Marine heatwave scorches pristine coral reefs of Lakshadweep

These marine heat waves pose a severe threat to coral health, said scientists at the ICAR-Central Marine Fisheries Research Institute (CMFRI) as they observed alarming levels of coral bleaching, indicating significant stress on marine ecosystems in the region.

Coral bleaching occurs when the water temperature becomes excessively warm, causing corals to expel the microscopic algae residing within their tissues. Experts say bleached corals are not dead but are at risk of starvation and disease.

“Such heat stress levels signify a severe threat to coral health, leading to extensive bleaching where corals lose the symbiotic algae (zooxanthellae), compromising their survival by depriving them of essential nutrients. If the DHW continues to rise, reaching beyond 12 °C weeks, it could precipitate an unprecedented biodiversity crisis due to multispecies mortality,” KR Sreenath, senior scientist at CMFRI, said on Monday 6 May.

According to the National Oceanic and Atmospheric Administration (NOAA), this level of DHW poses a substantial risk of coral bleaching, threatening the region’s diverse marine ecosystems.

Corals are living organisms that make up the reefs and provide the ecosystem for marine life to thrive, especially fish. Coral reefs are a natural barrier, protecting these islands against the swelling of the seas, and keeping salt water out of the limited freshwater sources in the region.

The heatwaves also threaten other critical marine habitats, including sea-grass meadows. Similar to corals, sea-grass meadows are experiencing detrimental impacts due to the heat waves such as impaired photosynthesis, reduced growth, and hindered reproductive functions.

The waters of the archipelago, though, are spread over 400,000 square kilometres and are rich in marine life and resources. But the CMFRI observation has come as an alarm to the authorities.

Furthermore, the heat waves also endanger critical marine habitats like sea-grass meadows, impairing photosynthesis, growth, and reproductive functions. The degradation of these ecosystems can disrupt local marine food webs, impacting a wide range of species, from fish communities to marine mammals like dugongs and dolphins.

To address these challenges, CMFRI is actively researching ecological changes affecting coral reefs and has initiated a national project to investigate coral reef resilience. By integrating advanced climatic modeling, deep-learning, and ecological research, the institute aims to develop resilience-based management strategies to ensure the long-term sustainability of coral reef ecosystems.