1. How is each reef structure formed?

- Fringing reefs have a horizontal surface, with the coral maintaining a level close to the surface by means of animal growth; over the years, the reef will gradually advance seawards.
Barrier reefs form further from the coast. They are constantly pounded by the ocean waves and, as their name suggests, form a barrier that protects the coastline. These barriers have a frontal reef zone that takes the brunt of the ocean’s assault and where construction continues steadily, either thanks to madrepora* or calcareous algae. Atolls are formed entirely of calcium carbonate; the part above water level is made of sand and coral debris that has been washed up by the waves, and the dominant form of vegetation is generally palm trees. Atolls usually form a ring around a central lagoon; some lagoons are quite shallow while others are nearly 100 metres deep.The lagoons are connected to the outside ocean by channels or gaps in the reef that may be used by boats, and sometimes by shallow-water passes or simply by the fact that waves can swirl over submerged parts of the reef.
2. Where is each reef structure found?

- Fringing reefs are found in the Bismarck Archipelago in the southwest Pacific.

- Atolls always occur n the Indo-West Pacific Region, which is mean which always appear in the tropical Indian and western Pacific oceans.

- Barrier reefs always found in the Caribbean lies of the coast of Belize, Central America. They also found in Florida, New Caledonia, New Guinea，and Fiji in Pacific。

3. What is the trophic structure of a reef?

- That’s the tropical water where coral reefs are found are usually poor in nutrients and therefore have very little phytoplankton or primary production. zooxanthellae provide food and help make the calcium carbonate skeleton. In return the zooxanthelae get not only a protected place to live, but also a steady supply of carbon dioxide and nutrients such as nitrogen and phonsphorus. Also, nutrient recycling occur not only corals and their zooxanthellae, but all with sponges, sea squirts, giant clams, and other reef invertebrates have symbiotic algae or bacteria and recycle nutrients just as corals do.
4. How does the location and type of reef influence the trophic structure?

- Coral reef communities use nutrients very efficiently as a result of recycling. Coral reefs have among the highest rates of nitrogen fixation of any natural community. The main nitrogen fixers are cyanobacteria, especially a free living one called Calotbrix and another group that live symbiotically in sponges.
5. Give examples of the types of corals found on reefs.

-example:

1. Elkhorn coral is among the different forms of coral found on the reefs of Biscayne National Park.

2. Soft coral (Sarcophyton) fond on the coral reef.

3. Staghorn Coral

6. Give examples of competition, predation, and grazing
example:

Competition: Chevron butterflyfish ( Chaetodon trifascialis)

Predation: Sea Star ( Acanthaster Planci)

Grazing: Sea urchin (Diadema Antillarum)