Invasion is an ecological phenomenon of introduction of organisms to areas outside their native ranges. It concerns all aspects relating to their transport, establishment and spread in a new region . An invasive species causes imbalance to the ecosystem by monopolizing food and spatial resources and consequently disrupting the native community . Biological invasion is presently one of the major sources of stress to the coral reef habitats, which harbour 25% of total marine biodiversity and contribute to 10% of total fishery production .

Increasing sea surface temperature (SST) and its consequences on marine ecosystems are widely discussed. Andaman Sea witnessed a few bleaching events during 1998, 2002 and 2005. The present study was taken up to assess the extent of bleaching during 2010 in selected reef sites in the Andaman through line intercept transect survey.