Year: 2026
Type: preprint
Abstract: South Asian coral reefs extend from approximately 10.80°S to 25.06°N across India, Bangladesh, Sri Lanka, the Maldives and the Chagos Archipelago. They cover an estimated 8,282.6 km², representing approximately 4% of global coral-reef extent, and encompass 13 ecoregions delineated using the Marine Ecoregions of the World framework and regional expert input. The region supports diverse reef-building corals, reef fishes and associated benthic communities across oceanic atolls, fringing, barrier, patch and platform reefs. Environmental settings range from clear, oligotrophic oceanic waters to highly turbid continental-shelf systems influenced by monsoon circulation, freshwater discharge, sedimentation, strong currents and seasonal upwelling. These ecosystems face interacting pressures from marine heatwaves and mass bleaching, overfishing and destructive fishing, coastal development, dredging, sedimentation, pollution, tourism, anchoring and reef-resource extraction. The IUCN Red List of Ecosystems assessment applied Criteria A–D using coral-reef extent data, in-situ benthic and fish monitoring, satellite-derived Degree Heating Weeks and records extending to 2026 where available. No ecoregions were assessed as Least Concern across all criteria, highlighting the widespread and escalating pressures facing reefs in the region. In summary, 54% (n=7) were Vulnerable, 31% (n=4) were Endangered and 15%(n=2) were assessed as Critically Endangered. Risk was driven most consistently by restricted geographic distribution under Criterion B; observed severe thermal stress under Criterion C1 and degradation of hard-coral cover and fish indicators under Criterion D increased risk in several ecoregions. Criterion A identified one Vulnerable ecoregion, while five ecoregions were Data Deficient under Criterion D. Projected thermal exposure for 2026–2075 indicated substantially greater risk once projected heat stress is included, although Criterion C2 was reported separately. The findings demonstrate an urgent need to reduce manageable local pressures, protect geographically restricted and recovery-capable reefs, strengthen spatial and long-term benthic and fish monitoring, validate reef-extent data, and integrate climate adaptation and coral-reef recovery into coordinated national and regional marine policy.
DOI: 10.32942/x29h6v
Institutions: International Union for Conservation of Nature (Bangladesh), International Union for Conservation of Nature (United States), International Union for Conservation of Nature (Guinea-Bissau), The University of Melbourne, Marine Research Centre, Zoological Survey of India, Nature Conservation Foundation, Bangor University
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223188297