Bleaching event kills corals at 3 spots in India
MUMBAI: Rising sea temperatures caused by climate change, which killed corals in different parts of the world during the third and longest global coral bleaching event between 2014 and 2017, also destroyed coral reefs in the Gulf of Mannar (GoM) and Konkan coast, new findings revealed.
The results of underwater surveys by the Suganthi Devadason Marine Research Institute (SDMRI), Tuticorn, revealed that a rise of 2-3 degrees Celsius in sea-surface temperatures killed 16% of corals in GoM between March and October 2016. An increase of one degree Celsius killed 8% corals around the Sindhudurg island fort in the Malvan Marine Sanctuary (MMS), in December 2015.
The extent of bleaching was more in MMS, with 70% corals affected in December 2015 — only 29% were found intact. At GoM, about 23.92% corals were bleached during AprilJune 2016. Another study published earlier this month says in Lakshadweep, more than 30% corals were severely bleached between 1998 and 2016.
Studies have shown that global temperatures in 2015, 2016 and 2017 were the warmest since instrumental record-keeping began in the 19th century.
Corals are sensitive to temperature fluctuations. Their primary source of food is an algae living in their tissues, which converts sunlight into food, and gives them colour. When temperatures rise, corals expel these algae and as a result get bleached (or turn white) with a chance of recovery since they can survive for three months without food. However, if the temperature stress continues, corals die of starvation. The third global coral bleaching event was driven by climate change and El Nino.
Although they occupy less than 1% of the ocean floor, reefs — they are referred to as the rainforests of the oceans — are home for a million species, which includes onefourth of the world’s fish.
“In addition to maintaining biodiversity, the mortality of corals directly affects fishing as they serve as breeding grounds and shelter for fishes. Their death will also affect tourism as tourists go scuba diving or snorkeling to see corals,” said JK Patterson Edward, director, SDMRI. The Malvan study was in collaboration with the United Nations Development Programme (UNDP) and Bombay Natural History Society.