Our Living World: Earth's Biomes - Volume 3: Rivers, Streams, Lakes, and Ponds

volume

3 L I V I N G

W O R L D :

E A R T H ’ S

B I O M E S

Rivers, Streams, Lakes, and Ponds

T R A D I T I O N A

N E W

B O O K S

T R A D I T I O N

®

, I N

M A P L E

P L A I N ,

C H I L D R E N ’ S

Barbara A. Somervill

M I N N E S O T A P U B L I S H I N G

TM

Rivers, Streams, Lakes, and Ponds

O U R



ABOUT THE AUTHOR

Barbara A. Somervill is the author of many books for children. She loves learning and sees every writing project as a chance to learn new information or gain a new understanding. Ms. Somervill grew up in New York State, but has also lived in Toronto, Canada; Canberra, Australia; California; and South Carolina. She currently lives with her husband in Simpsonville, South Carolina.



CONTENT ADVISER

Susan Woodward, Professor of Geography, Radford University, Radford, Virginia

4

In gratitude to George R. Peterson Sr. for introducing me to the beauty of creation —George R. Peterson Jr., Publisher, Tradition Books® Published in the United States of America by Tradition Books® and distributed to the school and library market by The Child’s World® [ACKNOWLEDGMENTS] For Editorial Directions, Inc.: E. Russell Primm, Editorial Director; Dana Meachen Rau, Line Editor; Katie Marsico, Associate Editor; Judi Shiffer, Associate Editor and Library Media Specialist; Matthew Messbarger, Editorial Assistant; Susan Hindman, Copy Editor; Lucia Raatma, Proofreaders; Ann Grau Duvall, Peter Garnham, Deborah Grahame, Katie Marsico, Elizabeth K. Martin, and Kathy Stevenson, Fact Checkers; Tim Griffin/IndexServ, Indexer; Cian Loughlin O’Day, Photo Researcher; Linda S. Koutris, Photo Selector For The Design Lab: Kathleen Petelinsek, design, art direction, and cartography; Kari Thornborough, page production [PHOTOS] Cover/frontispiece: Steve Austin; Papilio/Corbis. Interior: Animals Animals/Earth Scenes: 24 (Victoria McCormick), 35 (Erwin & Peggy Bauer), 43 (Phil Degginger), 51 (Carmela Leszczynski); Darren Bennett/Animals Animals/Earth Scenes: 5, 30; Corbis: 10 (David Muench), 11 (James Amos), 14 (Rob Howard), 33 (Charles Krebs), 34 (Lynda Richardson), 36 (Jay Dickman), 44 (Tom Brakefield), 53 (Niall Benvie), 56 (Joe McDonald), 57, 59 (Terry Eggers), 61 (Raymond Gehman), 66 (Chris Hellier), 67 (Stuart Westmorland), 68 (Paul A. Souders), 71 (Brandon D. Cole), 73 (Staffan Widstrand), 80 (Theo Allofs), 82 (Bettmann), 83 (Galen Rowell), 86 (Charles E. Rotkin), 87 (Julia Waterlow; Eye Ubiquitous), 90 (Angelo Hornak), 91 (John Henley); Digital Vision: 41, 62, 85; Ecoscene/ Corbis: 4 (Andrew Brown), 79 (Joel Creed); Frank Lane Picture Agency/Corbis: 27 (Douglas P. Wilson), 49 (B. Borrell Casal), 55 (Tony Wharton); Getty Images/Brand X Pictures: 6, 7, 8, 12, 40, 65; Getty Images/The Image Bank/Davies & Starr: 45; François Gohier: 74; Randall Hyman: 75, 76; Dwight R. Kuhn: 39, 52; Frans Lanting/Minden Pictures: 63; Mary McDonald/ Naturepl.com: 50; Gary Meszaros/Dembinsky Photo Associates: 48, 88; Photodisc: 20, 29, 31, 32, 70; Douglas Stamm: 54; Tom Stack & Associates: 28 (Tom & Therisa Stack), 46 (Tom Stack), 60 (Doug Sokell), 72 (Jeff Foott). [ L I B R A RY O F C O N G R E S S C ATA L O G I N G - I N - P U B L I C AT I O N D ATA ] CIP data available

Table of Contents

Table of Contents [Chapter One]

4 Defining Rivers, Streams, Lakes, and Ponds [ C h a p t e r Tw o ]

24 Focus on Key Species [Chapter Three]

35 Predators [Chapter Four]

45 Prey [Chapter Five]

55 Flora [Chapter Six]

62 Herbivores [Chapter Seven]

67 A Cycle of Life [Chapter Eight]

73 The Amazing Amazon [Chapter Nine]

82 The Human Touch 92

[Chart of Species]

93

[Index]

4

1

[Chapter One]

Defining Rivers, Streams, Lakes, and Ponds

Defining Rivers, Streams, Lakes, and Ponds

4

4 The spring thaw releases water that has been bound up in ice and snow. Water trickles down a Rocky Mountain hillside. The trickle feeds a rushing stream. The stream swells a lake. Excess lake water pours into Colorado’s South Platte River. Each spring, water

 Cutthroat trout like this one nearly became extinct in Colorado’s lakes and streams.

moves across the land, renew-

by industries. The trout

ing waterways.

could breed and recover its

Fresh, flowing water is

normal population numbers.

essential for the survival of the

Today, greenback cutthroat

greenback cutthroat trout. The

trout swim in more than

species is native to Colorado’s

40 Colorado lakes

mountain streams.

and streams.

Once, greenback cutthroat trout faced extinction. A gov-

The Water Cycle

?

WORDS TO KNOW . . .

extinction (ek-STINGKT-shuhn) the state of having no more

ernment program changed

4 Water covers

living members of a species

the cutthroat trout’s fate. The

nearly three-fourths

native (NAY-tiv) originally from

program cleaned up streams

of earth. Yet very

a certain place

and reduced the use of rivers

little of that water

 A Colorado stream pours down a slope in the Rocky Mountains.

5

[Defining Rivers, Streams, Lakes, and Ponds]

is fresh. Just more

salt water and is not suitable

biomes (BYE-ohmz) large

than 97 percent

for drinking.

ecosystems in which the

of earth’s water

plants and animals are adapted

lies in oceans

less than 3 percent of earth’s

to a particular climate or

and seas. It is

water supply. Glaciers and ice-

?

WORDS TO KNOW . . .

Freshwater is limited to

physical environment

bergs hold two-thirds of that

groundwater (ground-WAW-

ice in water. About three-fifths

tur) water that exists in bedrock

of 1 percent is groundwater.

below the surface of the earth

And less than one-fifth of 1 percent fills rivers and lakes. Freshwater biomes include lakes, ponds, puddles, rivers, streams, and seeps (which are small springs). There is no “new” water. There is only water that has been recycled in hundreds of ways, thousands of times. Water, then, moves through a cycle over long periods of time. A single drop of water in the ocean may become water vapor and rise into the air. Later, it  Glaciers like this one in Antarctica hold about 2 percent of the earth’s water.

 DO IT! Are you a water waster? Look for ways to waste less water. Take shorter showers. Use cooled cooking water to water garden plants. Do not let the  Snowmelt fills mountain streams each spring.

faucet run while you brush your

may fall onto the earth as rain

and reenters the

teeth. Fill the kitchen sink with

or snow. Water drops may mix

water cycle.

water to rinse dishes, glasses,

with salt. They can be frozen and thawed. Water may even pass through the human body.

Rivers and Streams

and utensils.

?

WORDS TO KNOW . . .

It is then cleaned naturally or

4 Melted snow,

runoff (RUHN-awf) water that

at a water treatment plant.

rain, or runoff

travels over the ground

Then it returns to the ground

travels downhill. 7

Rivers and streams are moving freshwater. Streams often begin in mountains, on hillsides, or in underground springs. Runoff water collects into a stream. The stream feeds a river. The difference between a stream and a river is the amount of water it carries. Rivers carry more water than streams. When one river feeds another, it is called a tributary. A river’s age determines its flow. A younger river has fast-paced water. It cuts a straighter path through the ground and rock than an  Rivers cut narrow gorges through dense woodland.

Water goes wherever it flows most easily. Cracks in rocks

8

older river. Fast-moving water erodes, or grinds away, rock and soil. Older rivers wander along

and dips in the ground create

their routes. As the river

routes for running water.

erodes its banks, its path

[Defining Rivers, Streams, Lakes, and Ponds]

changes from straight to curvy.

Look at a map of the

The curves are called mean-

Mississippi River, the longest

ders. A very old river has many

river in the United States.

meanders. The more a river

The Mississippi begins as a

curves, the slower it moves.

small stream at Lake Itasca,

Misso uri

45˚N

isco

iss is

er Riv pi sip

River

is

te R ive r

W

M Pl at

nsin Riv

er

Yello ws t

r Rive

er one R i v

ansa

W

Illi

A rk

no

s Rive

River io Oh

r

er

M ississip p

iR

iv e

r

an C a nadi River

Red R iv

sha Rive r aba

sse ne T en

eR

iver

Atlantic Ocean 30˚N

N

Mississippi River watershed area 0 0

250 Miles

15˚N

250 KM

105˚W

90˚W

75˚W

 The Mississippi River’s watershed, or drainage area, along with several of its tributaries

9

Missouri, the Ohio, and the Red rivers. By the time it reaches Louisiana, the Mississippi is wider and carries more water than it did in Minnesota. The land area that a river drains is called a watershed. All the runoff, streams, and rivers of the watershed flow into the same body of water, which could be a larger stream, a lake, or the ocean. The Mississippi drains almost all the land between the Rocky Mountains and the Appa This peaceful lake forms the headwaters of the mighty Mississippi River.

