4.8.3. Classification and their location

♤ The coral reefs are classified depending on their locations into fringing, patch, barrier and atoll.

♤ The fringing reefs are contiguous with the shore and they are the most common - by occurring reef form, found in Andamans.

♤ Patch reefs are isolated and discontinuous patches, lying shoreward of offshore reef structures as seen in the Palk bay, Gulf of Mannar and Gulf of Katchchh.

♤ Barrier reefs are linear offshore reef structures that run parallel to coastlines and arise from submerged shelf platforms. The water body between the reef and the shore is termed as lagoon. Barrier reefs are seen in Nicobar and Lakshadweep.

♤ Atolls are circular or semi circular reefs that arise from subsiding sea floor platforms as coral reef building keeps ahead of subsidence. The examples are the atolls of Lakshadweep and Nicobar.

♤ When the reef building do not keep pace with subsidence, reefs become submerged banks as seen in Lakshadweep.

♤ Sea grasses grow on Kavaratti atoll, mangroves are prevalent on Andaman and Nicobar coral reefs.

♤ Among the four major reef areas of India, Andaman and Nicobar Islands are found to be very rich in species diversity followed by the Lakshadweep Islands, the Gulf of Mannar and finally the Gulf of Kachchh.