mitosis occurs. Because meiosis is suppressed, offspring are genetically identical to the parent. Automixis and apomixis are rare in centric diatoms, but have been reported in numerous pennate taxa (e.g. Geitler 1932, 1957, 1973, Mann et al. 1999, Roshchin and Chepurnov 1999), with automixis most prevalent. According to Geitler (1973), the only pennate diatom in which apomixis has been confirmed is in varieties of Cocconeis placentula. In comparison to the known diversity of diatoms, only between 200-250 taxa have had any aspects of their sexuality reported (Mann 1988). In this study, we present initial observations on similar strategies of uniparental auxosporulation in a natural population of Muelleria peraustralis (West and West) Spaulding and Stoermer and in a clonal culture of Scoliopleura peisonis Grunow. The shared reproductive strategies may add support to the systematic relationships among S. peisonis and members of the genus Muelleria, which share a number of valve features (Spaulding et al. 1999). MATERIALS AND METHODS Muelleria peraustralis was collected in cryptogamic mats from two localities in Antarctica (Alger 1999). Alger 23 was collected on 01 January 1998 from a sandy pool in Green Creek, Taylor Valley. Alger 104 was collected on 13 January 1998 from a sand mat at the Garwood Stream outlet into the Ross Sea, Garwood Valley. Samples were field-preserved in 5% formaldehyde. 214

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Preserved material was allowed to air dry onto coverglasses, rinsed with distilled water, ashed at 600°C, and the material remounted in Naphrax. Additional preserved material was prepared for cytological examination by staining with toluidine blue followed by rinsing with distilled water, dehydration in an ethanol series and mounting on microslides with Euparal. Light microscope observations were made with an Olympus BX50 with brightfield and DIC optics capable of 1000X magnification (N.A. 1.40). Microslides and subsamples of preserved Muelleria material have been deposited in the Diatom Herbarium at the California Academy of Sciences (CAS accession numbers 70444, 70445). Two cultures of S. peisonis were obtained from the Loras College Diatom Culture Collection (Strains L150 and 30/01/A) in 1997 and observed under the light microscope over a period of 72 hours. Both strains were originally isolated from Chevelon Creek Potholes, Navajo County, Arizona, USA, and maintained in CR1 medium (Czarnecki 1994). Strain L150 was collected December 4, 1988, while strain 30/01/A was collected in 1976 (Czarnecki et al. 1981, Czarnecki 1994). All samples were observed live in wet-mount prepared slides and were undergoing auxosporulation upon receipt in the mail. Light microscope observations were made with a Leitz DMBR with DIC optics. Further attempts to initiate sexuality in this material or in subsequent culture requests were unsuccessful. RESULTS Muelleria peraustralis Examination of ashed or toluidine blue-stained Antarctic material showed moderately abundant vegetative cells, gametangia, auxospores, perizonia, and initial cells of Muelleria peraustralis. Auxospore material consisted of single parental (gametangial) cells undergoing the various stages of uniparental auxosporulation (Figs 1-8, 12-14). Neither gametangial nor initial cells were found paired or within an obvious copulation mucilage, except for a single specimen of presumably paired gametangial cells that had produced two perizoniabound initial cells (Fig. 9). By examining many examples from the material we believe that most of the stages of uniparental auxosporulation could be determined. Uniparental gametangial cells of Muelleria peraustralis ranged in valve length from 27.5 µm to 41.0 µm (n = 59) and were not paired nor surrounded by any obvious copulation mucilage (Figs 12-14). Parental cells initially expanded along their pervalvar axis, possibly with the addition of multiple girdle elements (Figs 1-3). We were unable to determine from the preserved material whether uniparental gametogenesis was a result of automictic or apomictic reproduction; however, a single auxospore was clearly formed within the uncompromised parental frustule (Figs 1-3). The auxospore appeared to begin its bipolar expansion along the apical plane, still bounded within the parental cell. Later stages showed that the auxospore had split into two obvious end caps with the early perizonial bands while still within the parental frustule (Figs 1-3). Other specimens showed auxospores expanded sufficiently to have been freed from the parental frustule either from expanding bipolar and parallel to the loosely adherent mother valves (Figs 4, 5, 12, 13) or by release from the 215

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Figs 1-9. Muelleria peraustralis, light micrographs of ashed material, scale bar in Fig. 3a = 10 µm. Figs 1-3. Expanding auxospore within uniparental gametangial frustule. a. high focus. b. mid-focus. Fig. 4. Perizonium-bound auxospore expanding parallel to gametangial valves (g) located midway along the perizonium. Note thickened central perizonium band (cn), approximately 20 transverse bands (p), and siliceous endcaps (ec). Figs 5, 6. Initial epivalve (ie) formed within perizonium that has expanded parallel to gametangial valves. Fig.5. Gametangial valves located midway along the perizonium. Fig. 6. Gametangial valves located terminal to the perizonium. Fig. 7. Fully formed initial cell emerging from gametangial-perizonium complex. Gametangial valves positioned terminal to initial cell. Fig. 8. First cytokinetic mitotic division of uniparental initial cell. Top cell has remnants of perizonium attached. Fig. 9. The only example of potentially allogamous auxosporulation (perhaps Geitler’s Type IA1) in M. peraustralis. Two gametangial cells have paired and produced two initial cells (only initial epivalves has been formed) within perizonia that expanded parallel to the gametangial cells.

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gametangial cell end, which resulted in a perizonium-bounded auxospore that expanded away from (but parallel to) the terminally adherent mother valves (Figs 6, 7, 14). Bipolar expansion of the auxospore was likely controlled by both the end caps and a banded transverse perizonium (Figs 4-7, 12-14). The end caps were not destroyed by ashing of the material suggesting that they were in part siliceous (Figs 1-7); however, they were also heavily stained by toluidine blue attesting to the organic nature of the auxospore membrane (Figs 12-14). The remainder of the perizonium was constructed of 18-22 overlapping split transverse bands (Figs 4-8, 11-14) and a single closed and slightly thickened central tranverse band (Figs 4-8, 12, 13). No evidence of longitudinal perizonial bands was seen in the M. peraustralis perizonium. After auxospore expansion and perizonium construction,

Figs 10-14. Muelleria peraustralis, light micrographs of toluidine blue-stained material, scale bar in Fig. 10a = 10 µm. Fig. 10. Cytological arrangement of vegetative cell in valvar plane. a. high focus on valve. b. mid-focus showing central nucleus (n) and four pyrenoids. Fig. 11. Split transverse perizonium bands (arrow). Fig. 12. Gametangium-perizonium complex of M. peraustralis. Note parallel expansion of perizonium, mid-perizonium position of adherent gametangial valves (g), thickened central closed band (cn), numerous transverse bands (p), and heavily stained auxospore wall endcaps (ec). Fig. 13. Initial epivalve (ie) formed within a perizonium that has expanded parallel to gametangial valves. Note central nucleus and heavily stained endcaps. Fig. 14. Initial cell (i) in girdle view emerging from gametangium-perizonium complex. Note terminally adherring gametantial valves, heavily stained auxospore endcap, central nucleus (n), and four pyrenoids.

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specimens showed that the initial epivalve was formed in the plane of one of the parental valves (Figs 5, 6, 13). Formation of the initial hypovalve completed the initial cell frustule, again generally in the plane of the parental valves (Figs 7, 14). Initial cells of M. peraustralis ranged in length from 56.0 µm to 75.0 µm (n = 64). Initial valves were rounded along the transverse axis, but they appeared to have raphe systems and the general structure of vegetative valves (Figs 7, 8, 14). Although the initial valves were formed by either automixis or apomixis, they appear to have been viable, because many divided initial cells (Fig. 8), empty perizonia, and large vegetative cells were noted. Stained initial cells had a central nucleus and four pyrenoids arranged similar to vegetative cells (Figs 10b, 14). In the complete uniparental gametangium-perizonium-initial cell complexes of Muelleria peraustralis (n = 25), there appeared to be no clear relationship between the length of uniparental gametangial valve and the length of the initial cell produced either within or between the two collections (Fig. 15). In M. peraustralis, initial cells were generally larger than the parental valves by a factor of 1.62 to 2.31 (mean 1.90, n = 25). A single example of probable allogamous pairing was observed in burnmounted material from Alger 23 (Fig. 9). Although the preparation did not permit the details of gametogenesis or gamete exchange to be studied, it appeared that Muelleria peraustralis had undergone Geitler’s Type IA1 reproduction. Paired gametangial cells produced two initial cells that were aligned parallel to the apical axes of the gametangial cells (Fig. 9). In the allogamous pairing, gametangial cells were ca. 34.5 µm long and initial cells were ca. 64 µm long. These sizes were not significantly different from the gametangial and initial cell sizes resulting from uniparental auxosporulation (Fig. 15).

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Figs 15. Biplot of gametangial valve size (µm) and initial valve size (µm) in two uniparental auxosporulating populations (Alger 23, n = 14, Alger 104, n = 11) of Muelleria peraustralis. Arrows along graph axes indicate complete size range of gametangial and initial cells encountered. The open diamond symbol represents the one example of probable allogamic reproduction (Geitler’s Type IA1) we found.

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Scoliopleura peisonis Vegetative cells contained four chloroplasts (Figs 16-19). In valve view, chloroplasts were platelike, with lobes that extended toward the apices, visible at deeper levels of focus (Figs 16, 19). In girdle view, the chloroplasts appeared as short lobes appressed to the interior valve surface (Fig. 17). A centrally located nucleus was suspended by a cytoplasmic bridge (Figs 17, 18). Perizonium-bounded initial cells were also observed in the clonal cultures (Figs 20-22), and the initial cells appeared to be the result of uniparental auxosporulation. Arrangement of gametangial (parental) and initial cells (post-auxospore) was unlike an arrangement that would be expected following allogamous sexual reproduction in pennate diatoms. In sexual reproduction, paired gametangia often form mucilage envelopes or copulation tubes, but no such pairing or structures were observed in this material. In contrast to biparental exchange of gametes, both gametangial and initial cells occurred singly (Figs 20-22). Perizonia included a thickened, closed central band with 18-22 split tranverse bands (Figs 20-22), and at least one longitudinal band (Fig. 22b). End caps of the perizonium appeared to be siliceous (Figs 20-22), although the composition was not confirmed with burn mounts. An initial cell was formed within each perizonium. Initial cells ranged from 56 to 66 µm in length. Empty gametangial cells ranged from 24 to 40 µm and remained in close association with the perizonium and initial cell, generally adjacent to and parallel or terminal to the perizonium-initial cell complex (Figs 20-22). DISCUSSION These observations, albeit preliminary, represent the first reports of auxosporulation and restoration of maximum size in Muelleria and Scoliopleura. It was unfortunate that we were not able to determine with absolute certainty whether S. peisonis and M. peraustralis were undergoing automictic or apomictic auxosporulation; we simply could not identify the necessary stages of gametogenesis in the available material. We were, however, able to confirm that auxosporulation was uniparental, and that the auxospore complexes we examined were not artifacts of disassociated allogamic mating pairs. In M. peraustralis, initial formation and expansion of the auxospore occurred within the parent frustule before any evidence of separation of valve or girdle elements; presumably the frustule would have been compromised if gamete exchange had taken place between allogamous paired cells (but see Nitzschia, Mann 1986). In fact, M. peraustralis has been reported to possess few girdle elements (Spaulding and Stoermer 1997) and may actually have added elements in preparation for uniparental auxosporulation to allow for pervalvar frustule expansion. Furthermore, no evidence of a diffuse mucilage envelope was seen. Mucilage envelopes have been noted in allogamous pairings by Neidium and Biremis (Mann 1984, 1993). Last, no significant linear relationship was noted between gametangial cell size and initial cell size in M. peraustralis. Many, if not most, diatoms show linear relationships between gametangial cell size and initial cell size (Davidovich 2001, Edlund and Bixby 2001), with smaller gametangia (paired or uniparental) producing relatively smaller initial cells. However, the 219

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Figs 16-22. Live Scoliopleura peisonis, light micrographs, scale bar in Fig. 16 = 10 µm. Figs 16-19. Vegetative cells, each containing four plate-like chloroplasts, appressed to the valve face. Fig. 16. Valve view of cell. Chrysolaminarin bodies are visible, positioned diagonally from one another near midvalve. Fig. 17. Girdle view of cell at two depths of focus. A centrally located nucleus (n) is suspended by a cytoplasmic bridge. a. mid focus. b. high focus. Fig. 18. Valve view of cell, at shallow focus. Fig. 19. Valve view of cell at deep level of focus. Note notched lobes of chloroplasts extend to the valve apices. Nucleus is visible. Fig. 20. Perizonium-bounded initial cell in girdle view, two levels of focus. Empty gamatangial valves (g) are located terminal to the expanded perizonium, positioned at left end of initial valve. Lobed chloroplasts and a central nucleus are present within initial cell (i) bounded by auxospore consisting of transverse perizonal bands (p), and end caps (ec). a. mid focus. b. high focus. Fig. 21.Two levels of focus of the same perizonium bounded initial cell. Empty gametangial valve is present, positioned at the middle of initial valve. Perizonium of central thickened band and ca. 20 transverse bands. Note central nucleus and valve appressed chloroplasts. a. mid focus. b. high focus. Fig. 22. Two levels of focus of initial cell being released from perizonium, girdle view. Perizonium with approximately 20 transverse (p) perizonium bands, a slightly thickened central band (cn), a single longitudinal (l) perizonium band, and siliceous end caps (ec). a. high focus. b. mid focus.

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factor of expansion or the ratio of the initial cell size to uniparental gametangium size in M. peraustralis is generally in line with other diatoms (Davidovich 2001). If Muelleria and Scoliopleura were using automixis as a uniparental means of restoring their cell lines, we would have expected to document specific stages of gametogenesis, gametic fusion, zygote formation, and karyogamy depending on whether cells were undergoing autogamy or paedogamy (Geitler 1952, 1973). The single instance of probable allogamic pairing that we noted in M. peraustralis (Fig. 16) suggests that paedogamic automixis may have been the strategy used in uniparental auxosporulation. Mann (1993) proposed how a simple incompatibility breakdown could explain how paedogamy could have developed from Normal Type I allogamic auxosporulation. The other plausible mechanism for uniparental auxosporulation in Scoliopleura peisonis and Muelleria peraustralis is apomixis, or parthenogenesis. In pennate diatoms, this diploid mechanism (contrast haploid parthenogenesis, Mann 1994a, Chepurnov and Roshchin 1995) has been well characterized in two varieties of Cocconeis placentula Ehrenb. (Geitler 1982, Mizuno in Hori 1993). Apomixis results from a failed meiosis, in which a paired or unpaired gametangial cell falters during meiotic preparations and reverts to mitosis to produce two diploid gametes. One diploid gamete degenerates and the remaining diploid gamete is released as an auxospore to undergo perizonium-controlled expansion and initial cell formation (Geitler 1982). Scoliopleura peisonis and Muelleria peraustralis share similarities in uniparental auxosporulation that may support their close systematic relationship and provide further evidence for their relationship among the longitudinal canal-bearing diatoms (Scoliopleura, Muelleria, Neidium, Biremis, and Diploneis). From earlier work, chloroplast number and arrangement are consistent with a close relationship between Muelleria and Scoliopleura. Scoliopleura peisonis and M. peraustralis (Spaulding et al. 1999) both have four chloroplasts. Neidium (N. affine, Mann 1984) also has four chloroplasts, whereas Biremis [B. ambigua (Cleve) D.G. Mann (Cox 1990)] and Diploneis (D. didyma Ehrenb., Cardinal et al. 1984) are reported to have two chloroplasts per cell. Based on valve ultrastructure, we predict that Scoliopleura peisonis and Muelleria species share synapomorphies (shared, derived characters) of a longitudinal canal closely associated with the raphe system, and an internal, parallel termination of the longitudinal canals. The longitudinal canals of Biremis Mann and Cox in Round et al., Diploneis (Ehrenberg) Cleve, and Neidium (Ehrenberg) Pfitzer differ in placement or structure, or both, from that of S. peisonis and Muelleria, i.e. the longitudinal canals of Diploneis and Neidium are not homologous with those of S. peisonis and Muelleria. Reproductive characters may further support the systematic relationships among the genera Scoliopleura, Muelleria, Biremis, and Neidium. Within the species that have been investigated, this group produces partially silicified, bipartite auxospore membranes (this study, Mann 1984, 1993) that persist throughout the stages of auxosporulation. Apart from these four genera, silica incorporated within the pennate diatom auxospore membrane has only been reported in Frustulia rhomboides var. saxonica (Rabenhorst) DeToni (Kobayasi in Hori 1993) and as scales in Pseudo-nitzschia multiseries (Hasle) Hasle (Kaczmarska et al. 2000). Perizonia of Scoliopleura, Muelleria, Biremis, and Neidium are terminally bounded by the persistent auxospore membranes as end caps and the perizonia are similarly constructed of a 221

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single closed central hoop and numerous split transverse bands (Mann 1984, 1993). Scoliopleura peisonis and N. affine also share a single longitudinal perizonium element within the perizonium complex (Mann 1984). Muelleria peraustralis perizonia did not have longitudinal perizonium plates. Auxospore expansion is parallel to the adherent gametangial valves in all four genera. This arrangement seems to be present regardless of allogamic pairing of Type IA1 (sensu Geitler ([1973] in N. affine [Mann 1984], Biremis sp. [Mann 1993], and Muelleria [Fig. 9]) or uniparental auxosporulation in M. peraustralis and S. peisonis. Specific arrangement of initial cells to gametangial cells following sexual reproduction has been shown to be a character shared among related taxa in other lineages (Geitler 1932) although the broader application of Geitler’s classification scheme has received guarded criticism when individual sexual characters are not carefully considered in phylogenetic analyses (Kociolek and Stoermer 1986, Mann 1993). Finally, the shared pattern of uniparental auxosporulation between Muelleria and Scoliopleura is intriquing. If uniparental auxosporulation is a genetically determined and/or an available alternative to allogamy within a Scoliopleura-Muelleria lineage, additional details on the diversity of mixis types and mating systems may provide character data that are useful in phylogenetic analysis (see also Mann 1993). Uniparental auxosporulation may be a strategy of populations living in extreme environments. Muelleria peraustralis is endemic to Antarctica, and grows in abundance in temporary, shallow melt pools of the McMurdo Dry Valleys region (Spaulding and Stoermer 1997, Spaulding et al. 1999). In this region, air temperature is above the freezing point of water for, at most, a few weeks of the austral summer. Melting of glacial ice and the formation of melt pools is dependent on solar radiation and temperature, and the existence of water in the liquid state is temporary. Within this extreme environment, organisms must be able to carry out their growth and complete life cycle during the period that liquid water is available (McKnight et al. 1999). Scoliopleura peisonis grows in another type of extreme environment: temporary and brackish waters of western North America (Czarnecki et al. 1981, Czarnecki 1994) and inland saline lakes elsewhere (Cleve-Euler 1953, Krammer and Lange-Bertalot 1986, Soninkhishig 2003). Both taxa similarly live in ephemeral habitats of variable, to high, concentrations of salts. In such unstable environments, uniparental auxosporulation may be an adaptive strategy (or part of a mixed reproductive strategy) to insure size restoration when pairing is not a time-worthy task or if suitable mating partners are not available for outbreeding (Mann et al. 1999), while still maintaining the potential for adaptation through recombination (Schmid 1979). Alternatively, a proposal by Roshchin and Chepurnov (1999) suggests that automixis and apomixis may be limited to those taxa with monoecious (or possibly monoecious-dioecious) breeding systems. Although only a limited number of taxa have had their breeding systems studied, this proposal seems well-supported (Geitler 1985, Roshchin and Chepurnov 1999). Further linkages have been made to suggest that the taxa with monoecious or monoeciousdioecious breeding systems are associated with ecological euryhalinity (Roshchin and Chepurnov 1999). Whether this applies to M. peraustralis and S. peisonis will require detailed culture work to determine their breeding systems. The study of diatom life histories continues to attract the attention of a devoted set of researchers; however, the possibilities to advance this field are open to anyone interested in 222

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diatoms. Less than 1% of the known diatom species have had any aspect of their life histories reported; the casual, careful, or serendipitous observer may be rewarded. Even at the genus level we await reports of how some common taxa undergo auxosporulation (Mann 1988). Few studies have yet to address how the diatom life history impacts species or community-level ecology. Careful sampling to track population and cell sizes in natural communities over time can provide exciting new advances in phytoplankton and benthic ecology (examples in Edlund and Stoermer 1997). Last, recent successes have been made using culture studies to reveal the diversity of mating types among diatoms (Mann et al. 1999, 2004). Analyses may show that patterns of automixis and apomixis in diatoms, especially in relation to diversity of breeding systems, can be linked to broader phylogenetic, ecological (Roshchin and Chepurnov 1999), and biogeographic patterns of distribution, similar to patterns of parthenogenesis in higher plants (Bierzychudek 1987). ACKNOWLEDGEMENTS We thank Alex Alger for providing preserved material of Antarctic Muelleria and David Czarnecki at the Loras College Diatom Culture Collection for providing cultures of Scoliopleura peisonis. Several reviewers provided critical suggestions during earlier versions of this manuscript. This material is based partly upon work supported by the National Science Foundation (NSF) under grant DEB-0316503 to MBE. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF. Collection of Antarctic material by Alex Alger was supported by LTER grant OPP 9211773. REFERENCES ALGER, A.S. 1999. Diatoms of the McMurdo Dry Valleys, Antarctica: A taxonomic appraisal including a detailed study of the genus Hantzschia. - Master’s thesis, University of Michigan, Ann Arbor. BIERZYCHUDEK, P. 1987. Patterns in plant parthenogenesis. in: S. C. Stearns, editor. The Evolution of Sex and its Consequences: 197-217. Birkhäuser Verlag, Basel. CARDINAL, A., M. POULIN and L. BÉRARD-THERRIAULT 1984. Les diatomées benthiques de substrats durs des eaux marines et saumâtres de Quebec 4. Naviculales, Naviculaceae (à l’exlusion des genres Navicula, Donkinia, Gyrosigma et Pleurosigma). Le Naturaliste Canadien, 111: 369-394. CHEPURNOV, V. A. and A.M. ROSHCHIN 1995. Inbreeding influence on sexual reproduction of Achnanthes longipes Ag. (Bacillariophyta). - Diatom Res., 10: 21-29. CLEVE-EULER, A. 1953. Die Diatomeen von Schweden und Finnland. Teil III. Monoraphideae, Biraphideae 1. - Kunglica Svenska Vetenskapsakademiens Handlingar, Fjärde Serien, 4(5): 1-255.

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COX, E.J. 1990. Biremis ambigua (Cleve) D.G. Mann, an unusual marine epipelic diatom in need of further investigation. in: M. Ricard, editor. Ouvrage Dédié à H. Germain: 63-72. O. Koeltz Publishers, Koenigstein. CZARNECKI, D.B. 1994. The freshwater diatom culture collection at Loras College, Dubuque, Iowa. in: J. P. Kociolek, editor. Proceedings of the 11th International Diatom Symposium: 155-174. California Academy of Sciences, San Francisco. CZARNECKI, D.B., D. BLINN and M. PENTON 1981. The diatom flora of the Lower Chevelon Creek area of Arizona: an inland brackish water system. – Southwest. Nat., 26: 311-324. DAVIDOVICH, N.A. 2001. Species specific sizes and size range of sexual reproduction in diatoms. in: A. Economou-Amilli, editor. Proceedings of the XVIth International Diatom Symposium: 191-196. Amvrosiou Press, Athens. EDLUND, M.B. and R.J. BIXBY 2001. Intra- and inter-specific differences in gametangial and initial cell size in diatoms. in: A. Economou-Amilli, editor. Proceedings of the XVIth International Diatom Symposium: 169-190. Amvrosiou Press, Athens. EDLUND, M.B. and E.F. STOERMER 1997. Ecological, evolutionary, and systematic significance of diatom life histories. – J. Phycol., 33: 897-918. GEITLER, L. 1932. Der Formwechsel der pennaten Diatomeen (Kieselalgen). – Arch. Protistk., 78: 1-226. GEITLER, L. 1952. Untersuchungen über Kopulation und Auxosporenbildung pennater Diatomeen. I. Automixis bei Gomphonema constrictum var. capitata. - Öst. bot. Z., 99: 376-384. GEITLER, L. 1957. Die sexuelle Fortpflanzung der Diatomeen. – Biol. Rev., 32: 261-295. GEITLER, L. 1973. Auxosporenbildung und Systematik bei pennaten Diatomeen und die Cytologie von Cocconeis-Sippen. – Öst. bot. Z., 122: 299-321. GEITLER, L. 1982. Die infraspezifischen Sippen von Cocconeis placentula des Lunzer Seebachs. Arch. Hydrobiol., Suppl. 63 (Algol. Stud. 30): 1-11. GEITLER, L. 1985. Automixis bei pennaten Diatomeen. - Plant Syst. Evol., 150: 303-306. HORI, T., editor. 1993. An Illustrated Atlas of the Life History of Algae. Vol. 3. Unicellular and Flagellated Algae. - Uchida Rokakuho Publishing Co., Ltd., Tokyo. KACZMARSKA, I., S.S. BATES, J.M EHRMAN and C. LÉGER 2000. Fine structure of the gamete, auxospore and initial cell in the pennate diatom Pseudo-nitzschia multiseries (Bacillariophyta). - Nova Hedwigia, 71: 337-357. KOCIOLEK, J.P. and E.F. STOERMER 1986. Phylogenetic relationships and classification of mono-raphid diatoms based on phenetic and cladistic methodologies. – Phycologia, 25: 297-303. KRAMMER, K. and H. LANGE-BERTALOT 1986. Bacillariophyceae. 1. Teil: Naviculaceae. in: H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Süsswasserflora von Mitteleuropa 2(1): 1-876. Gustav Fischer, Stuttgart. MANN, D.G. 1984. Auxospore formation and development in Neidium (Bacillariophyta). British Phycological Journal, 19, 319-331. MANN, D.G. 1986. Methods of sexual reproduction in Nitzschia: Systematic and evolutionary implications. - Diatom Res., 1: 193-203. 224

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MANN, D.G. 1988. Why didn’t Lund see sex in Asterionella? A discussion of the diatom life cycle in nature. in: F.E. Round, editor. Algae and the Aquatic Environment: 384412. Biopress Limited, Bristol. MANN, D.G. 1993. Patterns of sexual reproduction in diatoms. - Hydrobiologia, 269/270: 11-20. MANN, D.G. 1994a. Auxospore formation, reproductive plasticity and cell structure in Navicula ulvacea and the resurrection of the genus Dickieia (Bacillariophyta). – Eur. J. Phycol., 29: 141-157. MANN, D.G. 1994b. The origins of shape and form in diatoms: the interplay between morphogenetic studies and systematics. in: D.S. Ingram and A.J. Hudson, editors. Shape and Form in Plants and Fungi: 17-38. Academic Press, London. MANN, D.G., V.A. Chepurnov and S.J.M. Droop 1999. Sexuality, incompatibility, size variation, and preferential polyandry in natural populations and clones of Sellaphora pupula (Bacillariophyceae). – J. Phycol., 35: 152-170. MANN, D.G., S.M. McDonald, M.M. Bayer, S.J.M. Droop, V.A. Chepurnov, R.E. Loke, A. Ciobanu and J.M.H. Du Buf. 2004. The Sellaphora pupula species complex (Bacillariophyceae). morphometric analysis, ultrastructure and mating data provide evidence for five new species. – Phycologia, 43: 459-482. MCKNIGHT, D.M., D.K. NIYOGI, A.S. ALGER, A. BOMBLIES, P.A. CONOVITZ and C.M. TATE 1999. Dry Valley streams in Antarctica: Ecosystems waiting for water. – BioScience, 49: 985-995. PICKETT-HEAPS, J. D., A.-M.M. SCHMID and L. EDGAR 1990. The cell biology of diatom valve formation. in: F.E. Round and D.J. Chapman, editors. Progress in Phycological Research 7: 1-168. Biopress Ltd., Bristol. ROSHCHIN, A.M. and V.A. CHEPURNOV 1999. Dioecy and monoecy in the pennate diatoms (with reference to the centric taxa). in: S. Mayama, M. Idei and I. Koizumi, editors. Proceedings of the 14th International Diatom Symposium: 241-261. Koeltz Scientific Books, Koenigstein. ROUND, F.E., R.M. CRAWFORD and D.G. MANN 1990. The Diatoms. Biology and Morphology of the Genera. - Cambridge University Press, Cambridge. SCHMID, A.-M.M. 1979. Influence of environmental factors on the development of the valve in diatoms. – Protoplasma, 99: 99-115. SONINKHISHIG, N. 2003. Diatoms of lake bottom sediments of Telmen and Bayan Nuur (Mongolia). - Ph.D. dissertation, Biological Sciences, National University of Mongolia, Ulaanbaatar. SPAULDING, S.A. and E.F. STOERMER 1997. Taxonomy and distribution of the genus Muelleria Frenguelli. - Diatom Research, 12: 95-115. SPAULDING, S.A, J.P. KOCIOLEK and D. WONG 1999. A taxonomic and systematic revision of the genus Muelleria (Bacillariophyta). – Phycologia, 38: 314-341.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 227-238) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Effect of abscisic acid on host susceptibility during different ontogenetic phases of the host alga in the pathosystem Scenedesmus acutus – Phlyctidium scenenedesmi Irina D. Pouneva and Christo Christov Institute of Plant Physiology, Bulgarian Academy of Sciences, Georgi Bonchev Str., Block 21 Sofia 1113, Bulgaria. E-mail: [email protected] ABSTRACT The effect of abscisic acid (ABA) on the infection process in the pathosystem green microalga Scenedesmus acutus and unicellular fungal parasite Phlyctidium scenedesmi was investigated. The influence of the endogenous ABA content on the pathogenesis in different ontogenetic phases of the host as well as the resistance induction after treatment of synchronous algal culture with ABA were studied. The higher levels of endogenous ABA during the algal autospore formation as well as exogenous ABA supply of (10-5 M) inhibited the infection process. The treatment with fluridone (10-7 M) an inhibitor of ABA biosynthesis increased the host susceptibility during all ontogenetic phases under study. Cytochemical investigation of a-esterase, glutamate dehydrogenase and alcohol dehydrogenase showed that the treatment with ABA of uninfected and infected Scenedesmus cultures inhibited enzyme activities in both algal and parasite cells. Inhibition was stronger expressed in the parasite cysts. Our investigation demonstrated that ABA is involved in defense response of Scenedesmus during pathogenic attack increasing host resistance. The susceptibility of S. acutus to the chytridial infection depended on the endogenous ABA level during different ontogenetic stage of alga. Key words: abscisic acid, fluridone, Scenedesmus acutus, Phlyctidium scenedesmi, host-parasite relationship

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INTRODUCTION Parasite infections are of great importance during laboratory and industrial microalgal cultivation as especially in the open air the parasitic contamination is a common phenomenon. Our previous study showed that about 98% of Scenedesmus production was abolished in semi-industrial ponds for microalgae cultivation in the open air as a result of infection with the hytridial parasite Phlyctidium scenedesmi Fott. This fact requires a detailed investigation of the complicated host-parasite relationship in infected algal cultures. Many evidences about regulatory role of the hormone ABA in plant development and stress responses have been presented in the literature (Hirsch et al. 1989, Murata et al. 2001) Moreover, it is known that the pathogen invasion of higher plants enhances synthesis of growth regulators in both parasite and host. Changes in hormone levels induce changes in disease susceptibility or resistance reactions (Singh et al. 1997). ABA is a hormone related with plant responses to pathogen invasion and takes part in plant-pathogen relationship (Fraser 1993, Ryerson et al. 1993, Audenaert et al. 2002). Data about the role of ABA molecule in expression of compatibility or incompatibility in different pathosystems are contradictory. McDonald and Cahill (1999) established that loss of ABA induces incompatibility and exogenously supplied ABA can increase the susceptibility to different parasites. Their results strongly contrast with these of Dunn et al. (1990) who showed that increased ABA concentrations in host tissues correlated with appearance of resistance. As the information concerning ABA significance for the pathogenesis in lower plants is rather meager, the aim of present study is to investigate the influence of ABA during the infection process in the pathosystem microalga-unicellular fungal parasite in different ontogenetic stages of the host alga. We used fluridone, a proven inhibitor of ABA biosynthesis (Popova and Riddle 1996, Yoshioka et al. 1998) to elucidate the role of ABA as a potential signal molecule in the host response. To understand the influence of endogenous ABA levels on the infection process the kinetics of ABA during different ontogenetic phases of Scenedesmus was investigated. As plant responses depend on the metabolism and developmental stages of the host (Genoud et al. 2001) the effect of exogenous ABA during different ontogenetic stages of synchronized Scenedesmus cultures was studied also. Cytochemical observation of a-esterase (a-E), glutamate dehydrogenase (GDH) and alcohol dehydrogenase (ADH) was made which give an information about general metabolism and respiratory processes in both host and parasite. The process of infection and defense reactions of higher plants in the beginning of the pathogenesis is usually related to separate cells of different tissues. For this reason very often in experimental studies, at present, the plant is reduced to cell suspension cultures (Low and Heinstein 1986, Apostol et al. 1989, Kauss et al. 1994). In this aspect, the pathosystem green microalga – unicellular fungal parasite used in the present study is especially convenient.

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MATERIAL AND METHODS The experiments were conducted using synchronous culture of green microalga Scenedesmus acutus Meyen strain Tomaselli 8 (Chlorophyta) kindly supplied by the Center for investigation of autotrophic organism, Florence, Italy. Besides the synchronous culture, unsynchronous algal cultures were inoculated with unicellular fungal parasite Phlyctidium scenedesni Fott strain Ilkov, P-2 (Chytridiomycota) isolated from infected semiindustrialy cultivated algal cultures in Roupite, Bulgaria was used. Conditions for synchronization of Scenedesmus acutus culture Synchronization of algae was carried out by alteration of light (8 hours) and dark (6 hours) periods. Synchronous population of S. acutus was cultivated in mineral nutrient medium in hemostat at 30o C during the light period and at 18o C during the dark one. The light intensity was 520 mEm-2 s-1. The algal suspension was aerated with 100 l/h air, enriched with 2% CO2. After synchronization, during the course of cultivation, the Scenedesmus cells were divided into age groups. The age groups were: at the beginning of the light period – 0 h - cells (they corresponding to autospores), 4 h - growing cells, 8 h - mature cells (belonging to in the end of the light period) and 12 h - mature cells starting to release autospore at the beginning of the dark phases. Cultivation conditions of the system Scenedesmus – Phlyctidium The pathosystem Scenedesmus - Phlyctidium was cultivated on the nutrient medium optimal for Phlyctidium, continuously illuminated with light (1130 520 mE m-2 s-1) at temperature 320C as previously described (Benderliev et al. 1993). Determination of ABA content in synchronous culture of Scenedesmus Samples for analysis were taken every two hours of the cell cycle. Microalgae were harvested by centrifugation, fixed with liquid nitrogen, disintegrated and extracted with chilled 80% ethanol containing 0.1 g/l-1 of the anti-oxidant 2,6-di-tert-butyl-4-methylphenol. Ethanol was removed by vacuum evaporation and the aqueous fraction was frozen, slowly thawed out and centrifuged. The supernatant was alkalized [pH 8,5] extracted with petroleum ether then acidified [pH 2,5] extracted with diethyl ether, re-extracted with 1% NaHCO3, acidified and again extracted with diethyl ether. The acid diethyl ether phase was dried and subsequently purified by column chromatography with Sep-Pak C18 cartridge and by thin layer chromatography. The methanol fraction was methylated with diazomethane. Quantitative determination of the methylated ABA, dissolved in methanol, was performed 229

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by gas chromatography on glass column packed with 2WHP 3% OV - 225. Pye Unicam gas chromatograph equipped with a 63Ni electron capture detector was used. The conditions were: column temperature 230oC, detector temperature 320oC, injector temperature 250oC, nitrogen flow rate 50 ml min-1. Treatment Synchronous culture of S. acutus was treated with ABA 10-5 M at the beginning of the light period (0 h.). To block the biosynthesis of endogenous ABA the algal cultures at the same phases of development were treated with fluridone (Flu) (1-methyl-3-phenyl-5-[3-trifluoromethyl-(phenyl)]-4-(1H)-pyridinone) 10-7 M. After 24 h incubation (a period which provides successive effect of all ontogenetic phases of the host development), ABA and Flu were removed trough washing. Afterwards, the algal cultures were infected with P. scenedesmi after re-suspending in the optimal for the parasite development medium. Infected unsynchronous cultures S. acutus cultures were treated with ABA or Flu simultaneously with the initial inoculation with P. scenedesmi. The infection degree was calculated by Burcker,s counting chamber. Counts were taken 48 h after maximal infection about 90% was obtained. Treated synchronous and unsynchronous cultures of S. acutus with ABA were investigated cytochemicaly for determination of a-E, GDH and ADH activities by the method of simultaneous azocopulation (Lojda at al. 1979). Cytochemical study is the only suitable approach for examination of enzyme activities of the host and parasite in the pathosystem because of the high obligation of Phlyctidium and impossibility to be isolated from the host alga in monoculture for biochemical assay. That is why the same enzymes were determined also in unsynchronous algal culture 48 h after simultaneous infection and treatment with ABA 10-5M or Flu 10-7M. The present data are the means of at last three independent experiments. The data were analyzed statistically according to Student. RESULTS The results revealed that considerable quantitative changes in the level of endogenous ABA occurred during S. acutus ontogenesis. Maximum ABA content was established in autospore. The level of ABA dropped in the process of maturation of algal cells. Mature cells at the end of the light period (8-th hour) showed minimum ABA value. Intensive biosynthesis of ABA was established during the dark autospore formation period (Fig. 1). A well-expressed dependence between host susceptibility and ontogenetic age of host alga was observed. The autospores (0 h) and young cells (4-th hour) were the most resistant. Maturation of algal cultures during the light period was associated with an increase in susceptibility to infection and the mature cells (8 hour) were the most susceptible.

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After entering the dark phase (cells of 12-th hour) resistance towards P. scenedesmi increased again. This trend was observed up to the 48th hour of the infection process, whereas the control reached maximum infected cells (2). All age groups of algae acquired resistance after exogenous treatment with ABA and inhibition of infection was significant. The induced incompatibility after ABA treatment was again clearly expressed in young cells during the interval from autospore to 4 h aged cells. The percentage of invaded host cells increased in the stage of mature cells from the end of the light period (8-th hour). The treatment with Flu enhanced susceptibility to infection in all ontogenetic phases investigated, and the percentage of infected cells exceeded that of untreated control where endogenous ABA is non inhibited (Fig. 2). Cytochemical examination after treatment with ABA showed a general tendency of decreased number of cells with positive cytochemical reaction for a-E, GDH and ADH in almost all age groups of uninfected algal cultures. As expected an increased number of cells with positive GDH reaction was observed in 12 h age cells. In the same time a-E, GDH and ADH activities in mature cells from the 8-th hour of the light period declined considerably. In growing algal cells (4-th hour) and mature cells from the beginning of the dark period starting to release autospores (12-th hour) the enzyme inhibition was weak or lacking. Flu slightly increased the percentage of cells with positive reaction for the three enzymes under study during all ontogenetic phases (Fig. 3). It was established that treatment with ABA of unsynchronous infected algal culture reduced the percentage of both infected host cells and parasite cysts with positive cytochemical reaction for a-E, GDH and ADH. The effect was stronger in the parasite cysts. On the contrary, Flu application in the infected cultures positively modulated the percentage of cells with active enzymes and it exceeded the percentage of stained cells in untreated controls or approached their values (Fig. 4).

Fig. 1. Kinetics of endogenous ABA content during different ontogenetic phases of S. acutus development. Bars present means and standard error.

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Fig. 2. Effect of ABA and fluridone treatments on the percentage of P. scenedesmi infected S. acutus cells during different ontogenetic phases of the host development

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Fig. 3. Effect of ABA and Flu treatments on a-E, GDH and ADH activities during different ontogenetic phases of S. acutus development expressed as percentage of cells with positive reaction

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Fig. 4. Influence of ABA and Flu treatments on the activities of a-E, GDH and ADH in unsynchronous culture of S. acutus infected with P. scenedesmi expressed as percentage of cells with positive reaction.

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DISCUSSION According to Genoud et al. (2001) plants have developed complex signal apparata that provide optimal response depending on the nature of the invading organism and allow them to avert most infection. The results of the present study indicated that defence responses of S. acutus after pathogenic attack depended on the level of endogenous ABA during different stages of algal development. We established that simultaneously with decreased concentration of endogenous ABA, during the light period, the susceptibility of S. acutus to infection increased. The most invaded were mature cells with lowest content of endogenous ABA. Whereas, during the dark period, simultaneously with the increased ABA content the resistance of algal cells towards P. scenedesmi rose significantly. The most resistant were the autospores with noticeable maximum of endogenous ABA. Moreover, our observations showed that the amount of endogenous ABA in the host cells influenced the result of exogenously applied ABA and the additive effect on the infection process exhibited the same trend. The strongest inhibition of infection was established in young cells (0 h - 4-th hour) where endogenous ABA level was high. In the mature algal cells with low ABA content exogenously supplied ABA had weaker influence on host resistance. This regularity was preserved during the dark period of the synchronous cycle of S. acutus when increased ABA level (12-th hour) and exogenous ABA treatment led to well expressed resistance. Data about strong reduction of infected algal cells after exogenous ABA application as well as dramatic enhancement of the infection after inhibition of ABA by Flu confirmed the role of this growth regulator in the host – parasite relationship. This study demonstrated that in the pathosystem unicellular green alga and unicellular fungal pathogen the increased ABA concentrations induced resistance in the host cells. The results of the present investigation are supported by the data of Jiang and Zhang (2001). They established that ABA treatment of maize seedlings considerably increased the levels of superoxide radicals and hydrogen peroxide followed by increased activities of antioxidant enzymes such as superoxid dismutase, ascorbat peroxidase and catalase. Algal cells responses like production of reactive oxygen species (ROS) has been found to be stimulated by various environmental stresses (Mallick and Mohn 2000). In addition, it has recently been shown that the generation of ROS and the enhanced activities of these enzymes in host after pathogenic invasion are connected with resistance responses of plants (Bolwell et al. 2002, McDonald et al. 2002, Shinogi et al. 2003). ROS exerted direct antimicrobial effect because they take part in different defence responses including lipid peroxidation and phytoalexins formation (Baker and Orlandi 1995). Our previous investigation showed that Phlyctidium is a highly specialized obligatory parasite and some of its metabolite pathways are directed by the host metabolism (Pouneva 1985). This fact can explain the suppression of a-E, GDH and ADH activities by ABA in both the infected host cells and the fungal cysts. In the most sensitive to infection mature cells from the end of light period (8-th hour) ABA induced the strongest inhibition of the there enzymes studied. Considering that a-E participate in general cell metabolism, that GDH is a key enzyme which associated protein and carbohydrate metabolism and that 235

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ADH is involved in the anaerobic degradation of carbohydrates, we suppose that their inhibition is connected with reduced resistance of mature algal cells. The observed stronger inhibition of these enzymes in the parasite cysts compared with invaded algal cells could explain the suppression of infection after ABA treatment. This fact concerns especially the esterase as it is well known that esterase activity in extracellular matrix of parasite hyphe is of great importance for the infection of the host plant (Jansson and Akesson 2003). The established decrease of a-E, GDH and ADH activities after ABA treatment is similar to observed inhibition of growth of higher plants (Angelova et al. 2002) and of some pathogens (Singh et al. 1997) by ABA. The experiments of Singh et al. (1997) proved that in Nevossisia indica ABA evoked in vitro not only effective decrease of mycelium growth and sporidium production but inhibited emergence of their teliospores. This is probably associated with established ABA inhibition of proteases (Angelova et al. 2002) and polyamine metabolism (Singh et al. 1997). Our results about the role of ABA in host-parasite relationship in the pathosystem microalga - unicellular fungal parasite are similar to that reported for some pathosystems in higher plants. Dunn et al. (1990) established that ABA treatment of Phaseolus vulgaris hipocotils induce resistance to a compatible race of Colleotrichium lindeminthianum invasion. Moreover, series of investigations showed that in higher plants pathogenic invasion is associated with increase of endogenous levels of ABA as a defence response of host (Steadman and Sequeira 1970, Whenham et al. 1986, Kettner and Dorffling 1995). The results obtained in this study of the pathosystem Scenedesmus - Phlyctidium are similar to findings in higher plants. ABA, as growth regulator, plays an important role in host-parasite relationship. The association of this hormone with resistance during the dispute about the role of ABA in the infection process was confirmed. We support the idea that the defense strategy of the plants and their responses to pathogenic attack depend on the nature of the pathogen and the ontogenetic stage of the host. A different susceptibility of S. acutus to the chytridial infection during the different ontogenetic stages of the host is probably associated with the different levels of the endogenous ABA. Our conclusions emphasizes the particular significance of ABA in the defense response of Scenedesmus acutus against Phlyctidium scenedesmi infection for the surviving of this alga population after parasite invasion in nature. REFERENCES ANGELOVA, Y.M., S.G. PETKOVA, N.I. POPOVA and L.K ILIEV 2002. Influence of ABA and 4PU-30 on the growth, proteolytic activities and protein composition of maize seedlings. - Biol. Plant., 45: 33-37. APOSTOL, I., P.F. HEINSTEIN and P.S. LOW 1989. Rapid stimulation of an oxidative burst during elicitation of cultured plant cells. Role in defense and signal transduction. Plant Physiol., 90: 109-116. AUDENAERT, K., G.B.DE MEYER and M.M. HOFTE 2002. Abscisic acid determines basal susceptibility of tomato to Botrytis cinerea and suppresses salicylic acid-dependent signaling mechanisms. - Plant Physiol., 128: 491-501. 236

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BAKER, C.J. and E.W. ORLANDI 1995. Active oxygen in plant pathogenesis. - Ann. Rev. Phytopathol., 33: 299-321. BENDERLIEV, K.M., I.D. POUNEVA and N.I. IVANOVA 1993. Fungicide effect of triton-N on Phlyctidium. - Biotechnol. Techniques, 7: 335-338. BOLWELL, G.P., L.V. BINDSCHEDLER, K.A. BLEE, V.S. BUTT, D.R. DAVIES, S.L. GARDNER, C. GERRISH and F. MINIBAYEVA 2002. The apoplastic oxidative burst in response to biotic stress in plants: a three-component system. - J. Exp. Bot,. 53: 1367-1376. DUNN, R.M., P. HEDDEN and J.A. BAILEY 1990. A physiologically-induced resistance of Phaseolus vulgaris to a compatible race of Colletotrichum lindemuthianum is associated with increases in ABA content. - Physiol. Mol. Plant Pathol., 36: 339-349. FRASER, R.S.S. 1993. ABA and plant responses to pathogens. in: Jones H.J. and W.J. Davies, editors. ABA: Physioloigy and Biochemistry. pp. 189-199. Oxford: Bios Scientific Publishers, UK. GENOUD, T., M.B.T. SANTA CRUZ and J.-P. METRAUX 2001. Numeric simulation of plant signaling networks. - Plant Physiol., 126: 1430-1437. HIRSCH, R., W. HARTUNG and H. GIMMLER 1989. Abscisic acid content of algae under stress. - Bot. Acta, 41: 21-53. JANSSON, H.-B. and H. AKESSON 2003. Extracellular matrix, esterase and phytotoxin prehelminthosporol in infection of barley leaves by Bipolaris sorokiniana. - Eur. J. Plant Pathol., 109: 599-605. JIANG, M. and J. ZHANG 2001. Effect of abscisic acid on active oxygen species, antioxidative defense system and oxidative damage in leaves of maize seedlings. Plant and Cell Physiol., 42: 1265-1273. KAUSS, H., W. JEBLICK, J. ZIEGLER and W. KRABLER 1994. Pretreatment of parsley (Petroselinum crispum L.) suspension cultures with methyl jasmonate enhances elicitation of activated oxygen species. - Plant Physiol., 105: 89-94. KETTNER, J. and K. DORFFLING 1995. Biosynthesis and metabolism of abscisic acid in tomato leaves infected with Botrytis cinerea.- Planta, 196: 627-634. LOJDA, Z., R. GOSSRAU and T.H. SCHIEBLER 1979. Enzyme Histochemistry. - Springer verlag, Berlin-Hheidelberg- New York. LOW, P.S. and P.F. HEINSTEIN 1986. Elicitor stimulation of the defense response in cultured plant cells monitored by fluorescent dyes. - Arch. Biochem. Biophys., 249: 472- 479. MALLICK, N. and F.H. MOHN 2000. Reactive oxygen species: responses of algal cells. - J. Plant Physiol., 157: 183-193. MCDONALD, K.L. and D.M. CAHILL 1999. Influence of abscisic acid and the abscisic acid biosynthesis inhibitor, norflurason, on interaction between Phytophthora sojae and soybean (Glycine max). - Eur. J. Plant Pathol., 105: 651-658. MCDONALD, K.L., M.W. SUTHERLAND and D.I. GUEST 2002. Temporary hypoxia suppresses the oxidative burst and subsequent hypersensitive cell death in cells of tobacco and soybean challenged with zoospores of incompatible isolates of Phytophthora species. Physiol. and Mol. Plant Pathol., 61: 133-140.