?

Minnesota. The

WORDS TO KNOW . . .

lachian Mountains.

Rivers and Ecosystems

ecosystems (EE-koh-siss-tuhmz)

Mississippi’s many

4 Rivers contain many

communities of plants and ani-

tributaries add to its

ecosystems. The age, flow,

mals and their relationships with

flow. The largest

and water quality of a river

the surrounding environments

tributaries are the

define the type of ecosystem

Illinois, the

that is formed. Fast-moving

10

Old, slow-moving rivers, like the Saranac River in New York, wind across the land.

[Defining Rivers, Streams, Lakes, and Ponds]

streams provide excellent

The Mississippi

homes for trout. The water

River and Africa’s

deltas (DEL-tuhz) deposits of

is quick and clear and has

Nile River deltas

silt, sand, and gravel at the

little plant life.

have many small

mouth of a river

Slow-moving rivers often

?

islands that become

carry soil and silt. The water

new wetland ecosystems.

is murky. Water plants grow

The islands support plant

along the banks. Slow-moving

and animal life, including

rivers can also form deltas.

reeds and water grasses, as

WORDS TO KNOW . . .

[Defining Rivers, Streams, Lakes, and Ponds]

well as shellfish, waterbirds,

as a stream trickling into the

and wading birds.

Gulf of California. The trout of

Fish and water plants that

the upper Rockies differ great-

live near a river’s source may

ly from the catfish of south-

be different from living things

western Arizona.

farther downstream. The Colorado River begins high in the

Lakes and Ponds

Rocky Mountain forests. It

4 Lakes and ponds are still

rushes through desert in Utah,

water, as opposed to the run-

Nevada, and Arizona. It ends

ning water found in rivers and

[Defining Rivers, Streams, Lakes, and Ponds]

streams. Land completely sur-

PROFILE: LAKE NATRON

rounds lakes and ponds. The

Lake Natron in Tanzania, Africa, has an

difference between lakes and

incredibly foul smell. The lake supports

ponds is the same as the differ-

few plants and animals. Algae, brine

ence between rivers and

shrimp, and

streams: Lakes are simply

insects somehow

larger ponds.

survive vile Lake

algae (AL-jee) simple, one-

Natron water.

celled plants

Although lake water doesn’t flow like river water, it

?

WORDS TO KNOW . . .

The lake lies

does move. Wind affects lakes

just south of the equator, where after-

of all sizes. Wind pushes the

noon temperatures can soar to 150°

water, forming waves. Large

Fahrenheit (66° Celsius). In that heat,

lakes, such as Europe’s Caspian

water evaporates quickly. Little rain falls

Sea and North America’s Lake

in the area. Underground hot springs full

Superior, may have huge waves

of sodium carbonate refill the lake. The

that can sink ships. Wave action

water is caustic. It burns or eats away

mixes and moves lake water.

human and animal flesh.

Seasonal changes also

Flamingos are the only large animals

move lake water. In autumn,

that wade in Lake Natron without

surface water cools and sinks.

suffering burns. Flamingos feast on

Top layers of water trade places

algae and brine shrimp without fear

with bottom layers. This action

of predators. No predators dare risk

is called turnover.

the stinging waters of Lake Natron.

 Canada’s Lake Louise is one of the most beautiful lakes in North America.

13

[Defining Rivers, Streams, Lakes, and Ponds]

Lakes can hold freshwater,

 WATCH IT!

river in the world

salt water, or alkali water. The

that flows both

Discover the story of cichlids,

Great Lakes are freshwater

north and south of

the amazing fish of Lake

lakes. The Great Salt Lake in

the equator. At 4,145

Tanganyika, Africa, in National

Utah and the Dead Sea are salt

miles (6,669 kilome-

Geographic’s Lake Tanganyika:

lakes. Lake Natron in Africa is

ters), the Nile is the

Jewel of the Rift [ASIN:

an alkali, or soda, lake.

world’s longest river.

0792241525]. The video features

There are two

fabulous photography and

branches of the

music, along with a truly inter-

Nile—the Blue Nile

esting story.

Rivers and Lakes around the World 4 Rivers and lakes are

and the White Nile.

found on every continent.

The Blue Nile is fed

Even frozen Antarctica has

by Lake T’ana in

basins (BAY-suhnz) areas of land

freshwater in places beneath

Ethiopia. Lake

around a river from which

the glacial ice. Bodies of fresh-

Victoria, Africa’s

water drains into the river

water nourish plants and ani-

largest lake, serves as

mals alike, including humans.

headwaters of the White Nile.

Most of Africa’s freshwater

?

WORDS TO KNOW . . .

Asia’s rivers provide fresh-

collects in eight river basins:

water for earth’s most populat-

the Nile, Congo/Zaire, Niger,

ed region. China’s largest

Zambesi, Limpopo, Kasai,

rivers are the Yangtze (3,720

Orange, and Volta. Africa’s

miles or 5,985 km) and the

Congo/Zaire River is the only

Huang, or Yellow, River

 The T’is Isat Falls drain Ethiopia’s T’ana Lake into the Blue Nile River.

15

[Defining Rivers, Streams, Lakes, and Ponds]

(2,903 miles or 4,671 km).

river, begins in China, and

The Huang is called China’s

flows through Thailand, Laos,

Sorrow because its floods have

Kampuchea, and Vietnam.

killed millions of people. The

India’s main rivers include

Mekong River, a major Asian

the Brahmaputra and the

Nile

i ve r

30˚N

R

20˚N

al

Sene g

e Nig

Riv

er

r

v Ri

Lake Chad

er

10˚N

Volta River

iver eR nu Be

r

go Rive Con 0˚

Lake Mai-Ndombe Ka

River sai

Atlantic Ocean

Lake Victoria

Lake Natron

Lake Tanganyika

10˚S

Lake Nyasa m

N

Za

bezi R iver

20˚S

0

opo Riv mp Li

500 Miles

er

0

500 KM

Indian Ocean

Orange Riv er 30˚S

10˚W

0˚

10˚E

 Africa’s major rivers and lakes

16

20˚E

30˚E

40˚E

50˚E

[Defining Rivers, Streams, Lakes, and Ponds]

Arctic Ocean

nisei Ye Ob’ R i

gara An

Rive

R sh Ir t y

i

ve

r

ver

Pacific Ocean

L en a

R i v er

er Riv

Lake Baikal r

Aral Sea Lake Balkhash

Hu

r

Rive ang

Caspian Sea

ges R

a h m aputra Ri v er

i v er

Me k

Ga n

iver

ng

Br

R tze

Ya

Ind

us R iv

er

o

ng

er

v

Ri

N

Indian Ocean

0 0

500 Miles 500 KM

 Asia’s major rivers and lakes

Ganges. The Brahmaputra

Mountains and eastern India

River starts on the Tibetan

before joining the Ganges

Plateau in China. It passes

River in Bangladesh. The

through the Himalayan

Ganges is India’s sacred river. 17

[Defining Rivers, Streams, Lakes, and Ponds]

Millions of people believe its

the bed is dry again. The

waters carry divine powers.

continent’s largest “wet”

Lake Baikal in Asian

river is the Murray/Dar-

Russia is considered the oldest

ling river system in south-

lake on earth. Scientists

east Australia.

think the lake has existed for

Australia also has many

more than 25 million years.

dry lakes. The world’s largest

It is certainly the deepest

dry salt lake is Lake Eyre. It

lake. Baikal plunges 5,314

covers 3,254 square miles

feet (1,620 meters) into the

(8,428 sq km). In the past

ground. That’s more than

100 years, Lake Eyre has

1 mile (1.6 km) deep!

held water only three times.

Australia has more

The most appropriately

dry rivers than wet ones.

named dry lake is Lake

Many riverbeds lie empty

Disappointment. It lies in

until heavy rains come—per-

Australia’s western desert

haps once a year

and undoubtedly disap-

or once every 10

pointed many travelers

river system (RIV-ur SISS-tuhm)

years. Flash floods

hoping to find water.

a major river and its tributaries

rush through the

?

WORDS TO KNOW . . .

riverbeds. The

18

South America’s great rivers lie east of the Andes

water empties into rivers,

Mountains. The Amazon,

seas, or oceans, and then

the world’s second longest

[Defining Rivers, Streams, Lakes, and Ponds]

river, begins as a stream

Rio Negro. The Plata-Paraná

in the Andes. Hundreds of

river system ranks as the

tributaries pour into the

world’s seventh largest river.

Amazon, including the

It passes through Brazil,

Madeira, the Purus, and the

Paraguay, and Argentina

10˚S

Indian Ocean 20˚S

iv e na

R

Fi t z r o

anti

er Riv

m

o

n

s Mu r c h i

y R iver

Lake Mackay

r

a

Lake Disappointment

r

G

e Riv

yne sco

Lake Eyre 30˚S

Lake Torrens

D

ia

Lake Frome

g rlin Da

er Riv

m rru Mu

Mu

gee River bid

rr a y River

Indian Ocean

N 40˚S

Water reservoir 0 0

250 Miles 250 KM

120˚E

130˚E

140˚E

150˚E

 Australia’s major rivers and lakes

19

before emptying into the Atlantic Ocean. Many great rivers carve North America’s lands. The Mississippi/Missouri system is the largest. In Canada, the Yukon, Mackenzie, and Fraser rivers flow in the west. In the east, Canada and the United States share the Saint Lawrence River. In the southPROFILE: SOUTH AMERICAN

west, the Rio Grande marks

WATERFALLS

the border between the United

South America claims two stunning

States and Mexico.

waterfalls. The world’s tallest water-

20

Canada and the United

fall—Angel Falls (3,212 feet or 979 m)—

States also share the Great

spills into the Orinoco River in

Lakes—Superior, Michigan,

Venezuela. The Iguazú Falls (above)

Huron, Erie, and Ontario.

are short by comparison. They are just

Man-made locks and canals

237 feet (72 m) high. However, the falls

connect the Great Lakes to the

stretch across 2 miles (3 km) of the

Saint Lawrence River, which

Argentina/Brazil border. They make up

flows into the Atlantic Ocean.

in width what they lack in height.

