Researchers at the ICAR-Central Marine Fisheries Research Institute (CMFRI) have observed extensive coral bleaching across the Lakshadweep Sea due to marine heatwaves. The survey conducted on several Lakshadweep islands revealed severe bleaching affecting a significant percentage of hard coral species. This bleaching phenomenon is primarily attributed to a prolonged marine heatwave that has been impacting the region since late October 2023.
Marine heatwaves are rare weather events characterized by prolonged periods of unusually high ocean temperatures, exceeding the 90th percentile of typical regional ocean temperatures based on historical data. In Lakshadweep, the Degree Heating Week (DHW) indicator, which measures accumulated heat stress, has risen above 4 degrees Celsius-weeks. According to the National Oceanic and Atmospheric Administration (NOAA), such elevated DHW levels pose a substantial risk of coral bleaching, posing a threat to the region’s diverse marine ecosystems.
Dr. KR Sreenath, a senior scientist at CMFRI, emphasized that the current heat stress levels pose a severe threat to coral health, leading to extensive bleaching, where corals lose their symbiotic algae (zooxanthellae), compromising their survival by depriving them of essential nutrients. Dr. Sreenath warned that if DHW continues to rise and exceeds 12 degrees Celsius-weeks, it could result in a biodiversity crisis due to multispecies mortality.
Dr. Shelton Padua, another senior scientist at CMFRI, attributed the primary causes of marine heatwaves to excessive atmospheric heat transfer coupled with shifts in ocean currents, resulting in unusually high water temperatures. Since October 27, 2023, the Lakshadweep Sea has consistently experienced these conditions, with temperatures registering more than 1 degree Celsius above the norm.
Highlighting the significance of marine ecosystems for coastal communities’ livelihoods, tourism, and fisheries sectors, Dr. Sreenath expressed concerns about the ongoing marine heatwaves causing significant economic losses by disrupting vital ecosystem services. He emphasized that the death and disintegration of coral reefs could leave coastal communities vulnerable to sea level rise impacts.
To address these ecological challenges, CMFRI has been actively conducting studies to better understand the ecological changes affecting coral reefs. Additionally, they have initiated a comprehensive national project aimed at investigating the resilience potential of various coral reefs in India.
