Gulf of Mannar is one of the unique coastal regions for rich biodiversity in India. There is a vast area between Tuticorin and Kanyakumari which has never been explored so far even its comes under Marine Biosphere Reserve and includes thousands of fishermen who depend on fishery for their daily livelihood. The present pilot scale study was conducted in kudankulam coast within a 4 km radius in marine zone from kudankulam nuclear power project which confirmed that southern part of the Gulf of Mannar can also provide plentiful resources including rich ecologically sensitive habitats like seagrass and coral ecosystem. The resources in this region may not be similar to the northern part between Rameswaram and Tuticorin, but they are potent enough to provide a good source for fishery. Since various developmental activities like the nuclear power plant which is to be operated in the near future, it is very important to have a detailed baseline data on the seagrass, corals and associated organisms of this coastal region.With this baseline data the number of species in the Gulf of Mannar Biosphere Reserve can be estimated in the future studies.