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MURATA, Y., Z.-M.PEI, I.C. MORI and J. SCHRODER 2001. Abscisic acid activation of plasma membrane Ca2+ channels in guard cells requires cytosolic NAD(P)H and is differentially disrupted upstream and downstream of reactive oxygen species production in abl1-1 and abl2-1 protein phosphatase 2C mutants. – The Plant Cell., 13: 2513-2523. POPOVA, L.P. and K.A. RIDDLE 1996. Development and accumulation of ABA in fluridone-treated and drought stressed Vicia faba plants under different light conditions. - Physiol. Plantarum., 98: 791-797. POUNEVA, I.D. 1985. Investigation of host-parasite relationship in the system ScenedesmusPhlyctidium. – Ph.D. Thesis, 167 pp (in Bulgarian). RYERSON, E., A. LI., J.P. YOUNG and M.C. HEATH 1993. Changes in abscisic acid levels during the initial stages of host and non-host reactions to the rust fungus. - Physiol. Mol. Plant Pathol., 43: 265-273. SHINOGI, T., T. SUZUKI, S. KURIHARA, T.Y. NARUSAKA and P. PARK 2003. Microscopic detection of reactive oxygen species generation in the compatible and incompatible interaction of Alternaria alternata Japanese pear pathotype and host plants. – J. Gen. Plant Pathol., 69: 7-16. SINGH, P.P., A.S. BASRA and P.P.S. PANNU 1997. Abscisic acid is a potential inhibitor on growth and sporidial formation in Nevossisia indica cultures: Dual mode of action via loss of polyamines and cellular turgidity. – Phytoparasitica, 25: 111-116. STEADMAN, J.R. and L. SEQUEIRA 1970. Abscisic acid in tobacco plants: tentative identification and its relation to stunting induced by Pseudomonas solanacearum. – Plant Physiol., 45: 691-697. WHENHAM, R.J., R.S.S. FRASER, L.P. BROWN and J.A. PAYNE 1986. Tobacco mosaic virusinduced increase in abscisic acid concentration in tobacco leaves: intracellular location in light and darkgreen areas, and relationship to symptom development. – Planta, 168: 592-598. YOSHIOKA, T., T. ENDO and S. SATOH 1998. Restoration of seed germination at supraoptimal temperatures by fluridone, an inhibitor of abscisic acid biosynthesis. – Plant Cell Physiol., 39: 307-312.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 239-250) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Diatom succession in the Ferdynandovian Interglacial lacustrine deposits of Poland Barbara Marciniak Institute of Geological Sciences, Polish Academy of Sciences, ul. Twarda 51/55, PL-00-818 Warszawa, Poland; e-mail: [email protected] ABSTRACT The characteristics of diatoms from four sites of the Ferdynandovian (Cromerian II and III) Interglacial lake deposits (Falęcice, Wola Grzymalina, Ławki, Popioły) are presented. In Poland the deposits of this interglacial are younger than the Sanian 1 (Elsterian 1) Glaciation and older than the Sanian 2 (Elsterian 2) Glaciation in the lower part of the Middle Pleistocene. At Falęcice diatoms have been observed in the middle part of the profile, mainly in clays with a shaly structure. These deposits yield a qualitatively poor, however, quantitatively diverse diatoms. Initially, during the development of leafy forests (at the turn of the 3 and 4 pollen phases in period III) the genus Aulacoseira dominated, followed (in period IV) by species of Cymbella and Fragilaria s.l. during the development of coniferous forests. At Wola Grzymalina and Ławki, deposits described as diatomites and lacustrine chalks yield numerous planktonic diatoms (mainly Cyclotella spp., Stephanodiscus spp., Synedra spp., Fragilaria crotonensis Kitt., Asterionella formosa Hassal, Aulacoseira spp.). Lake deposits at Popioły yield a diatom taxa composition close to that distinguished in type profiles of the Ferdynandovian Interglacial (Ferdynandów). Based on the observed diatom succession, five local diatom assemblage zones were distinguished at Popioły (PD-1 Periphyton-Fragilaria spp.; PD-2 Stephanodiscus-Cyclotella; PD-3 Periphyton-Stephanodiscus ; PD-4 Stephanodiscus-Aulacoseira; PD-5 Fragilaria-PeriphytonStephanodiscus-Aulacoseira). Synchronism of the analysed sediments is testified by numerous occurrences of extinct diatom taxa in the investigated sites. Key words: diatoms, paleolakes, Ferdynandovian Interglacial, Middle Pleistocene, Poland INTRODUCTION Characteristics are presented of the diatoms from four sites of lacustrine sediments of the Ferdynandovian Interglacial (Falęcice, Wola Grzymalina, Ławki, Popioły) and compared with 239

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the pollen analysis of those sites as well as the other sites - Ferdynandów (Janczyk- Kopikowa et al. 1981) and Podlodów (Fig.1). According to Lindner (1988, 1992) the Ferdynandovian Interglacial was a warming period during early part of the Middle Pleistocene which separated the Sanian Glaciation from the Sanian 2 one. It is correlated with 13-15 Oxygen Isotope Stages dated as 592-472 years BP. Rzechowski (1996) is of analogous opinion in this respect. According to Zagwijn (1996) the lower optimum of the Ferdynandovian Interglacial corresponds to the Cromerian II (Westerhoven = 15th Isotope Stage) whereas the upper optimum of this interglacial – to the Cromerian III (Rosmalen =13th Isotope Stage) of the Dutch profiles. Preliminary diatom studies of the Ferdynandovian Interglacial sediments have been undertaken first of all at Ferdynandów site (Khursevich et al. 1990, Przybyłowska-Lange 1991). Further the following sites: Falęcice (Lindner et al. 1991), Wola Grzymalina and Ławki (Marciniak 1991a), Podlodów (Marciniak 1991b) and Popioły (Marciniak 2000, Marciniak and Lindner 2003) were studied. MATERIALS AND METHODS The sediments samples were cleaned using hydrochloric acid and hydrogen peroxide and washed several times with distilled water. Light microscopic peparations were mounted in Naphrax (high resolution medium) and analyzed by Olympus BX51 microscope under 100xoil immersion objective. SEM observations were made using a JEOL JSM-840 A. Diatom identification were based on the following literature sources: Zabielina et al. (1951), Siemińska (1964), Round (1981), Theriot et al. (1988), Khursevich (1989), Krammer and Lange-Bertalot

Fig. 1. Location sketch-map of investigated sites. 1 – Extent of the Sanian 1 Glaciation; 2 - localities of the Ferdynandovian Interglacial; 3 – extent of the Sanian 2 Glaciation (after Lindner 1992).

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(1991). Taxa that could not be differentiated in LM, or with high numbers of broken valves, were grouped together. In the profile at Popioły the results of diatom analysis, after counting about 400 specimens of diatoms per sample, are presented in graphic form (see Fig. 2).

Falęcice

DESCRIPTION OF THE SITES

The lacustrine sediments of the Ferdynandovian Interglacial are represented there by silts, peats, and bituminous shales. They rest on till of the Sanian I Glaciation and are covered by till of the Sanian 2 Glaciation. Higher up there are sandy-gravelous sediments classified to the Mazovian Interglacial and till of the Odranian Glaciation and higher up – sands and gravels of the Lubavian Interglacial as well as the till and sands of the Wartanian Glaciation (Lindner et al. 1991, Marciniak and Lindner 2003). Diatoms were found in clayey-sandy sediments of the Ferdynandovian Interglacial which represent early, postglacial and preoptimal pollen stages (I and II) as well as the older part of the III-rd period. Their presence was noted starting from the middle part of the profile mainly in clays of shaly texture. The forms found are poor qualitatively but diversified in their quantities. Six diatom horizons (A-F) were distinguished on the basis of composition and quantities of the most common taxa (Lindner et al. 1991, Marciniak and Lindner 2003).

Fig. 2. Percentage contribution of periphytic diatoms sensu lato, Fragilaria spp. and planktonic diatoms in the profile Popioły.

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Aulacoseira (Melosira s.l.) was the most common diatom genus in the A and B horizons. At first mainly destroyed, difficult to determine fragments of Aulacoseira sp. and A. ambigua (Grunow) Simonsen were found in horizon A. Aulacoseira granulata (Ehrenberg) Simonsen found in horizon B was better preserved. Those are fresh-water, cosmopolite diatoms with wide distribution in eutrophic reservoirs species (Zabielina et al. 1951, Siemińska 1964, Krammer and Lange Bertalot 1991). The above species composition shows, that it was a period optimal of the development of planktonic species i.e. the best period in the Falęcice lake development. It had taken place when deciduous trees forest was in full development with Abies, Taxus, and Picea beginning with decline of pollen zones 3 and 4 during pollen period III (Lindner et al. 1991). The C horizon is characterized by almost complete decline of planktonic diatoms and presence of small quantities of difficult to determine fragments of Cymbella spp. In horizon D there appear littoral, alkaliphilous species of Fragilaria and planktonic forms appear again in great numbers (Aulacoseira spp.). In horizon E Fragilaria species dominated and the amount of coastal lake zones diatoms increased, while planktonic species decreased. The above changes in diatom assemblages had taken place when rapid changes appeared in the forests at the decline of pollen periods III and IV and in the older part of period IV (pollen phase 5). It was a period of development of coniferous forests with domination of pine (Lindner et al. 1991). The last horizon (F) coincides with the younger part of period IV (pollen phase 6) in which only few very destroyed diatom valves of Cymbella were identified. The pollen spectrum of that time showed increase of birch trees as well as of herbaceous plants which infers climate deterioration, mostly cooling, which in turn led to shallower depth and vanishing of the lake at the decline of period IV (Lindner et al. 1991, Marciniak and Lindner 2003). Wola Grzymalina and Ławki The lacustrine sediments of the Ferdynandovian Interglacial are here represented by silts, sands, peats, diatomites and sandy silts (Krzyszkowski, 1991). They rest on glaci-lacustrine sediments and till of the Sanian 1 Glaciation adn are covered with sands, gravels and till of the Sanian 2 Glaciation or by boulder lag and younger sediments classified to the Mazovian Interglacial. Higher up there are fragments of Odranian boulder till and 1-2 tills of the Wartanian Glaciation (Marciniak and Lindner 2003). In the lowermost part of the Wola Grzymalina profile diatoms were found only in two samples from a middle bed of laminated diatomites 0.5 m thick (Marciniak 1991a). Genus Cyclotella dominated there with large share of Cyclotella cf. reczickiae Khursevich & Loginova, which was found for the first time in the lacustrine sediments of the Belovezhian Interglacial at Krasnaya Dubrova in Belarus (Makhnach et al. 1982, Khursevich and Loginova 1986). Prevalence of fresh-water, planktonic, oligohalobous species of Cyclotella is usually characteristic for early stages of oligotrophic Quaternary lakes associated with colder periods. Diatoms were not found in the lower and upper parts of the laminated diatomites (probably due to dissolution).

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It is the first phase (I) of plant development in pollen succession in which Betula and Pinus dominated. Herbaceous plants typical for open communities (forest-tundra) characteristic in subarctic climate show large share (Kuszell 1991). The next part of the Wola Grzymalina profile embracing a bed of silty-clayey sediments 80 cm thick (known as massive diatomite) is represented by two samples. Aside of large share of Cyclotella spp. also numerous forms of Stephanodiscus and Synedra were found there. Several types of valves of Stephanodiscus are difficult to determine using light microscope so they must be examined in electron microscope. The above part of the profile represents the second phase (II) and the beginning of the third one (III) of plant development as distinguished on the basis of pollen analysis. The role of pine-birch forests with admixture of oak, elm and alder largely increased at those times. The climate was cool at first then gradually warming (Kuszell 1991). In the upper bed of massive diatomite (220 cm thick) and in the brown lacustrine chalk (25 cm thick) aside of Cyclotella spp. and Stephanodiscus spp. there are abundant Asterionella formosa, Fragilaria crotonensis and the share of Aulacoseira ambigua and A. granulata gradually increased. The diatom spectrum shows great diversity of abundant fresh-water, planktonic diatoms which are very common in pure, alkaline waters of meso- and eutrophic lakes. Diatom species composition inferred that those optimal light, thermal and edaphic conditions existed during the middle part of the Ferdynandovian Interglacial for planktonic diatom (phytoplankton) development. Pollen spectra of that part of the profile show large share of oak, elm and hazel which suggests that it was the warmest time (phase III), a climatic optimum of the Ferdynandovian Interglacial (Kuszell 1991). In the neighboring profile at Ławki in the six initially studied samples from its lower part the specific dominant diatom spectrum seemed similar to the described above from the upper bed at Wola Grzymalina. The diatom analysis confirmed that the sediments of this part of the Ławki profile may also represent optimal phase in the lake development (Marciniak 1991a). The pollen analysis of sediments from the lower part of the Ławki profile has revealed prevalence of pollen of deciduous trees over the coniferous ones with oak, elm as dominants and with large share of hazel and alder which is characteristic in the third plant succession phase of the Ferdynandovian Interglacial (Kuszell 1991). In the higher sediments of white lacustrine chalk planktonic diatoms are initially numerous. These are mainly Cyclotella and Aulacoseira then only Aulacoseira ambigua and A. granulata were found. Potentially some diatoms were dissolved during diagenesis of sediments containing large content of calcium carbonate (40-80 %). There were considerable trophic changes (lake eutrophication) as well as hydrologic alterations (probably lake shallowing) that might have played a role in the diatom destruction at the end of that phase. Results of pollen analysis of this part of the Ławki profile have shown that they correspond to the fourth phase (IV) of the plant succession according to the subdivision established in the Ferdynandów profile (Janczyk-Kopikowa 1975). High share of fir may suggest higher humidity of climate which was probably as warm as that during the preceding phase (Kuszell 1991). In the highest mineral-organic, highly weathered sediments neither diatoms nor pollen were found.

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Popioły At Popioły the oldest Pleistocene sediments are sands that infill a depression formed within the Tertiary rocks due to erosion. These sands represent most probably final part of the Sanian 2 Glaciation or initial phase of the Ferdynandovian Interglacial. They are covered by organogenic sediments some dozen meters thick which in the light of pollen analysis document a plant succession characteristic for the Ferdynandovian Interglacial (Winter 1992). These sediments in turn, are covered by sands of the youngest part of this interglacial. Higher up there are fluvial sands and gravels of the Eemian Interglacial. They infill a valley cut into tills of the Odranian and Wartanian glaciations. Higher up there are valley deposits of the Vistulian Glaciation that infill a depression cut into the tills of this glaciation (Marciniak and Lindner 2003). At Popioły the organogenic sediments of the Ferdynandovian Interglacial are represented by laminated silts, clayey silts, gyttjas and clayey gyttjas occurring at depth 47.50 –61.00m. In result of palynological studies of 31 samples (depth 50.0 – 57.8 m) from the Popioły profile Winter (1992) has distinguished five phases of plant development which represent a succession typical for the Ferdynandovian Interglacial. Qualitative and quantitative diatom analysis from the Popioły profile has been done using 33 samples of sediments from depth 50.50 –56.50m (Marciniak and Lindner 2003). A diagram (Fig.2) illustrates the share of the main planktonic diatom genera as well as the groups of periphytic forms. Five local diatom zones have been established in the Popioły profile (Local Diatom Assemblages Zones: PD-1 up to PD-5) which correlate fairly well with the palynological subdivision of the profile (Winter 1992). The initial development phase of the Popioły paleolake (diatom zone PD-1 PeriphytonFragilaria spp.) is represented by only one sample (depth 56.50- 56.60m) in which a small group of periphytic (sensu lato) diatoms was stated. The following forms dominate there: Cocconeis disculus (Schumann) Cleve, Fragilaria leptostauron (Ehrenberg) Hustedt, Diploneis domblittensis (Grunow) Cleve, Martyana martyi (=Opephora martyi Héribaud), Mastogloia elliptica (Agardh) Cleve, Gyrosigma attenuatum (Kűtzing) Rabenhorst, Navicula jentzschii Grunow, Fragilaria pinnata Ehrenberg, Epithemia spp. and Amphora spp. Occurrence of fresh-water, alkaliphilous species that are recently common in littoral or bottom lake zones particularly so in standing waters as well as low share of planktonic forms may suggest low lake level or low water temperature. That was a period of pine forests with admixture of spruce and larch. The climate was characterized by rather warm summers and cold winters (Winter 1992). Zone PD-2 Stephanodiscus-Cyclotella was characterized by very distinct enrichment in planktonic forms both in their number and specific composition with prevalence of Stephanodiscus taxa such as two morphotypes (S. rotula (Kűtzing) Hendey and S. niagarae var. insuetus Khursevich & Loginova) known also from the profile of Ferdynandovian Interglacial deposits at Podlodów (Marciniak 1991b, Figs 3-5). In this zone is noted presence of Cyclotella spp. (mainly Cyclotella reczickiae Khursevich & Loginova) and decrease of periphytic diatoms (Fig.2). Such changes may have been associated with considerable water level rise and better thermal and edaphic conditions in the paleolake. In the pollen profile it is the phase 2 with prevalence of deciduous trees over the coniferous ones. Trees like oak, elm and hazel with 244

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high share of alder attain maximal values here. This is the first, older part of the climatic optimum of the Ferdynandovian Interglacial (Winter 1992). The PD-3 zone Periphyton-Stephanodiscus has been distinguished on the basis of increased share of periphytic (sensu lato) diatoms (Cocconeis disculus, Diploneis domblittensis, Fragilaria leptostauron, Mastogloia spp., Martyana martyi, Epithemia spp.) increase of quantities of Aulacoseira spp. and

1

2

3

4

Fig. 3. Microscopic (SEM) photos of diatoms from the buried lake sediments at Podlodów. The valves types of Stephanodiscus rotula/niagarae complex” 1-4 Stephanodiscus sp. morphotype 1 (S. rotula (Kűtzing) Hendey) after Khursevich (1989); 1,2 scale = 10 µm; 3, 4 scale = 1µm.

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decrease of Cyclotella spp. in the final part of this zone. Changes of specific composition of planktonic diatoms and decrease of their quantities may result from periodical water level oscillations and trophy increase in the lake which had taken place at the decline of PD-3 zone. To the PD-3 zone corresponds the third phase of plant development in which the structure of deciduous trees forests has changed. This was a period of development of

5

6

7

8

Fig. 4. Microscopic (SEM) photos of diatoms from the buried lake sediments at Podlodów. The valves types of Stephanodiscus rotula/niagarae complex” 5-8- Stephanodiscus sp. morphotype 2 (S. rotula (Kűtzing) Hendey after Round (1981) or S. niagarae var. insuetus Khursevich & Loginova after Khursevich (1989); scale = 10 µm.

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deciduous forests with fir, yew and alder as dominant. This period represents the second, younger part of broadly termed lower optimum of the Ferdynandovian Interglacial during which the climate was moderately warm with oceanic influence (Winter 1992). The PD-4 zone Stephanodiscus-Aulacoseira is characterized by maximal share of Stephanodiscus. Few initially determined taxa (under the light microscope) were found there

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Fig. 5. Microscopic (SEM) photos of diatoms from the buried lake sediments at Podlodów. Two valves types of “Stephanodiscus rotula/niagarae complex” 9, 11 Stephanodiscus sp. morphotype 1 (S. rotula (Kűtzing)Hendey) after Khursevich (1989); 10, 12 Stephanodiscus sp. morphotype 2, (S. rotula (Kűtzing) Hendey after Round (1981) or S. niagarae var. insuetus Khursevich & Loginova after Khursevich (1989); 9, 10 scale = 10 µm , 11, 12 central part of valves; scale = 1 µm.

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(Stephanodiscus cf. peculiaris Khursevich, S. cf. determinatus Khursevich, S. styliferum Khursevich and S. cf. raripunctatus Khursevich & Loginova). They have been noted in fossil state for the first time at Krasnaya Dubrova. They are regarded to be typical for the Belovezhian Interglacial (Khursevich and Loginova 1986, Khursevich 1989, Khursevich et al. 1990). Further statistical studies (principal component analysis) are needed particularly so of Stephanodiscus sp. morphotypes 1 (S. rotula (Kűtzing) Hendey) and Stephanodiscus sp. morphotype 2 (S. niagarae var. insuetus Khursevich & Loginova) abundant in this zone (see also Figs 3-5). These figures illustrate two morhotypes or two species of Stephanodiscus from Ferdynandovian Interglacial lake sediments at Podlodüw while the description of diatom succession at Podlodów studied earlier by Marciniak (1991b). The morphotypes shown tentatively, informally as “S. rotula (Kützing) Hendey/S. niagarae var. insuetus Khursevich & Loginova complex” may be difficult to characterise in the light microscope. Theriot with co-authors (1988) wrote about similar group of fossil Stephanodiscus taxa from northeastern China informally designated as the “niagarae complex” which requires further studies. Aside of large share and rich species composition of planktonic diatoms from the genus Stephanodiscus there are distinct oscillations of numbers of Aulacoseira spp. and periphytic forms. This zone corresponds to the fourth phase of plant succession during which pine-birch forests developed (with admixture of spruce and larch) thus proving boreal climate (Winter 1992). In the last zone (PD-5 Fragilaria-Periphyton-Stephanodiscus-Aulacoseira) fresh-water diatoms dominated that are broadly distributed in waters of all types (mainly Fragilaria spp. and Martyana), which are typical in littoral lake zones. As compared to the preceding zone the share of planktonic forms diminishes. These changes may have been associated with lake shallowing or with considerable water level oscillations as well as seasonal water temperature changes that hampered planktonic diatoms development. This zone corresponds to the last 5-th phase of plant succession of the Ferdynandovian Interglacial in which forests of taiga type prevailed with patches of forest meadows. The climate must have been cool with warm summers and cold winters (Winter1992). FINAL REMARKS The most univocal geological situation of the Ferdynandovian Interglacial sediments is that one found in the lower Pilica river basin at Falęcice where they are covered with three glacigenic series associated with the Sanian 2, Odranian and Wartanian glaciations. They rest there on the till of the Sanian 1 Glaciation and at Podgórze on tills of the Nidanian and Narevian glaciations as well. At Wola Grzymalina and Ławki the sediments of that interglacial rest on tills of the Sanian 1 and Nidanian glaciations but higher up there is only a till of the Odranian (and possibly also of Wartanian) Glaciation (Marciniak and Lindner 2003). At Popioły the sediments of the Ferdynandovian Interglacial are best represented. Numerous diatoms occur there throughout almost the entire profile but there are no glacigenic series above and below. Diatomological investigations of the lacustrine sediments at Popioły have shown considerable affinity of species composition of the diatom flora in five local diatom zones 248

Diatom succession in the Ferdynandovian Interglacial lacustrine deposits of Poland

(Local Diatom Assemblage Zones LDAZ PD-1 up to PD-5) to the corresponding five development diatom stages during the Ferdynandovian Interglacial at Ferdynandów (Khursevich et al. 1990). Similar dominant assemblage (Stephanodiscus, Cyclotella) has been reported at Wola Grzymalina and Ławki near Bełchatów and at Podlodów (Marciniak 1991a,b, 2000). A very similar diatom succession has been described from the lower part of lacustrine sediments in the stratotype profile at Krasnaya Dubrova (southeastern Belarus) in three stages of the lake development during the Belovezhian Interglacial (Makhnach et al. 1982, Khursevich and Loginova 1986). The observed synchronicity of the analyzed micro flora is supported by the occurrence of some presumably extinct diatom taxa such as Cyclotella reczickiae, Stephanodiscus styliferum, S. peculiaris, S. cf. determinatus, S. cf. raripunctatus and “Stephanodiscus rotula/S. niagarae var. insuetus complex”. These taxa can be used now not only as biochronologic indicators for the Belovezhian Interglacial in Belarus but also for the Ferdynandovian Interglacial in Poland and for biostratigraphic correlations of Middle Pleistocene lacustrine sediments. REFERENCES JANCZYK-KOPIKOWA, Z. 1975. Flora of the Mazovian Interglacial at Ferdynandów. (In Polish, English summary) - Biuletyn Instytutu Geologicznego, 290: 5-86. JANCZYK-KOPIKOWA, Z., E. MOJSKI and J. RZECHOWSKI 1981. Position of the Ferdynandów Interglacial, Middle Poland, in the Quaternary Stratigraphy of the European Plain. Biuletyn Instytutu Geologicznego, 335: 65-79. KHURSEVICH, G. K. 1989. Atlas vidov Stephanodiscus i Cyclostephanos (Bacillariophyta) iz verkhne-kainozoiskikh otlozheniv SSSR. (Atlas of species from the Upper Cenosoic deposits of USSR) in: F. Yu. Velichkievich, editor. 86 pp. (In Russian): Nauka i Tekhnika, Minsk KHURSEVICH, G. K. and L. P. LOGINOVA 1986. Vozrast i palegeographicheskiye uslovya Phormirowaniya drevneozernykh otlozheniy Rechitskogo Pridneprovya. in: R. A. Zinova, editor. Pleistotsen Rechitskogo Pridneprovya Byelorussii: 76-142. Nauka i Tekhnika, Minsk. (in Russian) KHURSEVICH, G. K., W. PRZYBYłOWSKA-LANGE and L. P. LOGINOVA 1990. Floristic resemblance between Pleistocene diatom profiles of Krasnaya Dubrova (BSR) and Ferdynandów (Poland). (In Russian) - Doklady Akad. Nauk BSSR, 34: 179-183. KRZYSZKOWSKI, D. 1991. The Middle Pleistocene polyinterglacial Czyżów Formation in the Kleszczów Graben (Central Poland). - Folia Quaternaria, 61/62: 5-58. KRAMMER, K. and H. LANGE-BERTALOT 1991. Bacillariophyceae 3, Centrales, Fragilariaceae, Eunotiaceae. in: H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Süsswasserflora von Mitteleuropa 2, Fischer, Stuttgart.Teil 3: 1-576. Kuszell, T. 1991. The Ferdynandovian Interglacial in the Bełchatów outcrop, Central Poland. - Folia Quaternaria, 61/62: 76-83. Lindner, L. 1988. Stratigraphy and the extents of Pleistocene continental glaciations in Europe.- Acta Geologica Polonica, 38: 63-83. 249

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LINDNER, L. 1992. Stratygrafia (klimatostratygrafia) czwartorzędu. in: L. Lindner, editor. Czwartorzęd: osady, metody badań, stratygrafia: 441-633. PAE, Warszawa. LINDNER, L., B. MARCINIAK and M. ZIEMBIŃSKA-TWORZYDłO 1991. Interglacial sediments at Falęcice and their significance for stratigraphy of the Pleistocene in the Lower Pilica Drainage Basin (Central Poland). (In Polish, English summary). - Rocznik Polskiego Towarzystwa Geologicznego, 61: 231-256. MAKHNACH, N. A., G.K. KHURSEVICH and L. N. BOGOMOLOVA 1982. Novyye paleobotanicheskiye issledovaniya drevneozernykh otlozheniy razreza Krasnaya Dubrova. in: L. F. Azhgirevich, F. Yu. Velichkievich and R. A. Zinova, editors. Neogenovyye otlozheniya Byelorussii. 37-53. Nauka i Tekhnika. Minsk. MARCINIAK, B. 1991a. Diatoms of the Ferdynandovian Interglacial in the Bełchatów region, Central Poland (preliminary report). - Folia Quaternaria, 61/62: 85-92. MARCINIAK, B. 1991b. Diatoms in organic deposits of the Ferdynandów Interglacial at Podlodów, Central Poland. (In Polish, English summary). - Przegląd Geolologiczny, 5-6 (457-458): 280-284. MARCINIAK, B. 2000. Diatomées dans les sédiments lacustres du Pléistocène moyen en Pologne. - Cryptogamie Algologie, 21 (3): 217-218. MARCINIAK, B. and L. LINDNER 2003. Diatoms and geology of the Ferdynandovian Interglacial lake sediments in Poland. (In Polish, English summary). - Botanical Guidebooks, 26: 199-215. RZECHOWSKI, J. 1996. The Ferdynandovian Interglacial in the stratotype profile at Ferdynandów (southeastern Mazowsze). (In Polish, English summary). - Biuletyn Instytutu Geologicznego, 373: 161-171. PRZYBYłOWSKA-LANGE, W. 1991. The ultrastructure and morphological variability of fossil Cyclotella (Bacillariophyceae) from Ferdynandów Interglacial. in: L. Burchardt, editor. IXth Symp. Phycol. Section Pol. Botan. Assoc. Inter. Symp. “Evolution of freshwater lakes”. Poznań 16-22 May 1990. Cz. II. Uniw. A. Mickiewicza w Poznaniu, Ser. Biol. 46: 84-87. ROUND, F. E. 1981. The diatom genus Stephanodiscus: an electron-microscope view of the classical species. - Arch. Protistenk., 124: 455-470. SIEMIŃSKA, J. 1964. Bacillariophyceae - Okrzemki. in: Flora słodkowodna Polski 6, PWN, Warszawa, 1-610. THERIOT, E., Y. QI, J. YANG, and L. LING 1988 - Taxonomy of the diatom Stephanodiscus niagarae from fossil deposit in Jingyu County, Jilin Province, China.- Diatom Research, 3 (1): 159-167. WINTER, H. 1992. The Ferdynandów pollen succession in the profile of Popioły – Toruń Valley (in Polish, English summary). - Kwartalnik Geologiczny, 36 (3): 387-392. ZABIELINA, M. M., I.A. KISELEV, A.I. PROSHKINA-LAVRENKO and V. S. SHESHUKOVA 1951. Diatomovye vodorosli. Opredelitel presnovodnykh vodorosley SSSR. Gosud. Izd. “Sovyetskaya Nauka”. Moskva 4: 1-619. ZAGWIJN, W. H. 1996. The Cromerian Complex Stage of the Netherlands and correlation with other areas in Europe. in: W. Turner Ch., editor. The Early Middle Pleistocene in Europe: 145-172, A. A. Balkema, Rotterdam. 250

Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 251-265) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Environment variation in the Black sea region during the Late Quaternary based on fossil diatoms A. P. Olshtynskaya Institute of Geological Sciences, National Academy of Sciences, Ukraine 01054 Oles Gonchar str., 55-b Kiev, Ukraine ABSTRACT In this study the Late Pleistocene and Holocene diatoms of a shelf, continental slope and à deep-water part of the Black Sea were investigated. Species composition within the diatom communities was dependent on the environmental conditions in various sections of the basin. Comparison of diatom communities of the Late Neoeuxinian epoch from the Black Sea aquatory and coastal lagoons showed remarkable synchrony in age. Key words: diatoms, Late Pleistocene, Holocene, the Black Sea. INTRODUCTION The first records of diatoms and the distribution of diatom oozes intercalations in the Upper Quaternary sediments of the western region of the Black Sea were recorded by Arkhangelsky and Strakhov (1938). Diatom flora in the Holocene sediments of a shelf and continental slope of the north-western region of the Black Sea were examined by Mukhina (Shimkus et al. 1973), Zabelina (1974, 1975) and Shcherbakov et al. (1979). The presence of marine diatom associations has been established in the Jemetin, Kalamit, Bugaz-Vityaz sediments according to the stratigraphic scheme of the Black Sea and nonmarine associations in ooze of the upper part of the Neoeuxinian horizon (Fig. 1). The nonmarine association was dated by the end of the Late Pleistocene, the boundary between Pleistocene and Holocene is drawn by the top of this layer. In the thickness of the Pleistocene bottom sediments of the Black Sea the diatoms were mainly known from the deep-sea drilling materials collected by the expedition “Glomar Challenger” in 1978. Their distribution along the whole basin was not traced. In deep sea 251

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Fig. 1. The Stratigraphic scheme of the Holocene and late-middle Pleistocene (sensu Shcherbakov 1983, 1995)

Holes 379À and 380, Jouse and Mukhina (1978, 1980) have distinguished two diatom assemblages in sediments of the Late Pleistocene. The first assemblage, apparently of the Karangat age, has been established in the lower part of unit 3 of Holes 379À and 380. The time of its formation corresponds to the Eemian (the Mikulino) of the interglacial epoch, when Mediterranean waters were delivered to the Black Sea trough. The marine warm-water planktonic species predominate in the assemblage, among them there were: Cyclotella caspia, numerous Thalassiosira oestrupii, T. baltica, Coscinodiscus janischii, C. perforatus, Thalassionema nitzschiodes, and spores of the genus Chaetoceros. The diatoms composition in this period greatly resembled the diatom flora of the present-day Black Sea (Jouse and Mukhina 1980). The age of the second assemblage selected from unit 2 of Holes 379À and 380 corresponds to the Neoeuxinian, last glacial epoch (Würm, Valdaj), its composition differed essentially from Karangat (Jouse and Mukhina 1980). The dominants of the diatom assemblage were brackish and cosmopolite, moderately cold-water species such as Stephanodiscus rotula, S. hantzschii and Cyclotella kutzingiana atypical to the oligotrophic water bodies. This diatom composition indicates that at the beginning of the Neoeuxinian the salinity and the temperature of surface waters greatly decreased. The frustules of diatoms were numerous only in the lower part of layer, their abundance decreases in the upper part. The diatoms productivity decreased during the Neoeuxinian and was associated with deep regression of the Black Sea, with level and waters salinity falling and its conversion into a freshwater basin (Jouse and Mukhina 1980). 252

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The diatoms from the Neoeuxinian top sediments and the overlying Holocene sediments were known in the various sections of the shelf, continental slope, deep sea trough of the Black Sea and its north-western littoral (Shimkus et al. 1973, Zabelina 1974, Zabelina and Shcherbakov 1975, Melnik et al. 1990, Melnik and Olshtynskaya 1984, Olshtynskaya 1987, 1996). I studied variations in the diatom species composition and their ecological peculiarities both in the vertical and areal distributions. The paper generalizes the results of investigations on the dependence of the taxonomic composition and paleoecological characteristics of the Late Quaternary diatoms on the geological and paleogeographical events in the Black Sea region. MATERIAL AND METHODS Specimens of diatom-bearing bottom sediments were sampled from 40 cores of length from 1.5 to 5-6 m by materials of numerous research vessel cruises (Fig. 2). The studied sites were located in different sections of the Black Sea aquatory – the shelf, continental slope, deep sea trough. Diatoms from cores of several holes on the shelf of the Bulgarian section and in the north-western part of the Black Sea were also studied. The specimens were sampled at different steps: from 5 to 50 cm. Also an available literature data were analyzed.

Fig. 2. Locations of studied sections containing diatoms.

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The diatom specimens were prepared by the standard methods of Gleser et al. (1974). The specimens were examined under a LM and some under a SEM Jeol-35. The used terminology in the paper is principally that of Gleser et al. (1988) and Round et al. (1990) with a few additions from recent taxonomic changes. The quantity of the diatom taxa was determined by the relative scale as: (A) – abundant when 20 valves were present in one horisontal traverse at x 500, (C) – common when 3-19 valves were present at each horisontal traverse, (F) – few – 1-2 valves in each traverse, (R) – rare - less than one speciment in each traverse. For Hole 316 abundance was given percent value in total frustulae number. RESULTS AND DISCUSSION During the Pleistocene and the Holocene the glacioeustatic transgressions and changes in the brackish regime in the Black Sea basin caused repeated variations in the taxonomic composition of diatom assemblages. The latter was expressed in alternation of marine, brackish and freshwater communities in section of bottom sediments. Diatoms of each stratigraphic interval were distinguished by special characters. In various sections of the basin diatom associations of the same age also differed in species diversity. Top of the Neoeuxinian sediments were widely distributed in the Black Sea basin. They were represented by ooze, often marked by the interlayer of hydrotroilite of the black color (Shcherbakov et al. 1978, Shcherbakov 1983). The Late Neoeuxinian diatoms on the continental slope and the central deep-water part of the Black Sea were studied in the core sections. Bedding depths there varied from 200 cm near the Bosphorus to 240-590 cm near the Danube delta and to 250-590 cm in the central deep-water part of the sea (Olshtynskaya 1987, 1996). In certain sections of the continental slope and the central deep-water part of the Black Sea the top sediments of the Neoeuxinian emerged on the bottom surface and were not overlapped by younger sediments. The radiocarbon age of the top of the Neoeuxinian deposits was established by different data within the range of 7200-7600 (Ryan et al. 1997, Dimitrov et al. 2005), 7800-8500 (Shcherbakov 1983, 1995) or 9800-10200 years (Semenenko and Kovalyukh 1973, Semenenko et al. 1973). In these sediments there was peculiar moderate-cold-water, freshwater-brackish water diatom assemblage in which the plankton dominates and the benthos is poor. The frustule concentration in sediments was usually low. The investigated diatom flora is represented by more than 60 species belonging to 30 genera (Table 1). The most common species were from the genera Stephanodiscus, Diploneis, Aulacoseira and Cyclotella. The Neoeuxinian diatoms of the Black Sea were characterized by the very poor taxonomic diversity. The assemblage is often of monodominant character ànd these three species of the genus Stephanodiscus (S. robustus, S. rotula and S. hantzschii) made from 50 to 85% of the species composition. Aulacoseira granulata, Cyclotella kutzingiana were subdominants, Ellerbeckia arenaria, Diploneis domblittensis, Cymatopleura solea and Cocconeis disculus were present constantly. 254

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Table 1. Characteristic diatom taxa of the Late Neoeuxinian of the Black Sea shelf, continental slope and the deep-water part, with their relative abundance Taxon

Western shelf

South-western section

Central deepwater part

R R R R R R C R F R R R F F F F C F R R R R R C C R R R R F F

R C R R R F C F R R F R R R R R R F A R R R R R R C C R F F F R R

R F C R C R R R C R R R R R R R A A R R R R R R

Actinocyclus octonarius Ehr. Aulacoseira granulata (Ehr.) P. Sims Cocconeis scutellum Ehr. C. placentula Ehr. C. disculus (Schum.) Cl. Coscinodiscus radiatus Ehr. Cyclotella caspia Grun. C. kutzingiana Thw. C. ocellata Pant. Cymatopleura solea (Breb.) W. Sm. C. elliptica (Breb.) W. Sm. Cymbella cistula (Hemp.) Kirch. Diploneis domblittensis (Grun.) Cl. D. smithii (Breb.) Cl. D. subcincta (A.S.) Cl. Ellerbeckia arenaria (Moore) Craw. Epithemia turgida (Ehr.) Kutz. Gomphonema acuminatum Ehr. Grammatophora marina (Lyngb.) Kutz. Martyiana martyi (Herib.) Round Nitzschia granulata Grun. Paralia sulcata (Ehr.) Cl. Pinnularia major Kutz. Rabenh. Placoneis gastrum (Ehr.) Mer. Pseudosolenia calcar-avis (Schultz) Sundstr Rhopalodia gibba (Her.) O.Mull. Staurosria construens Ehr. Stephanodiscus binderanus (Kutz.) Kreig. S. hantzschii Grun S. robustus var. robustus Pr.–Lavr. S. rotula (Kutz.) Hust. Surirella fastuosa Ehr. Thalassiosira baltica (Grun.) Ostf. T. oestrupii (Ostf.) Pr.-Lavr. T. eccentrica (Ehr.) Cl. Toxarium undulatum Bail. Ulnaria ulna (Ehr.) Compere

Abundance : A – abundant, C – common, F – few, R – rare, - not noted.

