R.B. Sewell, the last British Director of the Zoological Survey of India has made considerable contributions (1922, 1932, 1935, 1936) on general pattern of Coral reefs in the Indian seas. Hydrographic surveys conducted by Sewell (1935-38) in the Bay of Bengal provide useful information regarding contours, depth and general oceanographic and meteorological conditions. However, it gives little information on reef characteristics and their growth.
Reddiah conducted a survey from September to November, 1972 in Andaman and Nicobar Islands, more particularly in South Andamans and Cincque Is., Ric.iiels Archepelago, Car Nicobar, Camorta and Nancowry islands and published his findings in 1977 with particular reference to reef structure.
In Andaman islands platform formation by coral reefs of about 500 metres in width are built by the corals belonging to the genera Ponies, Favia, Pocillopora and Acropora on the reef edge. The alcyonarians (soft corals) like Sarcophytum, Lobophytum, Sclerophytum and the gorgonids, and Chalcogorgia soil occur in shallow shores and reef edges. In the Nancowry Is. platforms upto 1,000 metres in width from the shore have been reported by -Reddiah (1977). These platforrrisconsist of Porites, Favia, Acropora, Pocillopora, Heliopora, Tubipora and Montipora which are the most common among the reef builders of Nicobar islands.
Reddiah (1977) has also given an account of geomorphological aspects of Coral reefs and distinguished the following categories of Coral reefs in Andaman and Nicobar Islands.
i) Emergent reefs of recent and subrecent origin.
ii) Modem reefs consisting of wind ward reefs, channel reefs, bay reefs, knoll reefs and patch reefs.
Reddiah et al (1974) described the presence of two coral knolls in the Bay of Bengal. In this particular study he has indicated the coral patches emerging from the shore reefs at Keelakarai in the Gulf of Mannar Biosphere Reserve area which according to him is the only shore reef present in the Indian coast. He has described about a knoll such as Klingan paar in Gulf of Mannar and predicts that it would ultimately develop into sand cays by deposition during the cyclone.
Recent investigations by the Marine Biological Station (MBS) of the Zooloclical Survey of India, Chennai in the Great Nicobar islands, during 1992 revealed the presence of 12 species of corals on the eastern side of the island along the intertidal region. Presently, MBS, ZSI, is carrying out extensive survey in the Gulf of Mannar Biosphere Reserve Area and studying corals and their formation around all the 21 islands.
The Zoological Survey of India has now given emphasis on studying coral associated fauna. ZSI Scientists have surveyed and studied the faunal diversity of the Marine National Park of Gulf of '<atchch (Gujarat) and an article dealing with 402 spp. (42 spp. of sponges, 48 sDp. of corals, 205 spp. of molluscs, 29 spp. of echinoderms and 78 spp. of fishes) is almost finalised.
Since the inception of the Andaman & Nicobar Regional Station at Port Blair in 1977 several intensive and extensive surveys have been conducted to explore and assess the faunal diversity of the islands. 45 islands of Andamans and 8 islands of Nicobars have been surveyed and fauna of some of the reef areas like North Reef and South Reef sanctuaries, Nortn Aiddle and South Buttom National Parks, iviahatma Gandhi Marine National Parks (all in the Andamans) are being documented. This Regional Station has also taken up a project on "Study of fauna associated with Coral reefs of Andaman and Nicobar islands". In this connection several islands have been surveyed and a large number marine species belonging to sponges, anthozoans including corals, polychaetes, crustacea, molluscs, echinoderms and fishes have been identified. Studies on ornamental fishes and fishes associated with coral reefs have also been carried out. The Station has also undertaken projects on marine sponges, soft corals (Alcyonarians) and echinoderms and collected 35 spp. of marine sponges, 40 spp. of soft corals and 60 spp. of echinoderms.
The Zoological Survey of India is also engaged in carrying out Environment assessment stugdies in some reef areas. A recent study conducted by Marine Biological Station, ZSI, Chennai, in the Gulf of Kachch area indicates that coral reefs located closer to shores have been extensively damaged/destroyed due to industrial installation like chemical factories, fertiliser factories, salt pans and for laying the pipeline to pump crude oil from the Gulf of Kachch area by placing a Single Point Mooring near Coral reefs.
Bibliography of articles/books published by ZSI scientists on the subject
REDDIAH. 1977. The Coral Reefs of Andaman & Nicobar Islands. Rec. Zool. Surv. India. 72: 315-324.
REDDIAH et al. 1974. Two Indian Ocean Coral Knolls. Indian J. Mar. Sci. 3: 67-71.
SEWELL, P,.B.S. 1932. The Coral Coasts of India. Geographical J., 79: 444-462.
SEWELL,R.B.S. 1935. Geographic and Oceanographic Research in Indian Waters. Pt.8. Studies on Coral and Coral formation in Indian Waters. Mem. Asiatic. Soc. Bengal, 9: 461-540.
SEWELL, R.B.S. (1935-1938). Geographic and Oceanographic Research in Indian Waters. Mem. Asiatic. Soc. Bengal, 19: 1-539.
SEWELL, R.B.S. 1936. An account of Addu atoll (Maldives) Scient. Repts. John Murray Exped. 1933-34, 1: 63-93.
TIKADER, B.K. and DAS, A.K. 1985. Glimpses of Animal life of Andaman and Nicobar Islands, xi + 170 pp. Spl. Publ. Zool. Surv. India, Calcutta.
TIKADEP,, B.K., DANIEL, A. and SUBBA RAO, N.V. 1986. Sea Shore Animals of Andaman and Nicobar islands, xii + 188 pp. Spi. Publ, Zool. Surv. India, Calcutta.
List of field stations of ZSI dealing with the subject
1. Andaman & Nicobar Regional Station, Port Blair. 2. Marine biological Satiation, Chennai.