Coral rehabilitation is an effective adaptive mechanism to cope with the impact of climate change and to restore the eco-system service through resilience. This was evidenced from the comparatively less coral mortality at Thoothukudi coast during the coral bleaching event in 2016, according to J.K. Patterson Edward, Director, SuganthiDevadason Marine Research Institute (SDMRI), Thoothukudi.

Out of the total 110 sq km reef area, about 30 sq km has been degraded due to anthropogenic and natural factors, especially due to climate change, Mr Edward pointed out. Though coral mining stopped completely in 2005, there was an increase of live coral cover in the degraded areas thereafter. However, climate change impact caused coral bleaching and mortality and led to loss of habitat and biodiversity including migration of fish. The elevated temperature due to climate change in 2010 caused mortality of about 9.9% live corals in the Gulf of Mannar (GoM), but the rehabilitation of corals mainly helped in the revival with plenty of new coral recruits and, hence, live coral cover increased to 39% in 2015.

In the subsequent year, the GoM lost 16.2% live corals in 2016 due to coral bleaching. Almost 90% mortality was recorded on the fast growing coral genera Acropora, Montipora and Pocillopora. They were the most affected with severe mortality, while boulders including genera Porites, Favia and Favites were found resistant to the bleaching. Mortality was higher in Mandapam group of Islands (22.17 percent), followed by Keelakarai group (17.15 percent) and Thoothukudi group (9.19 percent) during 2016. But in 2017, there was no bleaching and the affected corals were recovering slowly, he told The Hindu here on Sunday.

In 2002, coral rehabilitation was first initiated by SDMRI with the support of the Ministry of Environment, Forest and Climate Change at Thoothukudi coast. The researchers successfully standardized and field tested the low cost and low tech transplantation technique using artificial substrates like cement frames and multipurpose fish houses with native coral species. So far, over eight acres of degraded reef area at various islands, including Vaan, Koswari, Vilanguchalli, Kariyachalli, Puluvinichalli, Shingle and Poomarichan in GoM, had been successfully rehabilitated, he said. Following the GoM, Maharashtra also took up the coral rehabilitation at Malvan coast through UNDP-GEF Sindhudurg project with the technical expertise from SDMRI, he said.