Coral reef cover in Indian waters is roughly estimated up to 19,000 sq.km. With about 200 coral species belonging to 71 genera. Andaman and Nicobar Islands being the richest harbours 179 species (Subba Rao, 1989).
They occur principally on Gulf of Kutch, Southern mainland coasts, and around a number of islands opposite to Sri Lanka, Andaman, Nicobar and Lakshadweep island groups (UNEP/IUCN, 1988) (Figure 3.10). Exploitation of corals, coral debris and coral sands is widespread on Gulf of Mannar and Gulf of Kutch.
Ornamental shells, chanks and pearl oysters are basis of reef industry in south India. Reefs have been distributed in six regions, viz., Gulf of Kachchh, Lakshadweep island, Gulf of Mannar, Palk Bay, Andaman and Nicrobar islands and recently identified table reefs in Malwan coast (Ratnagiri) of Maharashtra States.
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Reefs are distributed along west coasts at restricted sites. Coral reefs of Indian Ocean include sea level atolls, fringing and barrier reefs, elevated reefs and submerged reef platforms. Fringing reefs arc found in Gulf of Manner and Palk Bay.
Platform reefs are seen along Gulf of Kutch. Atoll reefs are recorded in Lakshadweep archipelago. Fringing and barrier reefs are found in Andaman and Nicobar Islands (Anon, 2000).
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A total of 155 hermatypic coral species belonging to 50 genera and 44 ahermatypic species belonging to 21 genera are known from four coral region of India. Coral of Gulf of Kutch includes 56 species under 24 genera.
Geographic isolation may be the reason for reduced distribution of corals in Gulf of Kutch (Patel, 1978). Most live coral reefs are part of marine protected Area (MPA). At present, corals growth in MPA is of patchy type, seen either on intertidal sand stone or on surface wave, cut and eroded shallow bank. Most reefs are narrow and live corals are found at edges of seaward slope of reef (Anon, 2000). Andaman and Nicobar Island harbour 135 species of scleractinian coral species belonging to 59 genera.
Andaman reefs are in better conditions than reefs in other regions of India. Damage and death of coral due to siltation and effluent discharge from shore areas of south and middle Andaman is reported. Wafer (1986) taking into accord the lagoon and submerged banks, estimated reef area to be 11,000 sq.km. for Andaman and 2.700 sq.km. For Nicobar.
Five National parks and 7 sanctuaries cover major part of coral reefs but substantial marine biodiversity area remains outside the MPA. Ninety four scleractinian coral species under 37 genera are recorded in Gulf of Mannar and Palk Bay (Gopinath Pillai, 1971). Palk Bay is not rich in corals with only 20 recorded species. In Gulf of Mannar, southern side of islands is covered with dense corals, which are more diverse than those on northern side.
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Life Gulf of Kachchh, coral in this area too are degrading fast due to anthropogenic activities. Lakshadweep Island consists of 37 islands, 12 atolls, 3 reefs and 5 submerged coral banks. Islands are small in size, ranging from O.l to 4.4 sq.km. In area, and are encircled by fringing reefs with information of lagoon on western side.
Total land area of Union Territory is 32 sq.km. and total extent of lagoon is about 420 sq.km (Chandra Mohan et al.1973). A total of 104 scleractinian corals belonging to 37 genera are reported from these islands. Increase in human populations and cargo, dramatic increase in density of houses, tourists and traffic cause tremendous biotic pressure on coral reefs.