Coastal Biomes:
Where the Land
Meets the Sea
1 videocassette............................................... 27 minutes
Copyright MMI
Rainbow Educational Media
4540 Preslyn Drive
Raleigh, NC 27616-3177
Distributed by:
United Learning
1560 Sherman Ave., Suite 100
Evanston, IL. 60201
800-323-9084
www.unitedlearning.com
www.unitedstreaming.com
CREDITS
Author and Producer:
Principal Videography:
Narrators:
Curriculum Consultant:
Peter Cochran
Paul Norton
Richard Cassell
Randye Kaye
Michael Worosz
Produced for Rainbow Educational Media by
Cochran Communications
Purchase of this program gives the user the right to reproduce or duplicate, in whole or in part, this teacher's guide
and the blackline master handouts that accompany it for the
purpose of teaching in conjunction with this video. This
right is restricted for use only with this video program. Any
reproduction or duplication in whole or in part of this guide
and the blackline master handouts for any purpose other
than for use with this video is prohibited.
TABLE OF CONTENTS
Introduction ...................................................................4
Viewing the Video......................................................... 4
Program Summary......................................................... 5
Objectives...................................................................... 8
Review Questions.......................................................... 9
Activities...................................................................... 11
Glossary....................................................................... 13
Bibliography................................................................ 16
Related Videos from Rainbow .................................... 17
Appendix: Organizations to Contact........................... 18
Script............................................................................ 19
INTRODUCTION
Coastal Biomes: Where The Land Meets The Sea provides
student viewers an overview of seashore biomes. It describes different kinds of seashores, how they are formed,
what kinds of life inhabit them, and how different living
things have adapted to the specific conditions found in
them.
The video examines how these essential biomes are threatened by development, pollution, and global warming. It
also describes steps people are taking to protect and conserve these important ecosystems.
Grade Level: The video is appropriate for use with students in grades 4 through 8.
VIEWING THE VIDEO
The video is divided into three segments, each with its own
subtitle. One segment examines the physical characteristics
of seashores. Another focuses on plant and animal life and
how they adapt to different conditions. A final section looks
at the human impact on coastal ecosystems.
While the program can easily be viewed in one sitting,
some teachers may find it more convenient or useful to
show the segments on different days.
PROGRAM SUMMARY
This program begins by defining a coastal biome as a place
where the land meets the sea. It shows that there are a
variety of coastal biomes, including sandy beaches, rocky
shores, salt marshes, and mangrove swamps. It describes a
biome as a place that has certain types of plants and
animals. Unlike biomes such as deserts and rain forests,
however, coastal biomes don't have a characteristic climate.
Segment One: Physical Features of the Seashore
This segment explores in more detail physical features of
coasts, stressing that they constantly undergo change. Focusing first on sandy beaches, the program describes the
effects of the erosion and depositing of sand. It explains
how the sand on the beaches of Cape Cod, Massachusetts,
resulted from glacial deposits thousands of years ago; how
the black sand in Hawaii results from volcanic activity; and
how the sand in the Caribbean is composed largely of tiny
bits of coral excreted by parrot fish.
The program shows how currents and winds move and
deposit sand, changing the way sandy coasts appear. It also
describes how global warming may be causing sea levels to
rise with the result that low lying coastal areas may flood.
Segment Two: Life of the Shore
In the next segment, the video briefly describes mangrove
swamps, a shore environment that exists in the tropics. It
shows mangrove trees, the birds that live in their canopies,
and the fish that live among their roots.
The program then examines the kinds of life found in
different zones of a sandy beach. The swash zone exists
near the pounding surf. There are no rooted plants here
because such plants cannot withstand the battering of
waves. Among the few animals in this zone are coquinas,
which burrow into the sand.
Dunes form a zone farther back from the surf. Dennis
Murley, a naturalist with the Massachusetts Audubon Society, describes how grasses stabilize the dunes and how
certain plants have adaptations that help them survive
harsh, dry conditions. The program describes how maritime forests form behind dunes. The trees in such a forest
are often gnarled and stunted because of their exposure to
winds and salt spray.
Next, the program describes the zones of a rocky coast,
focusing on how the boundaries and characteristics of these
zones are determined by the tides. The splash zone lies
above the high tide mark, where the rocks are moist from
the sea spray at high tide and then dry out as the tide
recedes. A dark band formed by blue green algae often is
found in this zone. The intertidal zone ranges from where
the ocean water reaches at high tide to where it meets the
shoreline at low tide. This section of the video includes a
description of life in tide pools.
