Live Coral Cover in Lakshadweep Fell From 37.24 Percent in 1998 to 19.6 Percent in 2022, and the Government Put the 2023 to 2024 Bleaching There at 84.6 Percent

A monitoring record in Lakshadweep that runs from 1998 to 2022 shows coral cover falling from 37.24 percent to 19.6 percent, according to a 2025 paper in Diversity and Distributions. On 4 December 2024 the Ministry of Earth Sciences told the Lok Sabha that bleaching in 2023 to 2024 stood at 84.6 percent in Lakshadweep, 27 percent in the Gulf of Mannar and 15 to 18 percent in South Andaman.

A bleached coral has lost the tiny algae, called zooxanthellae, that give it colour and food, and it is still alive. J. K. Patterson Edward and colleagues write in Current Science that corals recover if normal temperature returns within a short time, and die if the stress goes on. So the share of corals bleached, the share killed and the share of seabed still covered by live coral are three separate numbers, and the Indian surveys below report different ones.

April to July 1998: the first Indian survey

Rohan Arthur of the Nature Conservation Foundation surveyed three reef regions between April and July 1998, during one of the most extreme El Niño events in recent history. El Niño is the periodic warming of the tropical Pacific, which our monsoon explainer links to dry Indian years. His paper in Current Science, published in December 2000, used quantitative rapid-assessment methods.

The Gulf of Kutch reefs averaged 11 percent bleached coral, with no apparent bleaching-related mortality. In the lagoon reefs of Lakshadweep, bleached coral made up 82 percent of coral cover, and in the Gulf of Mannar 89 percent. Bleaching-related mortality was 26 percent in Lakshadweep and 23 percent in Mannar. Arthur adds that surveys by Ravindran and others reported heavy bleaching in the Andaman Islands in July 1998.

A later paper counts the same Lakshadweep event differently. Yadav, Alcoverro and Arthur monitored six shallow reefs for two decades and put coral mortality after 1998 at 87 percent. The abstract does not say when that count was made, so the 87 percent cannot be set against the 26 percent from the 1998 survey.

May 2010: site-by-site numbers from the Andamans

The best-documented Andaman event in the literature is the one in May 2010. P. Krishnan and colleagues, writing in Current Science in 2011, used line-intercept transects (a tape laid along the reef, with every coral under it recorded) at selected sites. Fully bleached coral as a share of total coral cover was 69.49 percent at Havelock Island, 67.28 at South Button Island, 56.45 at Nicolson Island, 43.39 at Red Skin Island, 41.65 at North Bay and 36.54 at Chidiyatapu. Branching corals were hit hardest and massive corals held up better. The paper lists earlier Andaman bleaching in 1998, 2002 and 2005.

The Gulf of Mannar lost cover the same year. Patterson Edward’s team at the Suganthi Devadason Marine Research Institute (SDMRI) in Tuticorin records live coral cover of 42.85 percent in 2009 and 33.2 percent in 2010, which it attributes to bleaching mortality. In Lakshadweep, Yadav and colleagues put coral mortality after 2010 at 44 percent. Our piece on Ram Setu and the geology of Adam’s Bridge covers the shoals between Rameswaram and Mannar, which hold living corals according to a 2021 paper it cites.

2016: every reef surveyed in Lakshadweep bleached

A team of six Nature Conservation Foundation biologists surveyed 11 atolls in Lakshadweep in 2016. Mongabay reported on 11 May 2016 that bleaching showed on every reef they surveyed, and that Arthur recorded dead corals and dead reef fish. Sea surface temperature from February to May averaged about 30 degrees Celsius, roughly one degree above the 15-year average. Yadav and colleagues put coral mortality after the 2016 event at 31 percent.

In the Gulf of Mannar, SDMRI surveyed all 21 islands from March to October 2016. Bleaching averaged 23.92 percent (plus or minus 10.55) between April and June. Live coral cover fell from 38.86 percent in 2015 to 22.69 percent in October 2016, a mortality of 16.17 percent. The Mandapam group of islands lost the most, with 22.17 percent mortality. Water temperature during the bleaching ran from 31.2 to 32.6 degrees. Fast-growing Acropora, Montipora and Pocillopora corals were worst hit, while boulder corals such as Porites, Favia and Favites resisted.

For the Andaman and Nicobar Islands, the figures come from the Zoological Survey of India (ZSI) as reported by the Press Trust of India on 27 May 2022. ZSI recorded 83.6 percent of hard corals bleached across the Bay Islands in April and May 2016, with a high of 91.5 percent on the Andaman Sea coast of South Andaman and a low of 83.2 percent in North Andaman. It reported 23.58 percent of live coral cover lost. We could not open ZSI’s own report, so these numbers are second-hand.

2019 and 2020: Mannar again, and a Lakshadweep year with two accounts

Koushik Sadhukhan, Ramesh Chatragadda, T. Shunmugaraj and M. V. Ramana Murthy of the National Centre for Coastal Research (NCCR) surveyed the Gulf of Mannar and Palk Bay from August 2018 to August 2020. Their 2022 paper reports severe bleaching in both places in the summers of 2019 and 2020. Average live coral cover across the surveys was 39.55 percent (plus or minus 15.45) in the Gulf of Mannar and 28.40 percent (plus or minus 14.60) in Palk Bay.

For Lakshadweep, two accounts disagree. Idrees Babu K. K., a scientist in the territory’s Department of Science and Technology, told Down To Earth in June 2024 that 2020 bleaching stood at 41.9 percent, against 81 percent in 1998 and 65 percent in 2010. The Ministry of Environment told the Lok Sabha on 5 August 2024 that bleaching events in Lakshadweep in 2020, 2021, 2022 and 2023 were not significant. The reply does not define significant, and Down To Earth does not describe the survey behind the 41.9 percent.