The Saint Lawrence Seaway

[Defining Rivers, Streams, Lakes, and Ponds]

is one of the busiest shipping

population. Rivers such as the

lanes in the world.

Danube and the Rhone pass

Europe’s rivers and lakes

through many countries. Get-

have endured difficult condi-

ting those countries to work

tions due to pollution and over-

together for cleaner water has

80˚W

70˚W

60˚W

50˚W

40˚W

30˚W 10˚N

co rino

Rio O

Lake Maracaibo

Atlantic Ocean

WJ van Blommestein Lake Rio Negro

0˚

tin s

M

sco anci Fr

Sã

10˚S

Rio

R

o

Rio Tocan

io

Rio Pu

rus

iv e r

ad eir a

zon R Ama

Lake Titicaca

Pacific Ocean

Rio P ara n

á

20˚S

Atlantic Ocean

Lagoa dos Patos

30˚S

La Plata

N 40˚S

0 0

500 Miles 500 KM 50˚S

 South America’s major rivers and lakes

21

[Defining Rivers, Streams, Lakes, and Ponds]

not always been successful.

The problems challenging

Factory waste, shipping, and

European rivers and lakes

large human populations place

are the same for freshwater

heavy demands on rivers.

resources around the world.

Arctic Ocean Yu

k on

River

r Mackenzie R i v e

Great Bear Lake

Great Slave Lake Lake Athabasca

Fraser Riv e

r

45˚N

th Nor So

uth

Saskatc

he w

a n River

nR S a s k c h ewa at

Lake Winnipeg

r i ve

Lake Manitoba Lake Superior Mi s s o

ur

iR

iv

Missi s s i ppi

er

Great Salt Lake

Lake Huron

Lake Michigan

Lake Erie

Lake Ontario

Atlantic Ocean

r Rive

30˚N

de

R io Gr an

N 15˚N

Pacific Ocean

0 0

105˚W

 North America’s major rivers and lakes

22

90˚W

75˚W

500 Miles 500 KM

[Defining Rivers, Streams, Lakes, and Ponds]

20˚W

10˚W

0˚

10˚E

20˚E

30˚E

40˚E

50˚E

60˚E

70˚E Ob

30˚W

60˚N

Atlantic Ocean

Lake Ladoga Lake Peipus

ive

Volga R

r

Lake Vänern

50˚N

T

ieper R Dn

r mes Rive ha

Ri v ine

Rh

i ve r

r

e

Se

in

ver

e Ri

Dan ub

e River

Rhone R i

ver

40˚N

Tagus

R i v er

N

30˚N

0 0

250 Miles 250 KM

 READ IT! Take a look at author Steve

 Europe’s major rivers and lakes

Parker’s Eyewitness: Pond &

Overcrowded riverbanks

worse than in the

River (DK Publishing, 2000).

damage Asia’s Yangtze and

Volga or Danube.

Learn about freshwater ecosys-

Huang rivers as much as

Problems are many,

tems, from fish to frogs, plants

they do Europe’s Rhine.

but solutions are

to pollution.

Pollution in the Ganges is far

few and expensive. 23

2

[ C h a p t e r Tw o ]

Focus on Key Species

Focus on Key Species

24

(10-centimeter) tree trunk. They bring down the birch tree in about 15 minutes. Next comes the hard work. The beavers strip the

4 In the quiet woods of New

branches from the trunk and

York’s Adirondack Mountains,

drag them to a stream. They

a beaver family sets to work.

are building their lodge across

The adults gnaw a 4-inch

the fast-flowing mountain

[Focus on Key Species]

 WATCH IT!

water. The tree’s leaves, twigs,

ponds and marshes.

and bark provide their food.

What was once rush-

Beavers are among nature’s best

They use tree trunks, limbs,

ing water becomes

engineers. They are always busy,

mud, and rocks to build their

still water. Animals

always building, and always

home. Their building skills are

and plants that

interesting. Discover their fasci-

so good that even a stick or

cannot live in fast-

nating lives in the video Beavers

two of dynamite would barely

flowing stream

[ASIN: B00003XAMO].

dent a beaver’s dam.

water take advan-

Keystone Species

tage of the beavers’

?

WORDS TO KNOW . . .

efforts. Cattails, wild

copepods (KOH-puh-pahdz)

4 A keystone species is an

irises, lilies, reeds,

small water animals related to

animal or plant that is vital

bulrushes, and water

shrimp that are the main food

for the survival of an ecosys-

grasses spring up.

of many small fish, reptiles,

tem. The species may change

The new plant life

and insects

the land or create new habi-

attracts insect and

phytoplankton (FIE-toe-PLANGK-

tats. Or the species may

bird species.

tuhn) one-celled floating water

be the main food of habitat

In the North

plants, such as algae or diatoms

predators. Keystone species

American west,

of rivers and lakes are

salmon is a keystone river

beavers, salmon, copepods,

species. About 140 different

and phytoplankton.

animal species depend on

Beaver lodges and dams change water flow and create

salmon for survival. Important species that feed on salmon

 Beavers gnaw tree trunks and strip branches to build dams strong enough to block raging rivers.

25

?

BEAVERS IN THE NEWS

include grizzly bears, otters,

Two conservation groups in Great Britain

and bald eagles. The young

plan to reintroduce beavers to Scotland.

salmon feed off adult salmon

They will place four Norwegian beaver

carcasses. Dead salmon also

families, each with a male, a female,

release nutrients into the

and three kits, in the Knapdale Forest

water. River plants feed and

WORDS TO KNOW . . .

of Argyll, Scotland.

thrive on the nutrients provid-

Beavers have not

ed by rotting salmon. The health of a lake

carcasses (KAR-kuhss-ez) the

lived in Great

bodies of dead animals

Britain for

ecosystem depends on tiny

larvae (LAR-vee) insects at the

400 years.

plants and animals called phy-

stage of development between

In the 1500s,

toplankton and copepods.

eggs and pupae when they look

beavers were prized

Phytoplankton feed young

like worms

for their thick fur.

fish, insect larvae, and dozens

nutrients (NOO-tree-uhnts)

The species was

of other animal species.

substances needed by plants,

hunted to extinc-

Copepods are tiny animals that

animals, or humans for growth;

tion in the British

are part of the zooplankton.

key elements of a food

Isles. This event

Some are not even as large as

zooplankton (ZOH-uh-PLANGK-

will mark the first

the head of a pin. They eat

tuhn) tiny water animals

time a native

phytoplankton, insect larvae,

unable to propel themselves

species extinct in

and fish eggs. In turn, cope-

against currents

Great Britain is rein-

pods are the basic food, or first

troduced there.

link, in the animal food chain.

26

Tiny plankton are a basic food for  fish, reptiles, amphibians, and small mammals.

[Focus on Key Species]

They feed water insects, wading birds, and mature fish.

Umbrella Species

?

WORDS TO KNOW . . .

endangered (en-DAYN-jurd)

4 Governments

close to extinction; few mem-

and copepods, fish, birds, and

pass laws to protect

bers of a species still surviving

water mammals could not

endangered or

microscopic (mye-kruh-SKOP-ik)

exist. These microscopic ani-

threatened plants

too small to be seen with the

mals and plants are the basic

and animals. Legal

naked eye; only seen with the

elements of life in freshwater.

protection stops

help of a microscope

Without phytoplankton

threatened (THRET-uhnd) at risk of becoming endangered

 READ IT! Life in a River (Lerner Press, 2003) by Valerie Rapp is an Ecosystems in Action book.

 Protecting manatees like this mother and calf helps protect other creatures in their habitat.

Follow the Columbia River

people from hunting

from its source to the sea,

an animal or digging

protected animal or plant that

through several ever-

up or cutting down a

spreads its legal protection

changing ecosystems.

plant. With rivers

over other creatures. Manatees

and lakes, laws may

travel through rivers, feeding

28

An umbrella species is a

limit boats, fishing, building,

on sea grass or water hya-

or human use.

cinths. They need protection

[Focus on Key Species]

from speedboats, fishing nets,

DDT, a chemical compound

and pollution. Laws establish

used to kill insects, reduced

areas in which boats can trav-

bald eagle populations.

el only at slow speeds or not

Bald eagles are at the top

at all. Other fish, reptiles, and

of their food chain. They eat

amphibians that live in the

fish, such as salmon and trout,

river share the manatees’

which feed on smaller fish.

protection. Reduced river

Small fish ate the bodies of

traffic and pollution-free water helps all river beings— not just manatees. Umbrella species may live in or near lakes and rivers. If they feed in freshwater, their food sources must be protected along with their habitats. Bald eagles are an umbrella species of freshwater biomes. Bald eagles were once an endangered species. Their populations dropped during the late 1940s and early 1950s. Scientists found that Bald eagles require pollution-free  rivers and lakes to survive.

