Kolkata: India’s four major coral reef regions — the Andaman and Nicobar Islands, Lakshadweep, the Gulf of Mannar and the Gulf of Kachchh — are staring at a critically endangered future, with rising ocean temperatures and increasingly intense marine heatwaves threatening to push these fragile ecosystems towards collapse. A landmark global assessment, co-authored by scientists from the Kolkata-headquartered Zoological Survey of India (ZSI), has warned that none of the country’s coral reef regions will remain untouched by the escalating climate threat over the next five decades.The first-ever global assessment of coral reef ecosystems under the International Union for Conservation of Nature’s (IUCN) Red List of Ecosystems, unveiled at the UN Biodiversity Conference (COP17) in Yerevan, Armenia, has sounded an unprecedented alarm over the future of the world’s reefs. It found that 96% of the assessed coral reef ecosystem units globally, accounting for 99.8% of the total assessed reef area, are projected to fall into the Critically Endangered category when future ocean warming and marine heat stress are factored in.Unlike the conventional IUCN Red List, which assesses the extinction risk of individual species, the Red List of Ecosystems evaluates the risk of entire ecosystems collapsing.All 13 coral reef ecoregions across India, Bangladesh, Sri Lanka, the Maldives and the Chagos Archipelago, spanning approximately 8,282.6 sq km, are projected to become Critically Endangered over the next 50 years under climate-change scenarios. Together, these reefs account for nearly 4% of the world’s coral reef area.While seven South Asian reef ecoregions were historically classified as Vulnerable, four as Endangered and two as Critically Endangered, the inclusion of projected marine heat stress pushes all 13 into the highest risk category.In India, the Andaman and Nicobar, Lakshadweep and Gulf of Kachchh reefs, historically classified as Vulnerable, are projected to become Critically Endangered. The Gulf of Mannar and Palk Bay reefs, already categorised as Endangered, face a similar escalation in risk.Four ZSI scientists — Dr C Raghunathan, Dr Tamal Mondal, Dr J S Yogesh Kumar and Dr Chandran Rethinaraj — co-authored the South Asian regional assessment. Their contribution draws on decades of work in coral taxonomy, underwater field surveys, reef mapping and marine biodiversity monitoring.India also accounted for the largest share of monitoring sites used for the regional assessment under Criterion A. Of the 350 sites considered, 162 or 46.3%, were located in Indian reef ecoregions.Marine heatwaves and mass coral bleaching emerged as the most significant threats identified by the researchers. The bleaching events of 1998 and 2016 underline how vulnerable these ecosystems are to rising sea temperatures. The threat is further compounded by coastal development, dredging, sedimentation, land-based pollution, marine debris and overfishing, all of which undermine the ability of reefs to recover from thermal stress.Coral reefs are vital to coastal livelihoods and support a range of marine life, making their deterioration an ecological as well as an economic concern.The researchers have stressed that improving water quality, enforcing stricter coastal zoning, promoting sustainable fisheries management and investing in reef restoration can help build resilience. However, such local conservation interventions, while essential, cannot independently counter the scale of the climate threat.The assessment makes clear that the long-term survival of coral reefs will ultimately hinge on substantial global reductions in greenhouse gas emissions.