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Different sections of the basin were characterized by variations in the diatom composition. The assemblages were distinguished by their plankton/benthic ratio being different relatively to the water salinity and temperature. This is associated with the influence of limiting hydrological, facial and climatic factors on the formation of the diatom assambleges. In the south-western section of the Black Sea and in the central deepwater part the top sediments of the Neoeuxinian were the most abundant with diatom frustules; on the western and eastern shelf their concentration is lower. Diatoms of the Black Sea western shelf were characterized by their relatively great taxonomic diversity, by the presence of littoral Paralia sulcata and the absence of benthic Cymatopleura solea typical for other aquatories. Here, mainly benthic genera Nitzschia, Ulnaria, Pinnularia, Cymbella, Gomphonema, Martyana were abundant. This diatom association is formed under the influence of multiple environmental factors, among them high rates of terrigenous material supply and the freshwater effect of the river flow. In the Bosphorus region the proximity of the Mediterranean Sea influenced diatom composition. The freshwater Stephanodiscus robustus, Aulacoseira granulata, brackishwater Cyclotella kutzingiana and euryhaline marine Thalassiosira oestrupii, T. eccentrica, Coscinodiscus radiatus were abundant in the plankton. There is an assumption that towards the end of the Neoeuxinian the inflow of sea water from the Sea of Marmara to the Black Sea due to the uplift of the ocean level has already begun (Shcherbakov 1983). The brackish Diploneis domblittensis was constantly present in the benthic composition. The appearance of freshwater Aulacoseira granulata indicates the inflow of river waters into this section. On the western continental slope of the Black Sea the diatom composition is more monotonous, here Stephanodiscus robustus, S. rotula, Cyclotella kutzingiana and Cymatopleura solea were the most abundant species. The influence of river waters on the shelf was smaller; the role of benthos was insignificant. In certain sections there is a rather monotonous planktonic diatoms association in which two taxa Stephanodiscus robustus and S. rotula made up about 90% of all frustules. This assemblage forms in sediments the biostratigraphic marker “ Stephanodiscus horizon”. The Late Neoeuxinian diatoms assemblage of the southern part of the basin (near the Anatolian coastal area differs from the other regions by a lower quantity of the dominating genus Stephanodiscus. Here Paralia sulcata was a subdominant diatom, there were also Cyclotella caspia, Thalasiosira baltica, T. oestrupii, Grammatophora marina, Coscinodiscus radiatus, Actinocyclus octonarius, Ellerbeckia arenaria and species from the genus Diploneis. The central deep-water part of the sea is characterized by diatoms species monotony, abundant development of the species Stephanodiscus robustus, S. rotula, C. kutzingiana and small quantity of benthos. For the interval higher of 2.5 m. in sediments cores a considerable quantity of the benthic diatoms were observed. The end of the Neoeuxinian is connected in time with degradation of the Würm glacier and the last desalting of the Black Sea. In this period the sea level, salinity and the water temperature were lower than those the present, the water exchange with the Mediterranean Sea was interrupted. The Upper Neoeuxinian sediments of the Black Sea were characterized by the monodominant composition of different groups of organisms composing them. Dreissena 256

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rostriformis Andrus dominates among mollusks from the Bulgarian shelf to the Sea of Azov (Nåvåsskaja et al. 1984). The monotonous assemblage of diatoms with Stephanodiscus robustus and S. rotula was observed for the whole area of these sediments distribution. There was evidence for weak differentiation of the hydrological situation in the Neoeuxinian basin and its desalted character (11-13 %). It is considered that this was the brackish water reservoir rather than the freshwater one. In the end of the Neoeuxinian the shore line of the north-western region of the sea passed farther south of the contemporary one and a considerable part of the present shelf was represented by lacustrine-alluvial plane. The boundary of distribution of the marine Neoeuxinian sediments here is confined to the isobathic line of 30-32 m. Over this isobathic line the lagoon and liman sediments were of age analogues of the Neoeuxinian layers (Shcherbakov 1983). Recently we have obtained new data on the diatoms presence in the Upper Pleistocene lagoon sediments from the contemporary north-western shelf of the Black Sea. The coastal accumulative plane was here for the Neoeuxinian time and at present the sea depth is 31 m. In core 316 (Fig. 1) diatomaceous samples were taken at the depth of 9.2 – 5.0 m. The assemblage includes more than 80 of well preserved diatom taxa (Table 2), many large and thin-walled frustules among them that indicate the favorable conditions of their living and burial. This assemblage has substantial difference in species composition and taxonomic diversity from diatoms of “Stephanodiscus horizon”. There are Aulacoseira granulata with varieties and Cymatopleura solea in the mass. Most species-rich genera were Navicula, Caloneis, Cocconeis, Pinnularia, Nitzschia, Ulnaria and Epithemia. In the lower part of diatom-bearing sediments Cyclotella distninguenda and species of the genus Gomphonema were very abundant. From bottom to top along the section in core 316 from 9.2 to 5.0 m both the diatom diversity and the quantity of frustules increase for species Cymatopleura solea, Cocconeis placentula, Cymbella cistula, Pinnularia viridis, ànd Aulacoseira granulata, A. granulata var. angustissima, and also for the genera Nitzschia, Ulnaria, Caloneis (Table 1). At the same time the quantity of frustules in Cyclotella distinguenda, Placoneis gastrum, Gomphonema acuminatum, Gomphonema olivacea decreases. The total quantity both of the planktonic Thalassiosira parva, Stephanodiscus sp., oligohalobous – indifferent Cymatopleura solea, Rhopalodia gibba and the brackish-water species Nitzschia sigma, Tabularia tabulata, Ulnaria capitata increases for the diatom assemblage within 6.7 to 6.2 m. At the same time the quantity of benthic and freshwater Pinnularia mictrostauron, P. viridis, Craticula cuspidata, species Ulnaria and Surirella decreases, that reflects a gradual depth and salinity increasing. The ecological spectrum of the diatom flora in core 316 from the depth of 9.2-5.0 m indicates its formation in a relatively shallow, desalinated or weakly brackish oligotrophic water body with clear water and calm conditions of sedimentation. Epiphytic and benthic taxa predominate quantitatively. The plankton is monotonous, but abundant. The diatom flora changes from bottom to top along the section confirm the evidence for fluctuation of its water level and salinity of the basin. The thickness of sediments with this diatom assemblage was formed in the coastal lagoon having no connections with the Black Sea in that period. Probably, water was delivered into the basin from the thawing glacier. The lagoon assemblage of the north-western shelf and the Late Neoeuxinian “Stephanodiscus horizon” of the Black Sea differ essentially in their species composition. 257

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Table 2. Diatom taxa in the Late Neoeuxinian assemblage of north-western shelf and their abundances ( %). Hole 316 Taxon

Interval, m 1,8- 2,0- 5,0- 5,6- 6,1- 6,4- 6,7- 8,8- 9,11,9 2,1 5,4 5,7 6,2 6,5 6,8 8,9 9,2

Achnanthes sp. Aneumastus tusculus (Ehr.) Mann et Stick. Anomoeoneis sphaerophora (Kutz.) Pfitz Aulacoseira distans (Ehr.) Simonsen A. granulata (Ehr.) Simonsen A. granulata (Ehr.) Simonsen var. angustissima (O.Mull.) Hust. A. italica (Ehr.) Simonsen. Caloneis amphisbaena (Bory) Cl. Caloneis sp. Campylodiscus sp. Cocconeis distans Ehr. C. pediculus Ehr. C. placentula Ehr. C. pseudomarginata Greg. C. vitrea Brun. Craticula cuspidata (Kütz.) Mann Cyclotella comta (Ehr.) Kütz. C. distinguenda Hust. C. iris Brun et Herib. Cyclotella sp. Cymatopleura elliptica (Breb. in Kütz.) W.Sm C. solea (Breb.) W.Sm Cymbella cistula (Ehr.) Kirchen C. ehrenbergi Kützing C. helvetica Kutz. Cymbella sp. Diatoma elongatum (Lingb.) Ag. D. vulgare Bory Diploneis smithii (Breb.) Cl. Diploneis sp. Epithemia turgida (Ehr.) Kütz. Epithemia sp. Gomphonema acuminatum Ehr. G. augur Ehr. G. constrictum Ehr. G. olivaceum (Horn.) Breb. Gomphonema sp. Gyrosigma acuminata (Kütz.) Rabenh. G. baicalensis Skv.

- 0.4 0.7 2,5 4,7 8,2 35,2 24,1 7,5 - 1.0 3.0 2.2 1.4

1,2 0,6 1,2 12,6 2.2

0,9 0,9 1,4 0,9 10,4 2,8 2.2 -

0,4 0,7 0,4 0,4 1,1 1,9 0,8 1,1 -

1,8 0,6 4,1 0,6 0,6 1,8 0,6 0,6 1,8 9,7 2,3 0,6 1,8 1,2 1,2 0,6 0,6 0,6 2,0 0,6

4,8 0.9 9,8 0,9 0,9 2,8 1,9 9,8 0,9 0,9 0,9 0,9 2,8 2,8 0,9 5,7 -

258

1,6 1,6 1,6 2,4 0,8 2,4 0,8 2,4 -

- 2,3 6,1 1,8 - 1,3 6,2 - 1,8 0,9 - 0,4 - 0,8 1,3 - 0,4 10,7 9,9 8,9 5,3 - 0,4 - 1,5 - 3,5 0,9 1,5 - 2,3 1,8 1,3 - 1,5 1,8 3,0 3,8 2,6 1,3 10,7 2,3 5,3 35,1 4,5 5,3 2,6 0,9 1,5 - 1,8 - 0.3 - 1,0 - 0,7 0,9 0,4 3,0 7,6 3,5 4,5 - 0,4 1,5 0,7 0,9 0,4 - 0,4 - 0,7 1,7 - 0,4 -

1,4 1,4 2,8 1,4 8,2 1,4 1,4 6,8 2,8 2,8 2,8 1,4 1,4 9,6 1,4 1,4

Environment variation in the Black sea region during the Late Quaternary based on fossil diatoms

Table 2. Continued. Taxon

Interval, m 1,8- 2,0- 5,0- 5,6- 6,1- 6,4- 6,7- 8,8- 9,11,9 2,1 5,4 5,7 6,2 6,5 6,8 8,9 9,2

Gyrosigma sp. Hantzschia sp. Martyana martyi (Herib.) Round Melosira moniliformis (O.Mull.) Navicula lanceolata (Ag.) Ehr. N. menisculus Schum. N. radiosa Kütz. N. reinhardtii (Grun.) Grun. N. unipunctata Skv. Navicula sp. Nitzschia obtusa W.Sm. N. sigma (Kütz.).W.Sm. Nitzschia sp. Paralia sulcata (Ehr.) Cl. Pinnularia borealis Ehr. P. lata (Breb.).W.Sm. P. microstauron (Ehr.) Cl. P. viridis (Nitzsch.) Ehr. Pinnularia sp. Placoneis gastrum (Ehr.) Mer. Rhoicosphenia curvata (Kutz.) Grun. Rhopalodia gibba (Ehr.) O.Muller R. gibberula (Ehr.) O.Muller Sceletonema sp. Sellaphora bacillum (Ehr.) Mann Stauroneis phoenicenteron Ehr. Staurosira construens (Ehr.} Staurosira sp. Stephanodiscus sp. Surirella fastuosa Ehr. S. linearis W.Sm. S. ovalis Breb. S. ovata Kutzing Tabularia tabulata (Ag.) Snoeijs Thalassiosira baltica (Grun.) Ostf. T. parva Pr.-Lavr. Thalassiosira sp. Trachineis aspera (Ehr.) Cl. Tryblionella gracilis W.Sm. Ulnaria capitata (Ehr.) Compere U. ulna (Ehr.) Compere

0,4 4,4 0,8 63,2 0,8 0,7 0,4 1,5

259

1,6 0,8 2,4 1,6 47,2 0,8 1,6 0,8

1,5 3,0 3,0 1,5 1,5 3,0 4,5 6,2 1,5 1.0 0.4 1,5 4,5 3,0

0,7 0,7 2,3 1,5 3,0 0,7 0.7 0,7 4,6 0,7 1,5 1,5 0,7 3,8

1,8 2,6 1,8 3,5 3,5 6,1 0.9 0,9 0,8 1,8 4,4 2,6

1,3 1,3 1,8 1,8 0,4 0,9 0,4 5,4 4,5 0,4 1,3 1,3 0,4 0,9 1,3 0,5 4,0 0,9 0,9 4,5

0,6 1,2 0,6 1,8 2,3 2,9 0,4 1,4 2,3 0,6 8,1 1,8 0,6 4,1 1,8 6,9 1,2 0,6 1,2 3,5

0,9 0,9 0,9 5,6 0,9 0,9 0,9 0,9 9,8 0,9 0,9 0,9 0,9 2,8 0,9 1,9 0,9 0,9

2,8 4,2 4,2 4,2 2,8 1,4 1,4 2,8 4,2 8,2 2,8 1,4 1,4 1,4 1,4

A. P. Olshtynskaya

Common species are predominantly brackish water and freshwater species of Diploneis smithii, Staurosira construens, Gomphonema acuminatum, Cocconeis placentula, Cymatopleura solea, Placoneis gastrum, Epithemia turgida, Martyana martyi, Rhopalodia gibba typical for the coastal regions of the Black Sea. Diatoms from core 316, the depth of 9.2-5.0 m, are considerably more freshwater than the “Stephanodiscus horizon”. However the lagoon assemblage contains several significant diatom species: Aulacoseira granulata var. angustissima, Thalassiosira parva, Cyclotella meneghiniana, C. distinguenda, Pinnularia viridis, Placoneis gastrum typical in the Upper Pleistocene for the north-east European part of Russia and in the Upper Pleistocene lacustrine sediments of the Eastern Europe middle belt (Khursevich 1976). The latter makes it possible to conclude that the diatoms from core 316 (the interval of 9.2-5.0) are of the Late Pleistocene age. Thus, there are reasons to assume in the Black Sea the lagoon assemblage of the northeastern shelf was similar to the “Stephanodiscus horizon” assemblage and corresponds to period of formation in the end of the Late Neoeuxinian. On the border of Neoeuxinian and the Bugaz-Vityaz time the hydrological regime of the Black Sea has changed. Penetration of the Mediterranean waters into the benthic layers of the Black Sea basin caused an increase of its salinity and changes in the entire biota composition including diatom flora. In the Atlantic time period, due to the uplift of the sea level, the littoral lagoons were submerged under the sea level. In the Subatlantic period approximately 3 thousand years ago, the level of the Black Sea and the shore line approached their present outline (Shcherbakov 1983). In core 316 within 5.0 to 2.1 m diatoms were absent and instead the low diversity assemblage of pollen peculiar of the Boreal period (the Early Holocene) is recorded. Abundant diatoms are present in the interval of 2.1-0.01 m, being of the same taxonomic composition with those in the Holocene sediments of the western and north-western shelf of the Black Sea. The connection with the Mediterranean Sea and biotopes diversity in the Black Sea promoted in the Holocene the formation of the diatoms associations with rich plankton, very diverse benthic and numerous epiphytic species (Table 3). The significant changes in diatom composition from the Bugaz-Vityaz period inferred rapid change in the environmental conditions. Diatoms in the Bugaz-Vityaz layers occurred in separate cores predominantly in the western and south-western part of the Black Sea (Melnik and Olshtynskaya 1984, Olshtynskaya 1987, 1996). The marine planktonic eurythermal and euryhaline species serve as a basis for this assemblage. There are dominants Thalassiosira oestrupii, T. eccentrica, subdominants Cyclotella caspia, Coscinodiscus radiatus and spores of the genus Chaetoceros. The Mediterranian and ocean species Rhizosolenia setigera, Bacteriastrum hyalinum, Coscinodiscus granii, and single Asteromphalus robustus were present here. The Late Neoeuxinian species Stephanodiscus robustus and S. rotula were observed in the lower part of the layer. On the western continental slope in the region of the Danube submarine canyon the brackish Late Neoeuxinian assemblage is rapidly changed by the marine Bugaz-Vityaz one and the transition beds with Stephanodiscus species are practically absent here. The marine diatoms are diverse, Rhizosolenia setigera, Proboscia alata and Thalassiosira oestrupii are dominants. 260

Environment variation in the Black sea region during the Late Quaternary based on fossil diatoms

Table 3. Characteristic Diatom taxa of the Holocene of the Black Sea, with their relative abundance Taxon

Jemetin

Kalamit

Bugaz-Vityaz

C A

C C C F R A C R F C R C C C C R R R F C C R R C R R F C F C R C C C C F C R

R F R R F R C R R F C C C R F F F F R C F F R R R R R C F A R F A F R R F R

Actinocyclus octonarius Ehr. Actinoptychus undulatus (Bail.) Ralfs Asteromphalus robustus Castr. Bacteriastrum hyalinum Lauder Campylodiscus fastuosus Ehr. Chaetoceros peruvianus Brightw. Chaetoceros sp. Cocconeis placentula Ehr. C. scutellum Ehr. Coscinodiscus granii Gough. C. janischii A.S. C. perforatus Ehr. C. radiatus Ehr. Cyclotella caspia Grun. C. kutzingiana Thw. C. ocellata Pant. Cymatopleura solea (Breb.) W.Sm. C. elliptica (Breb.) W.Sm. Cymbella ehrenbergii Kutz. Diploneis bombus Ehr. D. domblittensis (Grun.) Cl. D. smithii (Breb.) Cl.. D. subcincta (A.S.) Cl. Ellerbeckia arenaria (Moore) Craw. Epithemia turgida (Ehr.) Kutz. Gomphonema acuminatum (Kutr.) Rabenh. Grammatophora oceanica (Ehr.) Grun. Gyrosigma spenceri (Quek.) Grif. Hemiaulus hauckii Grun. Hyalodiscus scoticus (Kutz.) Grun. Lyrella hennedyi (W.Sm. ) Gusl.& Kar. Nitzschia granulata Grun. Paralia sulcata (Ehr.) Cl. Placoneis gastrum (Ehr.) Mer. Proboscia alata (Brightw.) Sundstrom Pseudosolenia calcar-avis (Schultz) Sundstrom Rhabdonema adriatica Ktz. Rhizosolenia setigera Brightw. Rhopalodia gibba (Ehr.) O. Mull. R. gibberula (Ehr.) O. Muller Staurosira construens Ehr.

C C AR R F R C C A R R R R R F R R R C R 4 F F R C R A F F C F -

261

A. P. Olshtynskaya

Table 3. Continued. Taxon

Jemetin

Kalamit

Bugaz-Vityaz

F R R C A R R -

C F R C A R R R

R R F R R C C R F R

Stephanodiscus robustus Pr.-Lavr. S. rotula (Kutz.) Hust. Thalassionema nitzschioides Grun. Thalassiosira baltica (Grun.) Ostf. T. decipiens (Grun.) Jorg. T. eccentrica (Ehr.) Cl. T. oestrupii (Ostf.) Pr.-Lavr. Toxarium undulatum Bailei Tryiblionella punctata W.Sm. Ulnaria ulna (Ehr.) Compere

Abundance : A – abundant, C – common, F – few, R – rare, - not noted.

For the peribosphorus region in the Bugaz-Vityaz assemblage Paralia sulcata, species from the genera Diploneis, Lyrella and Cocconeis are abundant, the genera Rhizosolenia and Proboscia is met more rarely that indicates the more shallow conditions. Near the Anatolian Coast, littoral species Paralia sulcata, Grammatophora oceanica predominate, the planktonic species Cyclotella caspia, Thalassiosira oestrupii and single freshwater Aulacoseira granulata are met rarely. The southwestern region is characterized by the presence of dominants Thalassiosira oestrupii, Cyclotella caspia, Paralia sulcata, by the abundant species of the genus Coscinodiscus, Chaetoceros spores and also by the silicoflagellate genus Distephanus (Olshtynskaya 1996). The overlying Kalamit diatomaceous layers are distributed in different sections of the Black Sea. In the assemblage the species Thalassiosira oestrupii, Rhizosolenia setigera, spores of the genus Chaetoceros dominate, Cyclotella caspia, Thalassionema nitzschioides, Asteromphalus robustus, Coscinodoscus radiatus, C. perforatus are numerous. In the upper part of the Kalamit layers the abundance of R. setigera decreases and of more warm-water Pseudosolenia calcaravis, Bacteriastrum hyalinum and species of the genus Asteromphalus increases. Silicoflagellates commonly occurred together with the diatoms. This association evidences for a rise of the water temperature in the superficial layer and for the continuing delivery of sea waters. On the western continental slope in the Kalamit assemplage Rhizosolenia setigera, Thalassiosira oestrupii are dominants, T. eccentrica, Coscinodiscus radiatus, C. granii, Cyclotella caspia, C. ocellata, Bacteriastrum hyalinum and spores of the genus Chaetoceros are numerous. Near the Bosphorus, Paralia sulcata and Thalassiosira oestrupii were the dominant diatoms, Grammatophora oceanica, Coscinodiscus radiatus, Actinocyclus octonarius were numerous, Diploneis subcincta, D. smithii, Lyrella hennedyi, Cocconeis scutellum, Rhabdonema adriatica, Rhopalodia gibberula are abundant. The species of the genus Proboscia and Pseudosolenia were observed more rarely than in the western region (Olshtynskaya 1996). The taxonomic composition of the diatom assemblage from the Jemetin layers was similar to the present-day diatom flora of the Black Sea, at the same time the generic composition of the Ancient Black Sea assemblage has completely been preserved in it. 262

Environment variation in the Black sea region during the Late Quaternary based on fossil diatoms

The assemblage of siliceous microfossils of the Subatlantic time of the Black Sea was characterized by the abundant warm water Mediterranean diatoms species and silicoflagellates that indicates their continuing migration from the Mediterranean Sea. The assemblage is presented by 94 species and varieties referring to 40 genera and near by 100 diatoms species. Most species-rich genera were Thalassiosira, Coscinodiscus, Diploneis (by 4-5 taxa in each) and Lyrella. As compared to the Kalamit in the Jemetin diatom assemblage the abundance of Rhizosolenia setigera and Pseudosolenia calcar-avis reduces, but the abundance of Proboscia alata and Chaetoceros peruvianus increased, as a result the later become dominant. The marine planktonic species Hemiaulus hauckii, Cyclotella caspia, Thalassionema nitzschioides, Thalassiosira oestrupii, Paralia sulcata are included in this assemblage. In the Black Sea western region the Jemetin layers possess abundant diatoms with diverse taxonomic composition and also silicoflagellates and ebriidea. Chaetoceros peruvianus, Thalassiosira oestrupii, Cyclotella caspia, C. ocellata, Proboscia alata, Coscinodiscus radiatus and the Mediterranean species Hemiaulus hauckii were dominants and subdominants in them. The species Paralia sulcata, Cyclotella caspia, C. ocellata, Thalassiosira oestrupii, Thalassionema nitzschioides, Chaetoceros peruvianus are typical for the Peribosphorus region, Hemiaulus hauckii was observedmore rarely, silicoflagellates and ebriidea are numerous. Near the coast there are single Ulnaria ulna, Toxarium undulatum, Achnanthes groenlandica (Cl.) Grun., Rhopalodia gibberula and other diatoms of the present-day coastal aquatory of the Black Sea. In its southern part the planktonic species in the assemblage are low and the number of benthic and periphytic ones from the genera Diploneis, Cocconeis, Lyrella, Rhopalodia increases (Olshtynskaya 1996). In conclusion, during the Late Neoeuxinian in the Black Sea the endemic taxonomically monotonous diatom flora of two dominant species of the genus Stephanodiscus was developed. It had formed the biostratigraphic marker – “Stephanodiscus horizon”. In coastal northwest lagoons taxonomically diverse freshwater diatom flora has developed then. Its composition and ecological spectrum significantly differs from the “Stephanodiscus horizon” and has more in common with the Late Pleistocene and Early Holocene lacustrine diatoms of the East Europe middle belt. Renewal of connection with the Mediterranean in the beginning of Holocene had higher salinity and wide distribution of the diverse marine diatom flora in the Black Sea. Diatom composition as well as paleoenvironment changed quickly. Because of sea level increasing marine diatoms penetrated into Neweuxinian lagoons and generated the modern community there. REFERENCES ARKHANGELSKY, A.D. and N.M. STRAKHOV 1938. Geological structure and history of evelopment of the Black Sea: 226. Moscow. (in Russian) DIMITROV, P.S., D.P. DIMITROV, D.P. SOLAKOV and V.D. PEICHEV 2005. The newest geological history of the Black Sea and problem about deluse. in: Geology and Mineral Resources of the World Ocean:102-111. Kiev (in Russian).

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GLESER, Z.I., A.P. JOUSE, I.V. MAKAROVA, A.I. PROSHKINA-LAVRENKO and V.S. SHESHUKOVA-PORETZKAYA 1974. The Diatoms of the USSR. Fossil and recent. 1. Moscow. (in Russian). GLESER, Z.I., I.V. MAKAROVA, A.I. MOISEEVA, and V.A. NIKOLAEV 1988. The Diatoms of the USSR. Fossil and recent. 2. Moscow. (in Russian). JOUSE, A.P. and V.V. MUKHINA 1978. Diatom units and the paleogeography of the Black Sea in the Late Cenozoic. in: Initial Reports Deep Sea Drilling Project, XLII, 2: 903949. Washington. JOUSE, A.P. and V.V. MUKHINA 1980. The diatoms stratigraphy of Cenozoic deposits. in: Geologicheskaya istoriya Chernogo moryja po rezultatam glubokovodnogo bureniya: 52-65. Nauka, Moskow. (in Russian) KHURSEVICH, G.K. 1976. History of development of diatoms from lakes of the Naroch basin: - Nauka i tekhnika, Minsk. (in Russian) MELNIK, V.I., T.I. KRYSTEV, A.P. OLSHTYNSKAYA, E.A. GERASIMOVA and N.N. KOVALYUKH 1990. Stratigraphycal and Geokronologycal data of the Late Quarterly bottom deposits of a continental slope of western part of the Black sea. – Geologicheskaya evolutia zapadnoj chasti Chernomorskoy kotloviny v neogen-chetvertichnoe vremya: 513-537. Sofia. (in Russian) MELNIK, V.I. and A.P. OLSHTYNSKAYA 1984. Diatom stratigraphy of bottom sediments of the Black Sea. in: Izuchenie geologicheskoy istoryi i processov sovremennogo sedimentogeneza Chernogo i Baltijskogo morey, 2: 37-41. Naukova Dumka, Kiev (in Russian) NEVESSKAJA, L.A., A.A. VORONINA and I.A. GONCHAROVA 1984. History of the Paratethys. in: 27 mejdunarodnyj geologichesky kongress. Paleookeanologija. Doklady, 3: 91-101. Nauka, Moskow (in Russian) OLSHTYNSKAYA, A.P. 1987. Peculiarity of distribution of diatoms in Late Quarterly deposits of the Black Sea. in: Aktualnye problemy sovremennoj Algologii: 87-90. Naukova Dumka, Kiev (in Russian) OLSHTYNSKAYA, A.P. 1996. Diatom flora from the bottom deposits of the Black Sea. – Geol. Journ., 1-2: 193-198 (in Russian) RYAN, W.B.F., W.C. PITMAN, C.O. MAJOR, K.M. SHIMKUS, V. MASKALENKO, G.A. JONES, P. DIMITROV, N. GÕRÛR, M. SAKTN and H. YÛCE 1997. An abrupt drowning of the Black sea shelf. – Marine Geology, 138: 119-126. ROUND, F., R. CROWFORD and D. MANN 1990. The Diatoms. Biology & Morphology of Genera. Cambridge, Cambridge Univ. Press. SEMENENKO, V.N., E.I. KOJUMDGIEWA and N.N. KOVALYUKH 1973. Radiocarbon age and korelation of marine Late Pleistocene deposites of Ukraine and Bulgarien Republik. – Quaternary, 16: 97-102. (in Russian) SEMENENKO, V.N. and N.N. KOVALYUKH 1973. Radiocarbon age of Late Quarterly deposits of the Azov-Black sea basin. – Geol. Journ., 33 (6): 91-97. (in Russian) SHCHERBAKOV, F.A. 1983. The continental slope in the Late Pleistocene and Holocene. – Nauka, Moscow (in Russian)

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SHCHERBAKOV, F.A. 1995. The Black Sea during the past 125 000 years. in: Climate and environment changes of east Europe during Holocene and late-middle Pleistocene. Preprint of research materials for IGU conference “Global changes and geography”. Moskow, August 14-18: 93-98. SHCHERBAKOV, F.A., E.V. KORENEVA and E.K. ZABELINA 1979. Stratigraphy of the Quaternary deposites of the Black Sea. in: Pozdnechetwertichnaya istorija i sedimentogenez okrainnych i vnutrennich morey: 46-51. Nauka, Moscow. (in Russian) SHCHERBAKOV, F.A., P.N. KUPRIN and L.I. POTAPOVA 1978. Sediment accumulation on the continental margin of the Black Sea. Nauka, Moskow. (in Russian) SHIMKUS, Ê.M., V.V. MUKHINA AND E.S. TRIMONIS 1973. The role of diatoms in the late Quaternary sedimentation in the Black Sea. – Oceanologia, 11-12 (6): 1066-1071. (in Russian) ZABELINA, E.K. 1974. Distribution of diatoms in sediment cores from northwest part of the Black sea. in: Micropaleontologia okeanov i morey, Nauka, Moscow: 173-177. (in Russian) ZABELINA, E.K. and F.A. SHCHERBAKOV 1975. On stratigraphy of the Late Quaternary sediments of the Black Sea. - Doklady AN SSSR, ser.geology, 4: 909-912. (in Russian)

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 267-281) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf Mariana Filipova – Marinova Museum of Natural History, 41 Maria Louisa Blvd., 9000 Varna (Bulgaria), e-mail: [email protected] ABSTRACT Complex lithostratigraphic and biostratigraphic investigation of dinoflagellate cysts, molluscan fauna, and pollen content was performed on a sequence 430 cm deep from the peripheral zone of the southern Bulgarian Black Sea shelf. Radiocarbon dating indicated that the analyzed sediments had accumulated during the last 30000 years. The data were employed to reconstruct both the changes of marine and continental environments. Pleniglacial and Late Glacial sediments were deposited from 29100±690 BP to 11590±240 BP (13520 cal. BP). They contain low-diversity dinoflagellate cyst assemblage of Spiniferites cruciformis Wall and Dale and Pyxidinopsis psilata (Wall and Dale) Head and molluscan assemblage of Dreissena rostriformis distincta Andrus. and Dreissena polymorpha regularis Andrus. These assemblages are associated with fresh-water to brackish-water settings and surface water salinity of less than 7‰. Pollen assemblages were dominated by Artemisia and Chenopodiaceae and suggested cold and dry climate. The beginning of the overlying Holocene sediments is dated at 6880±240 BP (7650 cal. BP). They contain Lingulodinium machaerophorum (Cookson and Eisenack) Wall – Cymatiosphaera globulosa Takahashi – Spiniferites ramosus Wetzel dinoflagellate cyst assemblages and molluscan assemblages dominated by Mytilus galloprovincialis Lmk. and after 3780 BP by Modiolus phaseolinus Phil. These sediments show increase in marine and Mediterranean affinities and surface salinity of more than 14 to 18 ‰. The pollen spectra suggest optimal climatic conditions and domination of mixed oak forests along the coast. The unconformity of sediments and significant depositional hiatus at the Late Glacial/ Middle Holocene boundary due to the significant rise in sea level is observed. Key words: dinoflagellate cysts, pollen, palaeoenvironmental reconstructions, Black Sea, Bulgaria 267

Mariana Filipova – Marinova

INTRODUCTION Dinoflagellates are unicellular eukaryotic organisms. They represent an important component of marine phytoplankton especially for their primary productivity. Dinoflagellates are able to produce cysts characterized by specific morphology, structure, dimensions (generally from 10 to 60 µm) and ability to fossilize. Cyst becomes fossilized by impregnation of its wall with resistant substance of organic, calcareous, or rarely siliceous composition. Distribution of these fossilized cysts in marine sediments reflects a complexity of ecological factors and shows environmental and climatic trends (Dale 2004). This ecological information is increasingly used in palaeoclimatic research and helps to form the basis for using cysts as indicators in environmental studies and reconstructions. There have been few previous studies (Wall et al. 1973, Wall and Dale 1973, 1974, Ross and Degens 1974, Traverse 1988, Mudie et al. 2001, 2002, 2004). They revealed that Quaternary dinoflagellate cyst are the most suitable proxies for use in quantitative modeling of past changes especially in sea surface temperature and salinity of the Black Sea. Palaeontological studies of cysts concentrated also on stratigraphic distribution and included more palaeoecological considerations to meet challenges of sequence stratigraphy. Results of dinoflagellate cyst analysis of deep-water and shelf sediments of the western Black Sea area have been combined with data from lithological, palynological, and molluscan fauna analyses (Filipova – Marinova 1986, 2003, Atanassova and Bozilova 1992, Bozilova et al. 1992, Shopov et al. 1992, Atanassova 1995, Filipova-Marinova et al. 2004). Conclusions have been drawn that dinoflagellate cysts are well preserved not only in deepwater sediments, but in shelf sediments as well. They could be used for the reconstruction of hydrological changes. The purpose of this paper is to provide a detailed analysis of the dinoflagellate cyst assemblage distribution in peripheral shelf zone of the southwestern Black Sea to compare results with data of other biostratigraphic and lithostratigraphic analysis and to apply these new data to interpretation of major environmental and hydrological changes in the Black Sea area during the last 30 kyrs. THE STUDY AREA – GEOMORPHOLOGY OF THE BLACK SEA SHELF On the basis of the relief, shape, time of formation, and speed and character of sedimentological processes, three geomorphologic zones were outlined in the Western Black Sea Shelf: littoral (inner), central, and peripheral (outer)(Dimitrov 1979). The littoral (inner) zone is considered to be of Holocene age (Dimitrov 1979). It begins at the coast and continues to a depth of 50 m. Active wave impact, erosion, and accumulation are characteristic (Khrischev 1984). The littoral zone is separated from the central zone by a depression 17-20 m deep in the Northern Black Sea Shelf and 65-70 m deep in the Southern Bulgarian Black Sea Shelf. 268

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf

The central zone is situated at a depth of 50 m to 120 m. In this zone three sub zones run parallel to the coast: an inner depression, a depositional bar, and a depositional plain. The area is characterized by a high sedimentation rate (Khrischev 1984). The peripheral (outer) zone is subdivided into an outer depression and a barrier bar and is characterized by a low sedimentation rate due to high activity of bottom currents. MATERIALS AND METHODS The location of the core investigated C-2345 (42°24’02'’ N, 28°19’00'’ E) was taken from the peripheral shelf zone in the area of depositional bars at a depth of 122 m below sea level during the Bulgarian-Russian geological expeditions on Academician Orbeli scientific research vessel (Fig. 1). Sediments to a depth of 430 cm were collected with a piston corer with diameter of 67 mm. They were continuously sampled at every 10 cm or in some intervals (from 90 to 145 cm) at every 5 cm for dinoflagellate cysts, pollen, and molluscan faunal analyses. Lithology was described and the content of calcium carbonate and organic matter were determined (Fig. 2). The laboratory treatment was performed according to standard methods (Faegri and Iversen 1989) including removal of mineral components with sodium pyrophosphate and hydrofluoric acid (Birks and Birks 1980). The percentage dinoflagellate cyst-pollen diagram of selected taxa is based on the pollen sum (PS) of arboreal (AP) and non-arboreal (NAP) taxa (Fig. 3). Pollen of aquatics, and spores are excluded from the PS. The frequency of dinoflagellate cysts is presented in percentage on the base of the total PS. Dinoflagellate cysts nomenclature follows that used by Wall et al. (1973) and Eisenack and Kjellstrom (1975). Pollen taxa and dinoflagellate cysts with low values or values of low significance are not shown in the pollen diagram. Statistical data processing and their graphic presentation were made with TILIA and TILIA.GRAPH software programs (Grimm 1991). Dinoflagellate assemblage zonez (DAZ) and their subsequent correlation were based on important changes in the presence of the main taxa, and by the application of CONISS (Grimm 1987). Nine molluscan shell samples selected mainly at the boundaries of different lithological units were sent to the Laboratory for Physicogeological Properties at the Institute of Oceanology, Russian Academy of Sciences, and to the Institute of Oceanography-Woods Hall (USA) for 14Cdating. Radiocarbon dates have been calibrated according to Stuiver and Reimer (1993). RESULTS Radiocarbon dating The nine radiocarbon dates on mollusk shells are shown in Table 1. They were used to correlate the dinoflagellate cyst-pollen diagram and indicate the age of the sediments. The position of these dates in relation to the diagram helped assess their accuracy. The date of 29650 (at a depth of 225-240 cm = Lab № 790) was out of sequence and was not taken into consideration. 269

Mariana Filipova – Marinova

Fig. 1. Scheme of the location of the core C-2345 1. Coastal line 2. Boundary between the shelf and the continental slope. 3. 100m isobaths 4. Basic tectonic zones: I. Eastern Balkan Range; II. Bourgas Depression. 5. Basic fault zones reflected in the bottom relief: 1. Pre-Balkan fault; 2. Hind Balkan fault; 3. Sozopol fault; 4. Eastern Rezovo fault.

270

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf

Fig. 2. Lithology of the Core C-2345

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Table 1. Results of radiocarbon measurements from Core-2345 Depth (cm)

14

15-20 85-95 110-125 140-150 225-240 275-280 410-420 430-440 420-440

- (Woods Hall) 2.430 (Woods Hall) 791(IOAN) 161(IOAN) 790(IOAN) 162(IOAN) 164(IOAN) 165(IOAN) - (Woods Hall)

C Lab. No.

Age BP

Calibrated years BP

3780 6880±260 11590±240 11710±1100 29650 26950 27780 28100 29100±680

4097 (4118-4090) 7650 (8137-7229) 13520 (14125-13011) 13750 (16761-10800) n/a n/a n/a n/a n/a

Dinoflagelate cyst assemblage zones (DAZ) Three dinoflagellate cyst assemblage zones are recognized in the core based on the dinoflagellate cyst composition and abundance of dominant taxa. Dinoflagellate assemblage zones are compared with pollen assemblage zones and molluscan assemblages, and synchronized with the climatic subdivision of the Late Pleistocene and Holocene (Table 2, Fig. 3). DAZ I (430-95 cm) This zone is dominated by Pyxidinopsis psilata (Wall and Dale) Head and Spiniferites cruciformis Wall and Dale. P. psilata reaches its maximum frequency of 46.6% (340 cm). S.cruciformis increases towards to the top of the zone up to 27.3% (110 cm). Single specimens of Pediastrum are identified at this level. DAZ II (95-20 cm) The beginning of this zone is delimited by the appearance and increase towards the top of the zone of dinoflagellate cysts of Lingulodinium machaerophorum (Cookson and Eisenack) Wall up to 74% and of acritarchs Cymatiosphaera globulosa Takahashi up to 37.6 %. L.machaerophorum cysts are represented by different morphotypes (normal and clavate). Different species of Spiniferites are also identified. Percentage presense of Spiniferites ramosus Wetzel is about 15%. Spiniferites bulloides Wall and Dale and Peridinium ponticum Wall and Dale cysts are few. Pollen assemblage zones (PAZ) The pollen percentage diagram from core C-2345 is divided into eight pollen assemblage zones (PAZ). PAZ 1 – PAZ 5 (430-95 cm) All of these zones are characterized by a high percentage of non-arboreal taxa (40 to 87.7%) and corresponds to DAZ-I. Artemisia prevails with 41 to 61%, Chenopodiaceae with 272

Increase of salinity

Boreal

First invasion of Mediterranean waters

BÖ

Chronological scheme of the Black Sea shelf (Shopov,1991)

Quercus, Ulmus, Carpinus, Fagus, Alnus, Salix

Mixed oak forests and formations of flooded forests

Lingulodinium machaerophorum Spiniferites ramosus

Increase of humidity,decrease of temperature,salinity-similar to the present days

Mytilus galloprovincialis, Cardium papillosum, C.exiguum,C.edule

Quercus,Carpinus betulus,Corylus,Ulmus Quercus, Corylus, Ulmus, Tilia, Carpinus betulus

Mixed oak forests; Cymatiosphaera increase of C.betulus globulosa ,Maximum of

Balanced mixed oak forests

Lingulodinium machaerophorum

Slight drying up of the climate, increase of salinity Maximum of temperature and humidity;increase of salinity

Regional stratigraphic hiatus

Regression

Transgression (- 90 +20m) Outflow to the Mediterranean Sea

Artemisia, Chenopodiaceae

Steppe

Pinus, Artemisia, Chenopodiaceae

Pine forests and steppe

Artemisia, Chenopodiaceae, Poaceae

Steppe

Pinus diploxylon, Artemisia

Pine forests and steppe

Cold and dry climate, slight freshening Cool climate, brackish water Cold and dry climate, cold brackish water Cool climate, brackish water

Cold and dry climate, cold brackish water

OD

Palaeoecological reconstructions

Pyxidinopsis psilata

ALL

Dinoflagellate assemblages

Spiniferites cruciformis

YD

Coastal vegetation

Steppe

Preboreal

sublayers New Black Modiolus phaseolinus Sea Spisula triangulata sublayer Old Black Sea sublayer

Atlantic

Pollen asemblages

regional layers

Black Sea layer

New Black Sea transgression

(Shopov, 1991)

Artemisia, Chenopodiaceae, Pinus diploxylon

13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

N y m p h a e a n Fanagorian Regression

Molluscan fauna

Dreissena rostriformis distincta, Dreissena polymorpha regularis, Monodacna caspia, Clessiniola variabilis

12

horizonts

U p p e r

11.8

Subboreal

Transgressions and hydrological regime (Fedorov, 1982)

N e w e u x i n i a n

11

Alpine Stratigraphic scale

Chronological scale [10³yrs]

10.3

Subatlantic

U p p e r P l e i s t o c e n e (W ü r m) Late Glacial P l e n i g l a c i a l

1 2 3 4 5 6 7 8 9

Holocen

Section and subsections

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf

Table 2. Stratigraphic scheme and palaeoenvironmental reconstruction for Bulgarian Southern Black Sea Late Quaternary sediments

16 to 35%. At PAZ-5 the pollen of Poaceae decreases from 9.1 to 2.5%. Arboreal pollen is mainly represented by Pinus diploxylon with 8.6 to 22%. Only in PAZ-2 and PAZ-4 an increase of arboreal pollen, mainly due to an increase in the values of Pinus diploxylon pollen up to 44.6% and 60% respectively is registered. PAZ 6 – PAZ 7 (95-20 cm) These zones are delimited by a sharp percentage increase of arboreal pollen up to 79.1% and of the frequencies of Quercus up to 29.4% and Corylus up to 12.3%. Both taxa remain dominant throughout the zones. A characteristic feature is the increase of Carpinus betulus in the PAZ-7 where this species reaches the maximum values of 12.9%. Other arboreal taxa such as Ulmus, Tilia, Alnus, and Fagus are constantly presented but do not exceed 4%. PAZ 8 (20-0 cm) AP dominates the zone with 71%. Quercus pollen prevails with 33.0%, followed by Ulmus with 4.5%, Fagus with 5.5%, and Pinus diploxylon with 11.0%. A slight pollen increase of Alnus and Fraxinus excelsior occurs too.

273

Fig. 3. Simplified percentage dinoflagellate - pollen diagram of Core-2345 (Southwestern Black Sea shelf) (Analyzed by Mariana Fillipova-Marinova).