Salt marshes are another kind of shore environment. The
program describes how different kinds of spartina have
adapted to conditions in these marshes. Amy Kiebala, an
educator with the Massachusetts Audubon Society, explains that salt marshes are rich in nutrients and that when
the plants in a salt marsh die, they decompose and form
detritus that other living things feed on. The video shows
examples of animal life in a salt marsh, including fiddler
crabs and a great blue heron.
Segment Three: Effects of Humans
The next segment of the program examines the impact of
humans on coastal ecosystems. It briefly looks at the
importance of seashores to fishing and tourism. It notes that a
large part of the population of the United States now lives
within 100 miles of the ocean and that coastal areas are
threatened by housing and commercial development.
In addition to discussing issues of pollution and habitat
destruction, the program focuses on the controversy over
attempts by developers and home owners to prevent coastal
erosion. Graham Giese of the Woods Hole Oceanographic
Institution describes how seawalls interfere with the natural
erosion that occurs along sandy beaches and eventually lead
to narrower beaches and other problems .
Finally, the program documents ways in which people are
helping to protect coasts by eliminating or reducing pollution and by establishing parks and protected areas.
A brief summary concludes the video.
OBJECTIVES
After viewing the program students will be able to:
1. define the characteristics of different types of seashores.
2. describe the physical features of seashores and how they
change.
3. give examples of animal and plant life in coastal biomes
and how different plants and animals adapt to seashore
conditions.
4. describe photosynthesis and decomposition and how
energy flows through seashore communities.
5. describe the human impact on coastal biomes.
REVIEW QUESTIONS
1. What are the major types of coastal biomes?
The types described in the video are sandy beaches,
rocky shores, mangrove swamps, and salt marshes.
Some students may also cite coral reefs.
2. Where does the sand on sandy beaches come from?
The sand on the beaches described in the program
were created by glaciers, volcanoes, and by fish that
excrete pieces of coral.
3. How does erosion affect a sandy beach from season to
season?
During the winter, a beach may shrink as strong waves
erode it and carry the sand offshore. During the
summer, the same beach may widen as gentler waves
redeposit this sand.
4. What is global warming?
Global warming is what many scientists believe is a
gradual increasing of the temperature of the earth's
atmosphere.
5.
How might global warming affect coastlines worldwide?
If global warming is occurring, sea levels will rise as
ice melts. As a result, low lying coastal areas may
flood.
6. What are some of the different zones of a sandy beach?
The program describes the swash zone, dunes, and the
maritime forest.
7. Why don't rooted plants grow in the swash zone? They
cannot withstand the battering of waves.
8. How do beach grasses stabilize dunes?
Their roots hold the sand in place.
9. Why do conditions vary in different zones of a rocky
shore?
The tides affect how different zones are affected by
exposure to water and dry air.
10. What is detritus in a salt marsh?
Detritus is mainly made of decomposed plant matter.
11. How have salt marshes been destroyed or threatened
by human activity?
Salt marshes have been filled in for housing and
industry or dredged to make harbors and marinas.
12. How can seawalls on a sandy beach cause long term
problems?
Seawalls prevent the natural erosion and movementof
sand and may cause beaches to thin because they don't
get enough sand.
10
ACTIVITIES
1. Students can compare coastal ecosystems to another
biome, such as a rain forest, grassland, or desert. Have
them compare coastal plants and animals to those of the
biome they have chosen. Ask them how the conditions
of each biome affect the kinds of life that live there.
2. Students can research and report on a coastal animal or
plant and describe how it has adapted to its environment.
They can report in more detail on a plant or animal
depicted in the video, or choose a different one.
3. Students can draw a seashore food chain showing how
energy flows from the sun to plants and from plants to
animals. After students have illustrated different chains,
have them combine their information to construct a
more complex food web.
4. Students can research and report on different threats to
seashores and what can be done to alleviate these threats.
Possible topics include habitat destruction, global warming,
and pollution. Students can write to organizations listed
in the appendix for more information.
5. There are many ways students can help reduce threats to
coastal biomes.
• Students can participate in beach cleanups. Contact
the Center for Marine Conservation for more information. Their address is listed in the appendix.