Some eggs hatched young with birth defects. Protection for bald eagles was not protection of the eagles’ territory. It was protection from DDT. The eagles gained an advantage because DDT was banned and therefore no longer poisoned insects. Other species that might have eaten DDT-poisoned food shared that benefit. Piping plovers are another example of an umbrella species  This eagle has made a catch! It is fish for dinner tonight.

30

in a freshwater biome. Plovers are shorebirds that breed on

insects killed by DDT. The

the sand dunes of Lake Mich-

chemicals stayed in the insects

igan. There are only a few

and fish, and eventually ended

dozen nesting pairs left in the

up being eaten by eagles. DDT

area. The plovers share their

caused eagles to lay eggs with

territory with sandhill cranes,

weak shells. Eggs broke when

herons, bufflehead ducks,

eagles sat on them to brood.

and turtles. Scientists want to

[Focus on Key Species]

protect the piping plover’s hab-

attention. Salmon, beavers,

itat. In doing so, they will also

whooping cranes, and bald

protect the plovers’ neighbors.

eagles are flagship species

Flagship Species

of freshwater environments. The problems faced by

4 Flagship species are

flagship species become public

species that attract the public’s

issues. When a flagship species

 Protecting the nesting areas of migrating birds like the great blue heron will help preserve wading bird species.

31

 This osprey is scanning a nearby lake for fish. It uses its sharp talons to scoop prey from just beneath the water’s surface.

makes news, politicians take

bald eagle is a national symbol

notice. Laws to protect flagship

of the United States. Politi-

species also protect other

cians had more interest in sav-

species and ecosystems.

ing bald eagles than vultures.

Consider the situation with bald eagles. They were not the only species damaged by DDT. Other birds of prey,

32

Laws passed to protect bald eagles saved the vultures, too.

Indicator Species

such as American peregrine

4 Indicator species measure

falcons, osprey, and vultures,

the health of an ecosystem.

also suffered. However, the

Many species indicate, or show,

The presence of blue damselflies indicates that this pond provides a healthy habitat. 

[Focus on Key Species]

problems in that ecosystem.

ly die or fail to produce

Pollution, overbuilding,

young in unhealthy situa-

erosion, and overhunting

tions. One way to check if

or overfishing change eco-

a local pond is healthy is to

systems. Indicator species

count the number of dragon-

measure those changes.

flies or damselflies hovering

Insects make excellent indicator species. They quick-

in the air. If there are few or no dragonflies, the pond is

 Mussels are filter feeders. When pollution is high in a stream, mussels will die.

 LOOK IT UP! Visit a dragonfly pond! Find out about the plants and animals

too polluted to

they filter food and water

support life.

through their bodies. When

Mussels serve

there is too little food or too

living around a small pond at

as indicator species

much pollution, mussel

http://www.units.muohio.edu/

in many rivers.

colonies die off. If the water

dragonfly/index.htmlx.

Mussels are filter

is healthy and food is plenti-

feeders. To eat,

ful, mussel colonies grow.

34

3

[Chapter Three]

4 Along the Amazon River

entire fish, head first. Otters

of South America, a giant

use this whirlpool trick to

river otter swims in a quick,

enjoy an easy catch.

tight spiral. The faster the

Predators

Predators

fish from the river muck below. The otter grabs its prey in its paws. It eats the

Giant otters need about

water moves, the tighter the

10 pounds (4.5 kilograms) of

water swirls. The movement

food each day. Their favorite

creates a whirlpool that sucks

meal is catfish, but they also

 When this giant otter finishes its meal, it will go hunting again.

35

PROFILE: PERU’S GIANT RIVER

eat crayfish and frogs. They

OTTER PROJECT

hunt, eat, and rest through-

Peru’s Giant River Otter Project identifies

out the day. Although otters

otter habitats and observes otters in the

live in burrows on land,

wild. The giant river otter is just one of

they hunt in the water. They

the many species unique to the Amazon

are active, aggressive fresh-

River (below) and its tributaries. Project

water predators.

scientists found mercury pollution in several sites where giant river otters feed.

Predators of Every Size

The scientists are trying to reduce pollu-

4 Freshwater predators

tion in otter habitats. As they study the

come in all sizes and shapes.

otters, scientists can decide what is need-

The tiniest is the copepod,

ed to preserve the species.

which is both predator and prey. Large predators include brown bears, otters, crocodiles, alligators, and water snakes. Predators live beside and in the water. They hunt from both above and under water. They crawl, slither, fly, swim, and pounce. Mammals are the largest predators. Brown bears fish

[Predators]

while salmon are spawning.

without leaving

The rest of the time, they eat

a scratch.

land animals and plants. River

The world’s

 WATCH IT! Crocodiles: Here Be Dragons (ASIN: 6304474598) gives view-

otters and weasels hunt for

largest snake is also

ers a close-up look at Nile croco-

fish, frogs, beavers, shrews,

a water predator.

diles and their lives as fierce

and muskrats. Although they

The anaconda of

predators and gentle parents.

catch their food under water,

South America

they usually eat their catches

lurks among the

on land or while floating on

reeds at the water’s

spawning (SPAWN-ing) produc-

their backs in the water.

edge. Anacondas

ing eggs or young

Reptiles sun themselves

?

WORDS TO KNOW . . .

eat wild pigs, deer,

on riverbanks in most warm,

fish, other reptiles, and even

freshwater regions. They usu-

jaguars. They eat prey whole.

ally live on land, but croco-

Their bodies digest skin,

diles and alligators spend as

bones, and fur.

much time in the water as on solid ground. These danger-

Birds That Fish

ous hunters glide through

4 Some birds swoop out of

water almost unseen. They

the sky, talons stretched, and

quickly seize prey and kill it

scoop up trout for dinner.

in their powerful jaws. Yet

Others bob along on the

mother crocodiles transport

water, waiting for a meal to

their young in their mouths

swim by. Then they dive down 37

PROFILE: THE NILE CROCODILE

and snap up prey in their bills.

Nile crocodiles can bring down wilde-

Still others wade into the water

beests or zebras with no trouble. They

and peck at fish, mussels, and

attack lions and water buffaloes. A

worms hiding in the shallows.

Nile crocodile’s jaws can break a man’s

Birds of prey rely almost

leg in two with one bite. In fact, Nile

entirely on meat for their diets.

crocs cause more human deaths than

Some birds of prey are fish-

lions, tigers, or rhinos.

eaters. Besides bald eagles,

Nile crocodile hatchlings must hide

African fish hawks and osprey

from predators. For their first few

hunt fish. They catch fish

years, they are preyed upon by male

while flying, and then return

crocodiles, birds, and large fish. It

to their nests to eat.

takes about seven years for a crocodile

Birds do not have to be

to reach adult age. Adult Nile croco-

birds of prey to be predators.

diles can weigh more than 1,500

Ducks may upend themselves

pounds (680 kg) and can reach 20 feet

to hunt snails, mussels, and

(6 m) in length. Only humans hunt

fish. Other birds dive for their

adult Nile crocodiles.

food. Dippers—common around fast-flowing mountain streams in the Rockies and the Andes, as well as in Europe and Asia—dive down to streambeds to find snails

38

 DO IT! Join a kids’ conservation group. The Wildlife Conservation Society has a kids’ Web page  A belted kingfisher dives into a stream in search of food.

called Kids Go Wild. You can

and small fish that hide among

ing branches. When

help save wildlife. Go to

the rocks. In North and South

fish swim beneath

http://www.KidsGoWild.com

America, Africa, and Asia,

them, they plunge

to find out how to join.

kingfishers perch on overhang-

into the water. 39

[Predators]

Cranes, egrets, herons,

the type of food the birds

and flamingos are wading

eat. Bills can be spoon-

birds. Their long legs allow

shaped, thin and straight,

them to walk through shal-

or curved. A spoonbill

low water in search of small

scoops up its food. Cranes

fish, shellfish, and insects.

and egrets peck with long,

The shape of their bills suits

sharp bills.

!  Flamingos use bony plates in their mouths to strain their food from the water.

Flamingos have bony plates in their mouths. They

Fishing Fish

WOULD YOU BELIEVE?

South America’s jacanas have extremely long feet and toes. Their feet spread out so far that jacanas look like they are

suck water through the plates.

4 Although some

walking on water! Actually,

Their beaks close, and they

fish feed on plants,

they are walking on floating

push out excess water. They

most are meat

water plants.

feed on brine shrimp, worms,

eaters. They prey on

and insects trapped in their

insects, eggs, larvae, and small-

mouth plates.

er fish species. The size of a

 African crowned cranes wade into the shallows looking for prey.

41

[Predators]

predator fish does not relate to

Garbage feeders play an

the size of its prey. Some fish

important role in keeping

prey on tiny zooplankton and

freshwater clean.

still grow remarkably large. The pirarucu of South America feeds only on larvae

Bottom of the Food Chain

and eggs. Adult pirarucus

4 At the bottom of the

measure about 13 feet (4 m)

food chain are creatures that

long and weigh up to 440

are both predators and prey.

pounds (200 kg).

Copepods, insect larvae,

Large fish,

and fish fry munch on one

fry (FRYE) the young of a

such as pike, trout,

another. They are also food

fish species

and salmon, form

for larger fish, frogs, and

the top of the fish

waterbirds. There is always

?

WORDS TO KNOW . . .

food chain in rivers and

something larger that will

lakes. Pike, in particular, are

eat the smaller animals of

aggressive hunters. They

a biome.

often devour all smaller fish from ponds or lakes. Catfish and carp may

42

Numbers of a certain species make a difference between destruction and sur-

feed along river or lake bot-

vival for predators. A dozen

toms. They eat dead animals

otters hunt in a mountain

and solid animal waste.

lake. They each eat quantities

[Predators]

 Catfish are bottom feeders. They keep river water clean by eating dead animals and animal waste.

