Integrated Role of SST, PAR and CDOM in Summer Reef Bleaching during 2010 and 2011 along the Lakshadweep Islands

Abstract

The role of sea-surface temperature (SST), photosynthetically active radiation (PAR) and chromophoric dissolved organic matter (CDOM) on bleaching events along the Lakshadweep archipelago was studied for the summer of 2010 and 2011. The present study revealed similar SST pattern (30.8-31.9°C) and high PAR availability (48-50 E m -2 day -1 ) during the summer weeks of 2010 and 2011. However, the CDOM content varied significantly between 0.5 and 7 during 2010 and 2011. Stress from the elevated SST and PAR levels coinciding with low CDOM content (ultra violet radiation (UVR) transparent water column) might have resulted in large-scale bleaching during 2010. Low PAR and high CDOM (UVR opaque water column) might have prevented Lakshadweep corals from large-scale bleaching during 2011. Statistical analysis also confirmed that the high bleaching event of 2010 was due to coupled stress imparted by SST, PAR, CDOM and the unusually calm state of the sea.