• Students can reduce the amounts of toxic chemicals
that reach ocean waters by helping their families
dispose of old paint, motor oils, pesticides and other
chemicals properly rather than pouring them down
11
drains or into storm sewers. Students should contact
their local sanitation departments for more information
about how to dispose of these chemicals.
• Students can help reduce the threat of global warming
by cutting down on their consumption of energy.
Turning off lights, taking public transportation or
walking instead of driving, and turning down the heat
are examples of measures that save energy and reduce
the amount of fossil fuels that power plants have to
burn to generate electricity.
• Students can write letters to local, state and national
government officials urging them to take steps and
enact legislation to protect coastal ecosystems.
6. Students can search the internet for information about
coastal biomes and efforts to protect them. Listed below
are web sites for parks and sanctuaries in the program.
Wellfleet Bay Sanctuary (Salt Marshes)
www.wellfleetbay.org
Cape Cod National Seashore (Sandy Beaches)
www.nps.gov/caco
Halibut Point State Park (Rocky Shores)
www.state.ma.us/dem/parks/halb
Many other sites focus on coastal ecosystems. Below
are two that have links to others.
National Audubon Society
www.audubon.org
Center for Coastal Studies
www.coastalstudies.org
12
GLOSSARY
barnacle: crustacean often found in the intertidal zone of a
rocky shore
biome: region of the earth that has characteristic kinds of
life, particularly plants
blue green algae: very primitive microscopic plants
coast: seashore, land next to the sea
coquina: type of clam
cord grass: type of spartina found in salt marshes
dark band: band caused by the growth of blue green algae
on a rocky shore
detritus: decomposed plant and animal material
dune: sand hill or ridge
erosion: wearing away and moving of rock, sand, and soil,
particularly by the action of water, wind, and glaciers
global warming: theory that the accumulation in the
atmosphere of gases produced by the burning of fossil fuels
traps heat from the sun and raises atmospheric temperatures
intertidal zone: zone on a rocky shore that ranges from
where the ocean water reaches at high tide to where it meets
the shoreline at low tide
Irish moss: type of seaweed found on rocky shores
13
mangrove swamp: coastal wetland consisting of mangrove trees whose roots lie partly in the water and provide a
refuge and nursery for marine life
maritime forest: zone of a sandy beach where shrubs and
trees grow
nutrients: materials needed for energy and growth
parrot fish: fish that eats coral and then excretes the coral
waste as sand
periwinkle: mollusk commonly found in the intertidal
zone of a rocky shore
photosynthesis: process by which light energy is used by
plants to make food
prop roots: roots that support mangrove trees in ocean
water
rockweed: type of seaweed found on rocky shores
rocky shore: type of coastline characterized by rocks
rather than sand
runner: stem that runs along the surface of the ground and
sends out roots
salt marsh: marshy tract that is wet with salt water or
flooded by the sea
sandy beach: type of seashore characterized by sand sea
hay: type of spartina found in salt marshes
14
seastar: echinoderm having a radial body, often in the
shape of a star. Also called a starfish.
seawall: wall or embankment designed to prevent the
encroachment of the sea
sickle leaf aster: plant adapted to dry conditions found in
dunes
spartina: grass that grows in salt marshes
splash zone: zone of sandy beach that is swept by waves
tide pool: pool of water that forms in a depression on a
rocky shore when the tide goes out
15
BIBLIOGRAPHY
Alevizon, William S. Coral Reef Ecology. Pisces Books,
1994.
Amos William H. and Amos Stephen H. Atlantic and Gulf
Coasts. (National Audubon Society Nature Guides). New
York: Alfred A. Knopf, 1985.
Daiber, Franklin C. Animals of the Tidal Marsh. New York:
Van Nostrand Reinhold Co., 1982.
Fox, William T. At the Sea's Edge. Englewood Cliffs:
Prentice-Hall, Inc., 1983.
Stephenson, T.A. and Anne. Life Between Tidemarks on
Rocky Shores. San Francisco: W.H. Freeman and Company, 1972.
Teal, John and Mildred. Life and Death of the Salt Marsh.
Ballantine Books, 1971.
