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The ecology of Coral Reefs
is very unique from other ecosystems. The lagoon
and the reef act very much like a field and a forest edge with different
animal in each one. The food web of the coral reef is very complex and
is still being discovered. Until recently it was thought that the classic
pyramid shape food web was inverted in coral reefs do to the lack of
producers (plants). This was clarified by the
discovery of zooxanthellae
in the live coral itself as well as in the dead coral skeleton. These
algae also grows in the sand and in the shingles of the reef edge. While
the zooxanthellae provide most of the nutrition necessary for the coral
polyps to live, coral polyps also feed at night on zooplankton.
Coral reefs are very dependent on this constant flow of nutrients from
the circulation of zooplankton
from the "open ocean". It is this flow of nutrients in the
form of plankton
that is the blood stream or coral reefs. The constant flow of zooplankton
into the coral reefs keeps the corals alive and growing, which keeps
the fish alive, which keeps the predators alive. The rest of the ocean
is also dependent of the reefs. The dead coral erodes in to calcium
carbonate which in turn helps to keep the pH
of the water salty, which keeps the marine animals alive. Now we begin
to explore the vast interdependence between coral reefs and the surrounding
environments. A common myth is that coral reefs are very stable environment,
the truth is that coral reefs (much like the other ecosystems in the
Everglades)
are very fragile. The sand around a coral reef
beaches and coral islands is very unstable and needs to be renewed and
replaced constantly. The source of this sand is the broken or chewed
skeletons from reef organism that have calcareous skeletons like coral,
crabs and coralline algae. The entire coral reef ecosystem
can collapses if the zooxanthellae leave there symbiotic
coral polyps. When this happens the coral turns white, often referred
to as coral
bleaching, because the zooxanthellae give the coral its viverante
colors. As mentioned before the symbiotic zooxanthellae provide up to
85% of the nutrients for some coral species, so when the zooxanthellae
leave the coral polyps die. When the coral polyps die the fish lose
there protective homes and there source of food. This goes on down the
food chain effecting every organism in the coral reef. The coral reef ecosystem in the Florida Keys is also dependent in the health of the Everglades. Many of the fish and crustaceans use the protective branches of mangrove forests to spawn there young. Most of these fish grow up and return to the coral reef to feed on coral and algae. These fish are preyed upon by larger fish, which are preyed upon by the top predators like sharks and eels. |