Mariana Filipova – Marinova

274

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf

DISCUSSION By studying both the marine (dinoflagellate cysts, acritarchs, and mollusks) and terrestrial (pollen grains and spores) fossil components of the same sediment samples of the marine core C-2345, information on simultaneous changes in both the continental and marine environment was obtained. Neoeuxinian sediments are characterized by a unique dinoflagellate cyst assemblage (DAZ-I) consisting of two species: Spiniferites cruciformis, and Pyxidinopsis psilata. This assemblage is similar to the freshwater to brackish water New Euxinic Stage assemblage (Unit 3) of Wall and Dale (1974) and to dinocyst assemblage zones B2 and B1c (Mudie et al. 2004). The low diversity is comparable to that described by Wall et al. (1973) and Mudie et al. (2001, 2002). The assemblage is associated with sea surface salinities less than 7‰ (Deuser 1972, Wall and Dale 1974, Mudie et al. 2001), while Chepalyga (2002) indicates a lower salinity (less than 5‰). According to Wall et al. (1973), S. cruciformis and P. psilata are cool water, low salinity stenohaline species that were common in the Late Glacial to Early Holocene sediments. Spiniferites cruciformis also occurred in the Late Glacial sediments from the Lake Kastoria, northern Greece (Kouli et al. 2001) and in the brackish Caspian and Aral Seas (Marret et al. 2004). Most characteristic of the Late Neoeuxinian molluscan assemblage that is corelated with DAZ-I are the brackish water Caspian molluscan species Dreissena rostriformis distincta and Monodacna caspia that tolerated maximum freshening (Shopov 1991). The complex also comprises Dreissena polymorpha regularis and Clessiniola variabilis. The presence of all these dinoflagellate cyst and molluscan species is probably connected with the eustatic regression of the World Ocean during the Pleniglacial causing a decrease of the Black Sea level down to -90-110 m and extinction of the two-way connection with the Mediterranean, as well as with the influx of glacial meltwater from the receding European ice sheet during the Late Glacial (Stanley and Blanpied 1980, Aksu et al. 1999, Chepalyga 2002). According to Major et al. (2002) these changes of sea level could be ascribed to changes in the river/precipitation input versus water loss by evaporation and periodic overflow of Caspian sea water to the Black Sea. The low values (5-8‰) of the oxygen isotopic measurements of Dreissena rostriformis shells prove the glacial origin of water mass of the Neoeuxinian basin. They were characterized by disparate physical, chemical, and ecological properties compared to that of the present day seawater (Chepalyga 2002). This melting ice also led to rising of the Black Sea level during the interval 10000 to 7000 BP, intensive overflow of fresh-water into the Sea of Marmara and prevent the rapid invasion of Mediterranean species into the Black Sea. The sea level has been stabilized since 8218 cal BP (Davis et al. 2003). Pollen spectra (PAZ 1 to PAZ 5) show the domination of herb communities over arboreal vegetation. The Pleniglacial and the stadials of the Late Glacial are clearly represented by the spread of cold steppe, with species of Artemisia, Poaceae, Chenopodiaceae, and many other taxa of Asteraceae predominating. The domination of non-arboreal taxa such as Artemisia and Chenopodiaceae in pollen spectra reflects the widespread of halophytic and xerophytic herb communities along the southwestern Black Sea coast during that time. Most probably, these communities occupied also a part of the present shelf after 275

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the withdrawal of the seawater. As a result of prevailing cold and dry conditions during the Late Glacial, Artemisia and Chenopodiaceae appear abundantly in the terrestrial and lacustrine deposits of southwestern and northern Turkey (Bottema et al. 1993-94) as well as northwestern Greece and Central Europe (Zeist et al. 1975). Palynological records from the deep basins of the Marmara Sea also suggest an abundance of Artemisia and Chenopodiaceae, indicative of a cold and dry climate during the Late Glacial (Caner and Algan 2002). Two maxima of Pinus diploxylon-type pollen in the Neoeuxinian sediments are probably connected with the spread of Pinus nigra forests into lower terrain together with the deciduous taxa Quercus, Carpinus betulus, Ulmus, Corylus, Tilia, Betula, etc., during the Bølling (13000-12000 BP)(15500-14000 cal. BP) and Allerød (12000-11000 BP)(14000-13000 cal. BP) interstadials of the Late Glacial. Some authors (Zeist et al. 1975) consider that the spread of pine forests during that time was probably stimulated by temporary climatic improvement and especially by the rise in humidity. A complete change of the sedimentation environment is identified at the boundary Late Pleistocene/Middle Holocene (11590±240/6880±260BP)(13520/7650 cal. BP). The organic matter fraction increased up to 2.5%, while the calcium carbonate concentration decreased to 15.4% marking the favorable climatic conditions and high non-carbonate phytoplankton productivity (Shimkus et al. 1979). Sand rich in molluscan detritus and whole shells of Caspian type mollusks (Dreissena rostriformis distincta and Dreissena polymorpha regularis) changed to aleuritic-pellitic silt with shells of euryhalinous Mediterranean species (Mytilus galloprovincialis, Cardium papillosum, Cardium exiguum, Cardium edule, and Hydrobia ventrosa). An abrupt change in the composition of dinoflagellate cysts also occurred. Mudie et al. (2001) consider that the virtual disappearance of Spiniferites cruciformis and Pyxidinopsis psilata suggests the inability of these stenohaline taxa to survive an apparently abrupt salinity change to values of 10-12‰ (Deuser 1972) or 18‰ (Wall and Dale 1974). The appearance of euryhalinous marine dinoflagellate species Lingulodinium machaerophorum, Spiniferites ramosus and acritarchs Cymatiosphaera globulosa (DAZ-II) indicated an increase of water salinity and a rise in the sea level at about 6880±260 BP (7650 cal. BP). This dinoflagellate cyst assemblage points to salinity of 17-19‰ (Deuser 1972). The isotopic salinity estimates are in closed agreement with the present-day surface salinity of 18‰ (Mudie et al. 2002), although values of 18-22‰ are cited by Wall and Dale (1974). Their demise could also be explained by low temperature tolerance of these species (Wall et al. 1973). The high productivity of phytoplankton was connected to the favorable climatic conditions along the coast. In continental slope sediments, this change is dated at 6135±75 BP (7010 cal. BP) and 6775±300 BP (7565 cal. BP) (Atanassova 1995). Though such a depositional pattern could result from an abrupt climatic change, it could also be the consequence of an unconformity in which sediment erosion leaves a hiatus. A similar unconformity has been recognized throughout the central and southern Bosphorus (Ulug 1994, Gokasan et al. 1997) and represents a depositional hiatus. According to Khrischev and Georgiev (1991) the established regional erosion affects mainly the sediment layers deposited near the Pleistocene/Holocene boundary and correspond to the drastic change in the hydrological regime during the fast sea-level rising and establishing the connection with the Mediterranean. However, this washout is not limited from above by an isochronal 276

Late Pleistocene/Holocene dinoflagellate cyst assemblages from the Southwestern Black Sea shelf

surface and thereby is not a product of one-act event. The latest 14C date for Neoeuxinian sediments is 10670 BP (12601 cal. BP) while the earliest date for the Early Holocene ranges between 8080±20 BP (8984 cal. BP) and 6100±70 BP (6940 cal. BP) (Dimitrov 1982). Based on evidence, Ryan et al. (1997, 2003) proposed that Black Sea salinification did not start until 7150±40 BP (7925 cal. BP) and that post-glacial connection between the Mediterranean and the Black Sea occurred as a catastrophic flood of saline water into the Black Sea that rapidly inundated the basin. The pollen record also indicates an abrupt change in environment. The warm and humid climate during the Atlantic climatic optimum stimulated the maximum distribution of the balanced mixed deciduous forests composed of different oak species (Quercus robur, Q. frainetto, Q. cerris), together with Ulmus, Tilia, Fraxinus excelsior, and Corylus. The pollen record suggests a trend towards an increased presence of Carpinus betulus in the mixed oak forests at the end of Atlantic and the beginning of Subboreal. Most probably, some decrease of temperature and humidity occurred. The maximum increase of Carpinus betulus in the Bulgarian Southern Black Sea Coast was dated to 5680±65 BP (6460 cal. BP) from the sediments from Lake Arkutino (Bozilova and Beug 1992), to 5280±180 BP (6030 cal. BP) in deep-water sediments (Filipova et al. 1989), to 6135±75 BP (7010 cal. BP) in the shelf sediments (Atanassova 1990, Shopov et al. 1992). During that period, vast hornbeam expansion and formation of a separate belt were established also for the Balkan Range (Filipovich 1987). After 3780 BP (4097 cal. BP) a change in sediments occurred. They were represented by phaseolinous and aleuritic silt with shells of Modiolus phaseolinus and Spisula triangulata. The increase of the Fagus curve and the presence of pollen of temperate moisture-loving tree species such as Ulmus, Alnus, Acer, and Fraxinus excelsior could be explained by the formation of the contemporary flooded (riparian) forests along the rivers draining into the Black Sea, due to climatic cooling and an increase in humidity during the Subatlantic. However, mixed oak forests were still dominant. CONCLUSIONS The sedimentologic evidence and changes of dinoflagellate cyst and molluscan assemblages reveals the presence of three distinct stratigraphic units in the preserved Quaternary sediments: Late Pleistocene (29100±680 to 11590±240 BP (13520 cal. BP)), Middle Holocene (6880±240 to 3780 BP)(7650 to 4097 cal. BP), and Late Holocene (from 3780 BP (4097 cal. BP)). The surface separating the two lower units is correlated with an unconformity recognized in almost all cores from the Black Sea shelf and represents a significant depositional hiatus. Micro and macrofossil elements (dinoflagellate cysts and molluscan shells) preserved in the Late Pleistocene sediments are of Ponto-Caspian affinity and are typical for fresh/ brackish settings, while in upper units (Middle and Late Holocene) they are exclusively of Mediterranean affinity and ecologically consistent with marine environment. 277

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ACKNOWLEDGEMENTS It is my pleasure to dedicate this paper to the 70th Anniversary of Prof. Dobrina Temniskova-Topalova. The author is grateful to Prof. P. Dimitrov of the Institute of Oceanology – Varna for the opportunity to investigate the material and for the description of core lithology, and wishes to express her gratitude to the late Prof. V. Shopov of the Institute of Geology, Bulgarian Academy of Sciences, for the analysis of molluscan fauna. The author also acknowledges with appreciation the help of Prof. Suzanne Leroy (Department of Geogrpahy and Earth Sciences, Brunel University) in critically evaluating this paper and providing many valuable comments. REFERENCES AKSU, A., R.HISCOTT and D. YASAR 1999. Oscillating Quaternary water levels of the Marmara Sea and vigorous outflow into the Aegean Sea from the Marmara Sea– Black Sea drainage corridor. - Marine Geology, 153: 275-302. ATANASSOVA, J. 1990. Vegetation development during the Late Quaternary on the basis of spore-pollen analyses of sediments from the western section of the Black Sea. Ph.D. Thesis. (in Bulgarian with English summary). ATANASSOVA, J. 1995. Dinoflagellate cysts from Late Quaternary and recent sediments of the Western Black Sea. - Annual of Sofia University “St. Kliment Ohridski”, Faculty of Biology, 87(2): 17-28. ATANASSOVA, J. and E. BOZILOVA 1992. Palynological investigations of marine sediments from the western sector of the Black Sea. - Proceedings of the Institute of Oceanology (Varna), 1: 97-103. BIRKS, H-J. and H.-H. BIRKS 1980. Quaternary Paleoecology. -Edward Arnold Ltd, London. BOTTEMA, S., E. WOLDRING and B. AYTUG 1993-4. Late Quaternary vegetation history of northern Turkey. – Palaeohistoria, 35/36: 13-72. BOZILOVA, E. and H.-J. BEUG 1992. On the Holocene history of vegetation in SE Bulgaria (Lake Arkutino, Ropotamo region). - Vegetation History and Archaeobotany, 1: 1932. BOZILOVA, E., M. FILIPOVA and J. ATANASSOVA 1992. Marine palynological data about paleoecological conditions and vegetation history of East Bulgaria during the last 15000 years. - Annual of Sofia University “St. Kliment Ohridski”, Faculty of Biology, 82(2): 79-87. CANER, H. and O. ALGAN 2002. Palynology of sapropelic layers from the Marmara Sea. Marine Geology, 190: 35-46. CHEPALYGA, A. 2002. Marine basins. in: A. Velichko, editor. Dynamics of terrestrial landscape components and inland and marginal seas of northern Eurasia during the last 130000 years. Atlas-monograph “Evolution of Landscapes and climates of 278

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KHRISCHEV, K. and V. GEORGIEV 1991. Regional washout in the Pleistocene-Holocene boundary in the Western Black Sea depression. - Comptes Rendus de L’Acad. Bulg. des Sci., 44(9): 69-71. KOULI, K., H. BRINKHUIS and B. DALE 2001. Spiniferites cruciformis: a fresh water dinoflagellate cyst? - Review of Palaeobotany and Palynology, 113: 273-286. MAJOR, C., W. RYAN, G. LERICOLAIS and I. HAJDAS 2002. Constraints on the Black Sea outflow to the Sea of marmara during the last glacial-interglacial transition. - Marine Geology, 190: 19-34. MARRET, F., S. LEROY, F. CHALIE and F. GASSE 2004. New organic-walled dinoflagellate cysts from recent sediments of Central Asian seas. - Review of Palaeobotany and Palynology, 129 (1-2): 1-20. MUDIE, P., A. AKSU AND D.YAșAR 2001. Late Quaternary dinoflagellate cysts from the Black, Marmara and Aegean seas: variations in assemblages, morphology and paleosalinity. - Marine Micropaleontology, 43: 155-178. MUDIE, P., A. ROCHON and A. AKSU 2002. Pollen stratigraphy of Late Quaternary cores from Marmara Sea: land-sea correlation and paleoclimatic history. - Marine Geology, 190: 233-260. MUDIE, P., A. ROCHON, A. AKSU and H. GILLESPIE 2004. Late glacial, Holocene and modern dinoflagellate cyst assemblages in the Aegean-Marmara-Black Sea corridor: statistical analysis and re-interpretation of the early Holocene Noah’s Flood hypothesis. - Review of Palaeobotany and Palynology, 128: 143-167. ROSS, D. and E. DEGENS 1974. Recents sediments of Black Sea. in: E. Degens and D. Ross, editors. The Black Sea – Geology, Chemistry and Biology: 133-165. Memoir 20, American Association of Petroleum Geologists, Tulsa, Oklahoma. RYAN, W., W. PITMAN III, C. MAJOR, K. SHIMKUS, V. MOSKALENKO, G. JONES, P. DIMITROV, N. GÖRÜR, M. SAKINÇ and H. YÜCE 1997. An abrupt drowning of the Black Sea shelf. - Marine Geology, 138: 119-126. RYAN, W., C. MAJOR, G. LERICOLAIS and S. GOLDSTEIN 2003. Catastrophic flooding of the Black Sea. - Annual Review Earth and Planetary Sciences, 31: 525-554. SHIMKUS, K., P. DIMITROV, S. CHABASHVILI, L. GOVBERG and Z. NOVIKOVA 1979. General lithological characteristics of cores. in: Y. Malovitskii, editor. Geology and Hydrology of the Western section of the Black Sea: 99-101. Publishing House of the Bulgarian Academy of Sciences, Sofia. (in Russian) SHOPOV, V. 1991. Biostratigraphy (based on the Molluscan Fauna) of Quaternary Sediments from the Bulgarian Black Sea Shelf. - Dr. of Sciences Thesis, Geological Institute of the Bulgarian Academy of Sciences, Sofia. (in Bulgarian) SHOPOV, V., E. BOZILOVA and J. ATANASSOVA 1992. Biostratigraphy and radiocarbon data of the Upper Quaternary sediments from the western part of the Black Sea. Geologica Balcanica, 22(2): 59-69. STANLEY, D. and C. BLANPIED 1980. Late Quaternary water exchange between the eastern Mediterranean and the Black Sea. – Nature, 285: 537-541. STUIVER, M. and P. REIMER 1993. Extended 14C data base and revised CALIB 3.0 14C calibration program. – Radiocarbon, 35: 215-230. 280

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TRAVERSE, A. 1988. Paleopalynology. - Unwin Hyman, Boston. ULUG, A. 1994. Bathymetrical and geophysical studies of the drinking water utility through the Bosphorus. - Ph.D. Thesis, Mar. Sci. Tech. Inst. Rep., Izmir (in Turkish) WALL, D. and B. DALE 1973. Paleosalinity relationships of dinoflagellates in the Late Quaternary of the Black Sea – a summary. - Geosci. Man., 7: 95-102. WALL, D. and B. DALE 1974. Dinoflagellates in Late Quaternary deep-water sediments of Black Sea. in: E. Degens and D. Ross, editors. The Black Sea – Geology, Chemistry and Biology: 364-380. Memoir 20, American Association of Petroleum Geologists, Tulsa, Oklahoma. WALL, D., B. DALE and K. HARADA 1973. Descriptions of new fossil dinoflagellates from the Late Quaternary of the Black Sea. – Micropaleontology, 19: 18-31. ZEIST, W. VAN, H. WOLDRING and D. STAPERT 1975. Late Quaternary vegetation and climate of Southwestern Turkey. – Palaeohistoria, 17: 53-143.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 283-291) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Diatoms as indicators of the influence of the Vistula river inflow on the Gulf of Gdańsk during the Holocene Katarzyna Stachura-Suchoples Institute of Oceanography, University of Gdańsk, Al. Piłsudskiego 46, PL-81-378 Gdynia, Poland Present address: Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, D-14473 Potsdam, Germany e-mail: [email protected] ABSTRACT Diatom record is presented here as tools to follow evidences of influence of the Vistula River on the environmental conditions of the Gulf of Gdańsk since the Ancylus Lake stage of the Baltic. It is distinguished and separated an impact of riverine waters not only based on halobian groups, which is the most obvious at the vicinity of the run-off. Here, the trophy factor that indicates the riverine influence further from the direct freshwater inflow and cannot be based on the halobian classification is documented. Key words: diatoms, estuary, Vistula River, Gulf of Gdańsk, the Holocene INTRODUCTION Estuaries are very sensitive regions not only because of mixing freshwater and brackishwater/marine waters, but riverine inflows also are sources of nutrients and nowadays of contamination. However, there is only a little information that gives a background for using diatoms as tools for estimation and reconstruction of nutrient and saprobian conditions in brackish-water conditions (e.g. Stachura-Suchoples 1999, 2001). Moreover, there are still only a few studies done, which deal with reconstruction of environmental conditions at the estuaries (e.g. Stachura-Suchoples 2002). However, costal areas have been a matter of interest for many years. In the Gulf of Gdańsk, the palaeoecological research, focused on the reconstruction of the Holocene history of different parts of the basin, based on diatom analyses was carried out by Schulz (1926), Sandegren (1935), Przybyłowska-Lange (1974), 283

Katarzyna Stachura-Suchoples

Bogaczewicz-Adamczak (1982), Witkowski (1994), Stachura-Suchoples (1999) and Witak (2002) to name a few. The aim of this research was to exam an use of diatoms to estimate an influence of the Vistula River inflow on the Gulf of Gdańsk during the Holocene. MATERIALS AND METHODS Diatom analyses of the Holocene sediment subsampled from the core No. 2ZG 138 (ö 54° 33,39284 N, ë 18° 47,50284 ) taken from the Gulf of Gdańsk were performed (Fig. 1). The length of the core was 400 cm. It contained mainly silt and at the uppermost 20 cm, 223-237 cm and 243-249 cm sand. The core was subsampled at the intervals 10 and 20 cm, and all together 25 samples were analyzed. Standard procedures were used for sample preparation and diatom analyses (Battarbee 1986, Bodén 1991). A minimum of 300 valves were counted per slide. The taxonomical identification of diatom taxa and halobian classification were

Fig. 1. Localisation of the analyzed core No. 2ZG 138 from the Gulf of Gdańsk (the Baltic Sea)

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based on the literature listed in Stachura-Suchoples (2001). The trophic preferences refer to Denys (1991), van Dam et al. (1994), Hofmann (1994) and Stachura-Suchoples (2001). RESULTS Diatom analyses of sediment core No. 2ZG138 from the Gulf of Gdańsk, in a relation to changes in live forms, halobian groups and species assemblages are presented here (Fig. 2). In the core 2ZG138, 249 diatom species and subspecies were identified. Based on diatom analyses 4 zones and 3 subzones in the most upper part of the core were distinguished. At the zone 2ZG138-I (225-400 cm), non-planktonic diatoms predominated. Regarding halobian preferences freshwater diatoms ranged from 63.1 – 90.9 %, halophilous up to 21 %, brackish water up to 9.3 % and marine below 1 %. Dominant species were represented mainly by eutrophic species as: Amphora pediculus (Kützing) Grunow, Aulacoseira granulata (Ehrenberg) Simonsen, Fragilaria geocollegarum Witkowski & Lange-Bertalot, Martyana martyi (Héribaud) Round, Pseudostaurosira brevistriata (Grunow) D.M. Williams & Round, Staurosira construens Ehrenberg and S. construens var. binodis (Ehrenberg) Hamilton (Fig. 2). At the zone 2ZG138-II (200-225 cm), non-planktonic diatoms were still the most abundant. However, brackish-water diatoms predominated (60%), and a significant increase of marine group was observed (up to 20%). Freshwater diatoms dropped down to 18-25 %. At the diatom assemblage the most common were brackish-water and marine species such as: Fragilaria guenter-grassii Witkowski & Lange-Bertalot and F. neoelliptica Witkowski (Fig. 2). At the zone 2ZG138-III (120-200 cm), a significant increase of planktonic diatoms was observed, however non-planktonic group remained predominate (c. 60 %). The marine (24-32 %), brackish-water (26.5 – 40.3 %) and freshwater (24.5 – 39 %) diatoms were the most frequent groups at the zone. The most abundant taxa: Diploneis didyma (Ehrenberg) Cleve, Fragilaria guenter-grassii, Actinocyclus octonarius Ehrenberg and Thalassionema nitzschioides (Grunow) Grunow have brackish-water and marine requirements (Fig. 2). At the zone 2ZG138-IV (0-120 cm), an abundance of non-planktonic diatoms reached up to 80 %. An increase of brackish-water (23.8 – 63.8 %), freshwater (20.3 – 47 %) and halophilous (c. 15 %) halobian groups was noticed. The marine diatoms decreased to 15 %. Diatom flora was dominated by Amphora pediculus, Fragilaria geocollegarum, F. guenter-grassii and Staurosira construens. Additionally, the zone 2ZG138-IV was divided into 3 subzones mainly due to changes concerning abundance of brackish-water and freshwater diatom species. For example Diploneis didyma was common at the subzone 2ZG138-IVA (80-120 cm), in a contrary a high frequency of Cyclotella choctawhatcheeana A.K.S. Prasad and Thalasiossira levanderi Goor was observed at the subzone 2ZG138-IVC (0-20 cm) (Fig. 2). DISSCUSSION During the last glaciation (Vistulian), in the territory of today’s Poland, it existed a net of riverine pre-valleys. They carried the riverine waters along the head of the ice-sheet to the 285

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Fig. 2. Diatom analysis core No. 2ZG 138 from the Gulf of Gdańsk

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north-west. The glaciation of the northern part of today’s Poland enforced the direction of the outflow of the Vistula River to the west, along the common pre-valley of two rivers the Noteć River and the Warta River. The progress of the deglaciation and the retreat of the ice-sheet caused that the waters of the Vistula River could run to the north. Together with the beginning of the development of Baltic Ice Lake, it started the process of the shaping of hydrologic regime in the Gdańsk Basin. The Vistula River, at the same time, begun to carry its waters through the lower part of its course, exclusively (Tomczak 1989). Obviously, this event marked also the beginning of the direct an influence of Vistula on the natural environment of the Gdańsk Basin. Analyzed core covered the early, middle and late Holocene sediment record. It allowed to trace and to reconstruct influence of the Vistula River on the Gulf of Gdańsk since the Ancylus Lake stage of the Baltic. The Ancylus Lake stage of the development of the Baltic begun, when the isostatic elevation of Scandinavia caused the break of the connection of the Baltic Sea with the oceanic waters (Hyvärinen 1988). The consequence of these changes was the decrease of the salinity of the Baltic. At the same time, it occurred the development of the freshwater diatom assemblage. In sediment studied from the core 2ZG138 (level 2ZG138-I, Fig. 2), the contents of the diatom assemblage referred to diatom zones of the Ancylus Lake (see also Bogaczewicz-Adamczak 1982, Witkowski 1994). The lithology of the core confirmed the presence of the mouth cone there (Stachura-Suchoples 1999). The non-planktonic diatom assemblage dominated by freshwater species (Amphora pediculus, Martyana martyi, Pseudostaurosira brevistriata, Staurosira construens and S. construens var. binodis) and halophilous taxa (Fragilaria geocollegarum) also indicated shallow-water conditions of sedimentation. Additionally, these species composition may suggest eutrophic conditions (StachuraSuchoples 2001) that may indicate an inflow of nutrients with the Vistula River waters and proof the better edaphic conditions in the Gulf of Gdańsk than e.g. at the Götland Deep (Westman and Sohlenius 1998). Due to the inflow of the oceanic waters through the Danish Straits into the Baltic Sea caused by the eustatic elevation of the ocean’s level, changes into environmental conditions occurred and the next stage of the Baltic’s development, the Mastogloia Sea begun. The Mastogloia transgression caused the displacement of the coastal line of the Gulf of Gdańsk 27 meters below the recent sea level (Rosa 1994). The result of that process was the shortening of the lower part of the course of the Vistula River and the displacement of its mouth to the present location (Mojski 1988). Changes in the diatom flora, which were traced in the core 2ZG138 (level 2ZG138-II, Fig. 2) refer to the diatom zones of the Mastogloia stage in the Gulf of Gdańsk (see also Bogaczewicz-Adamczak 1982, Witkowski 1994). Results of these studies revealed that in the diatom assemblage of the Gulf of Gdańsk, it occurred a rapid decrease of the frequency of freshwater and halophilous groups. It was also observed a simultaneous massive increase of brackish-water and marine species. In that way, it came into existence a new diatom assemblage dominated by eutrophic brackish-water taxa: Diploneis didyma, Fragilaria guenter-grassii and F. neoelliptica. The abundance of the freshwater diatom group (ca. 20%) indicated the partial freshening of that area caused by the inflow of the riverine waters. It was also observed the higher content of eutrophic taxa in the area 287

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studied, than in the remaining part of the Gulf of Gdańsk (see for comparison e.g. Witkowski 1994). The composition of diatom assemblage indicated that an influence of the Vistula River waters on the area studied of the Gulf of Gdańsk was comprisable with the presently observed influence of this river on the central part of the Gulf (see for comparison Stachura and Witkowski 1997, Stachura-Suchoples 2002). The consequence of the constant inflow of the oceanic waters through the Danish Straits was the development of the Littorina Sea and an increase of salinity of the Baltic Proper to ca. 15‰ (Hyvärinen 1988). For the comparison, in present times salinity of the Baltic amounted to merely 7-8 ‰ (Majewski 1990). In the material studied the Littorina stadium was observed in cores 2ZG138, level 2ZG138-III (Fig. 2). It was observed an increase of the frequency of the marine halobian group - over 30% - and planktonic taxa - also to ca. 30%. Dominated species were non-planktonic - Diploneis didyma, Fragilaria guenter-grassii - as well as planktonic - Actinocyclus octonarius and Thalassionema nitzschioides - taxa. The contents of the diatom assemblage indicated further deepening of the Gulf of Gdańsk in relation to the Mastogloia. The Littorina transgression caused displacement of the coastal line of the Gulf of Gdańsk to the level similar to the present one (Rosa 1994) and the retreat of the mouth of the Vistula River towards the south. The frequency of the freshwater group was a considerable part of the diatom assemblage (above 25%). In other cores taken from the Gulf of Gdańsk, it oscillated beneath 10% (e.g. Bogaczewicz-Adamczak 1982, Witkowski 1994). The taxonomical contents of freshwater species (Amphora pediculus, Aulacoseira granulata, Martyana martyi and Staurosira construens) indicated the influence of the waters of the Vistula River. This influence caused, besides freshening, an increase of trophy. The comparison of diatom phases indicated an intensification of the riverine inflow. This phenomenon was caused by an increase of temperature and humidity in the atlantic period. As the consequence, during the Littorina, more water flowed into the Gulf of Gdańsk than during the Mastogloia (Mojski 1988). In the valley of the lower course of the Vistula River the straightening of the bed of the Vistula River at the area of the Toruń Dell is postulated (Tomczak 1989). It was caused by the gradual decrease of the amount of water carried by the Vistula River (around 5500 yr. BP). The huge amount of freshwater diatoms of eutrophic edaphic preferences may indicate the strong inflow of the freshwaters carrying nutrients. The simultaneous gradual decrease of an abundance of the freshwater group may indicated a decreasing amount of the riverine waters flowed into the Gulf of Gdańsk. The Postlittorina, the next stage of the Baltic Sea development, was linked with the decrease of salinity caused by a decrease of the inflow of the oceanic waters through the Danish Straits (Hyvärinen 1988). In the diatom assemblages from the sediment core 2ZG138, level 2ZG138-IV (Fig. 2), it was observed a decrease of an abundance of marine diatoms and an increase of remaining halobian groups. This phenomenon was accompanied by a drastic decrease of a frequency of Thalassionema nitzschioides. At the level a frequency of brackishwater and freshwater groups exceeded 30%. An increase of the contents of the freshwater group was accompanied by a decrease of an abundance of brackish-water diatoms. This assemblage was dominated by the freshwater non-planktonic group of eutrophic requirements (Amphora pediculus, Martyana martyi, Pseudostaurosira brevistriata and Staurosira construens) as well as planktonic taxa (Aulacoseira granulata). A substantial abundance of eutrophic freshwater species indicated strong influence of the waters of the Vistula River - its mouth was located at 288

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the latitude of Gdańsk. At the same time, the Vistula River, to the end of the subboreal period, carried a decreasing amount of water. About 2000 yr. BP (the subatlantic period), in the valley of the lower course of the Vistula River, it occurred a tendency to rises of the river and an aggradation of the river bed (Tomczak 1989). The comparison of changes of the percentage abundance of freshwater taxa (sublevels 2ZG138-IVA and 2ZG138-IVB) indicated that after an increase, which occurred at the beginning of Postlittorina, there was observed a decrease of the abundance of freshwater taxa. Later, there was observed an increase of the freshwater species - to the border with the sublevel 2ZG138-IVC. These changes could testify to a decrease of the amount of water carried by the Vistula River to the Gulf of Gdańsk to the end of the subboreal period and its increase at the beginning of the subatlantic period. It was an interesting phenomenon, because the intensification of the process of aggradation was a result of deforestation of the basin of the Vistula River and intensified denudation. In that case, changes observed in the diatom flora of the Gulf of Gdańsk would be caused by the anthropogenic factor. Additionally, at the uppermost part of the cores (sublevel 2ZG138-IVC), it occurred a decrease of a frequency of freshwater diatoms (below 30%). It was a reaction to directing of the waters of the Vistula River through the ditch in Świbno. These changes were accompanied by a rapid increase of an abundance of planktonic freshwater and halophilous taxa (sublevel 2ZG138-IVB). They testified to the progress of the eutrophication of the Gulf of Gdańsk. Changes of the diatom flora of the Gulf of Gdańsk, which occurred as a result of an increase of trophy during last 200-300 years, have been presented in detail by Stachura-Suchoples (1999, 2002). SUMMARY The presented studies indicated the Vistula River inflow on the environmental conditions in the Gulf of Gdańsk since the Ancylus Lake stage of the Baltic. It was revealed by directly changes into an increase of frequency of freshwater diatoms, clearly noticed in brackish-water (the Mastogloia, the Postlittorina) and marine (the Littorina) stages of development of the Baltic. The riverine influence into the Gulf of Gdańsk was also traced by predomination of higher trophy preferences diatom species at the vicinity of the runoff and further from the inflow since the Ancylus Lake stage. ACKNOWLEDGMENTS Presented studies were carried out at the University of Gdańsk, Department of Marine Geology, as a part of author’s Ph. D. dissertation, under supervision of Prof. Dr. hab. Andrzej Witkowski and reviewed by Prof. Dr. hab. Jadwiga Siemińska and Prof. Dr. hab. Bożena Bogaczewicz-Adamczak to whom I express my thanks. The cores for diatom analyses were kindly provided by Dr. Joanna Zachowicz and Dr. hab. Szymon Uścinowicz from the Polish Geological Survey, Marine Branch in Sopot. This studies were partly granted by KBN PO4E 0058/97/13. 289

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REFERENCES BATTARBEE, R.W. 1986. Diatom analysis. in: B.E. Berglund, editor. Handbook of Holocene Palaeoecology and Palaeohydrology: 527-570. John Wiley & Sons, London. BODÉN, P. 1991. Reproducibility in the random settling method for quantitative diatom analysis. – Micropalontology, 37(3): 313-319. BOGACZEWICZ-ADAMCZAK, B. 1982. Nowa analiza okrzemkowa serii osadowej Półwyspu Helskiego. – Peribalticum, 2: 185-194. DENYS, L. 1991. A check-list of the diatoms in the Holocene deposits of the western Belgian coastal plain with a survey of their apparent ecological requirements. Service Geologique de Belgique. I. Introduction, ecolgical code and complete list. Ministerie van Economische zaken, Belgische geologische dienst. - Professional paper 1991/2, 246: 1-41. HOFMANN, G. 1994. Aufwuchs-Diatomeen in See und ihre Eignung als Indikatoren der Trophie. - J. Cramer, Berlin, Stuttgart. HYVÄRIEN, H. 1988. Definition of the Baltic stages. in: J. Donner and A. Raukas, editors. Problems of the Baltic Sea: 25-35. Annales Academiae Scientiarum Fennicae series A, 148. MAJEWSKI, A. 1990. Morfometria i hydrografia zlewiska. in: A. Majewski, editor. Zatoka Gdańska 10-19. Wydawnictwo Geologiczne, Warszawa. MOJSKI, J.E. 1988. Development of the Vistula river delta and evolution of the Baltic Sea, an attempt at chronological correlation. in: B. Winterhalter, editor. The Baltic Sea: 3951. Geological Survey of Finland, Special Paper 6. PRZYBYłOWSKA-LANGE, W. 1974. Rozwój Zalewu Wiślanego w świetle analizy okrzemkowej. - Prace IMGW, 2: 129-162. ROSA, B. 1994. O zmianach poziomu Baltyku poludniowego i pilnej potrzebie dalszych rozpoznań w tej dziedzinie. – Peribalticum, 6: 95-119. SANDEGREN, R. 1935. O iskacajemnoj mikroflorie ot burienija na Helskom polustowie i o postglacjalnych izmienieniach urownia Baltyki. - Spraw. PIG, 8: 51-61. SCHULZ, P. 1926. Die Kieselalgen der Danziger Bucht mit Einschluss derjenigen aus glazialen und postglazialen Sedimenten. - Bot. Arch., 13: 149-327. STACHURA, K. and A. WITKOWSKI 1997. Response of the Gulf of Gdańsk diatom flora to the sewage run-off from the Vistula river. - Fragm. Flor. Et Geobot., 42(2): 517-545. STACHURA-SUCHOPLES, K. 1999. Okrzemki jako wskaźniki oddziaływania Wisły na paleoekologię Zatoki Gdańskiej. [Diatoms as indicators of the Vistula River influence on the palaeoecological conditions in the Gulf of Gdansk]. - PhD dissertation, University of Gdańsk: 1-172. STACHURA-SUCHOPLES, K. 2001. Bioindicative values of dominant diatom species from the Gulf of Gdańsk (Southern Baltic Sea). in: R. Jahne R., J.P. Kociolek , A. Witkowski and P. Compére, editors. Lange-Bertalot-Festschrift-Studies on Diatom: 477-490. Gantner, Ruggell.

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STACHURA-SUCHOPLES, K. 2002. The environmental changes in the Gulf of Gdańsk (Southern Baltic) during the last 200 years as a response to the anthropogenic impact as the evidenced from the diatom analyses. in: J. John, editor. Proceedings of 15th International Diatom Symposium: 209-226. Perth, Australia. TOMCZAK, A. 1989. Ewolucja doliny dolnej Wisły w ostatnich 15 tysiącach lat I jej związek ze zmianami poziomu Bałtyku w świetle badań w Kotlinie Toruńskiej. - Stud. i Mat. Oceanol., 56: 209-221. WESTMAN, P. and G. SOHLENIUS 1998. Diatom stratigraphy in five off-shore sediment cores from the north-western Baltic implying large scale circulation changes during the last c. 8500 years. in: P. Westman Ph. D. dissertation: Salinity and trophic changes in the north-western Baltic Sea during the last 8500 years indicated by microfossils and chemical parameters in sediments: 1-12. Ser. A. (5). WITAK, M. 2002. Postglacial history of the development of the Puck Lagoon (the Gulf of Gdańsk, Southern Baltic Sea) based on diatom flora. – Koeltz Scientific Books, Koenigstein. WITKOWSKI, A. 1994. Recent and fossil diatom flora of the Gulf of Gdańsk, Southern Baltic Sea. – Koeltz Scientific Books, Koenigstein. VAN DAM, H., A. MERTENS and J. SINKELDAM 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. - Netherl. J. Aqua. Ecolo., 28(1): 117-133.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 293-317) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon, NW Poland, southern Baltic Sea Małgorzata Bąk1, Andrzej Witkowski1 and Horst Lange-Bertalot2 Institute of Marine Sciences, University of Szczecin, Waska 13, PL-71-415 Szczecin, Poland 2 Botanical Institute, J.-W. Goethe-University, Senckenberganlage 31–33, 60054 Frankfurt am Main, Germany 1

ABSTRACT The study focuses on the diversity of the diatom flora in a strongly eutrophic and polluted coastal lagoon (Szczecin Lagoon, Northern Poland). A total of 521 taxa (diatom species and varieties) belonging to 74 genera were identified in the samples. The diversity is expressed in terms of Shannon-Weaver index, Evenness and constancy of occurrence. Values of these indices showed spatial and temporal variation which was apparently dependent on two major factors: the freshwater and the saline water discharge into the Szczecin Lagoon. In general the diatom flora of the area studied was dominated by cosmopolitan taxa, but some rare and particular (exotic) species were also identified. In addition one species new to science, Karayevia temniskovae is described. Key words: Diatoms (Bacillariophyceae), biodiversity, Szczecin Lagoon, Baltic Sea INTRODUCTION Recent and fossil diatom floras of coastal lagoons and estuaries have always attracted much attention of ecologists and taxonomists (e.g. Brockmann 1954, Hustedt 1957, König 1959, Cholnoky 1968, Przybyłowska-Lange 1979, Snoeijs et al. 1990, Witkowski 1991, Cooper 1995, Sabbe 1997, Stachura and Witkowski 1997, Sullivan 1999, Bak et al. 2001, Silvestre et al. 2001, Busse and Snoeijs 2002). While the earlier works were mainly devoted to the general 293

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knowledge on taxonomy and ecology of diatoms inhabiting lagoons and estuaries (e.g. Hustedt 1957, König 1959, Cholnoky 1968), beginning from the late 80s and early 90s of the 20th century applied aspects have gained more importance. The major subject is an application of diatoms as indicators of human impacts in terms of eutrophication and pollution. Such studies include both, recent (Sundbäck and Snoeijs 1991, Witkowski 1994, Stachura and Witkowski 1997, Snoeijs 1999, Silvestre et al. 2001, Bak et al. 2001, 2004) and subfossil floras (e.g. Andrén 1995, 1999, Cooper 1995, 1999, Witkowski and Pempkowiak 1995, Witkowski et al. 2004, Garcia-Rodriguez et al. 2002). The lagoons and estuaries are inhabited by an interesting and species rich diatom flora, which has to adapt to changeable environmental conditions. The major factor affecting the distribution of diatoms in such water bodies is variation in salinity (e.g. Snoeijs 1999, Bak et al. 2001). This results from the location of lagoons and estuaries at the transition between terrestrial and fully marine environments. Changes in salinity depend on local morphology and climatic conditions. In estuaries located at the oceanic coast usually occurs a strongly developed salinity gradient, whereas in lagoons located in temperate climate such a gradient is usually weaker (e.g. Baltic Sea lagoons, Snoeijs 1999; Uruguay, GarciaRodriguez 2002). In subtropical and tropical climate, hypersaline conditions develop (e.g. Silvestre et al. 2001, Zalat 2002, 2003). In temperate climate lagoons and estuaries, riverine discharge and week salinity gradient enable adaptation of freshwater diatoms (e.g. Brockmann 1954, Przybyłowska-Lange 1979, Witkowski 1994, Busse and Snoeijs 2002, Bak 2004). Although coasts of such lagoons are usually strongly urbanised areas and therefore exposed to the human impact they apparently host a number of suitable habitats to accomodate diatom assemblages very rich in species number. As shown in several studies the number of taxa in temperate lagoons ranges from ca. 300 (Busse and Sneoijs 2002) to 400-500 in Chesapeake Bay, USA (Cooper 1995) the mouth of river Weser (Hustedt 1957) and in the Puck Bay (Bogaczewicz-Adamczak and Dziengo 2003). In Szczecin Lagoon the number of taxa exceeded 500 (Bak 2004, Bak et al. 2004, this study). A similarly rich flora was also encountered in Santa Lucia Lagoon in South Africa (Cholnoky 1968), although it is predominantly of marine origin. This results from the major role of marine water discharge and a limited role of freshwater inflow in the water balance of the Santa Lucia lagoon system. Unlike in temperate and subtropical systems with normal salinity gradients the diatom flora in hypersaline lagoons is usually much poorer in species richness. This has been shown by e.g. Silvestre et al. (2001) in Lagoa de Ararurama in Brasil. As a measure of diatom flora diversity the Shanon-Weaver index is applied. One of the first studies directed towards changes of diversity of coastal area was carried out by Hendey (1977). Hendey (op. cit.) has shown that discharge of polluted waters at the coast of Cornwall is best reflected in decreasing diversity expressed in terms of a decreasing Shannon-Weaver index. Recently this method has been applied to studies of diatom assemblages of riverine waters in Finland (e.g. Soininen et al. 2004) and in the Szczecin Lagoon (Bak 2004). The Szczecin Lagoon is a temperate climate lagoon with weak salinity gradient. The results of our study show that such transitional environment is characterised by a speciesrich diatom flora, which with respect to the species diversity is under strong influence of 294

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freshwater discharge of waters of the Odra River. Freshwater forms dominate in eastern and southern parts of the Lagoon. Saline waters impact the species composition to a significantly lower extent and they appear only in western and northern parts of the Lagoon, close to the Swina mouth, which is the main arm of the Odra mouth. STUDY SITE The Szczecin Lagoon is a vast, flow-through Baltic Sea coastal reservoir (Fig. 1). To the north, it is separated from the Baltic Sea by the so-called Swina Bar, the back-delta of the Swina River and by the islands of Wolin and Usedom. To the south, the Basin tapers into a narrow channel known as the Roztoka Odrzańska. The Polish part of the Lagoon (The Great Lagoon = Wielki Zalew), with its 687km2 area, is a main link in the Odra River discharge to the Baltic Sea. Three arms of the Odra mouth system (the rivers Peene, Swina, and Dziwna) are the major water exchange conduits between the Szczecin Lagoon and the Baltic Sea (Majewski 1980, Buckmann et al. 1998). The lagoon is a shallow basin, its average depth amounts to ca. 3.5m, while its maximum depth does not exceed 8.5m. The basin is intersected by an artificial navigation channel, ca. 11m deep, used by ships headed for the port of Szczecin. The channel is also a conduit for the Baltic water influxes up the Lagoon (Mikulski 1966, Majewski 1980). The Szczecin Lagoon capacity is 2.6km3. The freshwater discharge into the Lagoon originates primarily with the River Odra (97% of the total runoff), other rivers and the Baltic supplying much less water (3%; Mikulski 1966). Saline water enters the Lagoon during the wind-driven rise of the Baltic Sea water level in the Pomeranian Bay. Consequently, the Lagoon is always slightly saline. The long-term mean salinity is 1.2‰ (WIOŚ 2002), the highest salinity being recorded adjacent to the straits and in the navigation channel (Wypych 1970). The shallow water column of the Lagoon is strongly mixed and usually well oxygenated (Młodzińska 1980, Poleszczuk 1998). The main source of pollutants introduced into the Lagoon is the Odra runoff. MATERIAL AND METHODS The study is focused on the recent diatom flora of the Szczecin Lagoon. A total of 323 samples were collected in spring, summer, and autumn each year during 1998–2001. The samples were retrieved from various substrates in the coastal zone along the entire Polish part of the Lagoon, from a total of 26 sites located on the shores and on the bottom down to the depth of 1m (Fig. 1). Diatom samplings at each site were accompanied by collecting water samples for nutrient analyses and measuring some physical and chemical parameters (temperature, pH, O2, salinity, turbidity) with an integrated CTD profiler. The nutrient measured included inorganic (ammonia, nitrites, nitrates) and organic nitrogen as well as inorganic (orthophos295

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Fig. 1. Location of the study area.