16
RELATED VIDEOS FROM RAINBOW
Animal Profile Series:
Amphibians: Amazing Animals Beyond
the Bars: Zoos and Zoo Animals Cool
Creatures: Reptiles
Biomes/Environmental Series:
Coral Reef Biomes: Essential and Endangered
Desert Biomes: Essential and Endangered
Grassland Biomes: Essential and Endangered
Oceans: Our Last Frontier Our Changing Earth
Reduce, Reuse, Recycle: Environmental Concerns
River Biomes: Essential and Endangered Source of
Life: Water and the Environment Struggling to
Survive: Tropical Rain Forests Temperate
Deciduous Forests Threats to Biodiversity: Why We
Should Care Treasures of the Deep: Our Ocean
Resources Wetland Biomes: Essential and
Endangered
17
APPENDIX: ORGANIZATIONS TO CONTACT
American Oceans Campaign 725
Arizona Avenue, Suite 102 Santa
Monica, CA 90401
Coral Reef Alliance
64 Shattuck Square, Suite 220
Berkeley, CA 94704
Center for Marine Conservation
1725 DeSales Street, NW
Washington, DC 20036
Friends of the Earth 218
D Street, SE
Washington, DC 20003
(202)543-4312
National Wildlife Federation 1412
Sixteenth Street, NW Washington,
DC 20036
National Resources Defense Council
40 W. 20th St.
New York, NY 10011
The Nature Conservancy
1800 North Kent Street
Arlington, VA 22209
Reef Relief
P.O. Box 430
Key West, FL 33041
Sierra Club
30 Polk Street
San Francisco, CA 94109
18
SCRIPT
Title: Coastal Biomes: Where the Land Meets the Sea
Female Narrator:
Land and sea are the earth's two most visible features.
Oceans cover 70 percent of the planet's surface, while the
rest is covered mostly by continents and islands.
The boundaries between oceans and land are marked by the
earth's seashores, places that are neither all water nor all
land but in between.
Seashores are among the earth's most dynamic environments. Here, the borders between land and water are
constantly shifting as winds and waves sculpt the coastline
in ever changing shapes and as tides rise and fall.
Male Narrator:
There are different kinds of seashores. In some places there
are sandy beaches. In others, the shores are rocky. Salt
marshes are coastal environments that are particularly
abundant in plant and animal life. In the tropics, mangrove
swamps line many of the coasts.
All these places are examples of coastal biomes. A biome is
a place where certain types of plants and animals live.
Female Narrator:
There are many kinds of biomes, each with distinct kinds of
life. The plant and animal life in a tropical rain forest biome is
different from the kinds of life found in a desert.
Most biomes also have a characteristic climate. Deserts, for
example, have very little rainfall. Unlike most other biomes,
however, seashores don't have a characteristic climate.
19
They exist in different climates all over the world. Ice is a
dominant feature along the frigid coast of Glacier Bay in
Alaska. Sand and warm sunshine are typical of coasts in the
tropics.
While seashores vary, they have in common the fact that
they are all places where land and ocean meet. Among other
things, this affects how they look and how they change over
time.
Subtitle: Physical Features of the Seashore
Male Narrator:
Seashores constantly change. Every day, their appearances
change with the tides. Twice a day—as the tide comes in—
the grasses in this salt marsh are covered by ocean water.
Twice a day—as the tide goes out—you can see the mud
flats out of which the grasses grow.
Female Narrator:
The appearance of a shoreline may also reflect changes that
took place thousands of years ago. The National Seashore
along Cape Cod in Massachusetts is one example. Sandy
cliffs provide a dramatic backdrop to the surf below.
The sand that makes up the cliffs and beaches of Cape Cod
hasn't always been here. Thousands of years ago, during
the last ice age, glaciers like this one in Alaska advanced
over much of North America. As the glaciers advanced,
they pulverized bedrock and boulders, carrying the resulting
pebbles and sand with them as they advanced south.
When the climate warmed about 15,000 years ago, the
glaciers retreated, but left their cargo of sand behind. Much of
the sand we see today along the beaches of Cape Cod is the
pulverized remains of rock that was originally in
Canada.
20
Male Narrator:
On other beaches in other places, the origin of the sand is
different. Hawaii's black sand comes from volcanic rock.
Much of the sand on the white beaches in the Caribbean and
other tropical locations comes from coral. Along tropical
reefs, parrot fish bite off and grind up bits of coral to get at
the algae that live inside. They then excrete the resulting
sand. By some estimates, a single adult parrot fish can
produce as much as a ton of sand a year.
Female Narrator:
After sand has been deposited on a beach, erosion changes
the beach's appearance and contours. Erosion is the
moving of sand, dirt, or rock from one place to another.
