17 per cent coral bleach in Gulf of Mannar Marine National Park, but recovery on

However, the situation is not that bad as ocean temperatures have retracted to threshold levels allowing the bleached corals to slowly recover.
A Turbinaria coral in recovery from the recent bleaching event
A Turbinaria coral in recovery from the recent bleaching event Photo | Express

CHENNAI: A comprehensive rapid assessment conducted at the Gulf of Mannar Marine National Park has revealed that 17% of coral reefs have bleached due to the unprecedented marine heatwave that triggered a global coral bleaching event. However, the good news is that the corals have shown resilience and are currently in recovery.

Predominantly, fast-growing coral genera such as Acropora, Montipora and Pocillopora and slow-growing genera like Porites, Platygyra and Dipsastraea have been bleached. In Palk Bay, 14% of live corals have bleached.

Considering the kind of abnormal ocean temperatures observed between April to May this year, Tamil Nadu forest officials and experts feared there would be mass coral mortality, which would be detrimental for the ecosystem and fisheries production. However, the situation is not that bad as ocean temperatures have retracted to threshold levels allowing the bleached corals to slowly recover.

Additional Chief Secretary of Environment, Climate Change and Forests, Supriya Sahu, said the threshold level for Gulf of Mannar and Palk Bay corals is 30 degree Celsius. In April, the water temperature was 33.0-33.70°C. “Temperatures remained very high between 33.5°C and 34°C until mid-May, after which they decreased due to rainfall and winds, currently ranging from 28.5-31.5°C,” she noted.

The latest survey conducted from May 27 to June 5 included all 21 islands in the Gulf of Mannar and four reef sites in Palk Bay. The survey was done by Suganthi Devadason from the Marine Research Institute (SDMRI), who confirmed that branched coral reefs are beginning to recover. The NOAA Coral Reef Watch, which initially issued a red alert for the Gulf of Mannar in April, has also predicted cooler temperatures for the Gulf of Mannar supporting this recovery.

The Tamil Nadu government on Monday stated that the National Centre for Sustainable Coastal Management (NCSCM) is also conducting ocean circulation modelling studies using the Princeton Ocean Model (POM) and MIKE 3 FM modules to understand ocean temperature distribution around the coral reefs.

Exposed skeletons

Corals rely on single-celled algae called zooxanthellae living in their tissues for 90% of their nutrition and also their vibrant colours. When water temperatures exceed threshold levels, zooxanthellae leave the corals, exposing their white calcium carbonate skeletons, a phenomenon known as coral bleaching. Bleached corals can survive for only about two months, but can recover if temperatures are normalised

Related Stories

No stories found.

X
The New Indian Express
www.newindianexpress.com