Live coral cover in Gulf of Mannar increases to 42.9%

CHENNAI: The average live coral coverage inside Gulf of Mannar Marine National Park has increased to 42.9 per cent, reveals a new underwater survey conducted by Chennai-based National Centre for Coastal Research (NCCR). During 2001, the NCCR developed a Resource Information System of Gulf of Mannar (RISGOM) which is the only baseline data available currently to conduct monitoring of biodiversity in Gulf of Mannar and the coral area was only 25.76 per cent then. Thereafter, since 2018, an extensive underway survey was conducted to come out with a coral health index. 

The study report says the overall reef health status of Gulf of Mannar is in “fair” condition, although corals in almost 10 out of 20 Gulf islands are still in degraded condition. Reef area in seven islands is in fair condition and three islands in healthy conditions. Islands of Mandapam and Keezhakarai groups were found to be the well diversified reef areas than what existed two decades ago. 

NCCR director MV Ramanamurthy told Express that his team was preparing a new set of baseline data and would be ready in a year’s time. “We are also in the process of establishing a permanent observatory in Gulf of Mannar, Lakshadweep and Andaman Islands to study coral bleaching and their recovery.”

The official said the observatory will come up inside the sea made up of concrete fitted with multiple sensors, which will measure all the critical climate change and water quality parameters like sea surface temperature, dissolved oxygen, chlorophyll and blue algae that have a bearing on the health of corals.

“We don’t know when the next coral bleaching event would occur. Though the coral reefs in Gulf of Mannar showed great degrees of resilience in the face of climate change, continuous monitoring is needed. Corals bleach in summer, if the water temperature surpasses 30 degrees Celsius for a prolonged period of time. But they recover when the temperature comes down, which happens usually in August. But there is no scientific data available. The observatory will capture the entire process like in what condition bleaching happens and rate of recovery. This data will help in formulating long-term mitigation measures,” Ramanamurthy said.

On threats, NCCR scientists say presently natural threats are more pronounced than anthropogenic disturbance in the national park area. The outbreak of macroalgae growth constitutes 47 per cent of threat followed by sediment load (24 per cent), coral disease (20 per cent), and faunal infestation (5 per cent).

20 Gulf islands are still in degraded condition

Overall reef health status of Gulf of Mannar is in “fair” condition, although corals in almost 10 out of 20 Gulf islands are still in degraded condition