43

 River otters are excellent swimmers. They catch fish in the water but eat their meals on land.

44

of fish and frogs every day. A

year. Thousands of fish and

40-pound (18-kg) otter might

frogs live in the lake. How-

eat four fish and three frogs

ever, if there were 100 otters,

in one day, or approximately

there might not be enough

1,500 fish and 1,100 frogs per

food available to feed them.

4

[Chapter Four]

4 A lake trout hunts in the shallows of Lake Superior. It

with no jaws. Lamprey mouths are round and filled with sharp teeth. The lamprey attaches

can grow to be up to 45 inches

its mouth to the trout’s

(114 cm) long and can weigh

side. It clings to the trout

about 40 pounds (18 kg). Most

while it sucks the fish’s blood.

people would not consider lake

The lamprey feeds off the

trout prey. They are usually the

trout for a couple of days.

eaters, not the eaten.

Unfortunately for the trout,

As the trout feeds, a dangerous parasite approaches.

Prey

Prey

It is the lamprey eel, a creature

the lamprey will suck its life away.

 Lamprey eels prey upon lake trout like this one from Lake Superior.

45

 This carp doesn’t stand a chance for survival once a lamprey eel attaches itself to the carp’s body.

Prey by the Numbers

numerous prey are zooplank-

4 The largest group of prey

ton. The word plankton comes

is made up of the smallest-

from the Greek planktos,

sized prey. It’s a matter of

which means “wandering.”

how many prey must be eaten

Plankton doesn’t actually

to make a full meal. A predator

wander. It drifts.

may fill up on one frog or

46

The smallest and most

Zooplankton includes

two dozen tadpoles or 3,000

copepods and the eggs or

frog eggs.

young of larger animals.

[Prey]

Copepods are the most com-

PROFILE: EMPEROR DRAGONFLIES

mon kind of zooplankton.

Europe’s emperor dragonfly depends

Twelve thousand small

on lakes and ponds for producing

copepods weigh in at about

young. The female makes slits in the

1 ounce (28.3 grams). Dragon-

leaves of pond weeds above the water.

fly larvae are considered

She lays her eggs within the leaves. In

zooplankton, but an adult

three weeks, the eggs hatch, and the

dragonfly is not.

larvae drop into the water through

Fish and insect species lay eggs by the billions. The

the slits. Now begins a life filled with dan-

chances of any egg reaching

ger. Dragonfly larvae live in water

adulthood are small. With

for two years. They float among the

many species, fewer than

plants in shallow freshwater. They

three out of one hundred eggs

must hide if they are to survive to

become adults. Generally, the

adulthood. Frogs, carp, otters,

smaller the prey, the larger

shrews, and other insects feed on

the number of predators that

dragonfly larvae.

eat it. Insects, slugs, snails,

After two years of hide-and-seek,

small fish, worms, birds,

the larvae crawl out of the water. They

lizards, frogs, and larger fish

shed their skins. Soft wings emerge.

eat eggs. Huge numbers of

These newly adult dragonflies open

eggs are necessary if a species

their wings to the air. Once the wings

is to survive.

dry, the adults can fly.

47

[Prey]

Building up Defenses 4 Adult insects and beetles

water’s surface, feeding on their favorite food—mosquitoes. Because the whirligig is a

live in an endless

surface beetle, it is easy prey

cycle of eat-and-be-

for larger insects, birds, and

It’s not easy being a tadpole or

eaten. Whirligig bee-

fish. Its defense against preda-

a dragonfly. Learn about these

tles, for example, eat

tors is to fill surrounding

pond creatures in the National

all day long. They

water with a milky-white

Geographic Kids’ video

skim across the

substance. The beetle then

 WATCH IT!

Tadpoles, Dragonflies, and Caterpillars [ASIN: 6303379184].

 Damselfly larvae hide in plain sight. Their green bodies match the plants on which they live.

escapes in the murky water,

oring for the first

if it’s lucky.

year blends with the

camouflage (KAM-uh-flahzh)

riverbeds in which

coloring that blends in with

from their enemies. The larvae

they live. After a

the surroundings

of blue damselflies are green,

year, the young

like plants. The young shed

salmon change color. They

their skins while holding onto

become silver, which provides

plant stems. Their green color

camouflage while the salmon

makes them nearly invisible.

live at sea.

Camouflage hides prey

Atlantic salmon begin life in rivers or streams. Their col-

?

WORDS TO KNOW . . .

Other species use poison, hard shells, or sharp spines

 Whirligig beetles zip across a pond’s surface in constant search for insects and larvae.

49

[Prey]

 READ IT!

against their ene-

will also bite and sting preda-

David Josephs’ Lakes, Ponds,

mies. European

tors that come too close.

and Temporary Pools (Franklin

backswimmers suck

Their stings are painful, even

Watts, 2000) gives readers an

blood from their

for humans.

appreciation of freshwater life

victims. They poison

cycles. The information on tem-

small insects on

freshwater mussels survive

porary pools shows how life

surface water. They

because of their hard shells.

thrives—even in a puddle.

Hundreds of species of

The shells protect them from many possible predators, but not all. Muskrats, raccoons, and herons have no trouble cracking mussel shells to eat the meat inside. Sharp spines are the only protection the stickleback fish has from predators. The spines ward off smaller fish, but sticklebacks still have predators. Water shrews, otters, storks, and herons feed on sticklebacks. The spines are too small to bother these large hunters.  Raccoons are the neatest eaters. They like to wash their food in a stream before eating.

!

WOULD YOU BELIEVE?

Some kinds of water shrews  An infant snapping turtle bursts from its shell.

carry enough poison in their

a nest and lays 25 to

mouths to kill 200 frogs, toads,

50 eggs. Raccoons,

or mice. The shrews use the poi-

4 Reptiles, amphibians, and

weasels, and water

son to stun the larger prey and

rodents are common prey in

rats dig up the eggs

to keep them from struggling.

rivers and lakes. Many are

almost as soon as

victims only as hatchlings or

they are laid. Once the remain-

young. This is true for turtle

ing eggs hatch, the hatchlings

and crocodile hatchlings.

become prey for crows, hawks,

Other Prey

Snapping turtles lay their eggs on land. The female digs

wading birds, bullfrogs, snakes, and other turtles. Of the 51

 Water shrews have poison in their saliva. One nip, and their prey will die.

52

female’s 50 original eggs,

throughout their lives.

only three will reach adult-

Water shrews never weigh

hood. As adults, however,

more than 1 ounce (28.3 g).

snapping turtles have few

They spend their lives avoid-

enemies. They are defense-

ing predators.

less only when very young.

Water rodents are common

Other animals remain

river creatures. Water voles, for

small, even as adults, and

example, build their burrows

fall prey to larger animals

with underwater entrances.

A water vole munches on a leaf beside an English pond. 

[Prey]

Otters prey on water voles

almost any small prey, and

throughout the voles’ lives. The

they are eaten by nearly every

voles have developed protection

larger fish.

from otters. When hunted, they

Cichlids are another prey

scratch the muck from the bot-

species. More than

tom of the river. Then they dis-

600 different

appear in a cloud of mud.

species, including

The pumpkinseed sunfish,

tilapia and gobies,

found in eastern North America,

common prey. European min-

swim tropical lakes

preys on its own young. Females

nows have adapted to life in

and rivers in Africa

lay as many as 35,000 eggs, pro-

freshwater. Minnows are tiny

and South America.

ducing their own food source.

cousins of the carp. They eat

Like minnows, they

Luckily, enough young survive

Some freshwater fish are

!

WOULD YOU BELIEVE?

their cannibal parents for the species to continue to exist.

 Blue tilapia move in a school in an African lake.

travel in schools and make

waste good food. If there are

easy prey.

nutrients to be had, some-

Every animal that lives in freshwater biomes will at some point become the prey

thing will gnaw, suck, or chomp to get them. The food cycle depends on

of another species. Alive or

prey and predators. Without

dead, every animal feeds oth-

predators, prey would repro-

ers. Prey may be the eggs,

duce in massive numbers. Prey

infants, or adults of

populations would soon take

a species. It can

over lakes and streams.

carrion (CAH-ree-uhn) dead or

also be the carrion

Predators keep prey population

rotting flesh

left once adults die.

levels in check. This is an

Nature does not

example of nature’s balance.

?

WORDS TO KNOW . . .

54

5

[Chapter Five]

Flora

Flora

It is the smallest known plant. The man-made pond is a sewage treatment tank.

4 A tiny plant, barely the

Minerals in the water fuel

size of a fly’s eye, grows on the

duckweed’s rapid growth

surface of a man-made pond.

rate. In effect, duckweed

The plant has two small leaves,

drinks sewage

a flower, and a root. It is duck-

water. It feeds

weed, and thousands of them

on chemicals,

sewage (SOO-ij) waste products

cover the pond’s surface water.

such as

carried by water from factories

?

WORDS TO KNOW . . .

and homes

 Tiny duckweed filters sewage from pond water.

55

 A bullfrog peeps out from beneath a pond’s duckweed-covered surface.

phosphates and nitrogen. When the duckweed’s job is done, machines ?

WORDS TO KNOW . . .

called skimmers

refreshed water is recycled for human use.

River and Lake Plants

chlorophyll (KLOR-uh-fil) a

remove the plants

4 Rivers and lakes support

green substance plants use that,

from the water. The

many of the same plants. Water

when combined with sunlight,

“used” duckweed is

and sunlight provide the fuel

helps produce food and oxygen

fed to cattle or

for plant survival. Plants com-

farmed fish. The

bine sunlight and chlorophyll

56

Willow moss grows on the rocks in a rushing stream. 

