Biodiversity and community structure of coral reefs around Krusadai Island, Gulf of Mannar, India

This paper gives the results of the surveys conducted in the Krusadai Reef for the assessment of the coral cover and biodiversity during March-May 2005, following the Line Intercept Transect Method. A total of 35 hard coral species were recorded in this reef. The total live, dead and bleached coral cover for the reef as a whole was estimated as 54.9, 18.7 and 15.4% respectively and the remaining part was covered with soft corals, sponges, seagrasses, sand and rubble. Dead coral cover was dominated by porites. Further, relative abundance values were derived for each species and they were assigned the status dominant/ abundant/ common/ uncommon/ rare. Although, no species was assigned “dominant” status, Acropora formosa belonged to the category “abundant” and all other species were either of “common” or “uncommon” status only. Fisher and Shannon diversity indices were highest (3.68 and 2.14 respectively ) in 8th site. Pielou’s evenness was highest in 7th site. SIMPER analysis revealed that Acropora formosa (33.95%) along with Acropora humilis (15.85%), Porites mannarensis (12.97%) and Montipora digitata (12.07%) were responsible for dissimilarity among various sites in the island. The average similarity in species composition was 20.5%