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phates) and organic phosphorus. Diatom permanent preparations were made following the standard procedure (e.g. Battarbee 1986). In each slide 300 to 600 valves were counted. All permanent preparations and cleaned samples are deposited in collection of the Department of Palaeoceanology, Institute of marine Sciences, University of Szczecin. To analyse the diatom community structure, relative abundances (domination, Tümpling et al. 1999) of particular taxa, biodiversity index (Shannon and Weaver 1949) were calculated in each sample. Constancy of occurrence was calculated for each species identified in each sample. RESULTS Diversity During the sampling period in each year (spring, summer and autumn), the water temperature ranged from 2.41 to 21.34ºC. Salinity of the Lagoon varied within 0.15–3.49‰, while the dissolved oxygen concentration ranged within 42.4–224.9% (5.12–22.74mg/dm3) and showed a distinct seasonal variability. Water pH and turbidity varied within 7.25–9.58 and 1.5–464.2 NTU, respectively. Orthophosphate contents changed only slightly (0.017–0.088mg PO4/dm3), while organic phosphorus contents were higher (0.024–0.275mg/dm3). Total phosphorous contents ranged within 0.0068–0.363mg/dm3. Nitrate, nitrite, and ammonia contents varied within 0.051–0.242mg N–NO3/dm3, 0.002–0.034 mg N–NO2/dm3, and 0.013 –0.171 mg/dm3, respectively. Total nitrogen contents ranged within 0.255–1.159mg/dm3. In the recent diatom flora of the Lagoon a total of 521 taxa (species and varieties) were identified. They represented 74 genera. 45 taxa (species and varieties) belonged in the subclass of centric diatoms (8 genera), while 468 taxa were pennate diatoms (66 genera). Amongst all taxa identified 30 belonged in the group of the so called euconstant, i.e. those which were found to occur in 75 to 100% of samples analysed, 28 taxa were considered constant (occurred in 50–75% of samples), 48 taxa were found as accessory forms (present in 25–50% of the samples studied). The largest group of taxa – 369 were incidental forms, which were identified in 1 to 25 % of samples. A detailed list of constancy of occurrence of particular diatom taxa is given in Table 1. The analysed diatom flora is characterised by high species diversity. The number of taxa identified at particular sampling sites in all seasons ranged from 52 to 129 (median 83, average 81 taxa). The lowest number of taxa was recorded during summer 2000 at site 1 (Nowowarpieńskie Lake), while the highest one in spring 2001 at site 5 (Szczecin Lagoon, Brzózki). A certain spatial pattern in the diversity of diatoms in terms of species number was observed. The lowest numbers of taxa identified were recorded at sampling sites located in the northern or western Lagoon part, mainly during the summer or autumn. On the contrary the highest diversity was noted in southern or eastern sites and chiefly in spring and autumn. The Shannon–Weaver diversity index at 94.5% of sampling sites in all seasons exceeded values of 4. Values ranged from 3.38 to 5.92 (median 4.95, avearage 4.89). The lowest values of Shannon–Weaver diversity index were similar to the species number, recorded 297

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Table 1. List of taxa (species, varieties, forms) identified in the Szczecin Lagoon including their constancy of occurrence and the degree of domination (D = domination degree: +=<1%, 1= up to 1-3%, 2= up to 3-5%, 3= up to 5-10%, 4= up to 10-20%, 5= up to >20%, C = constancy of occurrence). TAXA

D

C [%]

Achnanthes bahusiensis (Grunow) Lange-Bertalot Achnanthes brevipes C. Agardh Achnanthes dispar Cleve Achnanthes lanceolata var. robusta (Hustedt) Lange-Bertalot Achnanthes lauenburgiana Hustedt Achnanthes lemmermannii Hustedt Achnanthes ploenensis var. gessneri (Hustedt) Lange-Bertalot Achnanthes ploenensis var. woldstedtii (Hustedt) Lange-Bertalot Achnanthes vistulana Witkowski Achnanthidium coarctatum (Brébisson) Grunow Achnanthidium minutissimum Kützing Achnanthidium subsalsum Petersen Actinocyclus normanii (Greg. ex Greville) Hustedt Adalfia aquaeductae (Krasske) Moser, Lange-Bertalot et Metzeltin Adalfia minuscula (Grunow) Lange-Bertalot Adalfia minuscula var. muralis (Grunow) Lange-Bertalot Amphora acutiuscula Kützing Amphora aequalis Krammer Amphora calumetica (Thomas) M. Peragallo Amphora coffeaeformis (C.A. Agardh) Kützing Amphora commutata Grunow Amphora copulata (Kützing) Schoeman et Archibald Amphora crucifera Cleve-Euler Amphora fogediana Krammer Amphora inariensis Krammer Amphora montana Krasske Amphora ovalis Kützing Amphora pediculus (Kützing) Grunow Amphora veneta Kützing Aneumastus balticus Lange-Bertalot Aneumastus minor (Hustedt) Lange-Bertalot Aneumastus stroeseii (Østrup) D.G. Mann Aneumastus tusculus (Ehrenberg) D.G. Mann et Stickle Anomoeoneis sphaerophora Pfitzer f. costata (Kützing) Schmidt Asterionella formosa Hassall Aulacoseira alpigena (Grunow) Krammer Aulacoseira ambigua (Grunow) Simonsen Aulacoseira crenulata (Ehrenberg) Thwaites

+ + + + + 4 1 + 1 1 4 + 3 + + + 3 + 1 1 + 3 + + 1 1 1 5 + + 1 1 + + 2 1 4 +

1,4 5,6 2,8 4,2 1,4 58,3 12,5 1,4 1,4 2,8 30,6 1,4 88,9 1,4 8,3 1,4 11,1 1,4 9,7 9,7 1,4 97,2 4,2 8,3 55,6 2,8 52,8 93,1 1,4 4,2 30,6 36,1 20,8 2,8 47,2 13,9 95,8 5,6

298

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Aulacoseira granulata (Ehrenberg) Simonsen Aulacoseira granulata var. angustissima (O. Müller) Simonsen Aulacoseira granulata var. valida (Hustedt) Simonsen Aulacoseira islandica (O.Müller) Simonsen Aulacoseira italica (Ehrenberg) Simonsen Aulacoseira italica var. tenuissima (Grunow) Simonsen Aulacoseira muzzanensis (Meister) Krammer Aulacoseira subarctica (O.Müller) Haworth Baccilaria paradoxa Gmelin Berkeleya rutilans (Trentepohl) Grunow Caloneis amphisbaena (Bory) Cleve Caloneis bacillum (Grunow) Cleve Caloneis lundii Hustedt Caloneis molaris (Grunow) Krammer Caloneis permagna (J.W. Bailey) Cleve Caloneis schumanniana (Grunow) Cleve Caloneis schumanniana var. biconstricta (Grunow) Reichelt Caloneis silicula (Ehrenberg) Cleve Catenula adherens Mereschkowsky Cavinula scutelloides (W. Smith) Lange-Bertalot Chamaepinnularia krookiformis (Krammer) Lange-Bertalot et Krammer Chamaepinnularia krookii (Grunow) Lange-Bertalot et Krammer Cocconeis disculus (Schumann) Cleve Cocconeis hauniensis Witkowski Cocconeis hoffmanii Simonsen Cocconeis neodiminuta Krammer Cocconeis neothumensis Krammer Cocconeis pediculus Ehrenberg Cocconeis peltoides Hustedt Cocconeis placentula Ehrenberg var. euglypta (Ehrenberg) Grunow Cocconeis placentula var. lineata (Ehrenberg) Van Heurck Cocconeis placentula var. placentula Ehrenberg Cocconeis placentula var. pseudolineata Geitler Cocconeis pseudothumensis Reichardt Cocconeis scutellum Ehrenberg Cosmioneis pusilla (W. Smith) D.G. Mann et Stickle Craticula halophila (Grunow ex Van Heurck) D.G. Mann Craticula molestiformis (Hustedt) Lange-Bertalot Cyclostephanos dubius (Fricke) Round Cyclostephanos invisitatus (Hohn et Hell.) Theriot, Stoermer et Håkansson

4 + 2 4 2 + 1 2 + + 1 + + + + + + + + 1 + + 1 + + 4 2 5 + 1 2 5 + 2 + 1 2 + 1 +

95,8 9,7 4,2 20,8 34,7 2,8 11,1 34,7 1,4 8,3 26,4 16,7 5,6 9,7 1,4 9,7 1,4 5,6 2,8 83,3 2,8 4,2 68,1 4,2 1,4 68,1 29,2 86,1 1,4 9,7 23,6 97,2 4,2 22,2 4,2 2,8 5,6 1,4 37,5 18,1

299

Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Table 1. Continued. TAXA

D

C [%]

Cyclostephanos tholiformis Stoermer, Håkansson et Theriot Cyclotella atomus Hustedt Cyclotella bodanica Grunow Cyclotella choctawhatcheeana Prasad Cyclotella comensis Grunow Cyclotella distinguenda Hustedt Cyclotella gamma Sovereign Cyclotella meneghiniana Kützing Cyclotella radiosa (Grunow) Lemmermann Cyclotella scaldensis Muylaert et Sabbe Cyclotella stelligera Cleve et Grunow Cyclotella stelligeroides Hustedt Cyclotella striata (Kützing) Grunow Cymatopleura solea (Brébisson) W. Smith Cymatopleura solea var. apiculata (W. Smith) Ralfs Cymbella affinis Kützing Cymbella ancylli Cleve Cymbella aspera (Ehrenberg) Cleve Cymbella cistula (Ehrenberg) Kirchner Cymbella compacta Østrup Cymbella helmckei Krammer Cymbella helvetica Kützing Cymbella lanceolata (Ehrenberg) Van Heurck Cymbella minuta Hilse ex Rabenhorst Cymbella naviculiformis Auerswald Cymbella subaequalis Grunow Diadesmis contenta (Grunow ex Van Heurck) D.G. Mann Diatoma ehrenbergii Kützing Diatoma hyemalis (Roth) Heiberg var. hyemalis Diatoma moniliformis Kützing Diatoma moniliformis ssp. ovalis (Fricke) Lange-Bertalot Diatoma tenuis Agardh Diatoma vulgaris Bory Dickieia subinflata (Grunow) D.G. Mann Dickieia resistans Witkowski, Lange-Bertalot et Metzeltin Diploneis boldtiana Cleve Diploneis decipiens var. parallela A. Cleve Diploneis didyma Ehrenberg Diploneis domblittensis (Grunow) Cleve Diploneis oblongella (Naegeli) Cleve-Euler

+ 2 + + + + + 1 + + + + + + + + + + 2 + + + 1 + + + 4 + + 1 + 2 + + 1 1 + + + +

2,8 40,3 1,4 26,4 1,4 1,4 1,4 93,1 22,2 1,4 1,4 1,4 2,8 4,2 1,4 1,4 1,4 1,4 33,3 1,4 1,4 2,8 11,1 1,4 1,4 1,4 4,2 1,4 1,4 34,7 2,8 69,4 15,3 1,4 25 15,3 2,8 1,4 50 2,8

300

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Diploneis ovalis (Hilse) Cleve Diploneis parma Cleve Diploneis pseudovalis Hustedt Diploneis smithii (Brébisson) Cleve Diploneis smithii var. dilatata (M. Peragallo) Terry Diploneis smithii var. recta Mereschkowsky Diploneis smithii var. rhombica Mereschkowsky Ellerbeckia arenaria (Moore) Crawford Encyonema caespitosum Kützing Encyonema prostratum (Berkeley) Kützing Encyonema silesiacum (Bleisch) D.G. Mann Enoyonopsis microcephala (Grunow) Krammer Entomoneis costata (Hustedt) Reimer Entomoneis paludosa (W. Smith) Reimer Epithemia adnata (Kützing) Brébisson Epithemia frickei Krammer Epithemia sorex Kützing Epithemia turgida (Ehrenberg) Kützing var. turgida Eunotia bilunaris (Ehrenberg) Mills var. bilunaris Eunotia circumborealis Nörpel et Lange-Bertalot Fallacia cassubiae Witkowski Fallacia clepsidroides Witkowski Fallacia forcipata (Greville) Stickle et D.G. Mann Fallacia lenzii (Hustedt) Reichardt Fallacia pygmaea (Kützing) Stickle et D.G. Mann Fallacia semilyrata (Simonsen) D.G. Mann Fallacia subhamulata Cleve-Euler Fallacia tenera (Hustedt) D.G. Mann Fistulifera saprophila (Lange-Bertalot et Bonik) Lange-Bertalot Fragilaria amicorum Witkowski et Lange-Bertalot Fragilaria atomus Hustedt Fragilaria berolinensis (Lemmermann) Lange-Bertalot Fragilaria brevistriata Grunow Fragilaria capucina Desmazieres Fragilaria capucina var. mesolepta (Rabenhorst) Rabenhorst Fragilaria capucina var. vaucheriae (Kützing) Lange-Bertalot Fragilaria cassubica Witkowski et Lange-Bertalot Fragilaria construens (Ehrenberg) Grunow var. trigona Brun et Héribaud Fragilaria crotonensis Kitton Fragilaria delicatissima (W. Smith) Lange-Bertalot

+ + + 3 + 1 + + 1 + + + + + 1 + + + + + + 2 + + + + + + + 1 + 4 4 4 + 5 1 + + +

1,4 1,4 1,4 45,8 5,6 5,6 1,4 9,7 9,7 2,8 12,5 1,4 1,4 6,9 18,1 4,2 13,9 4,2 2,8 1,4 8,3 29,2 1,4 4,2 12,5 1,4 1,4 1,4 5,6 1,4 1,4 79,2 98,6 58,3 2,8 84,7 4,2 2,8 1,4 2,8

301

Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Table 1. Continued. TAXA

D

C [%]

Fragilaria dilatata (Brébisson) Lange-Bertalot Fragilaria elliptica Schumann Fragilaria famelica (Kützing) Lange-Bertalot Fragilaria gedanensis Witkowski Fragilaria gracilis Østrup Fragilaria inflata (Heiden) Hustedt var. istvanffyi (Pantocsek) Hustedt Fragilaria lapponica Grunow Fragilaria martyi (Héribaud) Lange-Bertalot Fragilaria nanana Cleve-Euler Fragilaria neoelliptica Witkowski Fragilaria oldenburgiana Hustedt Fragilaria parasitica var. parasitica (W. Smith) Grunow Fragilaria pinnata Ehrenberg Fragilaria pinnata var. intercedens (Grunow) Hustedt Fragilaria polonica Witak et Lange-Bertalot Fragilaria pulchella (Ralfs ex Kützing) Lange-Bertalot Fragilaria schulzii Brockmann Fragilaria sopotensis Witkowski et Lange-Bertalot Fragilaria subsalina (Grunow) Lange-Bertalot Fragilaria zeileri Héribaud Frustulia creuzburgensis (Krasske) Hustedt Frustulia vulgaris (Thwaites) De Toni Geissleria deccussis (Østrup) Lange-Bertalot et Metzeltin Geissleria ignota var. acceptata (Hustedt) Lange-Bertalot et Metzeltin Geissleria schoenfeldii (Hustedt) Lange-Bertalot et Metzeltin Geissleria similis (Krasske) Lange-Bertalot et Metzeltin Gomphonema acuminatum Ehrenberg Gomphonema affine Kützing Gomphonema angustatum (Kützing) Rabenhorst Gomphonema angusticephalum Reichardt et Lange-Bertalot Gomphonema aquaeminerale Lange-Bertalot et Reichardt Gomphonema augur Ehrenberg Gomphonema bohemicum Reichelt et Fricke Gomphonema bozenae Lange-Bertalot et Reichardt Gomphonema olivaceum (Hornemann) Brébisson Gomphonema olivaceum var. balticum (Cleve) Grunow Gomphonema parvulum Kützing Gomphonema productum (Grunow) Lange-Bertalot et Reichardt Gomphonema pseudoaugur Lange-Bertalot Gomphonema pseudobohemicum Lange-Bertalot et Reichardt

+ + 2 + + 3 + 3 + + + + 4 + + 4 + 4 3 + + + + + + + + + + + + + + + 3 4 4 + + +

1,4 4,2 44,4 1,4 4,2 56,9 2,8 91,7 1,4 1,4 1,4 1,4 98,6 1,4 1,4 29,2 2,8 94,4 68,1 2,8 1,4 9,7 26,4 1,4 18,1 1,4 2,8 1,4 5,6 1,4 1,4 1,4 1,4 1,4 72,2 33,3 81,9 1,4 1,4 1,4

302

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Gomphonema pseudotenellum Lange-Bertalot Gomphonema sarcophagus Gregory Gomphonema stauroneiforme (Grunow) Fricke Gomphonema tergestinum (Grunow) Fricke Gomphonema truncatum Ehrenberg Gyrosigma acuminatum (Kützing) Rabenhorst Gyrosigma attenuatum (Kützing) Cleve Gyrosigma nodiferum (Grunow) Reimer Gyrosigma wansbeckii (Donkin) Cleve Hantzschia amphioxys (Ehrenberg) Grunow Hippodonta arconensis Lange-Bertalot, Metzeltin et Witkowski Hippodonta capitata (Ehrenberg) Lange-Bertalot, Metzeltin et Witkowski Hippodonta costulata (Grunow) Lange-Bertalot, Metzeltin et Witkowski Hippodonta costulatoides Lange-Bertalot, Metzeltin et Witkowski Hippodonta hungarica (Grunow) Lange-Bertalot, Metzeltin et Witkowski Hippodonta lesmonensis (Hustedt) Lange-Bertalot, Metzeltin et Witkowski Hippodonta linearis (Østrup) Lange-Bertalot, Metzeltin et Witkowski Hippodonta neglecta Lange-Bertalot, Metzeltin et Witkowski Karayevia clevei (Grunow) Round et Bukhtiyarova Karayevia clevei var. bottnica (Grunow) Round et Bukhtiyarova Karayevia laterostrata (Hustedt) Round et Bukhtiyarova Karayevia oblongella Østrup Karayevia temniskovae sp. nov. Kolbesia kolbei (Hustedt) Round et Bukhtiyarova Kolbesia ploenensis (Hustedt) Round et Bukhtiyarova Lemnicola hungarica (Grunow) Round et Basson Leptocylindrus danicus Cleve Luticola geoppertiana (Bleisch) D.G. Mann Luticola mutica (Kützing) D.G. Mann Luticola mutica var. ventricosa (Kützing) Hamilton Luticola muticopsis (Van Heurck) D.G. Mann Mayamaea agrestis Hustedt Mayamaea atomus (Kützing) Lange-Bertalot Melosira dickei (Thwaites) Kützing Melosira moniliformis (O.F. Müller) Agardh Melosira varians Agardh Meridion circulare (Greville) C.A.Agardh Navicula antonii Lange-Bertalot Navicula arkona Lange-Bertalot et Witkowski Navicula bacilloides Hustedt

+ + + + + + + + + + + 3 1 + 3 2 2 + 2 + + + 1 + + 3 1 + 4 + + + 1 + + 3 + 1 + +

1,4 1,4 23,6 6,9 9,7 19,4 22,2 15,3 1,4 4,2 1,4 26,4 37,5 4,2 91,7 51,4 43,1 1,4 76,4 2,8 1,4 1,4 9,6 2,8 6,9 30,6 1,4 1,4 37,5 1,4 1,4 1,4 20,8 1,4 1,4 12,5 6,9 15,3 1,4 2,8

303

Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Table 1. Continued. TAXA

D

C [%]

Navicula biskanterae Hustedt Navicula bottnica Grunow Navicula bourrellyivera Lange-Bertalot, Witkowski et Stachura Navicula capitatoradiata Germain Navicula cari Ehrenberg Navicula cincta (Ehrenberg) Ralfs Navicula constans Hustedt Navicula contenta Grunow Navicula cryptocephala Kützing Navicula cryptotenella Lange-Bertalot Navicula cryptotenelloides Lange-Bertalot Navicula digitoconvergens Lange-Bertalot Navicula digitoradiata (Gregory) Ralfs Navicula exilis Kützing Navicula germanopolonica Witkowski et Lange-Bertalot Navicula graciloides Mayer Navicula gregaria Donkin Navicula hanseatica Lange-Bertalot et Stachura Navicula integra (W. Smith) Ralfs Navicula iserentantii Lange-Bertalotet et Witkowski Navicula kevfingensis (Ehrenberg) Kützing Navicula lanceolata (Agardh) Ehrenberg Navicula latens Krasske Navicula menisculoides Hustedt Navicula menisculus var. menisculus Schumann Navicula meniscus Schumann Navicula microcari Lange-Bertalot Navicula minima Grunow Navicula modica Hustedt Navicula moskalii Metzeltin, Witkowski et Lange-Bertalot Navicula namibica Lange-Bertalot et Rumrich Navicula opportuna Hustedt Navicula oppugnata Hustedt Navicula paul-schulzii Witkowski et Lange-Bertalot Navicula pelliculosa (Brébisson ex Kützing) Hilse Navicula peregrina (Ehrenberg) Kützing Navicula perminuta Grunow Navicula phyllepta Kützing Navicula platystoma Ehrenberg Navicula pseudoanglica Cleve-Euler

+ + + + 1 1 + + 2 3 + 3 + + + + 5 3 + + + 1 + + 3 + + 4 + + + + 1 + + + 3 + + +

2,8 1,4 1,4 6,9 65,3 40,3 1,4 1,4 16,7 66,7 5,6 18,1 11,1 1,4 1,4 2,8 100 70,8 1,4 1,4 9,7 54,2 1,4 1,4 45,8 29,2 4,2 37,5 1,4 5,6 1,4 1,4 62,5 1,4 5,6 2,8 5,6 1,4 11,1 2,8

304

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Navicula pseudolanceolata Lange-Bertalot Navicula radiosa Kützing Navicula recens (Lange-Bertalot) Lange-Bertalot Navicula reichardtiana var. reichardtiana Lange-Bertalot Navicula reinhardtii (Grunow) Grunow Navicula rhynchocephala Kützing Navicula rhynchotella Lange-Bertalot Navicula rostellata Kützing Navicula salinarum Grunow Navicula seminulum Grunow Navicula slesvicensis Grunow Navicula striolata (Grunow) Lange-Bertalot Navicula subminuscula Manguin Navicula submuralis Hustedt Navicula subplacentula Hustedt Navicula subrhynchocephala Hustedt Navicula subrotundata Hustedt Navicula tenelloides Hustedt Navicula tripunctata (O.F. Müller) Bory Navicula trivialis Lange-Bertalot Navicula uppsaliensis Grunow Navicula vaneei Lange-Bertalot Navicula veneta Kützing Navicula wiesnerii Lange-Bertalot Navicula witkowskii Lange-Bertalot, Iserentant et Metzeltin Neidium dubium (Ehrenberg) Cleve Neidium iridis (Ehrenberg) Cleve Neidium opulentum Hustedt Nitzschia acicularis (Kützing) W. Smith Nitzschia acicularoides Hustedt Nitzschia acuminata (Smith) Grunow Nitzschia aequorea Hustedt Nitzschia agnita Hustedt Nitzschia amphibia Grunow f. amphibia Nitzschia aurariae Cholnoky Nitzschia austriaca Hustedt Nitzschia brevissima Grunow Nitzschia calcicola Aleem et Hustedt Nitzschia calida Grunow Nitzschia capitellata Hustedt

+ + + 3 1 + 1 + + + 2 + + + 2 + + + 3 + + + 2 + + + + + 1 1 + + + 3 + + + + + 2

4,2 4,2 6,9 62,5 45,8 5,6 9,7 1,4 2,8 5,6 41,7 4,2 2,8 4,2 36,1 1,4 16,7 2,8 93,1 1,4 1,4 1,4 61,1 8,3 1,4 5,6 22,2 1,4 11,1 4,2 1,4 4,2 11,1 26,4 1,4 1,4 4,2 1,4 4,2 50

305

Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Table 1. Continued. TAXA

D

C [%]

Nitzschia commutata Grunow Nitzschia constricta (Kützing) Ralfs Nitzschia debilis (Arnott) Grunow Nitzschia diserta Hustedt Nitzschia dissipata (Kützing) Grunow var. dissipata Nitzschia dubia W. Smith Nitzschia filiformis (W. Smith) Van Heurck Nitzschia fonticola Grunow Nitzschia fontifuga Cholnoky Nitzschia frustulum (Kützing) Grunow var. frustulum Nitzschia gracilis Hantzsch Nitzschia graciloides Hustedt Nitzschia heufleriana Grunow Nitzschia hungarica Grunow Nitzschia inconspicua Grunow Nitzschia levidensis (W. Smith) Grunow Nitzschia levidensis (W. Smith) Grunow var victoriae (Grunow) Cholnoky Nitzschia levidensis var. salinarum Grunow Nitzschia linearis (Agardh) W. Smith var. linearis Nitzschia littoralis Grunow Nitzschia microcephala Grunow Nitzschia nana Grunow Nitzschia palea (Kützing) W. Smith Nitzschia paleacea (Grunow) Grunow Nitzschia parvula W. Smith Nitzschia pellucida Grunow Nitzschia perindistincta Cholnoky Nitzschia perminuta (Grunow) M. Peragallo Nitzschia perspicua Cholnoky Nitzschia pura Hustedt Nitzschia pusilla (Kützing) Grunow Nitzschia recta Hantzsch ex Rabenhorst Nitzschia rectirobusta Lange-Bertalot Nitzschia rosenstockii Lange-Bertalot Nitzschia scotica (Grunow) Van Heurck Nitzschia sigma (Kützing) W. Smith Nitzschia sigmoidea (Nitzsch) W. Smith Nitzschia sociabilis Hustedt Nitzschia supralittorea Lange-Bertalot Nitzschia thermaloides Hustedt

+ + + + 1 + + 1 + 4 1 + 1 + 4 + + + + + 2 + 2 1 + + + 1 + + 1 1 + 2 + + + + 2 +

5,6 2,8 4,2 1,4 61,1 4,2 6,9 15,3 4,2 83,3 9,7 5,6 13,9 6,9 50 5,6 1,4 2,8 9,7 1,4 55,6 1,4 84,7 29,2 1,4 1,4 1,4 2,8 6,9 1,4 18,1 18,1 1,4 26,4 2,8 1,4 6,9 1,4 29,2 1,4

306

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Nitzschia tubicola Grunow Nitzschia umbonata (Ehrenberg) Lange-Bertalot Østrupia zachariasi (Reichelt) Hustedt Opephora krumbeinii Witkowski, Witak et Stachura Opephora mutabilis (Grunow) Sabbe et Vyverman Parlibellus protracta (Grunow) Cleve Parlibellus protractoides Hustedt Petroneis humerosa (Brébisson ex W. Smith) Stickle et D.G. Mann Pinnularia alpina W. Smith Pinnularia borealis Ehrenberg var. borealis Pinnularia gibba Ehrenberg Pinnularia microstauron (Ehrenberg) Cleve Pinnularia neglectiformis (Mayer) Berg Pinnularia nodosa (Ehrenberg) W. Smith Pinnularia obscura Krasske Pinnularia rupestris Hantzsch Pinnularia similis Hustedt Pinnularia sinistra Krammer Pinnularia subcapitata Gregory var. subcapitata Pinnularia subrostrata (A. Cleve) Cleve-Euler Pinnularia sudetica (Hilse) Hilse Pinnularia viridis (Nitzsch) Ehrenberg Placoneis clementis (Grunow) Cox Placoneis elginensis (Greg.) Cox var. elginensis Placoneis elginensis var. cuneata (Moller ex Foged) Haw et Kelly Placoneis gastrum (Ehrenberg) Mereschkowsky Placoneis gastrum var. signata (Hustedt) Mayama Placoneis placentula (Ehrenberg) Heinzerling Placoneis porifera Hustedt (Ohtsuka et Fujita) Planothidium delicatulum (Kützing) Round et Bukhtiyarova Planothidium engelbrechtii (Cholnoky) Round et Bukhtiyarova Planothidium frequentissimum (Lange-Bertalot) Round et Bukhtiyarova Planothidium hauckianum (Grunow) Round et Bukhtiyarova Planothidium joursacense (Héribaud) Lange-Bertalot Planothidium lanceolatum (Brébisson) Round et Bukhtiyarova Planothidium peragalli (Brun et Héribaud) Round et Bukhtiyarova Planothidium septentrionalis (Østrup) Round et Bukhtiyarova Pleurosigma normanii Ralfs Pleurosira laevis (Ehrenberg) Compere f. polymorpha (Kützing) Compere Psammmothidium biorettii (Germain) Bukhtiyarova et Round

2 + + + 5 + + + + + + + + + 1 + + + + + + + 2 1 + + + 2 + 5 5 + + + 4 + + + + +

56,9 6,9 1,4 2,8 98,6 13,9 2,8 2,8 2,8 4,2 1,4 5,6 1,4 1,4 2,8 1,4 1,4 1,4 1,4 1,4 1,4 9,7 70,8 8,3 2,8 6,9 2,8 31,9 4,2 100 97,2 5,6 2,8 15,3 88,9 1,4 1,4 1,4 4,2 4,2

307

Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Table 1. Continued. TAXA

D

C [%]

Reimeria sinuata (Gregory) Kociolek et Stoermer Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot Rhopalodia gibba var. gibba (Ehrenberg) O. Müller Rhopalodia gibberula (Ehrenberg) O. Müller Rhopalodia rupestris (W. Smith) Krammer Sellaphora americana (Ehrenberg) D.G. Mann Sellaphora bacillum (Ehrenberg) D.G. Mann Sellaphora laevissima (Kützing) D.G. Mann Sellaphora mutata (Krasske) Lange-Bertalot Sellaphora mutatoides Lange-Bertalot et Metzeltin Sellaphora pseudopupula (Krasske) Lange-Bertalot Sellaphora pupula (Kützing) Mereschowsky Skeletonema subsalsum (A. Cleve) Bethge Stauroneis acuta Smith Stauroneis anceps Ehrenberg Stauroneis kriegeri Patrick Stauroneis smithii Grunow Stauroneis thermicola (Petersen) Lund Staurosira binodis (Ehrenberg) Lange-Bertalot Staurosira construens Ehrenberg Staurosira construens var. exigua (Smith) Lange-Bertalot Staurosira subsalina (Husted) Lange-Bertalot Staurosira venter (Ehrenberg) Cleve et Möller Stephanodiscus alpinus Hustedt Stephanodiscus binderanus (Kützing) Krieger Stephanodiscus galileensis Håkansson et Ehrlich Stephanodiscus hantzschii Grunow Stephanodiscus hantzschii var. tenuis (Hustedt) Håkansson et Stoermer Stephanodiscus medius Håkansson Stephanodiscus minutulus (Kützing) Sims Stephanodiscus neoastraea Håkansson et Hickel Stephanodiscus parvus (Grunow) Sroermer et Håkansson Stephanodiscus rotula (Kützing) Hendey Surirella brébissonii Krammer et Lange-Bertalot Surirella elegans Ehrenberg Surirella marina Krammer Surirella ovalis Brébisson Surirella patella Kützing Tabellaria fenestrata Falfs Tabellaria flocculosa (Roth) Kützing

1 5 + 1 + + + + + + + + 2 + + + 1 + 2 3 + 1 2 2 + + 5 + + 2 3 2 1 2 + + + + + +

1,4 100 5,6 1,4 1,4 1,4 5,6 1,4 8,3 2,8 1,4 29,2 37,5 1,4 1,4 1,4 2,8 1,4 48,6 50 8,3 38,9 40,3 83,3 1,4 1,4 94,4 1,4 1,4 13,9 86,1 48,6 25 33,3 2,8 1,4 1,4 1,4 1,4 1,4

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Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

Table 1. Continued. TAXA

D

C [%]

Tabularia fasciculata (Agardh) Williams et Round Tabularia investiens (Smith) Williams et Round Terpsinoe americana (Bailey) Ralfs Thalassiosira baltica (Grunow) Ostensfeld Thalassiosira levanderi Van Goor Thalassiosira proschkinae Makarova Thalassiosira pseudonana (Husted) Hasle et Heimdal Ulnaria acus (Kützing) Compère Ulnaria oxyrhynchus (Kützing) Compère Ulnaria ulna (Nitzsch) Compère

3 + + + + + + + + 1

61,1 1,4 1,4 22,2 1,4 2,8 4,2 18,1 1,4 50

at site 1 in summer 2000, while the highest at site 5 in spring 2001. The values of Evenness ranged from 0.59 to 0.87 (median 0.78, average 0.77). The lowest value of Evenness was recorded on site 1 in summer 2000, while the higest on site 7 in spring 2000. Spatial and temporal distribution of Shannon-Weaver and Evenness indices showed the same pattern as the distribution of taxa. Taking into consideration seasonal pattern changes, the diversity of the diatom community was analysed in spring, summer and autumn. During all spring seasons the number of taxa in the Lagoon on the whole ranged from 59 to 129. The median and average values (87 taxa) were the highest compared to the other seasons. Diversity index attained values ranging from 4.09 to 5.92 (median 4.97 average 5.02). Whereas, ecological Evenness values ranged from 0.65 to 0.87 (median and average 0.78). The lowest average values of all parameters characterising the diversity were recorded in summer seasons. The number of species at particular sampling sites ranged from 52 to 93 (median 71, average 73), the Shannon-Weaver index of biological diversity attained values 3.38-5.41 (median 4.8, average 4.71) and Evenness 0.59-0.84 (median 0.78, average 0.76). In autumn the range of taxa number at particular sampling sites resembled that of spring period (54 to 126), but average values were lower (median and average – 83 taxa). The Shannon-Weaver index of diversity ranged from 3.96 to 5.71 (median 5.09, average 4.95), and Evenness index attained values of 0.67-0.86 (median 0.8, average 0.78). Despite seasonal differences, chiefly in their averages, of parameters characterising the diversity, a certain pattern of distribution is observed. Respectless the season of the year they reached the lowest values in the northwestern part of the Lagoon (sampling sites 1, 20, 24), and the highest in southern and eastern parts (sampling sites 3, 5, 7, 13, 15).

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Małgorzata Bąk, Andrzej Witkowski and Horst Lange-Bertalot

Description of a new species Karayevia temniskovae Witkowski, Lange-Bertalot & Bąk spec. nov. Diagnosis differens versus Karayevia clevei (Grunow) Bukhtiyarova 1999 Valvae late lanceolate ad lanceolatae-ellipticas vel paene ellipticae quoad individua minutissima apicibus plerumque plus minusve cuneatis. Longitudo 6-14 µm, latitudo 4-5.5 µm (ita dimensiones circiter inferiores quam K. clevei). Raphovalva: Raphe recta extremis centralibus densius sitis inter se. Area axialis angustissima distaliter tum dilatata ad aream centralem indistincte parvam versus. Striae transapicales radiantes omnino vel mediis fere parallelis, 25-27 (nec 16-24) in 10 µm. Areovalva: Area axialis comparate latior fere lanceolata ad instar quia distincte dilatata in media parte. Striae transapicales densius sitae, 24-26 (nec 9-16) in 10 µm. Aspectus ultramicroscopicus externus internusque vide etiam Round et Bukhtiyarova 1996, figurae 17 et 18 (nec fig. 1316 repraesentantes vero K. clevei).

Typus: Praep. No. 7933 in Coll. A. Witkowski Isotypi: Slide No. ZU5/95, Friedrich Hustedt Diatom Collection, AWI Bremerhaven; Slide No. BM 101274 Natural History Museum London; Locus typicus: Danziger Heisternest, Bohrung 43-45 m, Leg. Paul Schulz This taxon is dedicated to our colleague, Prof. Dr. Dobrinka Temniskova-Topalova on the occasion of her 70th birthday. Description (LM). Valves linear lanceolate to lanceolate-elliptic or almost elliptic in smallest specimens; ends more or less cuneately rounded. Length 6-14 µm, breadth 4-5.5 µm. Raphid valve: raphe straight, axial area narrow, slightly broadened into a small or indistinctly circular central area. Transapical striae radiate becoming subparallel in the central part of the valve, 25-27 in 10 µm. Rapheless valve: axial area relatively broad, linearlanceolate, distinctly expanded in the middle. Transapical striae composed of relatively robust elongate puncta, best developed in the valve marginal zone, 24-26 in 10 µm. Description (SEM) Remarks: So far only rapheless valves have been observed in our investigations. Observation of raphe valve of Karayevia temniskovae is based on illustrations provided by Round and Bukhtiyarova (1996, figs 17, 18). They have used these figures erroneously to illustrate raphe valve of Karayevia clevei (cf. Fig. 13 in the same publication, which shows the raphe valve of K. clevei). RLV: Sternum linear-lanceolate, expanded in the middle. Transapical striae composed of elongate areolae. RV: raphe straight, external central raphe endings close-standing and slightly expanded, apical raphe endings bent in the same direction. Sternum narrow, linear-lanceolate, slightly expanded in the middle. Central area very small to absent. Transapical striae composed of irregularly spaced areolae, with slit-like marginal and adjacent to the raphe areolae.

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Differential diagnosis compared to Karayevia clevei It is the raphe valve of both species, which is similar in particular the raphe and the striation pattern. They differ, however, with respect to the distance between the raphe external central endings distinctly closer in K. temniskovae than in K. clevei, very narrow axial area in K.

Figs 2-20. Figs 2-17. LM, scale bar for all light microscope images = 10 µm. Karayevia temniskovae, specimens from the type population. Fig. 18. SEM, scale bar = 10 µm. Rapheless valve of K. temniskovae, note elongated areolae and distinctly broadened strenum. Figs 19, 20. LM. Light microscopic images of Karayevia clevei to compare with a new species. Fig. 19. Rapheless valve of K. clevei, note very narrow sternum and parallel striae composed of round areolae. Fig. 20. Raphe valve of K. clevei, note distinct, in comparison to K. temniskovae, radiate striation.

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temniskovae and the striae density which is finer in K. temniskovae than in K. clevei. Moreover the most distinct difference between the two taxa is the striation pattern. In K. clevei the striae of RLV are composed of almost circular areolae and the sternum is relatively narrow, whereas in K. temniskovae the sternum is broader, expanded in the middle and the striae are composed of elongate, irregular areolae. In addition K. temniskovae has a higher number of striae. The number of striae is 24 to 26 in 10 µm (not 9-16 in 10 µm as in K. clevei). Ecology and distribution Karayevia temniskovae is found in several localities around the southern and south-western Baltic Sea coast. It always occurred in association with predominantly brackish-water species, which tolerate salinity up to ca. 10 psu and some freshwater species which tolerate weakly saline waters. These are e.g. Amphora pediculus, Fallacia clepsidroides, Fragilaria atomus, F. sopotensis, Melosira lineata. K. temniskovae is quite frequent in the Szczecin Lagoon, the Gulf of Gdańsk (up to 10 m water depth) and in the littoral of the Puck Bay. Its frequent occurrence there, near the discharge from the waste water treatment plant in Swarzewo, indicates that K. temniskovae belongs to a species group tolerating polyeutrophic waters. We have also identified it frequently occurring in the Holocene marine sediments of the southern and south-western Baltic Sea coast characteristic for the initial stage of the Littorina transgression, the so-called Mastogloia Sea. From the SEM image provided by Round & Bukhtiyarova (1996) we assume that the species occurs also in England. We suspect that it is fairly widespread in the Baltic Sea but was errneously identified as K. clevei. DISCUSSION The whole area of the Szczecin Lagoon was characterised by very high species diversity of diatom flora in terms of Shanon–Weaver index values exceding 4. Such high species diversity resulted from occurence of freshwater taxa, as they constituted the largest halobous group with respect to the species number. Simultaneously they reached insignificant relative abundance. 239 taxa out of the total number of 521 taxa which were represented in recent diatom flora of the Szczecin Lagoon belonged in freshwater group, altough at all sampling sites of the Lagoon dominated taxa representative for other halobous groups. Similar situation was observed in case of other diatom ecological groups. A species group of circumneutral pH preferences (102 taxa), and also oligosaprobiontic forms (56 taxa) were characterised by a number of taxa all of which attained quite low relative abundance. All three analysed parameters of biodiversity (species richness, diversity index of Shanon–Weaver and Evenness) showed the same pattern. They reached the lowest values, regardless of the seasons, in northern and western part of lagoon, while the highest in southern and eastern ones. Analysis of the temporal pattern showed that highest average values were attained by the indices discussed in spring whereas the lowest ones in summer. Such a spatial and temporal distribution of the species diversity indicators was affected by 312

Diatom flora diversity in the strongly eutrophicated and β-mesosaprobic waters of the Szczecin Lagoon

two major factors. These were: marine waters which impacted the distribution of freshawater species and inflow of fertile Odra river waters, discharging nutrients and enhancing the growth of the whole diatom flora inhabiting the Szczecin Lagoon. Increase of the species number with an icreasing trophy is quite well known phenomenon and was also observed by e.g. Heinonen (1980) in Finish Lakes. Diatom assemblages with similar species composition were also recorded in other regions of the world, either in lagoons or in estuaries. A diatom assemblage including Aulacoseira granulata, Diploneis smithii, Diploneis bombus, Opephora mutabilis, Cocconeis placentula var. placentula, Fragilaria martyi, Catenula adherens, Rhopalodia gibba var. gibba, Actinocyclus normanii and Melosira moniliformis was recorded in two coastal lagoons–Laguna de Rocha and Laguna Castillos in Uruguay (Garcia–Rodriguez 2002). Whereas Cyclotella meneghiniana, Diploneis smithii, Navicula cryptocephala, Navicula lanceolata, Surirella brebissonii and Surirella robusta were constant components and attained highest abundance in Rupert Bay (James Bay) estuary in Canada (De Sève 1993). The taxa encountered in the Szczecin Lagoon e.g. Achnanthidium minutissimum, Amphora veneta, Berkeleya rutilans, Craticula halophila, Fallacia pygmaea, Fistulifera saprophila, Gomphonema parvulum, Hippodonta hungarica, Navicula gregaria, N. perminuta, N. salinarum, N. veneta, Nitzschia acicularis, N. acicularoides, N. aurariae, N. capitellata, N. frustulum, N. hungarica, N. microcephala, N. nana, N. palea and N. pusilla were also recorded in other geographic locations from fairly different climatic and hydrological conditions. The above diatom species have very broad distribution and were identified in various environmental settings. They were found to occur in subtropical lagoons including Mediterranean lagoons (e.g. Venice Lagoon, Cholnoky 1961, Santa Lucia Lagoon in South Africa, Cholnoky 1968; hypersaline Lagoa de Araruama in Brasil, Silvestre et al. 2001, in Albanian coastal Lagoons, Miho and Witkowski 2005), periodically dry Mediterranean salt marshes of Empordà in Spain (e.g. Trobajo–Pujadas 2003) and amongst the diatom flora of the temperate climate lagoons and estuaries (e.g. Brockmann 1950, Hustedt 1957, Kuylenstierna 1989-1990, Witkowski 1994, Busse and Snoeijs 2002). CONCLUSIONS 1. In all regions of the Szczecin Lagoon very high diversity of the diatom flora was encountered. The maesure of the diversity, Shanon–Weaver index values exceeded 4. The major factor affecting such high diversity was occurrence of freshwater taxa, which represented the largest halobous group with respect to species number but their abundance was insignificant. 2. Parameters of biodiversity i.e. species richness, Shannon–Weaver diversity index and Evenness, attained lowest values, regardless the season of the year, in northern and in western parts of the lagoon, whereas the highest in southern and eastern ones. The mentioned indices showed distinct seasonality reaching the highest average values in spring and the lowest in summer.

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ACKNOWLEDGEMENTS Access to the material of Paul Schulz deposited in the Royal Museum of Natural History in Stockholm was possible due to the scholarship granted by Swedish Institute to A.W. The authors are grateful to Prof. Urve Miller for supporting the grant application and to the Swedish Institute for financing the visit of A.W. to the Quaternary Institute of Stockholm University. This contribution was supported by grants No 6P04G 081 20 and 6PO4E003 16 from Polish Commitee on Scientific Research, granted to M. Bak. REFERENCES ANDRÉN, E. 1995. Recording environmental changes in the southern Baltic Sea - current results from a diatom study within project ODER. in: Proceedings of 13th International Diatomist Symposium 1994. Biopress, Bristol: 443-455. ANDRÉN, E. 1999. Changes in the composition of the diatom flora during the last century indicate increased eutrophication of the Oder Estuary, south-western Baltic Sea. Estuarine Coastal and Shelf Science, 48: 665-676. BąK, M. 2004. Changes in species composition of the diatom (Bacillariophyceae) flora of the Szczecin Lagoon (Northern Poland) as a result of long-term inflow of polluted Odra River waters. - PhD thesis, University of Szczecin: 230 pp. (in Polish) BąK, M., B. WAWRZYNIAK-WYDROWSKA and A. WITKOWSKI 2001. Odra river discharge as a factor affecting species composition of the Szczecin Lagoon diatom flora, Poland. in: Jahn, R., J.P. Kociolek, A. Witkowski and P. Compère, editors. Lange-BertalotFestschrift. - A.R.G. Gantner K.G., Ruggell: 491-506. BąK, M, A. WITKOWSKI, H. LANGE-BERTALOT and A. DADAŁ 2004. Ecology of the Szczecin Lagoon’s diatom flora with reference to the utility of diatom indices in assessing water quality. – Diatom. Japanese Journal of Diatomology, 20: 23-32. BATTARBEE, R.W. 1986. Diatom analysis. in: Berglund B.E., editor. Handbook of Holocene Palaeoecology and Palaeohydrology. Jonh Wiley & Sons: 527-570. BOGACZEWICZ-ADAMCZAK, B. and M. DZIENGO 2003. Using benthic diatom communities and diatom indices to assess water pollution in the Puck Bay (Southern Baltic Sea) littoral zone. - Oceanological and Hydrobiological Studies, 32(4): 131-157. BROCKMANN, C. 1950. Die Watt-Diatomeen der schleswig-holsteinischen Westküste. in: R. Mertens, editor. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft. Verlag Dr. W. Kramer, Frankfurt am Main: 1-26. BROCKMANN, C. 1954. Die Diatomeen in den Ablagerungen der ostpreussischen Haffe. – Meyniana, 3: 1-95. BUCKMANN, K., U. GEBHARDT, A. WEIDAUER, K.D. PFEIFFER, K. DUWE, A. FEY, B. HELLMAN and J. POST 1998. Simulation und Messung von Zirkulations und Transportprozessen im Greifswalder Bodden, Oderästuar und den angrenzenden Küstengewässeren. Greiswalder Geographische Arbeiten, 16. 314

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BUSSE, S. and P. SNOEIJS 2002. Gradient response of diatom communities in the Bothnian Sea (Northern Baltic Sea), with emphasis on responses to water movement. in: Benthic Diatoms in the Gulf of Bothnia, Community Analysis and Diversity. Acta Universitatis Upsaliensis, Uppsala: 1-34. CHOLNOKY, B.J. 1961. Ein Beitrag zur Kenntnis der Diatomeenflora von venetianischen Lagunen. – Hydrobiologia, 17: 287-325. CHOLNOKY, B.J. 1968. Die Diatomeen der Santa-Lucia-Lagune in Natal (Südafrika). – Botanica Marina Supplement, 11: 1-121. COOPER, S.R. 1995. Chesapeake Bay watershed historical land use: impact on water quality and diatom communities. - Ecological Applications, 5(3): 703-723. COOPER, S.R. 1999. Estuarine paleoenvironmental reconstructions using diatoms. in: E.F. Stoermer and J. P. Smol, editors. The diatoms: applications to the environmental and earth sciences. Cambridge Univ. Press, Cambridge: 352-373. DE SÈVE, M.A. 1993 Diatom bloom in the tidal freshwater zone of a turbid and shallow estuary, Rupert Bay (James Bay, Canada). - Hydrobiologia, 269/270: 225-233. GARCIA-RODRIGUEZ, F., N. MAZZEO, P. SPRECHMANN, D. METZELTIN, F. SOSA, H.C. TREUTLER, M. RENOM, B. SCHARF and C. GAUNCHER 2002. Paleolimnological assessment of human impacts in Lake Blanca, SE Uruguay. - Journal of Paleolimnology, 28(4): 786798. GARCIA-RODRIGUEZ, F. 2002. Estudio paleolimnológico de Lagunas de Rocha Castillos y Blanca, sudeste del Uruguay. - Tesis de Doctorado en Biologia, Opción Ecologia, Universidad de la República Montevideo, Uruguay 1-95. HEINONEN, P. 1980. Quantity and composition of phytoplankton in Finnish inland waters. - Publ. Water Res. Inst. Nat. Board of Waters, Finland 37: 1-91. HENDEY, N.I. 1977. The species diversity index of some in-shore diatom communities and its use in assessing the degree of pollution insult on parts of the North coast of Cornwall. - Nova Hedwigia, Beih. 54: 355-378. HUSTEDT, F. 1957. Die Diatomeenflora des Fluss-System der Weser im Gebiet der Hansestadt Bremen. - Abh. Naturw. Ver. Bremen., 34: 181-440. KÖNIG, D. 1959. Diatomeen der Bucht von Arcachon. Z. deutsch. Geol. Ges. 111: 33-61. KUYLENSTIERNA, M. 1989-1990. Benthic algal vegetation in the Nordre Älv Estuary (Swedish west coast). - Doctoral thesis, University of Göteborg. Sweden. Vol. 1: 244 pp., vol. 2: 76. MAJEWSKI, A. editor. 1980. Zalew Szczeciński (Szczecin Lagoon). 17-25. - Instytut Meteorologii i Gospodarki Wodnej. Wydawnictwa Komunikacji i Łączności. Warszawa. (in Polish) MIHO, A. and A.WITKOWSKI 2005. Diatom (Bacillariophyta) flora of Albanian coastal wetlands – taxonomy and ecology: a review. - Proceedings of the California Academy of Sciences, 56: 129-145. MIKULSKI, Z. 1966. Wasserhaushalt der baltischen Haffs. - Beiträge zur Meereskunde, Berlin 19.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 319-332) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Use of nonparametric multiplicative regression for modeling diatom habitat: a case study of three Geissleria species from North America Marina G. Potapova1 & Diane M. Winter2 Patrick Center for Environmental Research, The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103, U.S.A. 2 Department of Geosciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, U.S.A. 1

ABSTRACT Nonparametric multiplicative regression modeling (NPMR) was used to study the ecology of three Geissleria species found relatively frequently in rivers of North America: G. aikenensis Torgan et Oliveira, G. cf. kriegeri (Krasske) Lange-Bertalot, and G. lateropunctata (Wallace) Potapova et Winter comb. nov. NPMR models species abundance as a response to several possibly interacting environmental factors without predetermining the shape of that response. The data used for the analysis were collected within US Geological Survey National WaterQuality Assessment Program from rivers throughout United States. NPMR models showed that water ionic composition was the main factor that influenced distribution of three Geissleria species, while nutrients were less important. The typical habitats of all three species were lowconductivity, calcium-poor rivers of coastal areas, although there were definite ecological differences among species. G. aikenensis had affinity towards warm areas and larger rivers with water pH around 7 and conductivity 90-100 µs/cm, while G. lateropunctata and G. cf. kriegeri appeared less sensitive to temperature and most abundant at conductivity below 100 µs/cm and pH around 6. G. cf. kriegeri reached highest abundances in waters of especially low alkalinity while G. lateropunctata preferred slightly more elevated amounts of calcium bicarbonate, and sandy habitats. All three Geissleria species were most common in the southeastern part of the US, but G. aikenensis and G. lateropunctata were also observed in rivers along the US West Coast. Key words: Diatom ecology, Nonparametric Multiplicative Regression, Geissleria, rivers, North America 319

