Coral reef communities develop primarily in shallow, low-nutrient, tropical waters. Coral reefs are formed by coral polyps, which excrete the solid calcium carbonate skeleton that makes up the reef. A particular algae lives within the coral polyps and provides the polyps with nutrients from photosynthesis. Nutrients released by the algae and coral polyps are then filtered by sponges, forming the base of the coral reef community food chain which also includes fish, crustaceans, mollusks, and sea turtles.
Coral reefs can be damaged when an excess of nutrients, like nitrogen and phosphorus, enters the water through pollution. When this happens, the algae and the polyps die, and the coral skeleton eventually collapses.
After a coral reef collapses, which organisms are most likely to succeed the coral in this ecosystem?
A.
large reptiles that inhabit warm waters and act as top predators
B.
small fish that require protection from predators
C.
sea urchins that feed on decaying plant matter and sponges
D.
seaweeds that use sunlight for photosynthesis