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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
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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.]