Marina G. Potapova and Diane M. Winter

INTRODUCTION Successful use of diatoms as environmental indicators depends on the knowledge of their ecological characteristics and distribution. Until recently, that knowledge was mainly summarized with narrative descriptions of species ecological traits in diatom floras or monographs. Recent advances in computational techniques allowed, however, investigating ecological properties of diatoms in a more quantitative way than was possible in the past. For instance, the development and wide application of weighted averaging inference modeling in paleolimnology (Birks et al. 1990) led to publication of numerous lists of “species optima” and “tolerances”, which are the simple means of quantifying species distributions along environmental gradients (e.g., Juggins 1992, Cumming et al. 1995, Gasse et al. 1995). These absolute values of “optima” and “tolerances” are useful to infer conditions in samples collected in the same area and in water bodies similar to those of the training dataset, but vary considerably among individual studies and therefore cannot be a reliable source of information on the general ecology of diatom species. The main reason for such variability of optima and tolerances is their strong dependence on the values and distribution of environmental variables in the datasets (ter Braak and Looman 1986). Another cause for differences is the lack of taxonomic consistency between datasets produced by different diatomists. For these reasons it is often difficult to combine information on diatom optima and tolerances from separate datasets to create a comprehensive autecological “species profile” or to determine which factors influence species occurrence or abundance. Therefore, taxonomically consistent datasets covering large geographic areas and a wide variety of conditions are needed to investigate diatom ecology. Optima and tolerances are usually calculated either as weighted averages and weighted standard deviations or by fitting second-order regressions assuming that species follow unimodal “Gaussian” distribution along gradients (ter Braak and Looman 1986). It has been shown, however, that ecological response curves may be of varying shapes, and therefore more flexible approaches, such as nonparametric regression, are required to characterize species ecology (McCune and Grace 2002). Such nonparametric techniques as local-polynomial regression (LOWESS) and General Additive Models (GAMs), based on smoothing functions, are quickly gaining popularity in ecological studies, especially in studying species responses to environmental gradients (Bio et al. 1998, Oksanen and Minchin 2002). To understand species ecology it is also necessary to study simultaneous responses to multiple environmental factors using multiple regressions. GAMs can be used to fit individual regression terms (environmental variables or their combinations) to species data. McCune (2004) noted, however, that GAMs might distort species responses to multiple factors because individual terms are combined additively, while ecological factors typically interact in a multiplicative rather than additive way in their influence on species. McCune and Mefford (2004) developed a method of Nonparametric Multiplicative Regression (NPMR) that models species response to multiple variables in such a way that the effect of each variable can depend on the value of another variable. NPMR is implemented by 320

Use of nonparametric multiplicative regression for modeling diatom habitat: a case study of three Geissleria species

HyperNiche software, which uses kernel functions as a smoothing technique (McCune and Mefford 2004). Kernel functions are used to weight observations around each predicted point and in HyperNiche the optimal kernel functions are selected by cross-validation. In this study we employed the NPMR approach to study ecology of three relatively poorly known Geissleria species that are found quite often in rivers of North America: Geissleria aikenensis (Patrick) Torgan and Oliveira, G. lateropunctata (Wallace) Potapova et Winter comb. nov., and G. cf. kriegeri (Krasske) Lange-Bertalot. Our goals were to determine which environmental or geographical factors play the most important role in limiting distribution of each species and what are species responses to these factors. MATERIAL AND METHODS The data set used to characterize distribution and occurrence of three Geissleria species included 5670 diatom samples collected from 1300 sites in North American rivers and streams as part of the US Geological Survey National Water-Quality Assessment (NAWQA) Program. Environmental data were only available for part of these samples. They include various water quality characteristics, substrate, water temperature, site elevation, and watershed characteristics (mean annual air temperature, mean slope, and drainage area). For some NAWQA sites, more detailed habitat characteristics were recorded, such as current velocity, daily discharge, light availability, channel morphometry, etc., but these characteristics were not available for many sites where Geissleria species were especially abundant, e.g., in Florida and Georgia, and, therefore, we could not include them in our analyses. Diatom samples were processed in the Phycology Section of the ANSP, University of Louisville, and Michigan State University according to standard protocols (Charles et al 2002). Relative abundance of diatom species was determined from diatom counts. The absolute cell density of each species was calculated as a product of relative abundance of that taxon in diatom count and total diatom cell density in the sample, which was determined by enumerating all algae in the Palmer-Maloney counting chamber. Several analysts identified and enumerated diatoms. We then reviewed count results and corrected identifications when necessary. The type material of Navicula lateropunctata Wallace from the Diatom Herbarium of the ANSP was also investigated (slide GC 4072a, Upper Three Run, Aiken County, South Carolina, collected by J. H. Wallace on May, 1952). Light microscope observations were documented by digital images captured with a Spot Insight QE 4.2 camera installed on a Zeiss Axioscope 2. For SEM study, diatoms were mounted on aluminum stubs, sputtercoated with gold and palladium, and examined with a JEOL-6300FV. NPMR models were created with HyperNiche 1 (McCune and Mefford 2004). We used Gaussian weighting function and two types of the local model: local mean and local linear regression. The response variables were species relative abundances (%) and log-transformed cell densities (cells/cm2). The predicting variables were: latitude (decimal degrees, centered), longitude (decimal degrees, centered), water temperature (C°), pH, conductivity (log, µS/cm), total phosphorus (log, µg/L), orthophosphate dissolved (log, µg/L), total organic nitrogen 321

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plus dissolved ammonia or total Kjeldahl nitrogen (log, µg/L), nitrate plus nitrite dissolved (log, µg/L), calcium dissolved (% eq), sodium dissolved (% eq), potassium dissolved (% eq), magnesium dissolved (% eq), chloride dissolved (% eq), sulfate dissolved (% eq), carbonate plus bicarbonate dissolved (% eq), watershed area (log, sq. km), elevation (log, m), mean watershed slope (%), mean annual air temperature (C0), and substrate type. The number of samples (992) in the dataset used to fit models was higher than number of sites (517) because it included multiple samples collected from different substrates (rocks, wood, sand, or silt). The option “free search” in the HyperNiche allows searching for the model with best fit (highest cross-validated R2) for various numbers of predictors. There are no strict rules which model should be considered the best, although it is clear that the most parsimonious model should combine the best fit with lowest number of predictors. We choose to present here all models with the best fit for a given number of predictors until the cross-validated R2 stopped increasing with increasing number of predictors. RESULTS TAXONOMY Geissleria aikenensis (Patrick) Torgan and Oliveira (Figs 1-5) Synonyms: Navicula aikenenses Patrick, Geissleria schmidiae Lange-Bertalot et U. Rumrich Torgan and Oliveira (2001) transferred Navicula aikenenses (they spelled this name as aikenensis, which is correct Latin, but the original spelling was “aikenenses”) to the genus Geissleria and pointed out that G. schmidiae is a superfluous synonym of this species. Geissleria cf. kriegeri (Krasske) Lange-Bertalot (Figs 6-10) The diatom we call here Geissleria cf. kriegeri is similar to G. kriegeri as illustrated in Fig.14: 2124 of Lange-Bertalot et al. (1996). G. cf. kriegeri from North America has, however, denser striae (16-23 in 10 µm versus 14-18 in G. kriegeri according to Lange-Bertalot 2001) and more drawn-out apices, but this shape difference is subtle. Frustular dimensions are similar: in the North American materials we observed valves 5-7.5 µm wide and 11-23 µm long, and the valves of European G. kriegeri are 6-7 µm wide and 12-21 µm long (Lange-Bertalot 2001). We think that the morphological criteria do not allow either support or rejection of the hypothesis that Geissleria cf. kriegeri from America is not the same biological species as G. kriegeri from Northern Europe. We think that Metzeltin and Lange-Bertalot (1998) illustrated G. cf. kriegeri in their Fig.75: 31-34, as Geissleria neotropica (synonym of G. lateropunctata, see below), apparently thinking that these two diatoms represented a size diminution series of the same species. However, in the North American samples these two morphospecies do not intergrade and are always easily distinguishable. Unlike G. lateropunctata, G. cf. kriegeri does not have any isolated stigmata, and its central area is very small. 322

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1

2

3

4

5

7

6

8 9

10

Figs 1-5. Geissleria aikenensis. Indian Creek, South Carolina, NAWQA sample GS024161. Fig. 1. SEM. Scale bar 2 µm. Outside valve view. Figs 2-3. LM. Scale bars 5 µm. Slide 103266, ANSP. Figs 6-10. Geissleria cf. kriegeri. Figs 6-7. SEM. Scale bars 2 µm. NAWQA sample GS020301, Bear Creek, South Carolina. Fig. 6. Inside view of the apical part of the valve. Fig. 7. Outside valve view. Figs 8-10. LM. Turnpike Creek, Georgia, NAWQA sample GSL00807, slide 105701, ANSP. Scale bars 5 µm.

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Geissleria lateropunctata (Wallace) Potapova & Winter comb. nov. (Figs 11-18) Basionym: Navicula lateropunctata Wallace 1960, p. 4, pl. 2, Figs 3A-B. Synonym: Geissleria neotropica Lange-Bertalot and Metzeltin 1998, p. 108-109, Fig. 75: 25-30. The holotype slide made from a sample collected from the sandy bottom of a creek in South Carolina, contains one circle with three specimens of Navicula lateropunctata (Figs 1315). In his Latin description of N. lateropunctata, Wallace noted that its valve has one isolated “punctum” near the central nodule, which is true for the type population. Our examinations of NAWQA samples (Figs 11, 12, 16-18) showed, however, that the number of isolated areolae quite often varies between one and five within a population. Wallace’s (1960) morphometric data for this species were: valve 8 µm wide and 17-22 µm long, and 22-24 striae in 10 µm. Specimens of G. lateropunctata in the NAWQA samples had valve width 7-9 µm, length 15-25 µm, and striae density 18-22 in 10 µm. Metzeltin and LangeBertalot described the same species as Geissleria neotropica (1998) from Brazil, and noted that it has one isolated stigma, although, at least one of their images (Fig. 75: 29) shows a specimen with 4 isolated areolae in the central area. Metzeltin and Lange-Bertalot gave 11

12

13

14

16

17

15

18

Figs 11-18. Geissleria lateropunctata comb. nov. Scale bars 5 µm. Figs 11, 12. SEM. Suwanee Creek, Georgia. NAWQA sample GS003301. Figs 13-18. LM. Figs 13-15. Upper Three Run, South Carolina. Holotype slide GC 4072a, ANSP. Figs 16-18. LM. Fig. 16. Willamette River, Oregon. NAWQA sample GS016461, slide 103482, ANSP. Figs 17-18. Suwanee Creek, Georgia. NAWQA sample GS003301, slide 101915, ANSP.

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valve width 6-9 µm, length 13.5-27 µm, and striae density 18.5-21 in 10 µm. The wider range in their measurements compared with ours is due to the combination of two taxa, G. lateropunctata and G. cf. kriegeri, under the name G. neotropica. GEOGRAPHIC

DISTRIBUTION

Within United States all three Geissleria species were most abundant in the southeastern part of the country (Fig. 19), but G. aikenensis and G. lateropunctata were also found in rivers along the West coast in Oregon and California and occasionally in other areas. G. cf. kriegeri has never been found in the western part of the United States, but occasionally in its northeastern areas. NPMR

MODELING

NPMR models fitted to the relative and absolute abundances of Geissleria aikenensis (Table 1) showed that this species was most abundant and most likely to occur in the areas with mean annual air temperature around 18-190C (Fig. 20E) and in rivers with water conductivity around 100 µS/cm (Figs 20A, B), pH around 7 (Fig 20A), low relative calcium content (Fig. 20C), high relative potassium content (Fig. 20D), and low organic nitrogen and ammonia concentrations (Fig. 20B). Longitude was also often included as a predictor variable in models for this species (Table 1), reflecting its aggregated spatial distribution

Fig. 19. Distribution of the three Geissleria species in US rivers. Diameter of circles corresponds to species maximal relative abundance at each site.

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Fig. 20. Visualization of the NPMR model for relative abundance of Geissleria aikenensis based on locally mean regression and including six predictor variables. Three-dimensional plots show joint response to conductivity and pH (A) and conductivity and total Kjeldahl nitrogen (B). Two-dimensional plots show responses to % Ca (C), % K (D), and mean annual air temperature (E).

Fig. 21. Visualization of the NPMR model for relative abundance of Geissleria cf. kriegeri based on locally mean regression and including nine predictor variables. Three-dimensional plots show joint response to mean annual air temperature and water temperature (A) and to %HCO3+CO3 and %K (B). Two-dimensional plots show responses to %NO2+NO3 (C), PO4 (D), total Kjeldahl nitrogen (E), %Mg (D), and %Cl (G).

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with clusters in the eastern and western regions of the US (Fig. 19). G. aikenensis reached the highest absolute abundance in large lowland rivers. Evaluation of models for Geissleria cf. kriegeri showed that its distribution in North American rivers was mostly influenced by ionic composition of the water (Table 1). Two chemical variables that explained most of the variability of its relative abundance were ratio of the carbonates with respect to other anions and ratio of potassium in respect to other cations. The highest relative abundance was observed when carbonates were low and potassium was relatively high (Fig. 21B). Relative abundance of G. cf. kriegeri was also associated with low concentrations of mineral forms of phosphorus and nitrogen and average concentrations of organic nitrogen and ammonia. G. cf. kriegeri was most abundant in warm regions, but its response to water temperature was bimodal (Fig. 21A) due to high abundance of this species in several samples collected in winter. Absolute abundance of this species was tied most strongly with pH and water temperature (Table 1). G. cf. kriegeri is apparently quite tolerant of lower temperatures as a model for its absolute abundance

Fig. 22. Cell density of Geissleria cf. kriegeri as a function of water pH and mean annual air temperature (MAT) in the NPMR model based on locally mean regression and including six predictor variables.

Fig. 23. Visualization of the NPMR model for relative abundance of Geissleria lateropunctata based on locally mean regression and including six predictor variables. Two-dimensional plots show response to %K (A), %Ca (B), and pH (C). Three-dimensional plot shows response to conductivity and %HCO3+CO3 (D). Response to qualitative variable substrate type could not be plotted.

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showed that its response to mean annual air temperature was negligible compared to the response to pH (Fig. 22), with pH around 6 being optimal for this diatom. NPMR models for Geissleria lateropunctata also revealed the relative importance of water chemistry for this species (Table 1). Relative abundance of G. lateropunctata was highest when carbonates constituted about 40% of anions, at pH 6, and at conductivity below 100 µS/cm (Fig. 23). Models also showed that substrate type was influencing relative abundance of this diatom (Table 1): it was the highest on fine-grained sediments, especially on sand. Similarly to relative abundance, absolute cell density was related to ionic proportions (Table 1), but also to elevation, slope and nutrients. It was the highest in lowland rivers with rather low concentrations of nitrates and nitrites (0.1-1 mg/L) and intermediate concentrations of orthophosphate (10-150 µg/L). Table 1. Summary of nonparametric multiplicative regression models fitted to the relative abundance (% RA) and log-transformed absolute cell density of three Geissleria species in samples from US rivers. Variable abbreviations: Cond – conductivity, HCO3 – % carbonate + bicarbonate, Area – watershed area, MAT – mean annual air temperature, T – water temperature, NO3 – nitrates + nitrites, TKN – total Kjeldahl nitrogen, TP – total phosphorus, Slope – mean watershed slope. Models with the highest increase in cross-validated R2 (xR2) are highlighted by bold font. Response Locally mean model variable, number of predictors xR2 Predictors 1 2 G. aikenensis % RA 1 2 3 4 5 6 Cell density 1 2 3 4 5 6 7 8

Locally linear model

xR2 Predictors

3

4

5

0.01 0.05 0.08 0.10 0.11 0.12

Longitude Longitude, MAT MAT, Cond, Area MAT, Cond, Ca, TKN MAT, Cond, Ca, TKN, pH MAT, Cond, Ca, TKN, pH, K

0.01 0.05 0.11 0.17 0.19

Longitude Longitude, MAT Longitude, MAT, TKN Longitude, MAT, TKN, Area Longitude, MAT, TKN, Area, Ca

0.04 0.13 0.21 0.22

Longitude K, HCO3 Longitude, K, Cond Longitude, K, Cond, pH

0.04 0.17 0.24 0.27 0.29 0.30 0.31 0.33

Longitude Longitude, K K, Area, Cl Longitude, K, Area, Cond Longitude, K, Area, Cond, TP Longitude, K, Area, Cond, TP, HCO3 Longitude, K, Area, Cond, TP, MAT, TKN Longitude, K, Area, Cond, MAT, TKN, Elev, Slope

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Table 1. Continued. 1 2

3

4

9 G. cf. kriegeri % RA 1 2 3 4 5 6 7 8

5

0.33 Longitude, K, Area, Cond, TP, MAT, TKN, Elev, Slope

0.03 0.40 0.41 0.41 0.42 0.42 0.42 0.42

K K, HCO3 K, HCO3, T, K, HCO3, T, NO3, K, HCO3, T, NO3, PO4 K, HCO3, T, NO3, Mg, TKN K, HCO3, T, NO3, Mg, TKN, PO4 K, HCO3, T, NO3, TKN, PO4, Cl, MAT 9 0.42 K, HCO3, T, NO3, TKN, PO4, Cl, MAT, Mg Cell density 1 0.09 pH 2 0.20 pH, T 3 0.24 pH, T, Cl 4 0.27 pH, T, Cl, Lat 5 0.27 pH, T, Cl, Lat, K 6 0.27 pH, T, Cl, Lat, K, MAT G. lateropunctata % RA 1 0.03 pH 2 0.15 pH, HCO3, 3 0.34 pH, HCO3, Substrate 4 0.45 pH, HCO3, Substrate, Cond 5 0.48 pH, HCO3, Substrate, Cond, K, 6 0.49 pH, HCO3, Substrate, Cond, K, Ca 7 Cell density 1 0.10 K 2 0.33 K, Elev 3 0.44 K, Elev, HCO3 4 0.48 K, Elev, HCO3, Longitude 5 0.48 K, Elev, HCO3, Longitude, SO4 6 7

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0.04 0.31 0.39 0.40 0.42

HCO3 HCO3, K HCO3, Na, SO4 HCO3, Na, Ca, Longitude HCO3, Na, Ca, Elevation, pH

0.12 0.23 0.27 0.29

T T, pH T, pH, Cl T, pH, Cl, MAT

0.03 0.16 0.42 0.68 0.73 0.76 0.77

pH pH, MAT pH, HCO3, Substrate pH, HCO3, Substrate, Cond pH, HCO3, Substrate, Cond, PO4, pH, HCO3, Substrate, Cond, PO4, Slope pH, HCO3, Substrate, Cond, PO4, Slope, K

0.11 0.32 0.42 0.45 0.46 0.49 0.50

K K, Elev K, Elev, Mg K, Elev, Mg, Slope K, Elev, Slope, HCO3, PO4 K, Elev, Slope, Mg, HCO3, PO4 K, Elev, Slope, Mg, HCO3, PO4, NO3

Marina G. Potapova and Diane M. Winter

DISCUSSION NPMR models showed that major ion chemistry and climate were most important limiting factors for distribution of three studied Geissleria species in rivers of the United States. Although nutrients were selected as predictors in some models, it is clear that species response to nutrients was much weaker than to water ionic composition, because nutrient were usually not included in models that had sharpest increase of predictive power (crossvalidated R2). Using a traditional approach of relating species distribution to one variable at a time, we could possibly find statistically significant (considering the large number of observations) correlations between nutrients and species abundance. NPMR modeling showed, however, that the studied Geissleria species should not be regarded as reliable indicators of nutrients. This result disagrees with findings of Torgan and Oliveira (2001), who stated that Geissleria aikenensis indicates high nutrient concentrations and organic pollution. In fact, our models for that species showed that its relative and absolute abundance tends to be higher at low organic nitrogen and ammonia concentrations, and has no clear relation to phosphorus. The typical habitats of all three Geissleria species were low-conductivity, calcium-poor rivers of coastal areas, although there were definite ecological differences among species. G. aikenensis had affinity towards warm areas and larger rivers with water pH around 7 and conductivity 90-100 µs/cm, while G. lateropunctata and G. cf. kriegeri appeared less sensitive to temperature and most abundant at conductivity below 100 µs/cm and pH around 6. G. cf. kriegeri reached highest abundances in waters of especially low alkalinity while G. lateropunctata preferred slightly more elevated amounts of calcium bicarbonate, and sandy habitats. NPMR models constructed using different techniques (locally mean versus locally linear regression) often selected a somewhat different set of environmental variables as predictors. This happens when some variables are correlated and these different sets of variables describe the same pattern. For example, affinity of the studied Geissleria species towards waters with low calcium content could be reflected by the abundance decrease along calcium gradient or by its increase along gradients of other cations. Selection of longitude as a predictor in several models did not necessarily mean that geographical factors limited dispersal of Geissleria species. In the case of relative abundance of G. aikenensis, for example, longitude was no longer in the list of predictors of models based on locally mean regression, when the number of predictors was high. This indicates that some factors essential for that species, most probably water chemistry, co-varied with longitude. It is important to note that our choice of possible predictors for modeling species habitat was limited by the available measured characteristics of rivers and watersheds. Some of those characteristics were not factors that directly influence species abundance, but only surrogates of those factors. For example, it is clear that mean watershed slope does not influence diatoms directly, but is an indirect and very approximate measure of channel gradient, water current velocity and substrate composition. Several important habitat characteristics, such as hydrological disturbance, light availability, and grazer pressure were not available for many samples and could not be included in the models. These factors are especially important in 330

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limiting absolute cell densities (Stevenson et al. 1996), and their absence very much limits the value of our models with absolute cell densities as response variables. This study shows that nonparametric multiple regression techniques, such as NPMR, can be valuable tools in exploring diatom ecology. However, their use, as use of any other numerical technique in ecology, can be beneficial only when appropriate environmental data are collected and the quality of basic data is ensured. ACKNOWLEDGEMENTS This paper was produced within a cooperative research agreement with the USGS NAWQA Program. This manuscript is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints for governmental purposes. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the US Government. We are grateful to Donald Charles for his support of this study; to Steve Moulton, Pete Ruhl, and James Falcone for providing environmental information; to James Ferris for assisting with SEM work; to NAWQA biologists for collecting samples, and to the many phycologists who identified and enumerated diatoms in NAWQA samples. REFERENCES BIO, A.M.F., P. ALKEMADE and A. BARENDREGT. 1998. Determining alternative models for vegetation response analysis: a non-parametric approach. - Journal of Vegetation Science, 9: 5-16. BIRKS, H.J.B, J.M. LINE, S. JUGGINS, A.C. STEVENSON and C.J.F. TER BRAAK. 1990. Diatoms and pH reconstruction. - Philosophical transactions of the Royal Society, London, B 327: 263-278. CHARLES D.F., C. KNOWLES and R. DAVIS, editors 2002. Protocols for the analysis of algal samples collected as part of the U.S. Geological Survey National Water-Quality Assessment Program. Patrick Center for Environmental Research Report No. 02-06, The Academy of Natural Sciences, Philadelphia. [http://diatom.acnatsci.org/nawqa/] CUMMING, B.F., S.E. WILSON, R.I. HALL and J.P. SMOLL 1995. Diatoms from British Columbia (Canada) lakes and their relationships to salinity, nutrients and other limnological variables.- Bibliotheca Diatomologica, 31: 1-207. GASSE, F., S. JUGGINS and L. BEN KHELIFA 1995. Diatom-based transfer functions for inferring past hydrochemical characteristics of African lakes. - Palaeogeography, Palaeoclimatology, Palaeoecology, 117: 31-54. JUGGINS, S. 1992. Diatoms in the Thames Estuary, England: ecology, palaeoecology, and salinity transfer function. - Bibliotheca Diatomologica, 25: 1-216. LANGE-BERTALOT, H. 2001. Diatoms of Europe, V.2. Navicula sensu stricto. 10 genera separated from Navicula sensu lato. Frustulia. A.R.G. Gantner Verlag K.G., Ruggell. 331

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LANGE-BERTALOT, H., K. KÜLBS, T. LAUSER, M. NÖRPEL-SCHEMPP and M. WILLMANN 1996. Diatom taxa introduced by Georg Krasske. Documentation and Revision. Iconographica Diatomologica, 3: 1-358. MCCUNE, B. 2004. Nonparametric Multiplicative Regression for Habitat Modeling. Available at http://www.pcord.com/NPMRintro.pdf. MCCUNE, B. and J.B. GRACE 2004. Analysis of ecological communities. MjM Softweare, Gleneden Beach, Oregon, U.S.A. MCCUNE, B. and M.J. MEFFORD 2004. Nonparametric Multilicative Habitat Nodeling. Version 1. MjM Softweare, Gleneden Beach, Oregon, U.S.A. METZELTIN, D. and H, LANGE-BERTALOT 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. - Iconographica Diatomologica, 5: 1-695. OKSANEN, J. and P.R. MINCHIN 2002. Continuum theory revisited: what shape are species responses along environemntal gradients? - Ecological Modelling, 151: 119-129. STEVENSON, R.J., M. BOTHWELL, and R.L. LOWE 1996. Algae ecology: freshwater benthic ecosystems. San Diego, CA, Academic Press. TER BRAAK, C.J.F. and C.W.M. LOOMAN 1986. Weighted averaging, logistic regression and the Gaussian response model. – Vegetatio, 65: 3-11. TORGAN, L.C. and M.A. OLIVEIRA 2001. Geissleria aikenensis (Patrick) Torgan et Oliveira comb. nov.: morphological and ecological characteristics: 115-121. in: A. EconomouAmilli, editor. Proceedings of the 16th International Diatom Symposium, Athens, University of Athens. WALLACE, J.H. 1960. New and variable diatoms. - Notulae Naturae of the Academy of Natural Sciences of Philadelphia, 331: 1-6.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 333-352) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Density-dependent algal growth along N and P nutrient gradients in artificial streams Kalina M. Manoylov and R. Jan Stevenson Department of Zoology, Michigan State University, 203 Natural Science Bldg. East Lansing, MI 48824, USA ABSTRACT The relative importance of nutrients and density in benthic algal growth was studied experimentally along two nutrient gradients and in low and high community density. A broad species pool was inoculated in stream-side channels, among which a gradient of resource conditions was established. Growth rates decreased with increasing algal density on substrata. Responses of diatom species to each nutrient gradient were measured as differences in growth rates. Although, growth rates were mostly independent of the broad range of nutrient concentrations created in the experiment, some differences were noted and great differences in growth rates were noted among taxa and taxa responses to density. Achnanthidium minutissimum had relatively high growth rates at low nutrients compared to other species, it’s growth rates remained positive with nutrient increase in both low and were not affected by high density. Araphid genera like Fragilaria, Meridion, and Synedra had the highest growth rates of all taxa at low density, but were greatly affected by densitydependent interactions. Growth rates of Encyonema and Cymbella species were not affected by density. Representatives of the genus Nitzschia grew better at high than low nutrient concentrations, and density effects were species specific. Parameterizing nutrient responses of taxa may be difficult because of variability in adaptive strategies among species and density-dependent interactions. Adaptive strategies of benthic diatoms seem to have strong phylogenetic relationships that indicate evolutionary constraints on attributes that confer ecological fitness. Key words: algae, diatoms, artificial streams, N and P gradients, density-dependent growth

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INTRODUCTION Nutrients are important determinants of algal species composition in different aquatic ecosystems (McCormick and Stevenson 1991, Pan et al. 1996, Stevenson 1996). Nutrient availability or limitation can significantly influence algal growth in streams (Pringle 1990, Stevenson et al. 1991). In benthic algae, as in other organisms, species growth rates can be density-dependent (Stevenson 1990, Stevenson et al. 1991, Hixon et al. 2002). Species able to grow well at very high nutrients were unable to maintain growth rates as algal abundances increased on substrata; this negative relationship between growth rates and density on substrata has been related to nutrient availability (Bothwell 1989, Stevenson 1990, Stevenson et al. 1991). Algal density has negative effects on species within benthic mats, probably due to the additional reduction of nutrients within the mat (Stevenson and Glover 1993). Increases in benthic diatom density could decrease species growth rates because of competition for resources (Patrick 1976, Stevenson 1990) and potentially, allelopathy (Stevenson 1995). There are only a few reports on species-specific growth rates of benthic diatoms during periphyton community development and in different nutrient conditions (Stevenson et al. 1991, Stevenson and Pan 1994, Stevenson 1995). Covariation between species performances in different environments and their taxonomy has been reported as phylogenetic similarity (nestedness, Gaston 2003) and may be related to evolutionary development (Brundin 1988). Groupings at higher taxonomic level, such as genera, were found more reliable than species level in addressing colonization ability, dispersal, and extinction (Cutler 1998, Gaston and Chown 1999, Van de Vijver and Beyerns 1999, Ricklefs and Bermingham 2002), while species level identification is necessary in addressing biodiversity, speciation and assessment questions. For diatoms the genus specific characteristics of the raphe system, means of attachment, or degree of silification might be good traits for grouping and understanding adaptive ecological strategies. Phylogenetic relationships have been reported for early colonizers (Stevenson et al. 1991, Stevenson and Peterson 1991) that are usually araphid diatoms. Based on the presence/absence and type of raphe, diatoms can be divided in several categories: without a raphe (araphid, growing on ‘pin-cushions’ or in chains), with one raphe (monoraphid, growing close to the substrate) or diatoms with 2 raphes (biraphid with simple, keeled or with canal raphe, glide on substrate, burrow through sediment and benthic mat, grow on stalks or in tubes, Round et al. 1990). Diatoms, as other organisms have a variety of traits and adaptive strategies which can differentiate species response in different environmental conditions (Hudon and Legendre 1987, Stearns 1992, Van de Vijver and Beyerns 1999). Differences in diatom traits, such as size, growth form, growth rate, and attachment might change parallel with changes in environmental conditions (for example: nutrients and light, Manoylov 2005). At low density traits like high immigration ability and attachment to bare surfaces might be important, while at high density traits like resistance to shading and attachment to other algae should be advantageous. The relationship between nutrient availability, cell density on a substrate, and diatom growth rates was studied experimentally. In a near-natural setting, stream water from a 334

Density-dependent algal growth

pristine watershed was supplied to artificial streams in which nutrients were manipulated. Growth rates of individual diatom populations were measured along nitrogen and phosphorous gradients as algae colonized substrata and community density increased. For each nutrient combination growth rates were calculated based on species density. First, the relationship between diatom growth rates and nutrient concentrations was established at low and high density. Second, the similarity in the response of diatoms to changes in nutrient conditions and density was related to phylogenetic relations among species. MATERIAL AND METHODS The experiment was conducted at the University of Louisville Stream Research Facility in Bernheim Forest, Kentucky. 36 partially re-circulating, artificial streams were built next to a pristine third order stream. The artificial streams were closed 3.5 x 1.5 m loops of 10 cm diameter PVC (plastic pipe) with the top piece cut lengthwise (Fig.1, for details on the experimental design see Manoylov 2005). These loops were filled with stream water and set in one of 6 water baths, which were used to control water temperature. Current was generated in each loop, by forcing air into the bottom of one end of the loop through a hose with a Sweet Water™ model S45 Blower. Water was lifted at this end of the loop by air bubbles and produced current velocities of 25 cm s-1 in the open channel at the top of the loop. Turbulence was minimized by placing flow stabilizers, made from 15, 1.5 cm diameter plastic tubes, parallel to the flow at the head of each channel. Stream water was continuously exchanged in each water bath at a high enough rate to maintain temperatures in the re-circulating channels similar to those of the stream. Fresh steam water was slowly added to each channel at a rate of 7 ml s-1 by adding water from 200 L head tanks with plastic aquarium tubing. Excess water was allowed to overflow through a hole drilled in the ends of each channel. This allowed for complete turnover of water every 4 hrs. Treatment Additions

Stabilizers

Stream Water

Shade Cloth

Air

Over Flow Tiles Bubbles

Fig. 1. Schematic view of each channel with partial re-circulation of water.

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Kalina M. Manoylov and R. Jan Stevenson

Twenty unglazed ceramic tiles (29.2 cm2) were placed at the downstream end of each channel where turbulence was minimal. Light levels were reduced by placing two layers of greenhouse shade cloth, supported by 1 cm-2 wire mesh screen over the stream channels. This simulated the light regimes in the nearby stream. The shading allowed 12% of incident photosynthetically active radiation (measured with LiCorTM Model Li 189 Light Meter) to reach the tiles. To create a large pool of potential algal colonists from a variety of nutrient conditions, we added 500 ml of an algal inoculum to each stream on May 17, 1999 (one day before the start of nutrient addition). This inoculum was produced by scraping rocks from three streams differing in the level of human impact in the watershed. The first stream was Harts Run, the low nutrient stream where the experiment was run. The second was Wilson Creek located 5 km north of Harts Run. Wilson Creek has moderate agriculture in the watershed with moderate concentrations of nitrogen and phosphorus (R. J. Stevenson unpublished data). The third stream was the Middle Fork of Beargrass Creek, located within the city of Louisville, Kentucky. This creek has primarily an urban watershed and periodically has high nutrient concentrations (R. J. Stevenson unpublished data). Scrapings from the three streams were combined in a single container and homogenized before aliquots were added to each stream. The algal community in the inoculum was taxonomically evaluated to ensure that a large species pool was present. Stock nutrient solutions with different concentrations of NaNO3 and KH2PO4 were delivered from 1 L containers to each channel using peristaltic pumps (Manostat™ model STD) set at a drip rate of 0.3 ml min-1. We added nitrogen and phosphorus throughout the experiment at a rate that was expected to elevate ambient nutrient concentrations by the following amounts: 0, 16, 64, 256, 512 and 1024 µg N/L at 50 µg P/L, and 0, 2, 8, 32, 50 and 128 µg P/L at 500 µg N/L prior to uptake within the channels. Concentrations greater than 30 mg P/L and 500 µg N/L have been assumed to be saturating concentration, i.e. sufficient to satisfy demands for maximum growth rates. (Bothwell 1989). Nutrient supply was kept at a constant rate throughout the experiment. A total of three replicate channels were used for each treatment. Six nutrient treatments in each gradient were assigned randomly across the 36 channels. On the day of nutrient addition (May 18), the growth in each control treatment (0N/50P and 0N/500P) was determined. This allowed estimation of initial colonization and growth. Channels were sampled 5 times after that, approximately 72 hours apart. A total of 90 samples were collected. One channel in the P gradient with an 8P/500N treatment had variable volumes, so the data were not used. Sample collection Water samples were collected from the natural stream and from each channel on days 1, 3, 6, 8, 12, and 14 with acid washed 125 ml polypropylene bottles. Water samples were packed on ice immediately after sampling and returned to the lab for analysis. Nitrate + nitrite nitrogen, ammonium nitrogen (NH4-N), and silicate (Si) concentrations were estimated on a Skalar® auto-analyzer according to standard methods (APHA 1998). Since nitrate + nitrite 336

Density-dependent algal growth

nitrogen consists mainly of nitrate in this stream (R. Schultz unpublished data), we considered this a measure of nitrate nitrogen (NO3-N). Soluble reactive phosphorus (SRP) was also determined according to standard methods using a Hitachi® U-200 1 spectrophotometer (APHA 1998). Since nutrient uptake within each channel was probably important, we compared measured concentrations of NO3-N and SRP in the analyses with the predicted values. After determining that nutrient manipulations resulted in progressively greater concentrations as expected, the predicted concentrations were used in subsequent data analyses. We assumed that loaded concentrations were a better indication of nutrient availability than measured concentrations that do not account for uptake. Two tiles (not neighboring and not from the upstream end) were collected from each channel on days 3, 6, 10, 13, and 16 of community development. Periphyton samples were frozen until processing. Sampling stopped after day 16 because algae grew rapidly and sloughing was observed. In the laboratory algal material was scraped from the upper surface of the thawed tiles into a beaker with a toothbrush and razor blade. Samples were diluted to known volumes with deionized water, homogenized with a Biospec® model m133\1281-0 biohomogenizer, and then sub-sampled with a mechanical pipette while continuously mixing on a magnetic stir plate. Chlorophyll á was determined spectrophotometerically with Spectronic Genesys®2 spectrophotometer after 24 hours extraction in 90% buffered acetone (APHA 1998). Subsamples for counts were preserved with M3 for algae counts (APHA 1998). For algal enumeration semi-permanent syrup mounts were prepared with 0.2 to 2.0 ml sample on the coverglass (22mm x 22mm) and 4 ml Taft’s Mounting syrup (Stevenson 1984b). Initially a minimum of 300 natural units (live unicellular, filamentous and colonial algae) were identified and enumerated to the lowest taxonomic level. For diatoms only frustules with a visible, healthy looking chloroplast were enumerated. Counts were performed at 1000X on a Leica DMLB light microscope. Later the counts were continued until adequate numbers of cells were observed for precise estimation of algal density of the common taxa (15 valves per taxon per sample). Common taxa for this experiment are defined as taxa found in all treatments. This produced final counts of more than 1000 live cells in some counts. Total community and individual taxa densities were calculated (D, cells.cm-2). Log transformed densities were used to calculate per capita growth rates of individual taxa. Data analysis Growth rates (R) were estimated as the daily per capita rate of change in density in each channel and for each colonization period between successive sampling times using the following equation: Rxy=( ln D (y) – ln D (x))/y-x, where D is algal biomass (total density) and x and y are consecutive sampling dates. Growth rates (cells.cell-1).d-1 for each density level were designated based on species density on consecutive sampling days prior and after peak biomass. For each density level the effect of nutrient increase on species specific growth rates was assessed with ANOVA. Differences between treatments were calculated using Tukey HSD multiple comparison. 337

Kalina M. Manoylov and R. Jan Stevenson

Separate analyses of results from low and high density conditions and for N and P gradients reduced sample size by a factor of 4, so may have reduced sensitivity (power) of statistical detection of treatment effects. In addition, repeated measures from the same channels (necessary for assessing changes with density) are not technically statistically independent. The univariate approach to RM ANOVA takes into account correlation among repeated measures (sampling dates in the same channel), which can violate the assumption of independence between samples by confounding effects of time. Thus, treatment effects on whole community density and growth rates were tested using repeated measures analyses of variance (RM ANOVA) with N concentration, P concentration, and time as independent variables. The model also included and N x P interaction term. All results were adjusted for circularity with the GeisserGreenhouse epsilon (G-G, von Ende 2001), which is very statistically conservative. Time effects on nutrients were evaluated with polynomial contrast analyses in RM ANOVA. Sequential sums of squares were evaluated with univariate ANOVAs for each contrast (linear, quadratic etc.). The higher order term was considered first and was dropped from the model if not significant. Differences in levels of density were determined with Tukey HSD multiple means comparison tests. We defined ten traits for classification of the common diatoms in this experiment. Four traits were based on effects of nutrients (either N or P) on species growth rates in low and high density conditions. Each trait was classified as a positive, negative, or no relationship between species growth rates based on the statistically significant linear relationships between growth rates in nutrient concentrations: responses to N at either low or high density and responses to P at either low or high density. Cell size was categorized based on biovolume measurements in this study (Hillebrand et al. 1999) and literature values. Other traits were the type of raphe system (araphid, monoraphid, biraphid with simple raphe, and biraphid with canal raphe), growth form (prostrate, chains, in tubes or motile); attachment (raphe valve, spines, mucilage pad or valve face), immigration (fast and slow); and density resistance (high and low). Immigration abilities were determined from the literature. Density resistance was measured as similarity in growth rates in low and high density (averaged for both nutrient gradients); thus taxa with little difference in growth rates at low and high density were resistant to negative biotic interactions that could result from competition for nutrients and light and allelopathic interactions. Principle component analysis (PCA) and hierarchical agglomerative cluster analysis based on numerically quantified traits of each common diatom were used to identify patterns of phylogenetic similarity. The data matrices (14 common taxa and 10 traits) were oriented in two-dimensional space with PCA and also evaluated with a cluster analysis dendrogram. These direct analyses provided a quantitative assessment of relationships among multiple traits. Between and within group similarity was assessed using analysis of similarity test (ANOSIM test). This test uses a non-parametric permutation procedure, applied to the (rank) similarity matrix underlying the ordination or clustering classification of the species that we identified with PCA and Cluster analyses. The number of permutation was seeded at 999 and a significance level of sample statistics was set for 0.1%. 338

Density-dependent algal growth

Statistical analyses were performed with SYSTAT® 10 (Wilkinson 1989), except the PCA, cluster analysis, and ANOSIM were performed with Primer 5 (Primer –E Ltd, 2001, Plymouth UK). RESULTS Water temperatures in the re-circulating channels were approximately 20°C, which was close to temperatures recorded in Hart’s Run. Silicate concentrations were consistently high in Hart’s Run and the experimental channels, ranging from 11 to 12 mg Si/L. At the end of the experiment along the N gradient, P was less than the assumed P concentration, 32 µg P/L. Along the P gradient, N was less than the assumed N concentration, 256 µg N/L (Fig. 2 a, b). Grazers were excluded from the artificial streams. Light was constant for the duration of the experiment. Nutrient effect

Nutrient concentrations (µg/L)

Whole diatom community density in both gradients increased with nutrients and in time. The community density increased significantly with increasing N treatment (F 5, 12=4.11, p=0.0209). Adjusted for circularity the N x time interaction was not significant (F25, 60=2.02, p=0.0537). This indicates that the diatom communities in the N treatment gradient did not increase in density faster at the low N concentrations compare to the high N concentrations. Cell densities before and after day 6 were significantly different (F 5, 60=328.58, p<0.0001). Increased P concentration had a significant positive effect on diatom density also (F5, =5.41, p=0.0094). The P x time interaction after adjustment for circularity was significant 11 (F25, 55=2.45, p=0.0254). This significant nutrient x time interaction indicates that algal communities in the P treatment gradient increased in density faster at the low P concentrations than in the high P concentrations. Along the P gradient, cell densities were significantly different before and after day 6 also (F5, 55=317.64, p<0.0001). 1000

a.

b.

800 600 400 200 0

0 16 64 56 12 24 2 5 10

0

2

8 32 50 28 1

TN TP

P gradient (µg/L)

N gradient (µg/L)

Fig. 2. Nutrient concentrations (µg/L) along the 2 gradients. a. N gradient at high P; b. P gradient, at high N; Bars indicate standard error at the end of the experiment.

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Density effect Total community density prior to day 6 was significantly lower than the density at later time periods (Fig. 3). Growth rates between days 0 and 3 of community development were designated as growth rates at low density and growth rates between days 6 and 10 were designated as growth rates in high community density. Species response

Community density

A total of 138 taxa were recorded in the artificial streams. Fourteen taxa had sufficient densities to accurately estimate growth rates for all colonization periods, all treatments, and all channels. N concentration did not have a significant effect on growth for any of the 14 common diatoms. Growth rates of 9 of the common diatoms were significantly influenced by the increase in density on the substrates along the N gradient (Table 1). Increase in N concentration together with changes in density had significant effects on the two Achnanthidium species, Fragilaria nanana, and Nitzschia acicularis. Levels of available P significantly influenced Synedra ulna and Nitzschia palea. Those two diatoms had higher growth rates in high P concentrations when compared to limiting P concentrations. Growth rates of 10 of the common diatoms were significantly influenced by the change of density on the substrates. The combination of available nutrients and density significantly influenced growth rates of 50 % of the common diatoms along the P gradient (Table 1). The 14 common diatoms fell into 4 groups based on presence/absence of raphe and type of raphe (Table 2). The monoraphid species attached close to the substrate or to other algae. The araphid species grew in rosette colonies/pin-cushions (Fragilaria nanana and F. vaucheriae), as mostly single cells (Synedra ulna), or in chains (F. crotonensis, Meridion circulare). The biraphid species with a simple raphe grew on stalks (Cymbella affinis and C. cistula) or in tubes (Encyonema minutum). The biraphid species diatoms with a canal raphe were motile (Nitzschia species). 20 18 16 14 12

0 16 64 256 512 1024

N gradient (µg/L)

0

2

8 32 50 28 1

P gradient (µg/L)

Fig. 3. Whole community density (ln cells.cm ) along: a. Nitrogen gradient; and b. Phosphorus gradient; Bars indicate standard error of the treatment means. Open squares low density (day 3), solid squares high density (day 10). -2

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Density-dependent algal growth

Table 1. Summary of analyses of variance results of individual taxa growth rates along nutrient gradients and with density. N and P-nutrient effects, D- density effect, and N x D/ P x D is the respective nutrient - density interaction, LD and HD low and high density. p value level of significance at p<0.05, ns-not significant, (-, 0, +) regression slope direction, * <0.05, and ** <0.001. N Gradient Taxa

N

D N x D LD

Achnanthidium deflexum (Reimer) Kingston

ns ns ns ns ns ns ns ns ns ns ns ns ns ns

* ns ** ** ** ** ** ns ns ** ns ns ** **

Achnanthidium minutissimum (Kützing) Czar. Fragilaria crotonensis Kitton Fragilaria nanana Lange-Bertalot Fragilaria vaucheriae (Kützing) Petersen Synedra ulna (Nitz.) Ehr. Meridion circulare (Grev.) Ag. Encyonema minutum (Hilse) Mann Cymbella affinis Kützing Cymbella cistula (Ehrenberg) Kirchner Nitzschia acicularis (Kütz.) W. Sm. Nitzschia dissipata (Kütz.) Grun. Nitzschia linearis (Ag. ex W. Sm.) W. Sm. Nitzschia palea (Kütz.) W. Sm.