[Flora]

to make food. This process is called photosynthesis.

The speed and

 LOOK IT UP!

amount of water in

Alien plants are plants that

a river determine

arrive from other places. Some

single cells or as large as trees.

the types of plants

become invasive and take over

Single-celled plants called phy-

found there. A

their new homes. They make an

toplankton feed hundreds of

fast-moving stream

interesting science project. Learn

freshwater animals. Cypress

has fewer plants

more about non-native plants

and mangrove trees grow as

because plants

and the efforts to keep them

comfortably in water as maples

cannot root in

under control. Visit the Maine

and oaks do on land. Their

rushing water.

Department of Environmental

roots create a weblike nursery

Willow moss is

Protection’s invasive plants links

for young fish and reptiles.

one of the few

page at http://www.state.me.us/

Plants may be as small as

dep/blwq/topic/invasives/invlink. htm. Many other states have similar Web sites.

WATER HYACINTHS IN THE NEWS

plants that thrive in rapid

Lush lilac-colored water hyacinths add

streams. The moss clings

delicate beauty to tropical rivers in North

to rocks to survive.

America, South America, Asia, Australia,

Slow-moving rivers have

and Africa. This plant, however, is a killer

more plant life, both in vari-

in areas where it is not native.

ety and amount. Plants take

Water hyacinths develop into thick

root along riverbanks or in

mats in tropical rivers. They prevent sun-

shallows. Reeds, water grass-

light from reaching below the surface.

es, and bulrushes grow along

Few other plants and animals can grow

slow rivers. Where river

in these waters. Humans cannot travel or

water is particularly quiet,

fish in rivers clogged by water hyacinths.

duckweed, hornweed, water

Scientists experimented with hyacintheating insects in 20 countries with water hyacinth problems. The insects achieved

hyacinths, and other freefloating plants live. Water lilies are among

mixed results. New experiments are

the rooted plants that

under way with a water-hyacinth fly

thrive in slow-moving

recently found in the Amazon River of

rivers, ponds, and lakes.

South America. Meanwhile, water

Water lilies send roots

hyacinths grow unchecked.

into soft river mud. Their stems stretch through the water to the surface, where leaves and flowers grow.

58

?

WORDS TO KNOW . . .

limnetic (lihm-NEHT-ick) relating to surface lake water or pond water that is penetrated by sunlight littoral (LIHT-tor-ull) relating  A dense growth of water lilies prevents needed sunlight from reaching the lake bottom.

to water lying along lake or pond shorelines

littoral, limnetic,

profundal (pro-FUN-dull) relat-

and profundal.

ing to deep lake water that no

4 Freshwater lakes have

Plants can live only

sunlight can reach

three life zones. The zones are

in the littoral and

Lake Zones

59

limnetic zones. They do not live in the profundal zone because there is no sunlight. The littoral zone hosts cattails, reeds, and dozens of other wildflowers, ferns, grasses, and trees. The limnetic zone is home to phytoplankton. The green slime floating on still ponds is usually a type of phytoplankton called algae. Some plants live mostly below the water’s surface. Bladderwort, for example, survives under water by trapping and eating insects and larvae. The plant has bladders, or air pockets, that keep the branches upright. Bladderwort sends shoots above the surface only when it is time to flower.  Bright green algae cover the entire surface of this pond.

60

[Flora]

Surviving Winters

warms the surface

?

WORDS TO KNOW . . .

water. Water star-

dormant (DOR-muhnt) sleeping

4 Water plants in temperate

worts and frogbit

or inactive

zones adjust to weather

are winter sleepers.

temperate (TEM-pur-it) a

changes that come with winter.

Other water

climate zone with warm

When water temperatures

plants drop their

drop, ice may form on the sur-

leaves. Water lily

face, blocking sunlight. Some

leaves fall each autumn. The

plants simply sink to the lake’s

plant stores food in its roots.

bottom in winter. They lie

Spring brings new leaf growth

dormant until spring weather

and flowers to produce seeds.

summers and cold winters

 Water starwort thrives in still water where its leaves emerge above water level.

61

6

[Chapter Six]

Herbivores

Herbivores

?

Australia. Until swans reach adult-

4 A family of black swans

hood, they will eat insects and

glides across a still pond. The

small invertebrates, such as

cob (male) and pen (female)

slugs, snails, and worms.

mate for life. Their young,

When they reach adulthood,

WORDS TO KNOW . . .

invertebrates (in-VUR-tuh brits) animals with no backbones

62

Black swans are native to

called cygnets,

swans become herbivores—

swim behind

they eat only plants. They

their parents.

browse on grasses along the

 This hippo mother and baby seem to be sharing a joke.

shore. Swans also eat grains

are dugongs and

such as wild rice, which is a

manatees. These

kind of grass, and the roots

water mammals

Hippos spend up to 18 hours a

of water plants.

munch their way

day in the water. They may

through tons of

even give birth to their young

water hyacinth, eel-

underwater. But they do not

4 Freshwater plant eaters

grass, and sawgrass

eat in the water. At sunset, hip-

are as varied as meat eaters.

each year.

pos head to their favorite feed-

Plant Eaters in the Water

The smallest are zooplankton.

Plant eaters per-

They eat phytoplankton. The

form an important

largest freshwater herbivores

function in the

 These black swan mates have built a nest beside a quiet Australian pond.

!

WOULD YOU BELIEVE?

ing grounds. They eat grass and fruit.

63

PROFILE: ZEBRA MUSSELS

freshwater food web. They take

Zebra mussels are European imports

in plant nutrients, which col-

to North America. They arrived in the

lect in their bodies. As they

Great Lakes in the 1980s, probably

digest the plants, the plant

carried in the water that was in ships.

matter turns into energy.

They have been a problem there

Animals that eat herbivores

ever since. They reproduce more

also benefit from the plant

quickly than native North American

energy and nutrients stored in

mussels and freshwater clams. Zebra

their prey.

mussels are “muscling” the locals out of existence. In a space slightly larger than

plant-eating snails and mussels hug the river bottoms. Snails

1 square yard (.8 sq m), scientists

thrive on pond slime. They eat

counted 1,000 zebra mussels. Within

algae and rotting plants. Mus-

six months, the population had

sels are filter feeders. They

exploded. That same area had

take in water and phytoplank-

700,000 mussels.

ton. They strain plant food

Zebra mussels eat available phytoplankton. They reduce food for other species, such as freshwater shrimp. Where zebra mussel populations con-

64

Hundreds of varieties of

from the water.

Dining at the Water’s Edge

tinue to grow, the populations of

4 Some waterbirds, such as

native shellfish have dropped to zero.

swans, wigeons, and geese, eat

 Snow geese eat mostly plants, seeds, and grains.

mainly plants, seeds, and

are rodents. Nutrias, beavers,

grains. Others, such as

and capybaras are the largest

mandarin ducks and pintail

rodent herbivores. Throughout

ducks, prefer seeds, nuts,

their lives, their two

and roots. Some ducks also

extended front teeth

eat insects and shellfish.

continue to grow.

omnivores (OM-nuh-vorz)

They are omnivores.

They gnaw regularly

animals that eat both plants

to wear down their

and meat

Among water mammals, the most common herbivores

?

WORDS TO KNOW . . .

front teeth. 65

 This South American nutria resembles a skinny-tailed beaver. Nutrias, however, live in burrows instead of dams.

Nutrias look like thin-tailed

They eat bark, leaves, roots,

beavers. They munch their way

and twigs. They also feed on

through marsh grasses, crops,

water plants, such as cattails,

and just about any plant life

reeds, and bulrushes.

near their burrows. They will even eat bald cypress tree bark. Beavers prefer the young

66

Capybaras are the world’s largest rodents. They live in South America. Capybaras

saplings of oak, birch, elm,

spend most of their days wal-

and other deciduous (leaf-

lowing in mud. They feed on

bearing) trees. Beavers waste

reeds, lilies, grasses, bulrushes,

nothing of the trees they fell.

fruit, grains, seeds, and nuts.

7

[Chapter Seven]

river. Now, they have returned to breed. Danger lurks for salmon along their journey upstream. At the mouth of the

4 Salmon gather at the

Fraser, orcas and seals attack

mouth of the Fraser River in

the shoals of salmon.

Canada. They are driven there

A Cycle of Life

A Cycle of Life

swam out to sea from this same

The Fraser, like many

by instinct. Several years

rivers, has dams

before, these same salmon

and hydroelectric

?

WORDS TO KNOW . . .

instinct (IN-stingkt) a way of acting or doing things that comes naturally to a person or animal shoals (SHOLES) groups of fish

 Sockeye salmon head back to the stream where they were born to lay their eggs.

67

plants along its route. Salmon ladders allow some fish to move upriver past the dams. The ladders are levels of concrete over which water flows. The salmon hurl themselves up each step. Salmon use scent to tell them the exact place of their birth. This is where they will spawn. Female salmon dig shallow nests in the gravel. These nests, or redds, will be the nursery for her eggs. She may deposit all her eggs in one redd or use several nests. Female salmon carry between 2,500 and 7,500 eggs. They lay all their eggs in one season. Males swim over the redds and fertilize the eggs. The females then cover the nests with gravel.  A salmon’s journey home is a tough one and involves traveling over rapids and salmon ladders beside dams.

[A Cycle of Life]

 READ IT!

The adults usually have only

and grow to about

one chance to produce young.