What a degree heating week measures, and what NOAA says about the fourth event

NOAA Coral Reef Watch tracks heat stress in degree heating weeks. A degree heating week adds up, over a rolling 12 weeks, how far satellite-measured sea temperature has stood above the local maximum monthly mean, the highest summertime average, counting only readings at least 1 degree Celsius above it. The unit is written °C-weeks. At 4 °C-weeks, NOAA says reef-wide bleaching can be expected, especially in sensitive species. At 8 or more, reef-wide bleaching with deaths of heat-sensitive corals is likely.

NOAA and the International Coral Reef Initiative confirmed the fourth global bleaching event on 15 April 2024, and NOAA’s release that day says mass bleaching had been confirmed worldwide since early 2023. NOAA’s status page puts the share of reef area that met bleaching-level heat stress between 1 January 2023 and 30 September 2025 at about 84.4 percent, with mass bleaching documented in at least 83 countries and territories. The record before it was the 2014 to 2017 event, at 68.2 percent of reef area. In a release dated 2 June 2026, NOAA said the event likely ended in mid-2025, after it confirmed that no widespread bleaching was reported during the December 2025 to February 2026 austral summer.

For Lakshadweep, ICAR-Central Marine Fisheries Research Institute (CMFRI) scientists said in a release carried by the Press Information Bureau (PIB) on 6 May 2024 that sea temperatures had run more than 1 degree above normal since 27 October 2023 and that the degree heating week figure had passed 4 °C-weeks. Dr K. R. Sreenath of CMFRI added that a rise beyond 12 °C-weeks could bring death across many coral species.

2024: three regions, three counts

The ministry’s 4 December 2024 table lists the Andaman and Nicobar Islands at 15 to 18 percent in South Andaman only, the Gulf of Mannar at 27 percent and Lakshadweep at 84.6 percent. It describes the Andaman bleaching as small scale, Mannar as small scale in patchy areas and Lakshadweep as widespread, and attributes all three to higher sea surface temperature from El Niño. The table gives no survey method and names no agency for the percentages. The same 84.6 percent was given to Down To Earth by Babu as the result of the department’s last survey at the Kavaratti atoll, and the ministry’s table does not say where its figure was measured.

A separate survey of Kavaratti Island by B. Manikandan, P. Sawant, T. Lad and J. Singh of the CSIR-National Institute of Oceanography covered 13 sites between February and May 2024. Using belt transects 50 metres long and 2 metres wide, they recorded 1,252 colonies of 15 genera. Of these, 80.7 percent were severely bleached and 10.9 percent moderately bleached. More than 80 percent of colonies were severely bleached in the intertidal zone and the lagoons, and 78.4 percent were bleached on the outer reef. More than 60 percent carried at least one added stress such as turf algae, cyanobacterial mats (a slimy film of bacteria) or crown-of-thorns starfish. The authors call it the most severe event compared with 1998, 2010 and 2016, and write that Lakshadweep has no full bleaching response plan beyond monitoring.

In the Andamans, Tanmay Wagh of the Dakshin Foundation told Down To Earth in May 2024 that bleaching at Havelock Island had spread to South Andaman near Wandoor. The ministry’s table lists the Gulf of Kachchh among the regions affected without a figure. Sajan John of the Wildlife Trust of India said in May 2024 that corals at Mithapur, next to the Gulf of Kutch, had shown no signs yet and were being monitored.

What the two ministries told Parliament

The Ministry of Environment, Forest and Climate Change replied on 5 August 2024 through Minister of State Kirti Vardhan Singh. It called mass bleaching a natural phenomenon tied to warmer seas, said corals can recover when normal conditions return and listed coral transplantation by the Lakshadweep administration, ZSI’s long-term monitoring and INCOIS bleaching alerts, issued since 2011. It also said coral bleaching “is a sporadic event in India” without major effect on tourism and fishers “as of now”.

The Ministry of Earth Sciences replied on 4 December 2024 through Dr Jitendra Singh with the regional table above. It said the National Centre for Sustainable Coastal Management has mapped 1,439 square kilometres of Indian coral reef and runs a reef observation network with data buoys. The Space Applications Centre of ISRO found apparent loss of reef area at Malvan, Maharashtra, between 2007 and 2020, and at four of eleven mapped Gulf of Mannar reefs over 12 to 14 years. The reply also says more than 16,000 corals have been moved to new sites in the Gulf of Kachchh.

What has grown back

Arthur told Mongabay in 2016 that Lakshadweep recovered from 1998 better than he expected, with many new coral recruits and many reefs looking healthy within a decade. After 2010, he said, recovery had reached about halfway by 2016.

Yadav and colleagues measured the difference. Mortality fell from 87 percent after 1998 to 44 percent after 2010 and 31 percent after 2016, yet recovery rates dropped fourfold between the first two periods. Coral cover on their six shallow reefs went from 51.6 percent in 1998 to 11 percent in 2017. Dey and colleagues, using surveys from 1998 to 2022, found the same pattern across the archipelago and report that recovery rates rose sharply after six bleaching-free years.

In the Gulf of Mannar, SDMRI and the Tamil Nadu forest department put live coral cover at 37.0 percent in 2005 and 27.3 percent in 2021, as The Hindu reported. That is above the 22.69 percent of October 2016. The December 2024 reply says most reefs in the Andamans and Mannar recovered from the 2023 to 2024 bleaching, and some in Lakshadweep, with studies under way. We found no published count of coral deaths from the 2024 event in Lakshadweep.

NOAA’s coordinator Derek Manzello said in the 2 June 2026 release: “We are now in the era where reefs will bleach on a near-annual basis.”