* ** ns ** ns ns ns ns ns ns * ns ns ns

0 + + 0 0 0 0 + 0 + 0 0 0 +

P Gradient HD

P

D

+ + + + + + 0 + + + + +

ns ns ns ns ns * ns ns ns ns ns ns ns *

ns ns ** ** ** ** ** ns ** ** ** ns ** **

P x D LD

** ns * * ** ns ns * ns ns ns ns ** *

HD

0 -

+ 0 + 0 0 + 0 + + + +

Table 2. Life history traits of benthic diatom species. Literature source: 1 -Lowe and Pan 1996; 2 Round et al. 1990; 3 - Berber and Haworth 1994, 4 – Peterson and Stevenson 1990, 5 – Stevenson et al. 1991. *- this study, **- unpublished data.

Taxa

ABB

Achnanthidium deflexum

ACD

Achnanthidium minutissimum ACM

Biovolume Density 1 Raphe system 2 Growth form 2,3 Attachment 2 Immigration4,5 resistence* (µm3) ~130**

monoraphid

prostrate

raphe valve

fast

high

70

monoraphid

raphe valve

fast

high

spines

fast

low

Fragilaria crotonensis

FRC

700

araphid

prostrate ribbon-like chains

Fragilaria nanana

FRN

~290**

araphid

rosette

mucilage pad

Fragilaria vaucheriae

FRV

410

araphid

rosette

mucilage pad

Synedra ulna

SYU

1200

araphid

mucilage pad

Meridion circulare

MDC

450

araphid

rosette fan-shaped chain

Encyonema minutum

ENM

150

biraphid, simple

in tubes

low low fast

low

fast

high

slow

high

valve face

Cymbella affinis

CMA

350

biraphid, simple

on stalks

mucilage pad

Cymbella cistula

CMC

600

biraphid, simple

on stalks

mucilage pad

low high

Nitzschia acicularis

NIA

280

biraphid, canal

motile

Nitzschia dissipata

NID

300

biraphid, canal

motile

Nitzschia linearis Nitzschia palea

NIL NIP

850 200

biraphid, canal

motile

slow

low

biraphid, canal

motile

slow

low

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fast

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Kalina M. Manoylov and R. Jan Stevenson

Monoraphid species - In this experiment growth rates of the two monoraphid species were not affected by density (Fig. 4 a, c, ANOVA p>0.05). Achnanthidium deflexum growth rate did not change predictably with increasing P concentration at high density, and decreased with increasing P concentration at low density (ANOVA p<0.001, Tukey p<0.001). At high density along the P gradient most mean growth rates were positive with the highest mean at 50µg P/L (Fig. 4b, ANOVA p=0.01, Tukey p=0.01). Growth rate of A. minutissimum was not influenced significantly by either nutrient (Fig. 4 c, d; ANOVA p>0.05) at low or high density. Its growth rates were mostly positive in low and high density. Araphid diatoms - For all araphid diatoms growth rates were close 1 at low density and decreased close to zero at high density along both nutrient gradients. Fragilaria nanana and F. vaucheriae had high growth rates at low density along both gradients (Fig. 5). At low density Fragilaria nanana growth rates were decreased along the P gradient (ANOVA p<0.001, Tukey p<0.001). Fragilaria vaucheriae had the highest growth rates for this study of any taxon at low density, averaging 1.44 ±0.05 SE and 1.16±0.11 SE along the N and P gradient respectively. Growth rates increased significantly at high density along the N gradient (ANOVA p=0.01, Achnanthidium deflexum

Fragilaria nanana

2.0 1.5

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a.

b.

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Achnanthidium minutissimum

Fragilaria vaucheriae

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c.

d.

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0

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0 16 64 56 12 24 2 5 10

8 32 50 28 1

Phosphorus (µg P/L)

Nitrogen (µg N/L)

Fig. 4. Growth rates of Achnanthidium deflexum and A. minutissimum in different nutrient concentrations and cell densities. a. Achnanthidium deflexum along N gradient; b. A. deflexum along P gradient; c. A. minutissimum along N gradient; d. A. minutissimum along P gradient; Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

0

2

8 32 50 128

Phosphorus (µg P/L)

Fig. 5. Growth rates of Fragilaria nanana and F. vaucheriae in different nutrient concentrations and cell densities. a. Fragilaria nanana along N gradient; b. F. nanana along P gradient; c. F. vaucheriae along N gradient; d. F. vaucheriae along P gradient; Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

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Density-dependent algal growth

Tukey p=0.03). Along the P gradient growth rates decreased significantly at low density only (ANOVA p<0.001, Tukey p<0.001). Fragilaria crotonensis also had relatively high growth rates at low density, averaging 0.83 ±0.04 SE and 0.68±0.07 SE along the N and P gradients, respectively (Figs. 6 a, b). Growth rates were lower at high density than at low density along both gradients. Growth rates changed unpredictably along the P gradient concentration at low density. Growth rates were independent of N concentrations at low and high density (ANOVA p>0.05). Growth rates of Synedra ulna (synonym Ulnaria ulna (Ehr.) Compère, the largest araphid diatom in the study, were not affected by N concentration at both densities (Figs. 6 c, d, ANOVA p>0.05). In low density along the P gradient, its growth rates were negatively related to P concentrations (ANOVA p=0.02, Tukey p=0.04). Growth rates of Meridion circulare significantly decreased along the P gradient at high density (Figs. 7 a, b, ANOVA p=0.049, Tukey p=0.04). Biraphid diatoms with a simple raphe – Common birapids with a simple raphe varied in sizes and mode of attachment (Figs. 7 c, d and 8). Growth rates of Encyonema minutum, a smaller biraphid diatom and growing in tubes, were not affected by density or nutrients

Meridion circulare

Fragilaria crotonensis 2.0

2.0 a.

a.

b.

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1.5

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0.0

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Synedra ulna

Encyonema minutum

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2.0

d.

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Nitrogen (µg N/L)

b.

c.

d.

-0.5 0

2

8 32 50 28 1

0 16 64 56 12 24 2 5 10

Phosphorus (µg P/L)

Nitrogen (µg N/L)

Fig. 6. Growth rates of Fragilaria crotonensis and Synedra ulna in different nutrient concentrations and cell densities. a. Fragilaria crotonensis along N gradient; d. F. crotonensis along P gradient; c. Synedra ulna along N gradient; d. S. ulna along P gradient; Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

0

2

8 32 50 28 1

Phosphorus (µg P/L)

Fig. 7. Growth rates of Meridion circulare and Encyonema minutum in different nutrient concentrations and cell densities. a. Meridion circulare along N gradient; b. M. circulare along P gradient;; c. Encyonema minutum along N gradient; d. E. munitum along P gradient; Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

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(ANOVA p>0.05). Growth rates of Cymbella affinis, larger and with a stalk, were also not affected by nutrients or density (Figs. 8 a, b; ANOVA p>0.05). Growth rates of another stalked diatom, C. cistula, were not affected by density and by N concentrations at both densities (Figs. 8 c, d; ANOVA p>0.05). P also had no affect on its growth at high density, however at low density, growth rates decreased with increasing P concentrations (ANOVA p=0.03, Tukey p=0.04). The different effects of P in low and high density on growth of C. cistula were indicated by the statistically significant interaction term in the ANOVA results of Table 1. Biraphids with a canal raphe - Nitzschia species had particularly strong responses to nutrients compared to other taxa, but responses to density varied among taxa (Figs. 9 and 10, Table 1). Growth rates of all our Nitzschia except N. dissipata, were negatively affected by density. When analyzing responses to nutrients separately in low and high density, 15 of 16 responses of all our Nitzschia were the same. In low density, all our Nitzschia, except N. palea, were not affected by N concentration; however all were affected positively by increasing P at high density. In high density, all our Nitzschia were positively affected by increases in both nutrients.

Cymbella affinis

Nitzschia acicularis

2.0 a.

2.0

b.

a.

1.5

1.5

1.0

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b.

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Cymbella cistula

Nitzschia dissipata 2.0

1.5

c.

c.

d.

d.

1.5

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Nitrogen (µg N/L)

0

2

0 16 64 56 12 24 2 5 10

8 32 50 28 1

Phosphorus (µg P/L)

Nitrogen (µg N/L)

Fig. 8. Growth rates of Cymbella affinis and C. cistula in different nutrient concentrations and cell densities. a. Cymbella af finis along N gradient; b. C. affinis along P gradient; c. C. cistula along N gradient; d. C. cistula along P gradient; Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

0

2

8 32 50 28 1

Phosphorus (µg P/L)

Fig. 9. Growth rates of Nitzschia acicularis and N. dissipata in different nutrient concentrations and cell densities. a. Nitzschia acicularis along N gradient; d. N. acicularis along P gradient; c. Nitzschia dissipata along N gradient; d. N. dissipata along P gradient. Bars indicate standard error of the treatment means. Open squares low density, solid squares high density.

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Density-dependent algal growth

The common taxa separated into 4 groups according to phylogenetic similarity based on the 10 traits characterized in this study. The first two PCA components of the growth rates patterns explained 49.8 % of the variation (PCA1 contributed 28.8 %, PCA 2 contributed 21%, Fig. 11 a). PC 1 was strongly influenced by density levels, while PC 2 showed dependence on growth form and attachment. Nitzschia linearis 2.0 a.

b.

1.5 1.0 0.5 0.0 -0.5

Nitzschia palea 2.0 c.

d.

1.5 1.0 0.5 0.0 -0.5 0 16 64 56 12 24 2 5 10

0

Nitrogen (µg N/L)

2

8 32 50 28 1

Phosphorus (µg P/L)

Fig. 10. Growth rates of Nitzschia linearis and N. palea in different nutrient concentrations and cell densities a. Nitzschia linearis along N gradient; d. N. linearis along P gradient; c. Nitzschia palea along N gradient; d. N. palea along P gradient. Bars indicate standard error of the treatment means. Open squares low density, solid squares high density. b.

50 60 70 80 90

100

MDC SYU FRV FRN FRC CMC CMA NIP NIA NID NIL ENM ACM ACD

2.5 NIP NIL 2.0 NIA 1.5 NID 1.0 ENM 0.5 CMC 0 -0.5 FRC CMA SYU FRN FRV -1.0 ACM -1.5 MDC ACD -2.0 -4 -3 -2 -1 0 1 2 3

Similarity

PC2

a.

1 1 3 4 4 4 4 3 3 2 2 2 2 2

PC1

Fig. 11. Phylogenetic grouping of common diatom taxa. a. Score plot of PCA showing the separation of species within each group along PC1 and PC2 determined with numerically ranked traits. b. Cluster analysis dendrogram with the species and groupings; 1.monoraphid diatoms; 2. Biraphid with simple raphe; 3. araphid diatoms; and 4. biraphid with canal raphe. Abbreviations as in Table 2.

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Within group similarities were highest (ANOSIM Global R=0.66) for monoraphid (90.5 %), followed by biraphid diatoms with canal raphe (87%) and araphid (75%). Similarity within biraphid diatoms with simple raphe (Group 3, fig. 11 b) was lowest (47.4%). Between groups similarity was highest between araphid diatoms and diatoms with two canal raphes (78%). Between groups similarity was lowest between monoraphid diatoms and diatoms with two simple raphes (33%). DISCUSSION Disturbance provides opportunity for colonization of habitats. Following disturbance, benthic algal densities increase until peak algal biomass is reached (reviewed in Stevenson 1996, Sekar et al. 2004, Rier and Stevenson accepted). Immigration and reproduction can be important processes in colonization of benthic habitats after disturbance (Stevenson 1983, 1984a, 1986). Density-dependent interactions in periphyton have been indicated during colonization as algal biomass increases by the decrease in net growth rates of benthic algae (Stevenson 1984a, Stevenson et al. 1991). Resource competition for decreasing nutrients and light has been hypothesized as potential causes of these negative density-related responses (Patrick 1976, Hoagland et al. 1982, Hudon and Legendre 1987, reviewed by McCormick 1996). Allelopathy may also be an important factor in these dense communities in which flow of interstitial waters is slowed and secretion of allelopathic substances may confer a selective advantage for an organism in the dense periphyton matrix (Stevenson 1995). If biotic interactions are important and regulate fitness of periphyton, then tradeoffs may exist among these species traits because each requires allocation of energy and nutrients. Thus, each species may have evolved different sets of coadapted traits that confer different adaptive ecological strategies, such as r and k strategies (early and late successional strategies). Competition for nutrients was indicated in our results by the great decrease in growth rates with increasing density and differing effects of nutrients on growth during early and late stages of colonization (at low and high density). Nutrients and density both affected diatom growth rates, but effects of density were usually much greater than the effects of nutrients. Growth rates of many taxa decreased from about 1.0 to 0; whereas positive effects of nutrient enrichment were mostly observed in high density conditions and were usually of the magnitude of 0.3. Effects of density on growth were always negative, whereas effects of nutrient enrichment were either positive or negative, but were commonly absent. If negative effects of density on benthic algae were due to nutrient competition, we should have observed greater positive response to nutrients at high than low density. In fact, 11 of 14 species responded positively to N enrichment and 7 of 14 species responded positively to P enrichment at high density, whereas at low density only 5 species responded positively to N and no species responded positively to P (Table 1). The negative effect of P enrichment on so many species is perplexing, but may be due to indirect density effects. P enrichment may have stimulated growth rates and produced higher density earlier during colonization in high P than low P treatments. In our assumption that density effects would be demonstrated during early and late stages of 346

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succession, we did not account for the possibility that negative density effects could have masked slight positive effects of nutrients if density also increased with nutrient conditions. Effects of cell density on diatom growth rates were greater than effects of great difference in nutrient concentrations. Growth form and phylogenetic relationships explained similarities in species abilities to grow fast in low density or be relatively resistant to density effects. These results indicate the great importance of biological interactions in benthic algal assemblages, potential for tradeoffs in traits, and importance of adaptive ecological strategies, and phylogenetic constraints on species traits. Effects of density and nutrients on growth rates in our study differed greatly among species and these differences were related to growth form and phylogeny. Araphids, monoraphids, biraphids with mucilaginous stalks and tubes, and biraphids with canaled raphes had similar sets of traits. Many of these growth form traits are constrained by phylogenetic relationships. Traits for growth rates may also be heritable and species specific (Heath et al. 1993), but they are quite variable among species. Monoraphids, the two Achnanthidium species, were small, had relative low maximum growth rates, but had high resistance to density-dependent factors. In natural streams, Cholnoky (1968) and Kawecka (1981) reported high growth rates for A. minutissimum in both low and high nutrients compared to the relatively lower growth rates observed in this study. In a desert stream this species was resistant to density changes during benthic succession (Peterson and Grimm 1992). Similar to the findings reported here, A. minutissimum was persistent in different density in low nutrients, but grew better than other taxa at high nutrients and high density (Stevenson et al. 1991). Some of the monoraphid diatoms, for example Achnanthidium minutissimum, can attach to diatom stalks as well as to substrate (Roemer et al. 1984, Manoylov 2005), which may mediate effects of resource competition. The resistance of A. minutissimum and A. deflexum to density and low nutrient effects indicated why these taxa have high abundance in low nutrient habitats and persist in many high nutrient habitats as well (Manoylov 2005). Araphid diatoms (Fragilaria, Meridion, and Synedra) had high maximum growth rates at low density- but low resistance to density-dependent factors. Species like Fragilaria crotonensis, F. vaucheriae, and Nitzschia acicularis together with well established euthrophic species (Nitzschia dissipata and N. palea) had the highest growth rates observed in this study. Many of these taxa are known as early colonizers and fast immigrators in benthic diatom communities (Hoagland et al. 1982, Stevenson 1990, Stevenson and Peterson 1989), but were unable to grow well when density on substrate increased. Synedra ulna was found independent of nutrient enrichment, but only grew well in low community density in an N limited stream (Peterson and Grimm 1992). In high nutrients, many species had relatively high growth rates. The biraphids with stalks and tubes were relatively large, Cymbella and Encyonema, had low maximum growth rates, and were relatively resistant to density factors. Stalked diatoms have been assumed to be late succession species with their ability to grow into the canopy of periphyton assemblages and thereby mediate competition for nutrients and light (Patrick 1976, Hoagland et al. 1982, Hudon and Legendre 1987). Similar to the findings reported here, Encyonema minutum (synonym Cymbella minuta Hilse & Rabh.) was persistent in different densities, but grew better than other taxa at low nutrients rather than high nutrients 347

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(Stevenson et al. 1991). In the literature, Cymbella affinis Kütz. is reported growing better at low nutrients (Stevenson 1995); oligotroph and/or mesotroph (Kawecka 1981) and as a eutraphentic species (van Dam et al. 1994). Cymbella affinis was found to decrease with nutrients and density in an N-limited stream (Peterson and Grimm 1992). These differences in responses of Cymbella affinis Kütz. sensu lato may actually be due differences among species. Recent taxonomic developments by Krammer (2002) indicate many diatoms identified as Cymbella affinis in the US are C. excisa (Manoylov and Stevenson 2004). Thus, apparent discrepancies among literature reports for a species may be due to taxonomic problems or phenotypic plasticity, which must be resolved by future research. Biraphid diatoms with a canal raphe were, in general, like the araphids, but varied a bit more. Motility of the Nitzschia species has been hypothesized to be advantageous during development of benthic mat (Burkholder 1996), but density strongly affected all taxa, except Nitzschia dissipata. Like Encyonema or Cymbella, N. dissipata uses may mediate effects of competition by growing in tubes (Germain 1981). High growth of Nitzschia acicularis was limited to low density in another experiment (Stevenson et al. 1991). Many Nitzschia and some araphids are reported from nutrient-rich, eutrophic conditions (Kelly and Whitton 1995, van Dam et al. 1994) where nutrients may be sufficient to compensate for the negative effects of high algal density. These results strongly indicate the great importance of biological interactions in benthic algal assemblages and importance of adaptive ecological strategies. Effects of cell density on diatom growth rates were greater than effects of great differences in nutrient concentrations. Growth form, size, and phylogenetic relationships explained similarities in species abilities to grow fast in low density or be relatively resistant to density effects. Araphids and most Nitzschia had high maximum growth rates and low resistance to density effects, a classic r-selection strategy. Monoraphids with small size and biraphids with stalks and tubes had low maximum growth rates and high resistance to density effects, a classic kselected strategy. Small size, stalks, and tubes may mediate effects of resource competition. Future work must more clearly relate nutrient and density effects to resource depletion at the species level to confirm causes of negative density-dependent interactions, which could be due to competition for light or nutrients or due to allelopathic interactions. Results of experiments in controlled conditions, where cause-effect relations can be demonstrated, must be scaled-up to broad-scale surveys of aquatic ecosystems to test fidelity of experiments. Complementarily, responses of species in well controlled experiments corroborate autecological characterizations of species derived from broad-scale surveys and correlations between species relative abundances and environmental conditions. Linking results of observational surveys and experimental work at multiple spatial and temporal scales is critical for establishing cause-effect relationships and building a strong scientific foundation for advancing algal taxonomy and ecology. ACKNOWLEDGEMENTS KMM would like to dedicate this work to her teacher from Bulgaria, Prof. Dr. Dobrina Temniskova-Topalova. We would like to thank the graduate students in Jan Stevenson’s lab 348

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for the numerous interesting discussions of the presented results. Marina Potapova and Scott Rollins greatly improved an earlier version of this paper. REFERENCES APHA 1998. Standard methods for examination of water and wastewater. Washington DC, American Public Health Association. BARBER, H.G. and E.Y. HAWORTH 1994. A guide to the morphology of the diatom frustule, with a key to the British freshwater genera. – Freshwater Biological association, Sc. Public., 44: 1-110. BOTHWELL, M. L. 1989. Phosphorus-limited growth dynamics of lotic periphytic diatom communities: Areal biomass and cellular growth rate responses. – Canadian Journal of Fisheries and Aquatic Sciences, 46: 1293-1301. BRUNDIN, L.Z. 1988. Phylogenetic biogeography in: Myers, A.A. and P.S. Giller, editors. Analytical biogeography. An integrated approach to the study of animal and plant distributions. Pp343-369. Chapman and Hall, London. BURKHOLDER, J. M. 1996. Interactions of benthic algae with their substrata. in:Stevenson, R. J., Bothwell and R.L. Lowe, editors. Algal Ecology. Academic Press, San Diego, pp. 253-297. CHOLNOKY, B. J. 1968. Die Ökologie der Diatomeen in Binnengewässern. J. Cramer Verlag, Weinheim, 699 pp. CUTLER, A.H. 1998. Nested patterns of species distribution: processes and implications. in: McKinney M.I. and J.A. Drake, editors. Biodiversity dynamics. pp.212-231. Columbia University Press, New York. GASTON, K.J. 2003. The structure and dynamics of geographic ranges. Oxford University Press, Oxford. GASTON, K.J. and S.L. CHOWN. 1999. Geographic range size and speciation. in: A.E. Magurran and R.M. May, editors. Evolution of biological diversity. pp. 236-259. Oxford University Press, Oxford. GERMAIN, H. 1981. Flore des diatomées (Diatomophycées) eaux douces et saumâtres du Massif Armoricain et des contrées voisines d’Europe occidentale. Collection Faunes et Flores actuelles. N. Boubée ed., Paris. 444 pp. HEATH, D.D., N.J. BERNIER, J.W. HEATH and G.K. IWAMA 1993. Genetic, environmental, and interactions on growth and distress response of Chinook salmon (Oncorhynchus tshawytscha) fry. – Canadian Journal of Fisheries and Aquatic Sciences, 50: 435-442. HILLEBRAND, H., C-D. DÜRSELEN, D. KIRSCHTEL, U. POLLINGHER and T. ZOHARY 1999. Biovolume calculation for pelagic and benthic microalgae. – J. Phycol., 35: 403-424. HIXON, M.A., S.W. PACALA and S.A. SANDIN 2002. Population regulation; historical context and contemporary challenges of open vs. closed systems. – Ecology, 83: 1490-1508. HOAGLAND, K.D., S.C. ROEMER and J. K. ROSOWSKI 1982. Colonization and community structure of two periphyton assemblages, with emphasis on the diatoms (Bacillariophyceae). – American Journal of Botany, 69: 188-213. 349

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HUDON, C. and P. LEGENDRE 1987. The ecological implications of growth forms in epibenthic diatoms. – Journal of Phycology, 23: 434-441. KAWECKA, B. 1981. Sessile algae in European mountain streams. 2. Taxonomy and autecology. – Acta Hydrobiologica, 23: 17-46. KELLY, M.G. and B.A WHITTON 1995. The trophic diatom index: a new index for monitoring eutrophication in rivers. – Journal of Applied Phycology, 7: 4232-4244. KRAMMER, K. 2002. Cymbella. in: Diatoms of Europe (H. Lange-Bertalot, editor), Volume 3, 584 pp. Ruggell. A.R.G. Gantner Verlag K.G. LOWE, R and Y. PAN 1996. Benthic algal communities as biological monitors. in: Stevenson, R.J., M.L. Bothwell and R.L. Lowe, editors. Algal Ecology. 705-739. Academic Press, San Diego. MANOYLOV, K.M. 2005. Ecological strategies of benthic diatoms for nutrient competition. Ph.D. dissertation, Michigan State University, East Lansing, Michigan. MANOYLOV, K.M. and R.J. STEVENSON 2004. Cymbella excisa Kütz. in different nutrient conditions. in: Proceedings of the 17th International Diatom Symposium (M. Poulin, editor), Ottawa 2002, 31-45. MCCORMICK, P.V. 1996. Resource competition and species coexistence. in R.J. Stevenson, M.L. Bothwell and R.L. Lowe, editors. Algal Ecology 229-252, Academic Press, San Diego. MCCORMICK, P.V. and R.J. STEVENSON 1991. Mechanisms of benthic algal succession in different flow environments. – Ecology, 72: 1835-1848. PAN, Y., R.J. STEVENSON, B.H. HILL, A.T. HERLIHY and G.B. COLLINS 1996. Using diatoms as indicators of ecological conditions in lotic systems: a regional assessment. – Journal of the North American Benthological Society, 15: 481-495. PATRICK, R. 1976. The formation and maintenance of benthic diatom communities. – Proceedings of the American Philosophical Society, 120: 475-484. PETERSON, C.G. and N.B. GRIMM 1992. Temporal variation in enrichment effects during periphyton succession in a nitrogen-limited desert stream ecosystem. – Journal of the North American Benthological Society, 11: 20-36. PETERSON, C.G. and R.J. STEVENSON 1990. Post-spate development of epilithic algal communities in different current environments. – Canadian Journal of Botany, 68: 2092-2102. PRINGLE, C.M. 1990. Nutrient spatial heterogeneity: effects on community structure, physiognomy, and diversity of stream algae. – Ecology, 71: 905-920. RICKLEFS, R.E. and E. BERMINGHAM 2000. The concept of the taxon cycle in biogeography. – Global ecology and biogeography, 11: 353-361. RIER, S.T. and R.J. STEVENSON (accepted). Response of periphytic algae to gradients in nitrogen and phosphorus in streamside mesocosms. – Hydrobiologia. ROEMER, S.C., K.D. HOAGLAND and J.R. ROSOWSKI 1984. Development of a freshwater periphyton community as influenced by diatom mucilages. – Canadian Journal of Botany, 62: 1799-1813. ROUND, F.E., R.M. CRAWFORD and D.G. MANN 1990. The Diatoms. Biology and morphology of the genera. 747 pp. Cambridge University Press, Cambridge. 350

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SEKAR, R, V.P. VENUGOPALAN, K. NANDAKUMAR, K.V.K. NAIR and V.N.R. RAO 2004. Early stages of biofilm succession in a lentic freshwater environment. – Hydrobiologia, 512: 97-108. STEARNS, S.C. 1992. The evolution of life histories. Oxford University Pres, Oxford. STEVENSON, R.J. 1983. Effects of current and conditions simulating autogenically changing microhabitats on benthic algal immigration. – Ecology, 64: 15141524. STEVENSON, R.J. 1984a. How currents on different sides of substrates in streams affect mechanisms of benthic algal accumulation. – Internationale Revue gesamten Hydrobiologie, 69: 241262. STEVENSON, R.J. 1984b. Procedures for mounting algae in a syrup medium. – Transactions of the American Microscopical Society, 103: 320-321. STEVENSON, R.J. 1986. Mathematical model of epilithic diatom accumulation. in: M. Ricard, editor. Proceedings of the eighth International Diatom Symposium. Koeltz Scientific Books. Koenigstein, Germany. pp. 209231. STEVENSON, R.J. 1990. Benthic algal community dynamics in a stream during and after a spate. – Journal of the North American Benthological Society, 9: 277-288. STEVENSON, R.J. 1995. Community dynamics and differential species performance of benthic diatoms along a nutrient gradient. in: J.P. Kociolek and M.J. Sullivan, editors. A Century of Diatom research in North America. A tribute to the Distinguished Careers of Charles W. Reimer and Ruth Patrick. 29-45, Koeltz Scientific Books USA, Champaign. STEVENSON, R.J. 1996. An introduction to algal ecology in freshwater benthic habitat. in: R.J. Stevenson, M.L. Bothwell, and R.L. Lowe, editors. Algal Ecology. 3-30, Academic Press, San Diego. STEVENSON, R.J. and R. GLOVER. 1993. Effects of algal density and current on ion transport through periphyton communities. – Limnology and Oceanography, 38: 1276-1281. STEVENSON, R.J. and Y. PAN. 1994. Are evolutionary tradeoffs evident in responses of benthic diatoms to nutrients? in: D.Marino, editor. Proceedings of the 13th International Diatom Symposium. 71-81, Bio Press Ltd., Bristol. STEVENSON, R. J. and C.G. PETERSON. 1989. Variation in benthic diatom (Bacillariophycea) immigration with habitat characteristics and cell morphology. – Journal of Phycology, 25: 120-129. STEVENSON, R. J. and C. G. PETERSON. 1991. Emigration and immigration can be important determinants of benthic diatom assemblages in streams. – Freshwater Biology, 26: 279-294. STEVENSON, R. J., C. G. PETERSON, D. B. KIRSCHTEL, C. C. KING and N. C. TUCHMAN. 1991. Succession and ecological strategies of benthic diatoms (Bacillariophyceae): density-dependent growth and effects of nutrients and shading. – Journal of Phycology, 27: 59-69. VAN DAM, H., A. MERTENS and J. SINKELDAM. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. – Netherlands Journal of Aquatic Ecology, 28: 117-133. 351

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DE VIJVER, B. and I. BEYERNS 1999. Biogeography and ecology of freshwater diatoms in Subantarctica: a review. – Journal of Biogeography, 26: 993-1000. VON ENDE, C. N. 2001. Repeated-measures analysis. in: Scheiner, S. M. and J.Gurevitch, editors. Design and Analysis of Ecological Experiments. Oxford University Press, pp 134-157. WILKINSON, L. 1989. Systat: The System for Statistics. Evanston, 822 pp.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 353-363) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Atypical Tabularia in Coastal Lake Erie, USA E. F. Stoermer and N. A. Andresen School of Natural Resources and Environment University of Michigan, Ann Arbor, MI 48109-1115. E-mail: [email protected] ABSTRACT Tabularia populations collected at a coastal site in Lake Erie, near Cleveland, Ohio, USA exhibit highly abnormal morphology. Frustules may be bent, asymmetric, have irregular striae patterns, irregular margins, or any combination of these characters. The majority of specimens in the collection are abnormal to some degree. Although specimens are so atypical that identification is difficult, relatively simple morphometric analysis shows that morphologies similar to most described members of the genus are present in the collection. Tabularia is probably not indigenous to the Laurentian Great Lakes but occurs in areas that have been highly modified, particularly by saline discharges. The collection site is subject to such discharges, and also to other industrial contaminants. The abnormalities present may be related to these factors, or simply to stresses imposed on species growing out of their preferred habitat. In any case, the occurrence of numerous forms of Tabularia in a localized area where it is not native is remarkable. Key words: diatoms, Tabularia populations, morphological abnormality, Lake Erie INTRODUCTION There are number of causes of morphological abnormalities in diatom frustules. Nonlethal mechanical damage may produce clones of cells that have obvious structural defects. This is relatively rare in natural populations. The most obvious causes are attacks by grazers that damage frustules, but do not kill cells, and simple mechanical crowding, as is found in dense periphyton mats. Attacks by fungal or protozoan parasites may also cause abnormal structural changes in diatom frustules. Physical crowding may also produce frustular abnormalities in cultured populations, particularly benthic species (Drum 1964). Both simple frustular abnormalities and special adaptations such as craticular stages, internal 353

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valves, and different valve morphologies in a single species (Stoermer 1967) are often associated with habitats that periodically undergo desiccation. Based on our observations, it also appears that frustular abnormalities are common in diatom communities that undergo toxic stress. In general, it is probably safe to say that diatoms growing in unstable habitats are particularly susceptible to abnormal frustule formation. The nearshore waters of many areas of the Laurentian Great Lakes are examples of ecological instability. Large population and industrial centers on the shores of these originally highly oligotrophic lakes lead to large spatial and temporal gradients in nutrient, conservative ion, and toxic material concentrations. Partially because of the large variation in ecological conditions, a large number of diatom species have been reported from the Laurentian Great Lakes (Stoermer et al. 1999) and undoubtedly many remain to be discovered. These lakes are very young geologically, having reached their present configuration only ca, 4000 years ago. They lack the highly specialized indigenous floras characteristic of ancient great lakes (Stoermer and Edlund 1999), although speciation appears to have occurred in the offshore plankton (Theriot and Stoermer 1984). Some indigenous species appear to have been exterminated (Stoermer et al. 1987) and numerous non-native species have been introduced and become established (Mills et al. 1993). Most non-indigenous diatoms that have become successful in the Great Lakes come from estuarine habitats (Hohn 1969, Hasle and Evenson 1975, 1976, Hasle 1978). Considering their inland location and normally low salinities this may appear unusual, however, many industries in the region are based on extraction of salt (NaCl) from large deposits that underlie substantial parts of the area. Salt is also widely used as a melting agent to facilitate travel during the region’s notoriously harsh winters. The lakes are also directly connected to transoceanic shipping through the St. Lawrence Seaway and the Welland Canal. Thus, large salinity gradients, particularly in harbors has allowed invasion of many exotic invertebrates, such as zebra mussels (Dreissena spp.), fish, such as gobies (Gobius spp.), (Mills et al. 1993) and algae, such as Bangia (Lin and Blum 1977). In the following we discuss an unusual population of an apparently invasive taxon, Tabularia that is usually found in estuarine habitats. The genus was relatively recently separated from Synedra (Williams and Round 1986) and circumscription of species in the genus remains controversial. The population discussed comes from a site on the shores of Lake Erie that has had a long history of disturbances of several types. Lake Erie is generally considered the most modified of the Laurentian Great Lakes, and became a focus of concerns about water pollution in the later decades of the twentieth century. Although water quality has improved in the main body of Lake Erie, primarily due to reductions in phosphorus loading and increased transparency resulting from zebra mussel feeding (Stoermer et al. 1996), many shoreline sites remain problematic. MATERIALS AND METHODS The site from which the material used in our investigation was collected is such a problematic shoreline area. The material was collect by Dr. G. Sgro as part of the Great Lakes Environmental indicators project. The material collected is described as “algae 354

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growing on shoreline rocks”. The locality (41° 29' 0.9N; 81° 42' 58.7"W) of collection is locally known as Whiskey Island (Fig. 1). The island was actually a peninsula found at the mouth of the Cuyahoga River in Cleveland, Ohio. A shipping channel eventually cut it off from the mainland. Its name is derived from a distillery that was built there in 1836, hence its name. The island has been subjected to multiple uses. It has been an industrial site, ship graveyard and waste disposal area. It is currently the site of a salt mine, and has recently been developed as a large marina. Similar to other such areas in the Great Lakes region, further development as a recreational area is contemplated. In this regard, the area has a legacy of severe environmental problems. During the late 1950’s and 1960’s Lake Erie was often cited as an example of extreme water pollution because of large cyanobacterial blooms, massive overgrowths of Cladophora, and high levels of toxic materials. The Cuyahoga River gained particular notoriety in the period because it was so contaminated that it occasionally caught fire. The more obvious ecological problems have now been contained, if not eliminated, but the legacy of previous environmental insults remains. The material was prepared by oxidation in nitric acid. Acid was removed by decantation with distilled water to remove acid and oxidation by-products. The cleaned and washed material was dried on number one cover glasses and mounted in Naphrax. Prepared slides were observed and measurements were made with a Leica DMRX microscope. Images were captured with a Sony DKC 5000 video camera suing Adobe Photoshop software. Illustrations were prepared using the same software. Measurements were made of

Fig. 1. Outline map of Lake Erie, showing approximate location of sampling site. Insert shows detail of Whiskey Island.

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Fig. 2. Specimens with dimensions measured indicated: a - total length of frustule; b - maximum width of frustule; c - Maximum width of frustule end; d - Width of end constriction; e - maximum length of striae; f - Maximum width of central area; g - number of striae in 10 µm (bar is 10 µm).

100 unobstructed specimens and recorded using NIH Image software (Stoermer 1996). Measurement made (Fig. 2) include: A - Total length of frustule B - Maximum width of frustule C - Maximum width of frustule end D - Width of end constriction E - Maximum length of striae F - Maximum width of central area G - Number of striae in 10 µm Untransformed data were analyzed using Data Desk software. A cluster analysis (Fig. 3) was performed using the complete linkage option. RESULTS Initial observations showed an extreme variety of atypical shapes (Fig. 4), although it was apparent that some coherent trends in morphology were present. Results of the cluster analysis (Fig. 3) indicated the presence of five groups of specimens with similar morphology. Inspection of the cluster results indicate that more coherent morphological 356

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Fig. 3. Results of cluster analysis. Groupings and nominal name assignments for each cluster indicated below.

series may be present as indicated by high-level outliers in some of the groups. Besides possible lack of resolution due to under-sampling, taxonomic results are not entirely satisfying. We think it clear that these specimens belong to the genus Tabularia (Kütz.) Williams and Round, as currently conceived. The taxon was originally circumscribed as a subgenus of Synedra (Kützing 1844), and raised to generic status by Williams and Round (1986). As is the case with many diatom genera, Tabularia has historically been treated with very compressed taxonomy, which includes relatively few species and a large number of “varieties” or other subordinate taxa (Cleve-Euler 1953). Although taxonomic treatments have become more discriminatory in the past few decades, taxonomy of the genus and its assumed relatives remains controversial (e. g. Williams and Round 1986, Krammer and Lange-Bertalot 1991). Despite these difficulties, it is apparent that one of the series present, if not identical to, is at least closely related to T. tabulata (C. A. Agardh) Snoeijs. Similarly, another series most likely belongs to T. fasciculata (C. A. Agardh) Williams and Round. Nomenclaturally correct designation of the other populations present is more difficult. The more strikingly rostrate forms may belong to T. barbatula (Kütz.) Williams and Round (Synedra gracilis sensu Kützing 1844), although further study would be necessary to validate this conclusion. Other populations present have likely been referred to Synedra affinis Kützing (sensu Hustedt 1930) and Tabularia parva (Kütz.) Williams and Round. The latter species is reported as one of the more abundant periphyton species in the Salton Sea (Lange and Tiffany 2002), a highly polluted and unusual habitat. Other unusual habitats where Tabularia is found include sea ice (von Quillfeldt et al. 2003).

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1

2

3

4

5

6

7

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17 14

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11

Fig. 4. Representative species from the collection, arranged according to results of cluster analysis. Figs 1-3 group 3 (T. tabulata); Figs 4-7 group 1 (T. affinis); Figs 7-10 group 4 (T. barbatula); Figs 11-13 group 2 (T. parva - note that Fig. 11 is an extreme outlier and probably belongs to another taxon); Figs 14-17 group 5 (T. fasciculata).

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DISCUSSION Aside from problems caused by the abnormal forms exhibited by the specimens studied, firm identification of taxa present are complicated by present uncertainties in the taxonomy of Tabularia and its subsidiary taxa. Despite these difficulties, we think it clear that several taxa are present in this collection and that they are closely related to, if not identical with commonly reported marine and estuarine taxa. Further research will be necessary to firmly establish this conclusion. Given the apparent invasive capability of some diatom species, their ability to evolve rapidly, and the present state of diatom taxonomy resolving true relations will necessitate further taxonomic revision of this entire group. How and when these entities became resident in the nearshore waters of Lake Erie is a question of current interest. It is commonly perceived that the Laurentian Great Lakes are presently undergoing a high rate of invasions by non-indigenous species (Mills et al. 1993, Loughead and Stevenson 2004), but this may not be an entirely correct perception, at least in the case of diatom populations. We know that estuarine diatom species, such as Actinocyclus normanii fo. subsalsa (Juhl.-Dannf.) Hust. were present in Lake Erie in the mid 1800’s (Stoermer et al. 1987, 1996) and eventually became biomass dominants in the western basin of the lake (Hohn 1969). The date of first notable occurrences is soon after opening of the Erie Canal, which reached lake Erie in 1825, opening the first direct connection between the sea and the Great Lakes. As is often the case, diatoms could have been a useful early indicator of an emerging problem. Unfortunately, the history of this invasion was discovered only much later through paleolimnological studies. Of course, it is entirely possible that isolated populations of primarily marine diatom species were found in the numerous salt springs and seeps of the Great Lakes region prior to gross human modification of this ecosystem. At present, knowledge of the diatom flora of this region and its history are not sufficient to support any firm conclusions about the first occurrences of Tabularia, or any other primarily estuarine genus in this region. This problem might be solved through paleolimnological studies, but we are not aware of any effort directed at the problem of diatom invasions. There are indications that uncontrolled spread of non-indigenous diatom species is a worldwide problem. Asterionella apparently invaded New Zealand soon after European settlement (Harper 1994), and Gomphoneis relatively recently became a nuisance in French streams, a habitat where it had not previously been noted (LeCohu and Coste 1995). Similar nuisance occurrences of Didymosphenia are apparently now occurring in New Zealand (Cathy Kilroy National Institute of Water and Atmospheric Research, New Zealand, personal communication). The cause of frustular abnormalities observed is equally uncertain. Abnormalities in diatom valve structure have been noted and reported virtually since the group was first studied (Taylor 1929) and classifications of deformity have been proposed, both as to type (e.g. Cox 1891) and as to presumed causality (Barber and Carter 1981). Of the possible causes suggested by Barber and Carter, their first category, “chemical abnormalities in the habitat” seems most likely in the populations we studied. There is no evidence of 359

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parasitism or sexual reproduction, and the cells and types of abnormalities observed do not suggest clonal populations. Given the history and current impacts on the site studied, exotic chemical inputs are not unexpected. Given the plethora of possible “abnormal” chemicals affecting these populations, choosing a most probable cause without experimental evidence is difficult. In general, deformities have been associated with pollution or eutrophication (Antoine and Benson Evans 1986, Belcher et al. 1966, Klee and Schmidt 1987). More specific chemical causes include silica limitation (Booth and Harrison 1979) and increased salinity in freshwater habitats (Tuchman et al. 1984). Andresen and Tuchman (1991) noted widespread frustular abnormalities in planktonic diatom populations from several areas in the Laurentian Great Lakes collected in 1983, but were unable to assign any particular cause to their observations. Feldt et al. (1973) reported apparently abnormal Synedra populations were from Lake Superior, but these populations have persisted, and apparently are the result of genetic modification (unpublished observations). The occurrence of morphological abnormalities in birds (Ludwig et al. 1993, 1996) fish (Smith et al. 1994), and invertebrates (Dickman et al. 1992, Diggins and Stewart 1993), particularly in the coastal region of Lake Erie and its tributaries, is well known. These effects are usually attributed to toxic organic compounds. Reports of similar effects on benthic diatoms are more rare, but not unknown (Dickman 1998, Gómez and Licursi 2003). We are not aware of such published reports from the Laurentian Great Lakes. The late Brian Shero (personal communication, Dr. Brian Shero, Medaille College, Buffalo NY) found numerous deformities in diatoms collected from contaminated sites in the Niagara River, but these observations were apparently never effectively published. The presence of benthic diatoms that are atypical, in terms of both distribution and morphology, in the Great Lakes may offer valuable insights into toxic effects and the ability of exotic populations to invade the lakes. Although the present state of knowledge does not permit firm conclusions concerning the populations described here, investigation of benthic diatom populations in the Great Lakes is a neglected topic that deserves more research attention. ACKNOWLEDGEMENTS Dedicated to Dr. Dobrina Temniskova for her contributions to Phycology, particularly the study of fossil diatoms. This research was supported by a grant from the U.S. Environmental Protection Agency’s Science to Achieve Results (STAR) Estuarine and Great Lakes (EaGLe) program through funding to the Great Lakes Environmental Indicators (GLEI) Project, U.S. EPA Agreement EPA/R-8286750. This document has not been subjected to the Agency’s required peer and policy review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred. We thank Dr. G. Sgro for collecting the material used in our investigation and the late Dr. J. C. Kingston for discussions regarding initial results. 360

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REFERENCES ANDRESEN, N.A. and M.L. TUCHMAN 1991. Anomalous diatom populations in lake Michigan. - J. Great Lakes Res., 17: 144-149. ANTOINE, S.E. and K. BENSON EVANS 1986. Teratological variations in the River Wye diatom flora, Wales, U. K. in: M. Ricard, editor. Proc. Eighth Internat. Diatom Symp.: 375-384. Koeltz, Koenigstein. BARBER, H.G. and J.R.CARTER 1981. Observations on some deformities in British diatoms. – Microscopy, 34: 214-226. BELCHER, J.H., E.M. SWALE and F. HERON 1966. Ecological and morphological observations on a population of Cyclotella pseudostelligera Hustedt - J. Ecol., 54: 335-340. BOOTH, B. and P.J. HARRISON 1979. Effect of silicate limitation on valve morphology in Thalassiosira and Coscinodiscus (Bacillariophyceae). - J. Phycol., 15: 326-329. CLEVE-EULER, A. 1953. Die Diatomeen von Schweden und Finnland. Teil II. Arraphideae, Brachyraphideae. - Kungl. Svenska. Vetskapakademiens Handlingar, Fjärde Serien, Band 4, No: 1, pp.1-158, 35 Tafeln. COX, J.D. 1891. Deformed diatoms. - Proc. Amer. Microsc. Soc., 12: 178-183. DICKMAN, M. 1998. Diatom stratigraphy in acid-stressed lakes in the Netherlands, Canada, and China: 115-143. in: C. Suba Rao, editor. Acid Stress and Aquatic Microbial Interactions. CRC Press. DICKMAN, M., I. BRINDLE and M. BENSON 1992. Evidence of teratogens in sediments of the Niagara River watershed as reflected by chironomid (Diptera: Chironomidae) deformities. - J. Great Lakes Res., 18: 467-480. DIGGINS, T.P. and K.M. STEWART 1993. Deformities of Aquatic Larval Midges (Chironomidae: Diptera) in the Sediments of the Buffalo River, New York. - J. Great Lakes Res., 19: 648-659. DRUM, R. W. 1964. Notes on Iowa diatoms. VI. Frustular aberrations in Surirella ovalis. Proc. Iowa Acad. Sci., 71: 51-55. FELDT, L.E., E.F. STOERMER and C.L. SCHELSKE 1973. Occurrence of morphologically abnormal Synedra populations in Lake Superior. in: Proc. 16th Conf. Great Lakes Res., pp. 34-39. Internat. Assoc. Great Lakes Res. HARPER, M.A. 1994. Did Europeans introduce Asterionella formosa Hassall into New Zealand? in: J. P. Kociolek, editor. Proc. Eleventh Internat. Diatom Symp. - Memoirs of the California Academy of Sciences, 17: 479-484, California Academy of Sciences, San Francisco. HASLE, G.R. 1978. Some freshwater and brackish water species of the diatom genus Thalassiosira Cleve. – Phycologia, 17: 263-292. HASLE, G.R. and D.L. EVENSEN 1975. Brackish-water and fresh-water species of the diatom genus Skeletonema Grev; I; Skeletonema subsalsum (A Cleve) Bethge. – Phycologia, 14: 283-297. HASLE, G.R. and D.L. EVENSEN 1976. Brackish water and freshwater species of the diatom genus Skeletonema. II. Skeletonema potamos comb. nov. - J. Phycol., 12: 73-82. 361

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HOHN, M.H. 1969. Qualitative and quantitative analysis of plankton diatoms, Bass Island area, Lake Erie. - Bull. Ohio Biol. Surv., N. S., 3:1-211. HUSTEDT, F. 1930. Bacillariophyta (Diatomeae). in: A. Pascher, editor.Die Süsswasser-Flora Mitteleuropas, Heft 10, Zweite Auflage. - Gustav Fischer, Jena. KLEE, R. and R. SCHMIDT 1987. Eutrophication of the Mondsee (Upper Austria) as indicated by the diatom stratigraphy of a sediment core. - Diatom Res., 2: 55-76. KRAMMER, K. and H. LANGE-BERTALOT. 1991. Band 2 Bacillariophyceae. 3.Teil: Centrales, Fragilariaceae, Eunotiaceae. in: H. Ettl, J. Gerloff, H. Heynig and D. Mollenhauer, editors. Süßwasserflora von Mitteleuropa, II. - Gustav Fischer Verlag: NY, New York. KÜTZING, F.T. 1844. Die Kieselshaligen Bacillarien oder Diatomeen. Nordhausen. LANGE, C.B. AND M.A. TIFFANY 2002. The diatom flora of the Salton Sea, California. – Hydrobiologia, 473: 179–201. LE COHU, R. and M. COSTE 1995. Le genre Gomphoneis (Bacillariophyta): un nouveau modèl d’organization du cingulum. - Can. J. Bot., 73: 112-120. LIN, C.K. and J.L. BLUM 1977. Recent invasion of a red alga (Bangia atropurpurea) in Lake Michigan. - J. Fish. Res. Board Can., 34: 2413-2416. LOUGHEED, V.L. and R.J. STEVENSON 2004. Exotic marine macroalga (Enteromorpha flexuous) reaches bloom proportions in a coastal lake of Lake Michigan. - J. Great Lakes Res., 30: 538-544. LUDWIG, J.P., H.J. AUMAN, H. KURITA, M.E. LUDWIG, L.M. CAMPBELL, J.P. GIESY, D.E. TILLITT, P. JONES, N. YAMASHITA, S. TANABE and R. TATSUKAWA 1993. Caspian Tern Reproduction in the Saginaw Bay Ecosystem Following a 100-Year Flood Event. - J. Great Lakes Res., 19: 96-108. LUDWIG, J.P., H. KURITA-MATSUBA, H.J. AUMAN, M.E. LUDWIG, C.L. SUMMER, J.P. GIESY, D.E. TILLITT and P.D. JONES 1996. Deformities, PCBs, and TCDD-Equivalents in Double-Crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) of the Upper Great Lakes 1986-1991: Testing a Cause-Effect Hypothesis. - J. Great Lakes Res., 22: 172-197. MILLS, J.L., J.H. LEACH, J.T. CARLTON and C.L. SECOR 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. - J. Great Lakes Res., 19: 1-54. SMITH, S.B., M.A. BLOUIN and M.J. MAC 1994. Ecological Comparisons of Lake Erie Tributaries with Elevated Incidence of Fish Tumors. - J. Great Lakes Res., 20: 701716. STOERMER, E.F. 1967. Polymorphism in Mastogloia. - J. Phycol., 3: 73-77. STOERMER, E.F. 1996. A simple, but useful, application of image analysis. - J. Paleolimnol., 15: 111-113. STOERMER, E.F. and M.B. EDLUND 1999. No paradox in the plankton? - Diatom communities in large lakes. pp. 51-58. in: S. Mayama, M. Idei and I. Koizumi, editors. Proceedings of the 14th International Diatom Symposium, Tokyo. - Koeltz Scientific Books, Koenigstein. STOERMER, E.F., R.G. KREIS, JR AND N.A. ANDRESEN 1999. Checklist of diatoms from the Laurentian Great Lakes II. - J. Great Lakes Res., 25: 515-566. 362

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STOERMER, E.F., J.P. KOCIOLEK, C.L. SCHELSKE and D.J. CONLEY 1987. Quantitative analysis of siliceous microfossils in the sediments of Lake Erie’s central basin. - Diatom Res., 2: 113-134. STOERMER, E.F., G. EMMERT, M.L. JULIUS and C.L. SCHELSKE 1996. Paleolimnologic evidence of rapid recent change in Lake Erie’s trophic status. - Can. J. Fish Aquat. Sci., 53: 1451-1458. TAYLOR, F.B. 1929. Notes on Diatoms - Guardian Press, Bournemouth. THERIOT, E.C. and E.F. STOERMER 1984. Principal component analysis of Stephanodiscus: Observations on two new species from the Stephanodiscus niagarae complex. – Bacillaria, 7: 37-58. TUCHMAN, M.L., E.C. THERIOT and E.F. STOERMER 1984. Effects of low-level salinity concentrations on the growth of Cyclotella meneghiniana Kütz. - Arch. Protistenk., 128: 318-326. VON QUILLFELDT, C.H., W.G. AMBROSE, JR. and L.M. CLOUGH 2003. High number of diatom species in first-year ice from the Chukchi Sea. - Polar Biol., 26: 806–818. WILLIAMS, D.M. and F.E. ROUND 1986. Revision of the genus Synedra Ehrenb. Diatom Res., 1: 313-339.