Water is a powerful force in erosion. Waves eat away at the
sand, carrying it out to sea. Because of erosion, the sand that
forms the cliffs of the National Seashore in Cape Cod
retreats at an average rate of three feet a year.
The sand eroded from one place along the coast is usually
deposited somewhere else. In an area of Cape Cod called
the Provincelands, the dunes are made up of sand transported over thousands of years by ocean currents from the
eroded cliffs farther south. Waves deposited the sand
ashore, and winds carried it inland.
Male Narrator:
The erosion and depositing of sand is a constant ongoing
process. A beach can shrink or grow from one season to
another. During the winter, a beach may shrink as strong
waves erode it and carry the sand offshore, while during the
summer the same beach may widen as gentler waves
redeposit this same sand.
21
Other changes in the world's coastlines may be occurring
more slowly, but with much greater consequences. Many
scientists think we are experiencing global warming, a
gradual increase in the world's temperature. As the climate
warms, glaciers and polar ice melt, adding water to the
oceans and causing sea levels to rise.
Today, there is evidence that sea levels are rising along the
Gulf and Atlantic coasts at a rate of about 1 foot, or 30
centimeters, every hundred years. If this is true and the
trend continues, it could result in low-lying coastal areas in
Florida, Louisiana, and Texas being under water.
Subtitle: Life Along the Shore
Female Narrator:
The kinds of life along a shore depend in part on what kind of
shore it is.
Along Florida's southwest coast, mangrove swamps are
rich in many kinds of life. Mangrove trees grow where few
other trees can—in salt water. They have stilt-like roots,
called prop roots, that support the trees against rising and
falling ocean tides and waves. Mangrove trees provide a
home to birds, such as ibises and egrets, that nest in their
canopy. Below the surface, the roots provide shelter to
other kinds of life, including many species of fish.
Male Narrator:
A sandy beach is very different from a mangrove swamp.
The seashore here is divided into zones, and each zone has
different kinds of life.
The swash zone is the zone near the pounding surf. There
are no rooted plants here, because such plants cannot
survive the battering of waves. Coquinas, a kind of clam,
22
are among the few animals that can withstand this constant
battering. Coquinas inhabit sandy beaches from New York to
Florida and Mexico. Coquinas live in shallow burrows.
When a wave dislodges them, they quickly bury themselves back into the sand.
Gulls hover overhead on a beach, swooping down to feed
on clams and fish. Shore birds such as this sandpiper are the
most visible living things in the swash zone.
Female Narrator:
Beyond the swash zone are dunes. Dunes are formed from
sand carried inland by wind.
Dunes are a difficult environment for plants to grow in. The
sandy soil is poor in nutrients. Salt spray and wind also
make conditions hard. But there are plants that have features that help them survive in these conditions. Beach
grasses, for example, have extensive root systems that help
them absorb moisture that seeps down through the sand.
This root system also plays an important role in forming
and holding together the dunes themselves.
Dennis Murley, a naturalist with the Massachusetts Audubon
Society, describes how this works.
Dennis Murley:
This runner is sending out shoots every four to six inches.
The growing sands are trapped by these roots and by the
grasses themselves, and this is the glue that holds together
these dunes.
Female Narrator:
If grasses stabilize the moving sands in dunes, other plants
may take hold.
23
Dennis Murley:
If the primary dunes are doing their job, most motion of
sand stops and a certain stability applies to the valleys in
between dunes. The sand, then is not moving and many
other plants can move in here..bayberry...beach
plum...seaside goldenrod.
The moisture here is at a premium. Most rainfall goes right
through the sandy soil, and the plants here have desert-like
adaptations, particularly this one here called sickle leaf
aster. This has long linear leaves that have long hairs off
them and a waxy coating...anything that slows down the
evaporation off the leaf surface.
Male Narrator:
Dunes create a natural barrier against waves, wind and salt
spray. This barrier provides a shelter for less hardy plants to
grow. Shrubby plants such as poison ivy can take hold. The
leaves of these shrubs accumulate and decay and make the
soil richer.
Where there is enough rainfall, trees gradually take hold.
This zone beyond the dunes is called the maritime forest.
On Cape Cod the trees include pitch pine and red cedar.
Many of the trees of the maritime forest appear ragged and
stunted. This is because they are constantly pruned by
strong winds and salt spray.
Female Narrator:
Like sandy beaches rocky shores have different zones
characterized by different kinds of life. The boundaries and
characteristics of these zones are determined by the changing
tides.
