The Structures of Coral Reefs

The structure of coral reefs are divided into 6 zones.

The first zone:

The first zone is reef flat.The first region slopes not much down from the shore-line. This sandy expanse is frequently covered with turtle grass and usually ends in a fringing reef made up of elkhorn or staghorn corals with small coral heads.

The second zone:

Moderately inclined sand plain covered in clusters of coral heads called patch or algae reef ridge. It flourishes where wave breaks the reef. Have a elevated bank being formed.

The third zone:

It is called the terrace. Being below the algal ridge, we find many stout brain corals and seafans which are able to withstand the wave surge and strong currents which characterize this area. Parrot fish & surgeon fish populate this area, feeding on alge.

The fourth zone:

Sub-terrace , which is the fourth zone, it have flattened terraces that interrupt the gradient of the reef slope. It is protects the wave surge overhead yet still exposed to abundant sunlight, that we find lush gardens of corals with expansive body forms designed to maximize their exposure to sunlight.

The fifth zone:

Named the reef wall, this is a descending slope. We find corals continue to expand horizontally in shape in order to capture as much sunlight as possible. Branching forms found in shallow water are largely replaced by plate like forms below a depth of 180 ft.

The last zone:

The drop off, this is found in most reef, it is where a reef suddenly drop off, almost forming a vertical wall. At depths below 180 feet, the overlying water reduces the amount of light so much that few sunlight-dependent hard corals can survive. In these dim, quiet waters the delicate corals not dependent upon photosynthesis become common.