6 inches (15 cm)

Salmon Stream by Carol Reed-

Most adult salmon die after

long before they

Jones (Dawn Publications,

they have spawned. Only cut-

can leave the river.

2001) takes readers on the dan-

throat and steelhead salmon live to spawn a second time. Salmon eggs hatch about

Juvenile sal-

mon, called smolts,

gerous journey of the salmon cycle of life.

will leave the river

100 days after being laid.

and travel into the

The young salmon, called

ocean. Their bodies

juvenile (JOO-vuh-nile)

alevin, remain in the redd.

must change so they

young, not yet having

They live off their own yolk

can survive in salt

reached adulthood

for a month. Then they must

water. The smolts

leave the protected nest to

eat beetles, ants,

find food.

grasshoppers, and

Oregon’s Riverdale Grade School

worms. As the

hosts The Salmon Page. Learn

from the nest and immediately

smolts journey to

everything you need to know

search for food. They eat flies

the sea, squawfish,

about salmon at this Web site:

and other fish eggs. If carcass-

pike, loons, herons,

http://www.riverdale.k12.or.us/

es of dead adult salmon lie

and terns prey

salmon.htm.

near them, the fry eat the rot-

on them.

The month-old fry emerge

ting flesh. The fry hide among

?

WORDS TO KNOW . . .

 LOOK IT UP!

Adult salmon travel in

water plants and under fallen

huge schools, feeding on

tree branches. They must feed

copepods, krill, shrimp, 69

 Bears prove their skills as fishers when the salmon run on this Alaskan river.

and plankton. They swim

lock, tuna, cod, sea lions,

in ocean waters hundreds

swordfish, and orcas feast

of miles north of the

on adult salmon.

Fraser River. Most salmon spend from

70

Suddenly, the urge to reproduce strikes the sal-

one to seven years at sea.

mon. They head for their

Predators constantly hunt

home streams. Far out to

them. Salmon sharks, pol-

sea, they rely on instinct to

[A Cycle of Life]

 DO IT!

find their way back. Once

eagles, wolves,

they get close to the mouth

foxes, and minks

Fight water pollution.

of the Fraser, they “smell”

dine on dying

Encourage your parents to buy

their way home.

salmon. Salmon

biodegradable detergent for

carcasses rot and

laundry, dishes, and washing

bodies fulfill a final chore

feed the soil. They

cars. Most cleaning detergents

for nature. Grizzly bears,

add nutrients to

will kill the grass if you use them

When salmon die, their

outside to wash lawn furniture or the car. Cleaning chemicals and oil also filter into the soil and pollute groundwater.

 Bald eagles join the salmon feeding frenzy.

71

[A Cycle of Life]

 These tiny salmon eggs escaped being eaten. Will they survive to adulthood?

72

the river and, even in death,

mon. This is the salmon

feed their own young.

cycle of life. More than 140

Of the original thou-

animal species thrive because

sands of eggs laid, only about

of the salmon’s curious jour-

2 percent survive to spawn

ney from river to ocean to

another generation of sal-

river again.

8

[Chapter Eight]

The Amazing Amazon

The Amazing Amazon

4 A capybara drinks at the water’s edge. It is the world’s largest rodent, weighing about 80 pounds (36 kg). The capybara spends its days in water. It lives in groups of about

 A capybara in the Amazon marshes provides a comfortable resting place for a cattle tyrant bird.

73

[The Amazing Amazon]

20 other capybaras in the Amazon River marshes. Many predators lie in wait

presents the greatest danger. An anaconda slips unseen through the reeds. It eats

along the brown,

everything from wild pigs to

silt-filled Amazon.

wading birds. Today’s menu

caimans (KAY-mehnz) small

Capybaras are wary

features capybara.

members of the crocodile family

of jaguars, caimans,

?

WORDS TO KNOW . . .

harpy eagles, and large snakes. Today, a snake

The capybara has no chance against the anaconda. Adult anacondas stretch 16 feet (4.9 m) long and weigh about 500 pounds (227 kg). In the Amazon River basin, anacondas are top predators. Their only real enemies are humans.

The Greatest River 4 The Amazon River is a massive river system that moves two-thirds of the fresh river water and lake water in the world. The river’s volume is five times greater than that of the Mississippi River. The  Amazingly, this anaconda can stretch its jaws to eat a capybara whole.

[The Amazing Amazon]

Amazon carries 10 times more water than the Nile River. The water moves so quickly and with such force that Amazon River silt clouds the ocean water as far as 185 miles (298 km) into the Atlantic. The Amazon begins as a mere trickle more than 16,250 feet (4,950 m) up in the Andes Mountains. The river falls nearly 16,000 feet (4,877 m) in the first 600

 Look at the difference in the color of the water where the Rio Negro meets the Amazon near Manaus.

miles (965 km) of its flow. In all, the Amazon runs 3,900

More than

!

WOULD YOU BELIEVE?

miles (6,275 km). Tributaries

10,000 smaller

The black water of the Rio

of the Amazon collect water

rivers and streams

Negro meets the white

from Bolivia, Peru, Venezuela,

swell the Amazon’s

water of the Amazon near

Colombia, Ecuador, and Brazil.

waters. The largest

Manaus, Brazil. For more than

The river’s basin covers about

tributaries are the

50 miles (80 km), the two

2,700,000 square miles

Madeira, Purus,

waters travel side by side

(6,993,000 sq km)—about

Tocantins, Japurá,

without mixing together.

10 times the size of Texas.

and the Rio Negro. 75

[The Amazing Amazon]

 This oxbow lake formed near where the Jurua River feeds into the Amazon.

76

[The Amazing Amazon]

Together, they form a network of waterways running through rain forest, grasslands, swamps, and marshes. The Amazon and its tribu-

Amazon Plants and Animals 4 The most fascinating aspect of the Amazon basin

taries include white-water,

is the incredible number of

black-water, and clear-water

plants and animals found

rivers. The main river, the

there. Scientists have recorded

Amazon, is a white-water river.

40,000 different species of

In this case, white-water does

flowering plants, along with

not mean filled with rapids for

10,000 types of trees and grass-

kayaking or water rafting. It

es. Many Amazon species have

means filled with chalky, beige

not yet been discovered.

silt. Black-water rivers, such as

The region supports

the Rio Negro, are not really

1,800 types of birds and

black. Rotting plant matter

hundreds of different fish

dyes the water the color of

species. There are more

strong tea. The water travels

than 250 types of mammals,

over sandy beds, so it picks up

living in both the water and

very little silt or soil in it.

on the surrounding land.

Black-water rivers are clear, but

The broadest species range

dark. Clear-water rivers have

is in the insect world. Scien-

clean, clear, silt-free water.

tists know there are at least 77

PROFILE: A WET CLIMATE

15,000 species of insects.

The Amazon flows through one of

However, they estimate that

the wettest regions of the world. At

number may be as large as

certain places along the river’s route,

6 million.

rainfall measures more than 200

Willows, orchids, and cane

inches (508 cm) a year. Even the drier

grass are common. Not quite

areas are wet. Yearly rainfall averages

so common are strangler figs

100 inches (254 cm) across the river’s

and giant water lilies. Strangler

full length. Compare that to annual

figs begin as seeds high in the

rainfall rates in Los Angeles (15

branches of a host tree. The

inches/38 cm) or New York City

figs send roots down to the

(42 inches/107 cm).

forest floor. Eventually, the fig kills the host tree. Giant water lilies float in the quiet bends of the Amazon. They can grow as much as 7 feet (2 m) across.

 WATCH IT!

The thorny underside wards

Learn more about the Amazon

off herbivores. Giant water

River and its rain forest. Watch

lilies are so large that they

National Geographic’s Amazon:

have been used as boats.

Land of the Flooded Forest [ASIN: 6304473869].

Mammals of the Amazon basin range from screaming howler monkeys to silent

78

These giant water lilies are so large  that Amazon natives have used them as boats.

[The Amazing Amazon]

jaguars. River dolphins and

The region’s

!

WOULD YOU BELIEVE?

manatees are the largest

birds fill the land

The world’s only aquatic marsu-

water mammals. Both are

with color. Scarlet

pial, the water opossum, lives in

endangered species.

ibis, roseate spoon-

the Amazon basin. A marsupial is an animal that carries its young in a pouch.

[The Amazing Amazon]

bills, and jabirus feast on the fish, frogs, and insects along the Amazon’s banks. Kingfishers dive into the water below in search of cichlids. Jacanas use their long toes to walk on water as they hunt. Reptiles slink, slither, and slip through murky Amazon waters. Caimans sun themselves on the riverbanks. They hunt at night, when prey cannot see them approach. The Amazon has several deadly snakes. Poisonous fer-de-lance snakes slip along waterways and through wet forests. The Amazon’s bushmaster is the Western Hemisphere’s largest poisonous snake. Creatures that do not fear snake venom do fear boas and 80

 Caimans are the smallest members of the crocodile family, but their teeth seem plenty large!

[The Amazing Amazon]

anacondas. They are both

frenzy. A school of piranhas

constrictors. They squeeze

can reduce a much larger

their victims until they

animal to a pile of bones in

suffocate. The Amazon

mere minutes.

has red-tailed boas, Amazon

Insects, the largest group

tree boas, and rainbow

of animals in the Amazon,

boas, as well as two types

are too plentiful to list.

of anacondas.

