Damming of rivers and water
diversion projects lead to changes in downstream estuarine and marine communities,
because interruption of freshwater flow changes the physical environment
of such areas and the amount of nutrients that they receive.
Dams can also cut off species access to spawning areas.
This includes not only species that live in saltwater and reproduce in rivers (
such as salmon) but also freshwater species that breed at sea (such as freshwater eels).
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Consequences
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Intense exploitation of marine
resources can indirectly lead to habitat loss. trawling disturbs
bottom-dwelling communities, both adjacent to shorelines and
in deeper coastal waters. The nets scour seabeds and smother
burrowing creatures and other species with sediments. Fishing
with dynamite and harvesting of corals are major threats to
coral reef areas.
Between 1988 to 1991, people removed about 8 percent of all
annual primary production (the total amount of living carbon)
within aquatic ecosystems.
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