Coral bleaching and mortality in three Indian reef regions during an El Nino southern oscillation event

The 1997-1998 El Nino Southern Oscillation (ENSO) event, which elevated Sea Surface Temperatures (SSTs) of tropical oceans by more than 3 degreesC, wa s one of the most extreme ENSO events in recent history. Such increases in SSTs above the seasonal average can trigger widespread bleaching in coral r eefs. This study examined bleaching in three Indian coral reef regions in r elation to SSTs using quantitative rapid assessment methods between April a nd July, 1998. The Gulf of Kutch reefs showed an average of 11% bleached co ral with no apparent bleaching-related mortality. In contrast, bleached cor al comprised 82% of the coral cover in lagoon reefs of Lakshadweep and 89% of the coral cover in the Gulf of Mannar reefs. Bleaching-related mortality was high 26% in Lakshadweep and 23% in Mannar. The coral mass mortality ma y have profound ecological and socio-economic implications and highlights t he need for sustained monitoring for coral reef conservation in India.