J. Mar. Biol. Ass. India, 50 (1) : 87 - 97, January - June 2008 Introduction The coral reefs reported from the coastal waters of the Indian mainland, Lakshadweep and Andaman & Nicobar Islands have always been a subject of scientific interest. They include the fringing reef ecosystems in the Gulf of Mannar, Palk Bay, Gulf of Kutch and the atolls of the Lakshadweep Islands and the continental island reefs of Andaman and Nicobar, all covering an estimated area of approximately 1,217 sq. km (Pillai,1996). Intensive scientific effort to study the coral reefs of India was started in the early 1960s by the Central Marine Fisheries Research Institute (Devaraj, 1997). Since then, good amount of information have been collected on the species diversity and composition of the coral fauna of India (George and Sukumaran, 2007; Nair and Qasim, 1978; Pillai, 1972, 1983, 1986, 1996; Pillai and Patel, 1988; Pillai and Jasmine, 1996; Qasim and Wafar, 1979; Reddiah, 1977; Scheer and Pillai, 1974; Wafar, 1986). The taxonomic and ecological studies on the coral reef fauna was initiated as early as 1847 by Rink in Nicobar Island (Venkataraman and Wafar, 2005). Contemporary studies on corals are those of Species assemblage in the coral reef ecosystem of Netrani Island off Karnataka along the southwest coast of India * 1 P. U. Zacharia, 2 P. K. Krishnakumar, 3 A. P. Dineshbabu, 3 K. Vijayakumaran, 4 Prathibha Rohit, 3 Sujitha Thomas, 3 Geetha Sasikumar, 4 P. Kaladharan, R. N. Durgekar and K. S. Mohamed Central Marine Fisheries Research Institute (CMFRI), P.B.No.1603, Cochin-682 018, Kerala, India. *E-mail: zachariapu@yahoo.com 1 Tuticorin Research Centre of CMFRI, South Beach Road, Tuticorin 628 001, Tamil Nadu, India. 2 Veraval Regional Centre of CMFRI, Matsyabhavan, Bhidia, Veraval 362 269, Gujarat, India. 3 Mangalore Research Centre of CMFRI, P.B. No. 244, Bolar, Mangalore 575 001, Karnataka, India. 4 Visakhapatnam Regional Centre of CMFRI, Oceanview Layout, Pandurangapuram, Visakhapatnam 530 003, Andhra Pradesh, India. Abstract Netrani is an uninhabited island located nearly 18 km off Murdeshwar (Karnataka State) in the southwest coast of India (14°02’ N lat; 74°33’ E long.). So far the coral reef ecosystem around this island has not been reported in scientific literature. Therefore, an underwater visual census of the coral reef was undertaken in May 2006 by SCUBA diving. The survey has revealed the existence of a patchy reef surrounding this island consisting of 14 coral species belonging to 11 genera. Other flora and fauna comprised of fishes (92), seaweeds (7), sponges (6), jellyfish (2), holothuria (1), nudibranchs (7), zooplankton (25), bivalves (15), phytoplankton (16), gastropods (48), cephalopods (3), crabs (17), shrimps (2), lobsters (4), etc. Twenty-six species of fishes recorded from this island reef area were found to be new records from the Indian coast. Two IUCN Red Listed fish species, the humphead wrasse (Cheilinus undulatus) and the whale shark (Rhincodon typus) were recorded from the island area. Another IUCN red listed mollusc, the giant clam (Tridacna maxima) was found inhabiting this reef and this is a first report on the occurrence of this species from the mainland Indian waters. The Indian Navy based at Karwar uses the Netrani Island as target for shooting/shelling practice and evidence of the same was observed during the survey. The wealth of biodiversity around this reef emphasizes the need to conserve and preserve it. Keywords: Netrani Island, species assemblage, Coral reef, Tridacna maxima, humphead wrasse