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Abstract

The investigation was gone through to evaluate the present scenario of coral diverseness and water quality criteria of the only coral-bearing island of Bangladesh (Saint Martin's Island) from January 2018 to December 2021 in the eastern Bay of Bengal, which is known as a biologist promised land. The coral protects shorelines from storm surges and land erosion, creates job opportunities for locals and extends recreational activities. It is not only suitable for spawning, breeding, and nursery ground for different marine species but also acts as a reservoir of food and medicinal drugs. Coral specimens were collected at five stations around the Island by applying the best monitoring method as well as the Video Transects technique throughout scuba diving and snorkeling with the conventional underwater video camera. The primary video documentaries were examined and scrutinized at the BORI laboratory. A total of 72 species from 34 genera under 11 families of Scleractinian and 05 species from 4 genera under 2 families of soft corals were identified from the Island. Among Scleractinian corals Porites, Favia, Pavona, Favites, Goniastrea, Platygyra, Goniopora, Hydnophora, and Acanthastrea were the most abundant respectively and among the soft corals Gorgonian Sea fans, small sea fans, Sea whips were dominant primarily. Within the 11 families of hard corals Merulinidae, Faviidae, Mussidae, Agariciidae, Acroporidae, and Siderastrea were the most dominant, respectively. Seasonal change in water quality criteria (Transparency, Salinity, DO, TSS, Conductivity, Water p H , TDS, Water Temperature, PO4-P, NO3-N, NO2-N & SiO3-Si, Sediment flux) has great effects on coral diversity. The present investigation unveiled that due to heavy rainfall, a large amount of freshwater discharge from upstream, and a huge amount of sedimentation, global warming, and ocean acidification, about 15% of hard coral bleaching has occurred frequently during monsoon and pre-monsoon period. Generally, most of the bleached coral was naturally regenerated with changing environmental variables during the winter and early pre-monsoon season. Anthropogenic pollution causes coral degradation. It is high time to develop a comprehensive strategy for regular monitoring, conservation, and restoration of corals for sustainable ecosystem management of the vulnerable Island.