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Nadja Ognjanova-Rumenova & Kalina Manoylov (eds.) 2006 ADVANCES IN PHYCOLOGICAL STUDIES Festschrift in Honour of Prof. Dobrina Temniskova-Topalova (pp. 365–383) © PENSOFT Publishers & University Publishing House Sofia–Moscow

Refining diatom indicators for valued ecological attributes and development of water quality criteria R. Jan Stevenson Center for Water Sciences and Department of Zoology, Michigan State University, East Lansing, Michigan 48824, U.S.A. ABSTRACT This paper was written to stimulate advancements in our uses of diatoms in environmental assessment. Emphases are placed on redefining the importance of diatoms in assessment and on techniques that can be used to refine and apply diatom indicators. Redefinition of the importance of diatoms in assessment is based on new ecological assessment and management frameworks. These frameworks list the kinds of information that are needed to solve environmental problems. Arguments are presented for more emphasis on linking diatom indicators to valued ecological attributes such as biodiversity, rather than inferring stressor conditions. In addition, application of indicators in the development of environmental criteria is reviewed. The acceleration of global change and emerging opportunities for use of diatoms in environmental assessment make the reviewed issues timely and important. Key words: diatom indicators, VEAs, water quality INTRODUCTION Use of diatoms in environmental assessments of aquatic ecosystems is an important part of many management programs because they are so sensitive to environmental change and because they precisely indicate those changes. We have used diatom indicators to conclude one of 2 things: 1) that species composition of diatoms changes in response to alteration of aquatic ecosystems by humans or 2) diatom-inferred environmental conditions change due to human activities. These conclusions have been valuable for guiding management decisions that range from reducing acid-producing contaminants in power plant emissions to setting restoration targets for phosphorus in the Everglades (Dixit et al. 1992, Pan et al. 365

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2000, Stevenson et al. 2002). Despite the obvious contributions of diatom indicators in environmental research, I commonly am asked to answer the questions, “Why should the public care about a change in diatom species composition?” and “Why use diatoms to infer physico-chemical conditions when we can measure those conditions directly?” Addressing these questions should guide future refinements in development and application of diatom indicators and will increase our contributions to solving future environmental problems. Frameworks for environmental assessment and management can guide our refinements of diatom indicators. These frameworks list the information needed to solve problems and also describe how to use that information. Examples of such frameworks include ecological risk assessment and human health risk assessment (Suter 1993, Stern and Fineberg 1996, Goldstein 2005) and the recent millennial assessment by the UN (Millenium Ecosystem Assessment 2005). Many of these frameworks address the same basic questions: “Is there a problem? What is causing the problem? How can we fix the problem?” Alternatively, the questions might address threats when future problems are forecasted, such as global climate change and land use change. These frameworks show the kinds of information that decision makers need for environmental management, and that information should be the focus of our diatom assessments. In this chapter, I briefly introduce a framework that was designed specifically for and by aquatic resource managers, with some help by scientists, for the kinds of regional and national assessments in which algae are often used (Stevenson et al. 2004a, b). This framework shows how indicators of valued ecological attributes (VEAs) and environmental criteria are used to assess ecological condition and guide management decisions. VEAs refer to structural and functional characteristics of ecosystems that contribute directly or indirectly to human welfare, and are often the endpoints or targets of environmental management. Environmental criteria are specific levels of ecological conditions that trigger management actions. The main focus of the chapter will be a discussion of ways we can refine diatom indicators of VEAs and for criteria development. An Assessment-Management Framework Assessments, such as those mandated in the US Clean Water Act by the US Congress and the Water Framework Directive by the European Commission (2000), are designed to assess the status and trends in aquatic resources and to guide decisions by managers on actions that will restore or protect resources. In 2000, a group of 60 U.S. and European scientists and resource managers attended a workshop hosted by the Society of Environmental Toxicology and Chemistry. This group was charged with developing guidance for resource managers on how to conduct and communicate this type of ecological assessment. One subgroup was assigned the task of developing guidance for designing and implementing environmental assessments. That guidance emerged as a framework of related steps that could be used in environmental assessments and applied in management (Stevenson et al. 2004a, b). The framework highlights 4 stages in an assessment and management framework: design, characterizing condition, diagnosing causes and threats, and management (Fig. 1). 366

367 • Sampling Methods • QA/QC Plan

• Scale of Assessment

• Indicator Selection

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• Old vs. New Data

• Sites Selection

• Testable Hypotheses

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Response Indicators Stressor Indicators Land Use Indicators

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CHARACTERIZATION Refining diatom indicators for valued ecological attributes and development of water quality criteria

Fig. 1. The protocols for ecological assessment related in a framework. Three major steps are emphasized, study design, analysis, and integration. See Stevenson et al. (2004 a, b) for more detail.

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The design stage includes steps of defining objectives of the assessment, developing a conceptual model of relations between human activities and VEAs, and designing a study plan. Clear definitions of the objectives of the assessment require that the VEAs of ecosystems be identified. Then, in the conceptual model, VEAs are related in a causal pathway to the contaminants and habitat alterations (stressors) and the human activities causing stressors (Fig. 2). We emphasized grouping factors in the conceptual pathway into 3 categories, VEAs, stressors, and human activities, because of the use of the variables in management applications. The goal of management is to optimize VEAs and cooccurrence of human activities by minimizing stressors. For example, biodiversity and fisheries production (VEAs) could be maintained in a watershed with extensive agricultural use of the landscape (human activities) if stressors were sufficiently low. These stressors might be contamination by fertilizer and sediment and alterations of temperature, light, and hydrology. Stressor criteria would be established for levels of these contaminants and habitat alterations that would support the desired biodiversity and fisheries production. The desired biodiversity and fisheries production could also be quantified as biocriteria. However, we would regulate human activities with use of best management practices to meet stressor and biological criteria, not establish limits on human use of landscapes – unless, of course, stressor control was not possible. The design stage is concluded with development of the study plan that includes selecting variables and sampling strategies that provide the necessary information. Again, that information includes condition of VEAs, stressor levels, and human activities that could be causing stressors. During the characterization stage, conditions observed at sites are compared to expected conditions to determine effects of human activities on VEAs and the stressors caused by human activities. Of course, characterizing VEAs and stressors are essential in an assessment of ecological condition, but characterizing human activities in watersheds and zones near waterbodies can help identify sources of contaminants and habitat alterations. Without comparison of observed condition to an expected condition and relating effects to human activities, effects of human activities on VEAs can not be assessed. Expected condition can be delineated using frequency distribution or predictive modeling approaches (Hughes et al. 1986, Hughes 1995, Wiley et al. 2002). With both, we describe either: the desired conditions that would for example, support productive fisheries; natural or near natural conditions; conditions supporting native or endangered species; and clear water conditions meeting recreational uses by the public. Simply observing condition at a site is not enough. Comparison to expected condition describes whether there is a problem or not. Relating the deviation between observed and expected condition to human activities is important for distinguishing effects of natural and human factors. Characterizing expected condition of ecological attributes is important for establishing criteria. Measured conditions at assessed sites can be compared to criteria to determine effects of human activities, determine whether management actions are warranted, and determine which stressors should be the focus of management activities. The diagnosis stage identifies which stressors are most important causes or threats to management goals (expected condition). Ratios of observed and expected stressor conditions, sometimes called hazard quotients or toxic units (Suter 1993) provide indices 368

Increasing Population Roads Construction Point Sources Wastewater Pets

Dams Channelization Diversions Levees Revetments

Changes in flow, timing, amount, pathway

Urbanization/ Residential Development

Stream Channel Modification

Fragmentation Fertilizers Pesticides Roads Monoculture Compaction Sedimentation

369

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Fertilizers Livestock Pesticides Habitat Alt. Irrigation Compaction Animal Waste

Water Quality Chemical Habitat

Chemical Loading; Toxins Nutrients O2 Demand Acid/Base

Habitat Alt. Toxic Waste Oil Gravel Extraction Heavy Metals Liming

Mining

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Valued Ecological Attributes

Physical Habitat

Changes in sediment load

Agriculture

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Roads Construction Habitat Alt. Boating Fishing Fish Intro., Poisoning

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Mobilization of heavy metals

NO x SOx Air Toxics Liming

Atmospheric Deposition

Refining diatom indicators for valued ecological attributes and development of water quality criteria

2

Fig. 2. A conceptual model of human activities that produce contaminants and alter habitats that then affect the physical, chemical and biological integrity of stream ecosystems. The elements of the model are separated into three categories of variables should be considered in ecological assessments: land use, stressor, and response variables. This model was modified from a figure by Bryce et al. (1999) and Stevenson et al. (2004a).

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guiding management of specific stressors that can or are polluting waters. Expected stressor conditions can be any one of several benchmark doses based on the LC50, no observed effects concentrations, or lowest effects concentrations that were derived from laboratory toxicological studies (Suter 1993, Setzer and Kimmel 2003). In a similar way, benchmark doses for pollutants can be determined with “stressor-response relationships” between VEAs and pollutant that are developed from observed ecological conditions in aquatic habitats of a region (Dodds et al. 1997, Stevenson et al. 2002, Stevenson et al. accepted). As ratios between observed and expected stressor conditions increase and surpass 1.0, risk of problems increases and become more important. I will discuss criteria development more in a later section of the chapter. Management decisions are based on many factors, such as the options for reducing contamination and the effects of different options on human welfare (e.g. Dietz 2003). The political, legal, social, and economic factors that affect management decisions are complex and should be better understood by ecologists. Understanding how policies are made, the language of laws, variation in value of ecological attributes among cultures, and quantification of ecosystem services of VEAs in economic cost-benefit analyses is where results of diatom indicators are integrated into management decisions. Thus, understanding factors in management decisions must be included in our efforts to refine diatom indicators for use in environmental management. All these topics are reviewed in Stevenson et al. (2004a, b). The case of environmental problems in the Everglades can be used as an example to illustrate these concepts. The Everglades is a large wetland at the southern tip of Florida, a state in the Southeast US (Davis and Ogden 1994). The Everglades is prized for its support of biodiversity, so it must be protected at a high level according to legislation passed by the State of Florida (the Everglades Forever Act). One of the most sensitive responses of the Everglades to contamination is the loss of a floating calcareous algal mat, which plays an important role in primary production, formation of calcareous sediments, and as habitat for animals (Browder et al. 1994). Therefore calcareous algal mats were identified in the design phase as a valued ecological attribute that was likely affected by the nutrient enrichment or hydrologic alterations of Everglades by humans. Subsequent experiments showed that phosphorus contamination causes the breakdown and loss of this calcareous algal mat (McCormick and Odell 1996). Large-scale studies along a phosphorus (P) gradient showed a threshold response in calcareous algal mats about 7.75 km from a point-source of P (Stevenson et al. 2002). Calcareous algae covered about 75% of the open water in sloughs that were greater than 7.75 km from the P point-source and was usually absent from sloughs that were closer. Relations between total phosphorus and distance from that point-source indicate TP concentrations are less than or equal to 10 µg/L at 8 or more kms from the point source. Although natural TP concentrations average less than 10 µg/L, TP varies in any slough and can exceed 10 µg/L as much as 25% of the time in the areas that have the calcareous algal mat. So 10 µg/L TP has been selected as a TP criterion that would support the calcareous algal mat. Based on these findings, the expected conditions in future assessments are the presence of calcareous algal mats and TP concentrations less than 10 µg/L. If calcareous algal mats are not present and TP is greater than 10 µg/L, then we can conclude that human activities have impaired 370

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the Everglades and high TP is at least one cause of that impairment. Management options include establishment of storm-water treatment areas (STAs) that will reduce TP concentrations and several additional advance treatment technologies. Together, the STAs and advanced technologies will be expected to reduce TP concentrations to less than 10 µg/L in waters discharged into the Everglades (Chimney and Goforth 2001). Valued Ecological Attributes Historically, most diatom indicators have inferred physical and chemical conditions (i.e. stressors). Diatom indicators of pH, nutrient concentrations, organic pollution, conductivity and salinity are very sensitive and precise indicators of these physical and chemical variables. In some cases, such as paleoecological studies, biological indicators of physicochemical conditions may be our only assessment of these conditions (Charles et al. 1990, Dixit et al. 1999). For studies of existing ecosystems, we are starting to build a body of evidence that diatom indicators are more precise indicators of physicochemical conditions than one time sampling and measurement of those conditions that tend to vary greatly with diurnal and weather related factors (Stevenson and Smol 2002, Stevenson unpublished data). Thus, “Diatoms can be more precise indicators of some physico-chemical conditions than one time sampling and measurement of those conditions” is one answer to questions of why use diatom indicators. Another answer is that diatoms are complementary indicators; so even if they were not more precise than direct measurement, they provide additional lines of evidence about conditions at a site. Another opportunity for use of diatom indicators is measurement or indication of valued ecological attributes. In general, we manage resources to optimize valued ecological attributes by reducing contamination levels. Thus low stressors (e.g. contaminants and habitat alterations) are not valued by themselves as much as the public values clear water for recreation, safe water for drinking, and protection of the natural balance of flora and fauna in aquatic ecosystems. We do not have many thoroughly tested diatom indicators of clear and safe waters and support of natural biodiversity. In US water quality standards, clear and safe waters and biodiversity are “uses” for which we manage waters (USEPA 1994). When uses are not being met, then management actions are warranted. Changes in contaminants by themselves do not necessarily warrant management actions unless they threaten ecological or human health endpoints. Thus diatom indicators of VEAs and stressors are related differently to both legislation and management goals; they represent dependent and independent variables in the causal pathways layed out in our conceptual models of environmental problems and stressor-response relationships. Indicators of both VEAs and stressors should be included in indicator selection for assessments. We should spend more time thinking about them and developing them for application in a suite of diatom indicators used in environmental assessment. Similarity of diatom species composition to reference (natural or expected) assemblages, % expected taxa, % nuisance or non-native taxa are “valued” ecological attributes – sometimes valued positively and sometimes their absence is valued by the public. Thus, they are indicators 371

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of VEAs. In this case, the public is directly interested in changes in biodiversity, biomass, and function of diatoms. The public has particular value for local and regional loss of native taxa, yet we have little knowledge of how our measurements of diatom assemblages relate to these VEAs. Although the public may value invertebrates, fish and clear and safe water more than diatom attributes, they likely value diatom biodiversity and threats to human welfare more than just diatom inferences of stressors. In addition, as the public learns more about diatom biodiversity and functional changes in response to human disturbance, the intrinsic value of diatom attributes will increase. Either positive or negative, changes in these VEAs directly justify management actions, whereas changes in stressors do not. Changes in stressors, like pH and phosphorus, only matter to the general public if they affect one or more VEAs. The presence or absence of specific diatom species and other algae can have direct intrinsic value. Absence of nuisances, such as Didymosphaenia altering stream habitat, Aulacoseira clogging water filters, or toxic Nitzschia in coastal waters, are important for ecological and human health and their presence earns considerable public concern. Recent reports of the first sighting of the potentially toxic cyanobacterium Cylindrospermopsis in a Michigan lake generated articles in several state newspapers and remarkable public concern (personal communication, Sarah Wolf, Michigan Department of Environmental Protection). Biosecurity alerts are posted in parks of New Zealand to warn fishermen in streams to wash boots and thereby minimize introduction of Didymosphaenia to new streams. Loss of biodiversity of stream algae also warrants public support. Changes in species composition (relative abundances of taxa) probably warrant less public support than loss of taxa. Thus, we must develop better measures of taxa diversity in samples, better understand those measures of taxa richness, and relate them to other VEAs, such as maintaining ecosystem function and diversity of other microbes. Much of the current information that we have about the autecology of diatom species can be used to indicate valued ecological attributes. The % of taxa or individuals in assemblages that are sensitive to pollution and that occur in natural habitats, even though related to stressors, can be used as VEAs because they reflect the natural biodiversity and biological condition of ecosystems. Fore (2002) showed that indicators that use just one autecological class of taxa, such as % sensitive taxa or low phosphorus taxa, can be as precise as indicators that use all autecological classes and infer stressor levels. So diatom indicators of VEAs can be related to stressor indicators and development of stressor indicators, but differences in how the indicators are calculated, how they are considered in the conceptual models, and how they are explained to the public and managers make a difference in how they are used in assessments. Special note: I have not listed taxa number (usually measured as number of taxa observed per count of an a priori-specified number of valves) as a VEA because this indicator has many problems. First, taxa number in a count is highly dependent upon the number of valves counted and the evenness of species abundances in counts (e.g. Archibald 1972, Stevenson and Lowe 1986). It is a poor estimator of species numbers in samples because rare species are likely abundant and almost impossible to quantify (Mao and Colwell 2005). In addition, rare species would be important in maintaining ecosystem function as environmental conditions change as functionally redundant members of the algal assemblage, which is conceptually a very important reason for managing sustainable biodiversity. To imply that the number of 372

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taxa, say, in a 600 valve count, is a good estimate or even a good indicator of the number of taxa in a habitat is misleading and bad science. Yes, it is an easy statistic to measure and report, but it is seldom correlated well to human disturbance gradients (Stevenson 1984) – and should not be conceptually – thus it is not an indicator of human disturbance or biological condition (sensu minimally disturbed biological condition), unless constrained to very specific circumstances. Even if species richness were measured by more appropriate techniques, such as long counts and construction of log-normal curves (Patrick et al. 1954), it still should not be expected to be negatively related to human disturbance. For example, near natural aquatic habitats often have very low nutrient concentrations, which should constrain species richness. Increases in nutrient supply should increase the number of species that live in a habitat. If the taxa number in a count of a fixed valve number is used as a sample attribute, it should be used as an indicator of the evenness of species – in which case, why not use a better indicator of evenness of species abundance (such as % dominant taxon or Hurlbert’s evenness (Hurlbert 1971) and call it evenness? Diatom indicators could be developed to indicate other non-diatom VEAs, such as the probability that nuisance growths of algae could occur, summer algal blooms in lakes, toxic cyanobacteria blooms, red tides, or excess growths of benthic algae in streams. Diatom indicators could be developed to indicate that ecological conditions should support other organisms, such as invertebrates and fish – or indicate that waters are not likely contaminated by human wastes and microbial pathogens. In particular, we should develop the capability to determine whether diatom indicators are good indicators of microbial diversity in general. We could then use these new diatom inference models as complementary lines of evidence for the assessment of the biodiversity and ecosystem function of other organisms in ecosystems. So how do we go about developing and testing these indicators of VEAs? As simply and directly as possible, and using most of the same techniques with which we have developed indicators in the past. An indicator has more value and trust from the public and resource managers if it can be understood. Developing an indicator of non-diatom VEAs requires comparison of a diatom indicator to that VEA, such as water clarity, microbial contamination, probability of nuisance algal problems, or presence of the calcareous algal mat in the Everglades example. Best professional judgment and logical linkages (untested hypotheses) are not enough to earn the broad public support of results that is necessary to motivate public policy actions. For example, relating the saprobic index (Sládecek 1973, Lowe 1974) to microbial contamination and pathogens from human waste would be a critical step in developing a diatom indicator of human health. The value of a diatom indicator of microbial contamination (recreational safety for public health) is that the diatom indicator may better predict the likelihood of contamination at a site than measuring microbial contamination directly, which varies greatly with time due to weatherrelated loading from storm-water overflows of sewers and runoff. However, measuring microbial contamination is important to show that the problem exists and warrants public health warnings for bathing in contaminated water. The diatom index of microbial contamination could provide managers with a more precise indicator of whether restoration and protection efforts to reduce the frequency, intensity, and duration of contamination have been effective – and it could help map areas where microbial contamination is a risk, i.e. has a high probability of being unacceptable. 373

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Complex statistical analyses should be used with caution, especially during the final stages development and testing of indicators. They are often difficult for the public to understand. They are also difficult to relate to management strategies, such as criteria for reducing nutrient, sediment, or organic loading to restore uses. Probably the most direct and simple approach for developing diatom indicators of non-diatom VEAs is to relate relative abundances of diatoms species to non-diatom VEAs and develop weighted average inference models. Results of ordination analyses are examples of particularly difficult information to use in final management applications because they are difficult to explain to the public and clearly link to VEAs. However, these types of techniques are invaluable in the initial exploratory phases of relationships among biological and environmental conditions in habitats or developing multivariate indices of human disturbance. Another valuable but complex approach is the use of multivariate regression techniques. Multivariate regression will be invaluable for some methods of measuring ecological assessment that involve predicting natural or minimally disturbed condition (Wiley et al. 2002). It will help resolve biological responses to multiple stressors. The key to proper variable selection and analysis techniques is to carefully consider how the results of your research will be used by other scientists and resource managers to solve environmental problems. In addition, consider how thoroughly and clearly these results can be communicated to as much of the public as possible. One of the most effective ways to communicate results to the public has been use of multimetric indices of biological condition (IBC) of fish and invertebrate assemblages. These indices usually combine 5-10 indicators into a single index value that readily summarizes ecosystem status, yet can be broken down to understand which VEAs have been affected. Hill et al. (2000) and Fore (2002) have recently developed multimetric indices for diatom indicators, which included indices of VEAs and stressors. I’d argue that we should not use diatom indicators of stressor conditions in a multimetric index of biological condition, where biological condition is a VEA. Wang et al. (2005) took this next step to refine a diatom IBC that uses diatom attributes that were not simply inferring stressor condition. Wang et al. correlated a long list of diversity, biomass-related, % sensitive and % tolerant autecological indices, and taxonomic indicators of biological condition with % forest and a multivariate indicator of human disturbance. Indicators were evaluated for precision of the regression relationship, agreement with a priori predictions of positive or negative response to human disturbance, and separation power (an indicator of precision and the magnitude of change in an attribute). Some of the taxa-based metrics that Wang et al. tested have already been incorporated into state monitoring programs, such as the % Cymbella taxa or individuals in samples, which are indicators of the high biological condition of natural assemblages. Criteria Development Environmental criteria are levels of VEAs and stressors that indicate that assessed ecosystems meet or do not meet management goals. Water quality criteria could be values of a multimetric index of biological condition or specific concentrations of microbial contamina374

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tion, nutrients, or toxic chemicals that indicate support of specific uses, e.g. aquatic life use, recreation by the public, or safe fish production. Water quality criteria can be narrative as well as numeric. Narrative criteria, such as “concentrations shall not exceed levels that impair biological condition,” leave interpretation of the assessment and management decision up to government regulators, which can be helpful when systems are so complex that specific numeric criteria can not be agreed upon. However, ambiguity in that interpretation often leads to abuse and cases could end up in courts, where decisions are made by judges and costs escalate for all parties. Thus, derivation of numeric criteria is important. Different criteria are developed for different uses (e.g. aquatic life support, recreation, drinking water), where uses are defined sets of VEAs. For example, aquatic life uses are commonly assessed with fish and invertebrate indicators, and less commonly with algal, plant, and amphibian indicators. Recreational use of lakes could be assessed with measures of water transparency, chlorophyll a, filamentous algal cover, and microbial contamination. Another consideration for criteria development is the level of each type of use, because different criteria could be developed to protect all waters of a region versus the truly outstanding waters. Thereby, degradation of those outstanding waters could be prevented without unreasonable expectations being set for aquatic ecosystems in landscapes that are used extensively by humans. For example, if criteria were set only for safe basic uses of all waters, criteria for contaminants might be much higher than occur naturally and than occur in some outstanding quality waters of a region. Lower stressor criteria and higher criteria for VEAs could be established to protect these outstanding waters where human activities are currently not having great impacts. These so-called tiered criteria also provide incremental restoration targets for lower quality waters. Numeric criteria can be developed using 3 basic approaches. All these methods provide valuable complementary information. The first 2 approaches involve characterizing the central tendency and variability of conditions in a region and will be referred to as frequency distribution (FD) approaches. One FD approach uses all sites in the region (Fig. 3A), and the other uses only the best or reference sites (Fig. 3B). A common benchmark for criteria with this approach is to use the quartiles of distributions as criteria, the lower quartile of negative attributes and upper quartile of positive attributes (the 25th and 75th percentiles of a frequency distribution). These quartile benchmarks are considered to be reasonable compromises between being overprotective and underprotective of conditions as related to type I and type II statistical errors of hypotheses testing (false positive and false negative results of assessments). With both of these approaches, the relationship among VEAs, stressors, and human activities must be established. The “all-site” FD approach describes the range of attributes and the best conditions in the region. The problem with this “all-site” frequency distribution approach is that a specific number of sites is automatically assumed to fail the criteria, which is often not a scientifically reasonable assumption. The reference site FD approach distinguishes between sites that meet and do not meet expectations, which are used to define reference condition. Differences in definition of reference condition have challenged communication and application of the reference FD approach, but this issue can be and is being addressed (Stevenson et al. 2004b). Neither FD approach specifically provides what has been referred 375

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A Number of Reference Sites

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Ecological Attribute (e.g. Nutrient Concentration) Fig. 3. Frequency distributions of a negative attributes of ecological condition in (A) a probabilitistic sampling of all sites in a region and (B) a probabilistic sampling of reference sites, i.e, those sites that meet expected conditions. The limit of expected condition is marked with the arrow, which matches the 25th percentile of conditions at all sites or the 75th percentile of conditions at reference sites. The conditions delineated by these percentiles can be used to establish water quality criteria.

to as an effects-based approach, which relates specific effects of VEAs to specific levels of stressors. The third approach, the “stressor-response” approach (a concept and phrase modified from the risk assessment “dose-response” relationship), does relate VEAs to stressors and thereby informs “effects-based” criteria (Stevenson et al. 2004b). This approach usually earns greater support among the public for criteria because criteria are established that protect specific levels of effects that are considered undesirable. VEAs have many responses to stressors, but 3 of these illustrate how stressor-response relationships can be used in specific ways for developing criteria (Fig. 4). Non-linear responses, such as threshold responses with some assimilative capacity for contamination, are particularly valuable for establishing criteria because at some level of stressors, small changes make relatively great changes in VEAs (Fig. 4A). Stressor criteria would be established with a reasonable margin of safety at levels below the range where threshold responses in VEAs are observed. Non-linearities in negative exponential responses can also be used to establish stressor criteria because we would not want to lose all of an attribute (Fig. 4B). Indicators that linearly respond to VEAs are particularly valuable for establishing biocriteria or criteria for VEAs, but they are not as valuable for establishing stressor criteria. They are valuable for establishing VEA criteria because they sensitively and precisely 376

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Stressor (e.g. P, N, Silt, Salinity, pH) Fig. 4. Three relationships between a VEA and a stressor (contaminant or habitat alteration caused by humans). Each provide different values for establishing effects based stressor criteria. Examples of justifiable stressor criteria are illustrated by the vertical arrows.

respond to stressors throughout the entire range of stressor conditions (Fig. 5). For example, we would not be able to detect a change in VEAs that had threshold responses until the stressor levels had approached that threshold and then risk to further degradation would be unusually great. In contrast, VEA indicators that respond linearly to stressors will have detectable changes at low stressor levels and provide an early warning of threats to non-linear VEAs that have assimilative capacity. VEA criteria using indicators with linear responses could be justified at stressor levels that protect VEAs with threshold responses. These steps provide the foundation for an optimal criterion development protocol in which non-linear stressor-response relationships are used to establish stressor criteria and linear relationships are used to establish biological or VEA criteria. Precise stressor-response relationships are keys to effects-base criteria development, but observation of both linear and non-linear responses of ecological attributes along environmental gradients is troublesome because they may be masked by the scale or 377

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Fig. 5. Application of linear relationships between VEAs and stressors for established water quality criteria for VEAs, such as biological condition. Two horizontal arrows pointing to the VEA axis indicate 2 potential criteria. The higher criterion (top arrow) is the predicted value of the linear indicator at the stressor criterion that would protect the high quality condition of the VEA that responds nonlinearly along the stressor gradient. The lower criterion (bottom arrow) indicates the criterion associated with some variation in the predicted value of the linear indicator at the stressor criterion, such as the standard error or deviation in that value. The higher criterion should be used if multiple measures of the attribute are assessed to determine compliance with the criterion. Some error variance should be allowed compared to the expected value if only single measurements of conditions will be used to determine compliance with the criterion.

precision of our measurements. Resolving non-linear responses is a particularly great ecological challenge. It requires a thorough understanding of the processes that regulate response of ecological systems to environmental change. Most biological processes, such as metabolism, growth, and reproduction, are non-linear, so non-linear responses should be observed commonly along environmental gradients. However, these processes operate at multiple spatial and temporal scales. Thus, the scale of our measures of variables must be adjusted according to the biotic and abiotic processes that regulate non-linear responses. Some examples of refining measurements to resolve non-linear stressor-response relationships have emerged from our work on benthic algal response to nutrients. Historically, resolving relationships between algae and nutrients in streams has been challenging because of the spatial and temporal variability in algal biomass and nutrient concentrations (Stevenson 1997, Biggs 2000). Algal biomass is highly variable in streams, from riffle to pool and even from one rock to another in riffles. We can reduce that spatial variability by making measurements at the riffle-scale, which is greater than the rock scale and less than the reach scale (which is a length of stream that includes multiple riffles and pools). Temporal variability is another issue. Streams in many regions are characterized by weather-related hydrologic variability that causes alternating periods of scour and regrowth of periphyton in streams. To control that source of error, sampling should be conducted after recolonization as close as possible to peak biomass (Biggs 1996, Stevenson 1996). Measuring stressor exposure accurately is another problem. Nutrients are a particularly difficult stressor to assess. During the regrowth period, soluble nutrient concentrations may 378

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Fig. 6. The relationship between chlorophyll a of benthic algae and nutrient availability, indicated by measured total phosphorus (TP) concentration of stream water and by inferred trophic status (MAIA TSI) based on diatom species composition and autecological information (unpublished data). Precision of the relationship between chl and nutrient availability is much greater when using a diatom indicator of trophic status than measured total phosphorus concentration.

decrease as algae accumulate, nutrient demand and uptake increases, and loading sources from runoff and groundwater decrease (Stevenson, unpublished data). So soluble nutrient concentrations are often poorly correlated to benthic algal biomass in streams, even though they regulate the accumulation of that biomass (see discussion in Dodds 2003). Total phosphorus often correlates better than PO4 to algal biomass (Fig. 6A), probably because particulate phosphorus is comprised partly of benthic algae that have sloughed from substrata during the algal accrual phase. Perhaps our best indicator of phosphorus availability is a diatom indicator, because species composition is less variable than nutrient concentrations in streams and provides a temporally integrated signal of P regulation of species membership (Fig. 6B). In this example, I’ve used a diatom indicator of P conditions to infer P availability and better explain variability in algal biomass than TP concentrations measured in streams. Conclusions: Challenges and Opportunities We have made great strides in the application of algal indicators to solving environmental problems, but challenges and opportunities for refining these indicators are also great. As I have emphasized above, we must meet the challenge of working more closely with managers and other scientists that are using results of our research – and make our results as useful and valuable as possible. Refining diatom indicators of VEAs and using them to develop environmental criteria will be 2 of many challenges. As we scale up our work, we must strive 379

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to make our results as transferable among regions as possible. This can be accomplished by testing at the right spatial and temporal scale, but also by building our methods on firm ecological principles and conceptual models that should be transferable among regions (Stevenson 2005). We must collaborate with scientists and resource managers from many other disciplines, such as hydrology, biogeochemistry, engineering, sociology, economics, and political science. To make our results as useful as possible, we should have the broader interdisciplinary training and perspective to solve complex environmental problems. Finally, we must do high quality research from the perspective of technical quality. Accurate, consistent, and well-documented taxonomy becomes more important as we aggregate data among projects, from creating and using catalogs of autecological information (e.g. Van Dam et al. 1994, Potapova et al. 2004) to combining datasets from multiple laboratories for large regional, national, and even global syntheses. Assessing and reducing sources of error in sampling, sample analysis, and data handling should be more of a priority now that we have established the value of algal and diatom indicators and resources for these efforts can be justified. Addressing these technical challenges and justifying methods refinements must be done with the goals of our research in mind. While these challenges limit our current interpretation and application of results, they present opportunities for future research. REFERENCES ARCHIBALD, R. E. M. 1972. Diversity in some South African diatom assemblages and its relation to water quality. -Water Research, 6: 1229-1238. BIGGS, B. J. F. 1996. Patterns in benthic algae of streams. Pages 31-56 in R. J. Stevenson, M. L. Bothwell and R. L. Lowe, editors. Algal ecology: freshwater benthic ecosystems. Academic Press, San Diego, California. BIGGS, B. J. F. 2000. Eutrophication of streams and rivers: dissolved nutrient- chlorophyll relationships for benthic algae. – Journal of the North American Benthological Society, 19: 17-31. BROWDER, J. A., P. J. GLEASON, and D. R. SWIFT 1994. Periphyton in the Everglades: spatial variation, environmental correlates, and ecological implications. Pages pp.379418 in: S. M. Davis and J. C. Ogden, editors. Everglades, the ecosystem and its restoration. St. Lucie Press, Delray Beach, Florida. BRYCE, S. A., D. P. LARSEN, R. M. HUGHES and P. R. KAUFMANN 1999. Assessing relative risks to aquatic ecosystems: a mid-Appalachian case study. – Journal of the American Water Resources Association, 35: 23-36. CHARLES, D. F., M. W. BINFORD, E. T. FURLONG, R. A. HITES, M. J. MITCHELL, S. A. NORTON, F. OLDFIELD, M. J. PATERSON, J. P. SMOL, A. J. UUTALA, J. R. WHITE, D. R. WHITEHEAD and R. J. WISE 1990. Paleoecological investigation of recent lake acidification in the Adirondack Mountains, N. Y. – Journal of Paleolimnology, 3: 195-241. CHIMNEY, M. J. and G. GOFORTH 2001. Environmental impacts to the Everglades ecosystem: a historical perspective and restoration strategies. – Water Science and Technology,44: 93-100. 380

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DAVIS, S. M., and J. C. OGDEN 1994. Everglades, the ecosystem and its restoration. St. Lucie Press, Delray Beach, Florida. DIETZ, T. 2003 What is a good decision? Criteria for environmental decision making. Human Ecology Review, 10: 60-67. DIXIT, S. S., J. P. SMOL, J. C. KINGSTON and D. F. CHARLES 1992. Diatoms: powerful indicators of environmental change. – Environmental Science and Technology, 26: 23-33. DIXIT, S. S., J. P. SMOL, D. F. CHARLES, R. M. HUGHES, S. G. PAULSEN and G. B. COLLINS 1999. Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms. – Canadian Journal of Fisheries and Aquatic Sciences, 56: 131-152. DODDS, W. K. 2003. Misuse of inorganic N and soluble reactive P concentrations to indicate nutrient status of surface waters. – Journal of the North American Benthological Society, 22: 171-181. DODDS, W. K., V. H. SMITH and B. ZANDER. 1997. Developing nutrient targets to control benthic chlorophyll levels in streams: A case study of the Clark Fork River. – Water Research, 31:1738-1750. EUROPEAN COMMISSION. 2000. Directive 2000/ EC of the European Parliament and of the Council – Establishing a framework for Community action in the field of water policy., Brussels, Belgium. FORE, L. S. 2002. Response of diatom assemblages to human disturbance: development and testing of a multimetric index for the Mid-Atlantic Region (USA). Pages 445-480 in: T. P. Simon, editor. Biological Response Signatures: Indicator Patterns Using Aquatic Communities. CRC Press, Boca Raton. GOLDSTEIN, B. D. 2005. Advances in Risk Assessment and Communication. -Annual Review in Public Health, 26: 141-163. HILL, B. H., A. T. HERLIHY, P. R. KAUFMANN, R. J. STEVENSON, F. H. MCCORMICK and C. B. JOHNSON 2000. Use of periphyton assemblage data as an index of biotic integrity.- Journal of the North American Benthological Society, 19:50-67. HUGHES, R. M. 1995. Defining acceptable biological status by comparing with reference conditions. Pages 31-47 in: W. S. Davis and T. P. Simon, editors. Biological Assessment and Criteria: Tools for Water Resource Planning and Decision Making. Lewis Publishers, Boca Raton, Florida, USA. HUGHES, R. M., D. M. LARSEN and J. M. OMERNIK 1986. Regional reference sites: a method for assessing stream potentials. – Environmental Management, 10: 629-635. HURLBERT, S. H. 1971. The nonconcept of species diversity: a critique and alternative parameters.- Ecology, 52: 577-586. LOWE, R. L. 1974. Environmental Requirements and Pollution Tolerance of Freshwater Diatoms. EPA-670/4-74-005, US Environmental Protection Agency, Cincinnati, Ohio, USA. MAO, C. X. and R. K. COLWELL 2005. Estimation of species richness: mixture models, the role of rare species, and inferential challenges. – Ecology, 86: 1143-1153. MCCORMICK, P. V. and M. B. ODELL 1996. Quantifying periphyton responses to phosphorus in the Florida Everglades: A synoptic-experimental approach. -Journal of the North American Benthological Society, 15: 450-468. 381

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MILLENIUM ECOSYSTEM ASSESSMENT. 2005. Ecosystems and Human Well-being: Synthesis. Island Press, Washington, DC. PAN, Y., R. J. STEVENSON, P. VAITHIYANATHAN, J. SLATE and C. J. RICHARDSON 2000. Changes in algal assemblages along observed and experimental phosphorus gradients in a subtropical wetland, U.S.A. – Freshwater Biology, 43: 1-15. PATRICK, R., M. H. HOHN and J. H. WALLACE 1954. A new method for determining the pattern of the diatom flora. – Notulae Nature, 259: 1-12. POTAPOVA, M. G., D. F. CHARLES, K. C. PONADER and D. M. WINTER 2004. Quantifying species indicator values for trophic diatom indices: a comparison of approaches. Hydrobiologia, 517: 25-41. SETZER, R. W., JR. and C. A. KIMMEL 2003. Use of NOAEL, benchmark dose, and other models for human risk assessment of hormonally active substances. – Pure Applied Chemistry, 75: 2151-2158. SLÀDECEK, V. 1973. System of water quality from the biological point of view. – Archiv für Hydrobiologie und Ergebnisse Limnologie, 7: 1-218. STERN, P. C. and H. FINEBERG 1996. Understanding Risk: Informing Decisions in a Democratic Society. National Academy Press, Washington, D.C. STEVENSON, R. J. 1984. Epilithic and epipelic diatoms in the Sandusky River, with emphasis on species diversity and water quality. – Hydrobiologia, 114: 161-175. STEVENSON, R. J. 1996. An introduction to algal ecology in freshwater benthic habitats. Pages 3-30 in: R. J. Stevenson, M. Bothwell, and R. L. Lowe, editors. Algal Ecology: Freshwater Benthic Ecosystems. Academic Press, San Diego, California, USA. STEVENSON, R. J. 1997. Resource thresholds and stream ecosystem sustainability. – Journal of the North American Benthological Society, 16: 410-424. STEVENSON, R.J. 2005. Transferring methods and indicators among assessment programs. ALGAS Número Especial pp. 4-9. STEVENSON, R. J., J. ALBA-TERCEDOR, B. BAILEY, M. BARBOUR, C. COUCH, S. DYER, F. FULK, J. HARRINGTON, M. HARASS, C. J. HAWKINS, C. HUNSAKER, R. JOHNSON and K. THORNTON 2004a. Designing data collection for ecological assessments. in: M. Barbour, S. Norton, R. Preston, and K. Thornton, editors. Ecological Assessment of Aquatic Resources: Linking Science to Decision-Making. Society of Environmental Toxicology and Contamination Publication. STEVENSON, R. J., J. ALBA-TERCEDOR, B. BAILEY, M. BARBOUR, C. COUCH, S. DYER, F. FULK, J. HARRINGTON, M. HARASS, C. J. HAWKINS, C. HUNSAKER, R. JOHNSON and K. THORNTON. 2004b. Interpreting results of ecological assessments. in: M. Barbour, S. Norton, R. Preston, and K. Thornton, editors. Ecological Assessment of Aquatic Resources: Linking Science to Decision-Making. Society of Environmental Toxicology and Contamination Publication. STEVENSON, R. J. and R. L. LOWE. 1986. Sampling and interpretation of algal patterns for water quality assessment. Pages 118-149 in: A. S. B.G. Isom, editor. Rationale for Sampling and Interpretation of Ecological Data in the Assessment of Freshwater Ecosystems. American Society for Testing and Materials Publication, Philadelphia, PA.

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