Coral bleaching grips Indian coasts; Lakshadweep, Andamans most affected

Corals in the Lakshadweep coast on the Arabian Sea as well as those along the eastern coast of India on the Bay of Bengal are experiencing bleaching. 

The situation isn’t alarming yet and is restricted to some patches, according to researchers and government officials. 

In India, coral reefs are mainly found in Lakshadweep, Gulf of Kutch, Goa and Maharashtra on the Arabian Sea and Gulf of Mannar, Kerala and Tamil Nadu on Bay of Bengal. 

Lakshadweep islands are the only one reporting widespread bleaching as of now, experts shared. “The bleaching is widespread and noted especially in three locations of the Kavaratti island and neighbouring atolls,” said Maktub, a professional scuba diver.

The bleaching is more intense than what the island experienced during the 2015-16, he observed. “The visuals and extent of geographic area have been wider.”

Wenzel Pinto, research assistant at Oceans and Coasts Programme Nature Conservation Foundation said, “The bleaching is very widespread and there is now bleaching across almost all species in Kavaratti both inside and outside. The shallow lagoons often host monospecific stands of certain species like Acropora muricata and Porites cylindrica.”

Pinto said that these spaces have undergone widespread bleaching and large patches of reef are beginning to die. Meanwhile, species that are often more stress-tolerant, such as Porites lutea and Pavona varians have also begun to bleach. The effects of the bleaching event was observed as deep as 30 metres, as reported by diving instructors from a diving centre in Kavaratti, he informed. 

The researcher added that there also seems to be differences in how the bleaching is affecting different islands as well. “Divers from Agatti say that although there is bleaching there, the severity is much less than Kavaratti,” he said.

Reports and inspections also showed the impacts of the bleaching extend beyond just Scleractinian (hard coral). Soft coral species are also dying, as well as giant clams and sea anemones, which have bleached as well. 

In Goa, coral bleaching has started but is limited to one species, Goniopora, at the moment, said Venkatesh Charloo, founder trustee of Coastal Impact, an organisation involved in marine conservation, education and research. He added:

Bleaching in coral reefs of Goa is reported almost every year and starts around first week of May. But this year, the bleaching was reported in the last week of April itself.

Charloo said diving in Goa has been stopped until the end of the monsoon season from May due to visibility issues and rainfall. “The rains have brought relief for the past two days. Hopefully it should help to bring the ocean temperatures down. The next three weeks are crucial for corals,” he added.

In the Andamans, the coral bleaching that was being witnessed particularly in Havelock island, have now extended to South Andaman near Wandoor. “This is a visual update as corals have started becoming pale or the bleaching has begun,” said Tanmay Wagh, project coordinator with Dakshin Foundation, Bengaluru. “They are at high risk of undergoing bleaching if the temperatures remain high in the coming weeks.” 

The forest department of the government of Tamil Nadu has said that coral bleaching has been observed, but in patches. “The situation is not alarming as of now and the region has witnessed rains and, hence, the situation is likely to get contained as sea water temperatures drop,” said Srinivas Reddy, assistant principal chief conservator of forest and director of Arignar Anna Zoological Park, Vandalur.

Reddy said that if the temperatures are controlled, the affected coral areas should be able to recover from bleaching. “There are specific temperature-sensitive species that are undergoing the bleaching event. But the situation is not worrisome,” he said. 

A researcher from Suganthi Devadason Marine Research Institute,  a non-governmental research and higher education organisation in the discipline of marine science, said the institute is inspecting the extent of the impact. 

The ongoing bleaching has been declared as the fourth global mass coral bleaching experienced by the world. It is considered devastating for the marine life and species because corals are known to be ‘rainforests of the sea’, providing necessary food and habitat for survival. 

Read more: Fourth global mass coral bleaching? Great Barrier Reef severely affected, corals seen dying

Since 2023, mass bleaching episodes in coral reefs have been reported in more than 50 areas of the world. However, the high ocean temperatures and El Nino since April 15, 2024 had increased the coral bleaching area and threatening the corals. 

The current El Nino event is one of the primary contributors to the increased sea surface temperatures, triggering coral bleaching. Even bleaching events are reported in many parts of the country, the corals in and around Mithapur (reef adjacent to the Gulf of Kutch) haven’t showed any signs yet. “Our team is constantly monitoring to see any changes,” said Sajan John, co-principal investigator, marine projects, Wildlife Trust of India.

The high temperatures of water disturb the symbiosis between corals and zooxanthellae, a micro algae living in tandem with the coral tissues. The algae, once separated, make the corals look pale. 

The corals can recover from bleaching but long-term bleaching can lead to mass mortality, making them unable to recover. 

Global mass coral bleaching events have been reported in 1998, 2010, 2014 and 2017, according to the United States National Oceanic and Atmospheric Administration. 

In 2016-17, more than 50 per cent of the reefs were impacted in Australia. 

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