Estuary
- Description
- Reviews
- Citation
- Cataloging
- Transcript
Using exquisite underwater micro-photography, this National Film Board of Canada production provides a close-up look at an estuary-- the biologically important wetlands where the fresh water of a river meets the salt water of the ocean. As we watch barnacles feeding themselves and the comic acrobatics of diving ducks, the film details the complex ecology of estuarine life; and, in an understated manner, makes a powerful case for protecting wetlands.
'The concept of the food chain is soundly illustrated in this film...Provides a concise, enjoyable, and informative look at life in an estuary. Recommended for instructional use in general biology and ecology courses.' Choice
'Within its small, beautifully circumscribed compass, this is a perfect example of a fully achieved work which ultimately links the complexity of one particular ecostructure (and fills us with respect for its perfection) to our present-day social webs.' Amos Vogel, Film Comment
'The ecological principles are the same worldwide and their treatment in this film is valuable for upper elementary through adult education on estuarine ecology.' National Wetlands Newsletter
Citation
Main credits
White, Don (screenwriter)
White, Don (film director)
Jones, Peter (film producer)
Other credits
Cinematography, Doug McKay; editing, Haida Paul; music, Peter Bjerring.
Distributor subjects
Biodiversity; Biology; Ecology; Life Science; Oceans and Coasts; Rivers; WildlifeKeywords
WEBVTT
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[sil.]
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An estuary is such an ordinary place.
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A bit of sand and mud. Some grass
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to mark where river meets the ocean.
It\'s difficult to imagine
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the value of such a place.
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On a mountainous coast
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like British Colombia\'s, estuary marshes are short, often
extending no more than a 100 meters along a river,
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crammed in between the steep
side hills and the sea.
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An estuary is the entire region
where the salt water of the ocean
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is diluted by the fresh water of a river. Twice
a day, the marshes are flooded by the tide.
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[sil.]
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When the tide drops,
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fresh water from the river fills the
channel and salinity decreases.
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Animals which can move out
with the tide, do so.
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Those which cannot move, can survive
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for only a limited time in fresh water.
For them,
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death can come as easily as
from a prolonged spring runoff.
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[sil.]
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For the few species which can survive
in and estuary, life is harsh.
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It\'s easily destroyed.
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[music]
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Eel grass meadows flourish
beneath the surface.
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The meadows provide a rich
habitat for estuary life.
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[music]
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Grasses are a base of a life in an estuary.
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The annual growth and decay
of eel and sedge grass
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is the fewer one,
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which the estuary runs. Most of the grass
is consumed only after it is dead.
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Any piece of dead grass is
quickly covered by bacteria.
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The combination of plant and
bacteria is called Detritus.
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It is the major food of estuary animal.
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[music]
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The isopod is one of the primary
consumers of estuary detritus.
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The amphipod
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resembles a small shrimp, but it\'s
actually the common sand flea.
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The amphipod lives out it\'s
life among the estuary grasses.
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[music]
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In the return, the organisms
which eat detritus become food
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for larger life forms in the
complex food-webs of an estuary.
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[music]
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Feeding goes on continuously.
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The feather duster worm uses its tentacles to catch the
particles of detritus, snowing down upon it from above.
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[music]
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Rich clam beds
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exist on the estuary bottom. The
Makoma clam gsrowing no larger
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than one centimeter across its shell uses
its siphon like a miniature vacuum cleaner.
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The clam sucks detritus directly
from the surface of the mud.
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[music]
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[sil.]
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At the outer reaches,
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barnacles feed on microscopic
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forms of plankton. The barnacles
cannot survive in the fresher waters
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of the inner estuary.
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[music]
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In the inner reaches,
fish prey on the animals
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which eat the grass.
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Fish depends on estuaries.
An estuary can be a home,
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a nursery, or simply a place they
pass on their journey to the sea.
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Young salmons spend varying amounts of
time in the inner reaches, growing strong
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by feeding on the amphipods.
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[music]
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Man is much a part of estuary
food chains as the plankton
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or the detritus feeders.
Without estuary marshes,
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we would lose three species
of the civic salmon.
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Without estuaries, there would
not be the thousands of birds
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along the pacific flyway.
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Migrating waterfall find food
and shelter in the marshlands.
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[sil.]
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Snow geese and dabbling ducks
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feed directly on the grasses.
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[sil.]
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Diving ducks eat the detritus feeders,
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the clams and crabs that live
along the estuary bottom.
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[music]
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For something which is so important,
man has been careless of estuaries.
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On the coast of British Colombia,
almost all flat land is estuarial,
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making competition for these areas intense.
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Mudflats and marshes are shallow and can be
easily filled, to make new land for industry
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and housing. The marshlands of the
Frazer River have been reduced by 75%,
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and plans are underway
to reduce them further.
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Man must learn not only to find
a place for himself but also
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to find a place for nature.
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[sil.]
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It is so easy to be careless of an estuary.
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An estuary is such an ordinary place.
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[music]
