Post Bleaching Assessment of Corals in Andaman and Nicobar Islands

Reefs of Andaman and Nicobar Islands harbour 418 species of scleractinian corals spread over an area of 2,000 km². In April to May, 2010, due to the delayed onset of the southwest monsoon the sea surface temperature of the coastal and oceanic region increased to 31.7 °C in respect to the earlier record of maximum 29.0 °C during the said period. This resulted in mass bleaching of hermatypic corals during May, 2010. Rapid under water surveys have been conducted in reefs of Andaman and Nicobar Islands to assess the health of corals between May 2010 and August 2011. It is estimated that 76.62 ± (SD) 10.83 % of coral species are bleached up to a water depth of 10–15 m. Species from the genus Acropora appeared more susceptible to bleaching than those belong to the genus Porites. During the month of June 2010 the sea surface temperature was reduced to 29 °C perhaps due to the rainfall which stimulated rebuilding of zooxanthellae population in bleached corals. Recovery of 85.54 ± (SD) 6.33 % of bleached corals was seen during the study period of 11 months after the bleaching event. Porites spp. showed a high recovery rate, while Acropora spp. had the highest mortality rate. Coral mortality can have profound ecological and socio-economical implications and highlights the need for sustained monitoring for coral reef conservation in India. Hence, steps must be taken to improve management tools to protect these resources of global significance.