The splash zone is located on the rocks that are splashed by
waves at high tide. Here conditions change dramatically
24
throughout the day. When the tide is high, the rocks in this
zone are often wet from the salty spray. When the tide is
low, these same rocks dry out.
A dark band marks the rocks just above the high tide line on
this beach in Rockport, Massachusetts. This band is made
up of microscopic blue green algae. These primitive plants
can tolerate being wet from the salty sea spray and can also
tolerate hot sun and cold winter winds.
Male Narrator:
Below the splash zone is the intertidal zone, which ranges
from where the ocean water reaches at high tide to where it
meets the shoreline at low tide.
Within this zone there are different environments that vary
subtly in how they are exposed to waves or to dry air, and in
how long they are submerged in sea water.
This means that different kinds of life often exist within
short distances of each other. For example, on the rocky
shores of New England, Irish moss is the dominant seaweed closest to the ocean's edge at low tide. This species
of seaweed is covered most of the time by water. It would
soon dry out and die if it were exposed too long to the air.
Just above Irish moss, however, rocks are covered by
another kind of seaweed, rockweed. Rockweed can better
tolerate being exposed to the air.
Among the animals found in the intertidal zone are periwinkles, small snails that feed on algae. Along with periwinkles, clusters of barnacles grow attached to rocks.
Barnacles are small, shrimp like animals. They have shells
that they keep closed when they are not covered by sea
water.
25
Female Narrator:
When the tide goes out, depressions in the rocky shore
capture and hold water, creating tide pools. Tide pools
provide places where different creatures can survive until
the tide rises again.
Often you can see seastars in a tide pool. Most seastars have
five arms but some species have up to 24. Seastars use their
flexible arms to hug rocks or to wrap themselves around
prey such as mussels.
Tide pools are among the most interesting places to study
life at the seashore. A tide pool is like a natural aquarium.
In a single tide pool, such as this one on Long Island, New
York, you can find many kinds of creatures, including
mussels, periwinkles and hermit crabs. These live in their
own ecosystem, a kind of island of water surrounded by an
ocean of rock.
Male Narrator:
A salt marsh is another kind of shore environment greatly
affected by tides.
The vegetation in a salt marsh has adapted to survive
conditions that exist in this transition zone between salt
water and dry land. Each day as the tide comes in, the plants in
a salt marsh may be covered by salty and often cold
water; while at low tide they are exposed to the dry air
which, depending on the season, may be hot as well.
The grass in a salt marsh is called spartina. There are two
kinds of spartina.
Cord grass grows at lower elevations and along tidal
creeks. It can tolerate having its roots immersed in salt
water in the daily tides. Salt hay is less tolerant of being
26
flooded and grows in thick mats at slightly higher elevations.
Salt marshes contain huge amounts of plant matter. They
are also nurseries for fish and other marine life.
Salt marshes are excellent laboratories in which to study
many kinds of life.
This is Amy Kiebala, an educator with the Massachusetts
Audubon Society. She works at a salt marsh sanctuary on
Cape Cod.
Amy Kiebala:
The salt marsh is productive because it brings in nutrients
from both salt water and freshwater. The freshwater is
coming from rivers and streams. The salt water is coming in
from the oceans. We have the ocean currents as well as the
tides that come in here twice a day.
Female Narrator:
In a salt marsh you can clearly see the flow of energy that is
part of the cycle of life and death .
The ultimate source of almost all life's energy is the sun.
Plants use the energy of sunlight to produce their own food
and grow. This process is called photosynthesis.
When the plants in a salt marsh die, they break down, or
decompose, releasing their nutrients back into the environment where other living things can use them.
Amy Kiebala:
This muck that you see in a salt marsh is decomposed plant
matter called detritus. All the plants that you see in a salt
marsh are decomposed and made into detritus.
27
Female Narrator:
Microscopic bacteria play an important role in decomposing
dead plant and animals, but other creatures also act as
decomposers by chewing and shredding dead plants and
animals into smaller pieces.
When the tide is low, fiddler crabs feed on decaying pieces of
grass. Male fiddler crabs have one large claw. The only
uses of this claw are to attract a mate and to fight other
males. When the tide comes in, fiddler crabs retreat into
burrows.
Fiddler crabs, mussels, fish and other small animals are
themselves food for larger creatures. Salt marshes are
havens for many kinds of birds such as this great blue
heron.
