Coral Reefs

Fringing Reef

Barrier Reef

Atoll

1. How is each reef structure formed?
A fringing reef is formed when coral larvae settles on a hard surface and begins to grow. As the corals grow, they create their own hard bottoms, which creates a place for more coral to grow.
Barrier reefs are formed when sediment and coral rubble create a building foundation for the reef. Sea grass and seaweed beds, soft corals, and patches of cover coral are mixed in with the coral rubble to create a continuously growing bottom layer.
Atolls first start out as a fringing reef around a volcanic island. The reef gets wider and deeper as the island slowly sinks and eventually the reef flat becomes a lagoon and the fringing reef morphs into a barrier reef. When the island disappears completely the ring of growing reef left behind is the atoll.

2. Where is each reef structure found?
Fringing reefs are found on rocky shorelines close to land.
Barrier reefs, like fringing reefs, are found along the coast but farther out and separated by a lagoon.
Atolls are found on top of sunken volcanic islands which lie underneath a layer of calcium carbonate.

3. What is the trophic structure of a reef?
They are usually revolve around nutrient recycling. The zooanthellae take the coral nitrogen and phosphorus waste products and use the sun to create organic compounds which the corals need to survive. Without this process, corals would not be able to grow to their vast sizes since the water is usually poor in nutrients.

4. How does the location and type of reef influence the trophic structure?
Fringing reefs are close to shore so the water in which they live in gets run off and a mixture of nutrients and pollution from the land. Barrier reefs, however, are farther out so they have access to water from the lagoon and the deeper ocean. Additionally, the fish and other organisms that live in the reefs add and subtract from the nutrients in that community.

5. Give examples of the types of corals found on reefs.
Soft corals, hard corals, fast-growing corals, branching corals,and many more.

6. Give examples of competition, predation, and grazing.
Competition is an overgrowth or direct attack of one coral to another in their fight for growing space. A sea urchin is an example of predation since it eats and completely kills coral. Many types of fish eat coral polyps, but they don't eat enough to kill the whole organism. Grazing keeps coral populations in check.