Differential bleaching of corals based on El Niño type and intensity in the Andaman Sea, southeast Bay of Bengal

The Andaman coral reef region experienced mass bleaching events during 1998 and 2010. The purpose of this study is to investigate the role of the El Nino in the coral reef bleaching events of the Andaman region. Both Nino 3.4 and 3 indices were examined to find out the relationship between the mass bleaching events and El Nino, and correlated with sea surface temperature (SST) anomalies in the Andaman Sea. The result shows that abnormal warming and mass bleaching events in the Andaman Sea were seen only during strong El Nino years of 1997–1998 and 2009–2010. The Andaman Sea SST was more elevated and associated with El Nino Modoki (central Pacific El Nino) than conventional El Nino (eastern Pacific El Nino) occurrences. It is suggested that the development of hot spot patterns around the Andaman Islands during May 1998 and April–May 2010 may be attributed to zonal shifts in the Walker circulation driven by El Nino during the corresponding period.