Beetles, flies, ants, termites,

Amazon fish feed thou-

and mosquitoes thrive by

sands of people who live in

the billions in the Amazon’s

the region. The giant catfish,

warm, wet weather.

called the paraiba, makes a

The Amazon also sup-

tasty barbecue. Needlefish,

ports stunningly beautiful

sole, and smaller catfish are

butterflies. The Brazilian

also delicious to eat. One fish

morpho butterfly has vivid

that few people want to catch

blue wings on one side

is the piranha. Piranhas usu-

and camouflaged browns

ally swim alone. When they

and yellows on the other.

do travel in schools, they are

Green long-winged butter-

fearsome predators. Like

flies and Aurorina clear-

sharks, piranhas can smell

winged butterflies dance

blood in the water. The scent

among the shadows of

sends the fish into a feeding

the rain forest. 81

9

[Chapter Nine]

The Human Touch

The Human Touch

82

out. The damage was minor. However, the fact that an American river caught fire shocked the nation. For hundreds of years, the world’s cities used local rivers as sewer connections.

4 On July 23, 1969, the

Factories poured waste into

Cuyahoga River caught fire.

rivers and lakes by the ton.

The Cleveland, Ohio, fire

Storm runoff, complete with

department quickly put it

chemical pollution, swelled

 Today, the Cuyahoga River preserve shows what can be done when a community works for clean water.

streams and rivers. When the Cuyahoga

27 species of fish,

 WATCH IT!

including bluegill,

Africa’s Stolen River (ASIN:

caught fire, efforts were already

pike, and bass. The

6304473834) records the disap-

under way to clean it up.

river continues to

pearance of the Savuti Channel

Within three years, the Clean

need work and

of Botswana over seven years.

Water Act of 1972 passed. The

attention. Still, the

The video portrays the changes

new law added government

current Cuyahoga is

animals must make in order to

power to saving U.S. waterways.

vastly cleaner than

survive when their main water

Thirty years later, the

the 1969 river that

source is lost.

upper Cuyahoga supports

Time magazine

 In 1969, the Cuyahoga River, passing through Cleveland, Ohio, actually caught fire!

83

PROFILE: AMERICAN RIVERS

described: “Chocolate-brown,

American Rivers, a group dedicated to

oil, bubbling with subsurface

preserving and restoring U.S. rivers,

gases, it oozes rather than

has declared 11 rivers endangered:

flows.”

1. Upper Missouri River (Montana,

Threats to Clean Water

North Dakota, South Dakota) 2. Big Sunflower River (Mississippi)

4 In the United States, 40

3. Klamath River (Oregon, California)

percent of the nation’s fresh-

4. Kansas River (Kansas, Missouri)

water sources are undrinkable.

5. White River (Arkansas)

Throughout Europe, Asia,

6. Powder River (Montana, Wyoming)

and Africa, rivers and lakes

7. Altamaha River (Georgia)

struggle to refresh themselves.

8. Allagash Wilderness Water-

Freshwater problems exist

way (Maine) 9. Canning River (Alaska) 10. Guadalupe River (Texas) 11. Apalachicola River (Florida)

on every continent on which people live. Major threats come from chemical pollution, overdevelopment along rivers and lakes, sewage, industrial pollution, and species that are not native to the area. In regions with large rain forests, timber cutting increases erosion and

84

[ T h e H u m a n To u c h ]

the amount of soil in water. Change in water flow due to man-made dams also takes a serious toll on freshwater fish, snails, and mussels. Fertilizers and pest killers can be used hundreds of miles away and still affect an ecosystem. Chemicals enter rivers and lakes through runoff or groundwater. Fertilizers encourage the explosive growth of water plants and algae. Pest killers reduce the insect populations that control plant growth.

 Pollution pours into a stream from a chemical factory.

Poison sprayed on Iowa corn could easily end up in the

fossil fuels to power

bodies of Louisiana pelicans.

cars and trucks, heat

Acid rain is another form

?

WORDS TO KNOW . . .

homes, and run

emissions (i-MISH-uhnz) things

of chemical pollution. It comes

factories. Burned

that are sent off or out, such

from burning fossil fuels, such

fuel produces emis-

as gases

as oil, gas, or coal. Humans use

sions that contain 85

[ T h e H u m a n To u c h ]

sulfur, nitrogen, and

and chlorine combine with

atmosphere (AT-muhss-fihr) the

chlorine. These are

elements in the air, they form

layer of gases that surrounds

basic chemical ele-

acid. The acids exist with

the earth

ments found in

water vapor in our atmo-

nature.

sphere. When rain falls, so

?

!

WORDS TO KNOW . . .

WOULD YOU BELIEVE?

Sweden has 4,000 lakes that

When amounts of sulfur, nitrogen,

does the acid. Historically, people built

have such high acid content that animals cannot live in them. The acid comes from acid rain. The Swedish government must add different chemicals to lake water to reduce acid levels.

 Busy river transportation makes maintaining clean water difficult. These barges leak oil, dump trash, and occasionally sink.

86

 DO IT! The U.S. Environmental Protection Agency has a series  Garbage piles up on the banks of Egypt’s Nile River.

of programs for “adopting”

cities along rivers and lakes.

these sources for

area watersheds. Volunteers

These locations provided easy

human use creates

work to ensure clean water

access to freshwater. Shipping

problems in which

resources within each state.

and receiving goods by water

freshwater ecosys-

Look up the program in your

was quicker and cheaper than

tems suffer. In addi-

state at http://yosemite.epa.gov/

by land. The problem is that a

tion, huge popula-

water/adopt.nsf/adopt+forms+

river or lake has only so much

tions create large

by+state?openview.

water. Draining water from

amounts of trash 87

[ T h e H u m a n To u c h ]

and sewage. Increased facilities that handle trash and sewage have not kept up with growing populations. In the past, rivers also offered a convenient dumping ground for industrial waste. In many cases, the poisonous nature of waste products remained unknown. People became concerned only when frogs appeared with extra eyes or legs. All that time, human beings had been drinking the same water the frogs were in. Alien species have become a worldwide problem. These are not fish from Mars or plants from Venus. They are non-native species—animals and plants that may take over their new homes after they arrive from other places. Alien  Zebra mussels—an alien species in the Great Lakes—are unwanted invaders.

88

[ T h e H u m a n To u c h ]

water hyacinth has invaded

GANGES RIVER IN THE NEWS

Australia, Asia, Pacific Islands,

The Ganges River is holy water to

and the United States. Zebra

India’s many Hindus. It is the main

mussels, Asian clams, and sea

water source for 400 million people.

lampreys hitched rides to the

It is also one of the most polluted

Great Lakes on ships.

rivers on earth.

Once an alien species

Today, 27 major towns pour raw

takes hold, it is hard to

sewage into the Ganges. Factories

contain. Bringing in preda-

dump toxic waste into the water.

tors to attack the invaders

However, some of this pollution results

just creates new problems.

from Indian death rites. Bodies are

What happens when the

cremated, and the remaining ashes are

newly arrived predator gets

placed in the Ganges. Unfortunately,

out of control?

wood costs a lot of money in India.

Fifty years ago, England’s

To save on wood, bodies are only

Thames River was little more

partly cremated. The half-cremated

than an open sewer. Pollution

bodies float among sewage and

had killed most fish and water

industrial poisons.

animals in the Thames. The British government began a clean-up effort to restore the river. They built sewage treatment facilities. Laws stopped 89

[ T h e H u m a n To u c h ]

factories from dumping waste

in the world. Strictly enforced

into the river.

laws keep the Thames flowing

Today, fish swim happily in the Thames. The river is one of the cleanest city rivers

clean and clear. It would seem logical for humans, who need water to

 A family helps keep riverbanks clean by picking up trash.

live, to take care of the world’s

clean rivers and lakes, protect

water supply. Unfortunately,

freshwater species, and reduce

modern society is wasteful.

pollution. Without these

Most people never think that

efforts, the last drop of fresh

fresh, clean water will run out.

water from your faucet may

Serious efforts are needed to

drip sooner than you think.

 England’s now-beautiful Thames River was once as polluted as a sewer.

91

Chart of Species

[Rivers, Streams, Lakes, and Ponds]

KEYSTONE SPECIES

FLAGSHIP SPECIES

UMBRELLA SPECIES

INDICATOR SPECIES

AFRICA

phytoplankton, zooplankton, Nile crocodiles, hippopotamuses,

Nile crocodiles, hippopotamuses, crowned cranes, tilapia

cranes, osprey, hippopotamuses

dragonflies, beetles, mussels, oysters, water spiders

ASIA

phytoplankton, zooplankton

Ganges River dolphins, gharials, fishing cats, Indus River dolphins, river terrapins

cranes, osprey

damselflies, dragonflies, beetles, water spiders

AUSTRALIA

phytoplankton, zooplankton, Murray cod, trout cod, catfish

platypuses, dugongs

dugongs, osprey, platypuses

dragonflies, beetles, mussels, catfish, water spiders

EUROPE

phytoplankton, zooplankton, beavers

salmon, beavers, otters, water voles, kingfishers

great crested grebes, cranes, osprey

dragonflies, damselflies, mussels, beetles

NORTH AMERICA

beavers, salmon, copepods, phytoplankton,

salmon, beavers, whooping cranes, bald eagles, manatees, Eastern spiny softshell turtles

manatees, bald eagles, piping plovers, cranes, osprey

dragonflies, damselflies, mussels, catfish

SOUTH AMERICA

phytoplankton, zooplankton, caimans, giant river otters

giant river otters, dugongs, Amazon River dolphins

dugongs, osprey, giant river otters

mussels, beetles, water spiders, dragonflies

CONTINENT

 The above chart gives a starting point for identifying key species. Each river, stream, lake, and pond environment has its own key species. The above chart lists some of those species.

92

[Bold-faced entries are the ones discussed in the text.]