Male Narrator:
Salt marshes are important to many kinds of life, but in
many places salt marshes have been filled in for housing
and industry, or dredged for marinas and harbors. Along
the coasts of the United States, over 50 per cent of these
beautiful ecosystems have been lost in the last 250 years.
All kinds of coastal ecosystems are affected, and often
threatened, by human activity. We humans are another
species that are part of the many different environments of
seashores.
Subtitle: The Impact of Humans
Female Narrator:
People are drawn to the sea for many reasons.
Fish are an important source of food, and along coasts
throughout the world fishing is a major industry.
28
Tourism and recreation are other important industries.
Millions take advantage of the world's beaches and shorelines. Here, they can swim, surf, boat; or just relax an enjoy
the natural beauty around them.
Coastlines are where most major cities are situated, along
with their surrounding suburbs. Many of these cities are
important ports and shipping centers. More than a quarter of
the people in the United States live within 100 miles of the
ocean, and this pattern is repeated in many other
countries.
Male Narrator:
This concentration of people threatens seashores in several
ways. This beach on the Pacific coast of Costa Rica in
Central America provides a vivid example. Plastic bottles
and other trash cover the sand. Most of this trash along with
other human refuse reaches the beach via a river that acts as
an open sewer for communities farther inland. Ocean
currents and tides carries this refuse up and down the coast.
Female Narrator:
There are other threats along the world's coastlines. As
housing and commercial developments are built along
coastlines, birds and other wildlife lose important habitats.
Sea turtles are one example. Along the Georgia coast,
female sea turtles come ashore once a year to lay eggs; but
many of their nesting areas have been destroyed or damaged by human activity.
Human activity can also damage the grasses that hold sand
in place in dunes. These grasses are easily killed when
people walk on them. When the grasses die, their roots no
longer hold the sand in place and the dunes erode.
29
Male Narrator:
In other places, human activity affects the natural erosion
that is a fundamental part of the changes that occur along
coastlines.
We've seen how seashores, particularly sandy beaches,
constantly change. Sand eroded from one beach is deposited
elsewhere, building up another beach.
In some places, home owners and communities try to stop
this natural erosion by building seawalls to prevent the
movement of sand by waves and current; but such efforts
in the long run often create larger problems.
Graham Giese, an ocean geologist with the Woods Hole
Oceanographic Institution on Cape Cod, explains why.
Graham Giese:
The thing we have to remember is that the beach itself is
made of sand that comes from erosion.. .that is to say that all
of the beach that we see in front of us , all of the sand that
makes up that beach, comes from material that is e.roded
from the bluff. We have no other source of beach sand here
on Cape Cod. So if we prevent the erosion of that bluff by
seawalls, then we lose the source of our sand and our
beaches become thinner.
Male Narrator:
This beach supports Graham Giese's argument. The part of
beach where the sandy bluffs are protected by a seawall
have little sand and are completely covered by water at high
tide.
Only a short distance away, however, there is much more
sand at high tide because there are no seawalls to prevent
the natural erosion of sand from the bluff above.
30
Graham Giese:
We love the shore, we love the beach, we love the sea. And
we tend to build our houses as close to it as we can get
because we want to be close to it. What is hard for us to
understand is that by living so very close to the sea we
interrupt the processes which make the beaches we love so
much.
Female Narrator:
Fortunately, people have begun to wake up to the what we
stand to lose if we continue to damage our seashores .
Federal and state governments and local communities have
worked to preserve our seashores. Among other things,
environmental laws have been passed to clean up coastal
waters and to cut down on pollution.
Some communities are placing restrictions on building
near coastlines, and others are trying to conserve the salt
marshes that support many kinds of wildlife.
Male Narrator:
People also are trying to learn more about the ecology of
seashores near which they live. In New York City, for
example, the waterfront is a complex urban ecosystem.
These students are part of a program that measures and
records data about the water quality. Periodically they
gather samples of the water, and then measure its temperature
and salinity, or salt concentration. By keeping careful
records, they can observe seasonal changes in the water
quality as well as changes that occur over a number of
years.
31
Female Narrator:
Seashores exist for all people to enjoy with proper respect
and care. Some value seashores for swimming, boating and
other activities.
Male Narrator:
For others, seashores offer unique opportunities for studying
plants and wildlife; and many value the seashore simply for
the feeling of peace that comes from walking along an
empty beach and watching and listening to the rhythm of
waves.
END
32