Overview:
A new international study finds that 309 Indo-Pacific atolls contain more than 27,000 square kilometers of shallow coral reef habitat, making them one of the world’s largest reef networks. Researchers say atolls deserve greater attention in global conservation efforts because they support biodiversity, fisheries, island formation and the communities that depend on healthy reefs.
A new international study suggests that atolls, the ring-shaped coral reef ecosystems scattered across the Pacific and Indian oceans, represent one of the world’s largest coral reef networks yet remain underrecognized in global conservation planning.
Published in Frontiers in Marine Science, the study found that 309 Indo-Pacific atolls contain more than 27,000 square kilometers of mapped shallow coral reef habitat, accounting for 41.5% of all mapped reef areas surrounding Indo-Pacific islands and nearly 8% of the world’s mapped shallow reefscape. Collectively, atoll reefs occupy nearly as much area as Australia’s Great Barrier Reef.
The findings challenge the perception of atolls as isolated or peripheral coral reef systems and suggest they should be more explicitly incorporated into coral conservation strategies.
“Atolls are often discussed as small, vulnerable islands, but when we look at the reefs associated with them collectively, they emerge as one of the planet’s major coral reef systems,” said Alex Wegmann, lead author of the study and Lead Scientist for Island Resilience with The Nature Conservancy. “If we want coral reef conservation to reflect the full diversity and scale of the world’s reefs and address the associated challenges, atolls need to be part of that conversation.”
The study brings together atoll scientists, conservation practitioners, and community leaders from across the Pacific, Indian Ocean, North America, and Europe. Using a curated database of Indo-Pacific atolls and high-resolution reef mapping from the Allen Coral Atlas and the Interactive Data Portal for Indo-Pacific Atolls, researchers quantified the extent of reef habitat associated with atoll ecosystems and compared it to other globally recognized reef regions.
Researchers say the findings are particularly relevant as coral reefs worldwide face increasing pressure from climate change.
For decades, atolls have frequently been portrayed as ecosystems destined to disappear beneath rising seas. However, a growing body of research shows that healthy atolls are dynamic systems whose futures depend on the condition of the coral reefs that support them. Intact atoll reefs generate sediment, support island formation, sustain fisheries, and maintain ecological connections between land and sea.
“Too often, atolls are framed as doomed landscapes rather than living reef systems with remarkable ecological complexity,” said Sebastian Steibl, atoll scientist from the University of Auckland and co-author of the study. “The science increasingly shows that these systems are dynamic, resilient in important ways, and worthy of far greater attention from the conservation community.”
The authors also point to emerging evidence that some atoll reefs may harbor coral communities with elevated heat tolerance, potentially making them important sources of climate-resilient corals in a warming ocean. Research from places such as Palmyra Atoll has documented reef habitats that experienced widespread bleaching during marine heat waves but relatively limited coral mortality.
“Atolls offer a unique opportunity to understand how coral reefs can persist under climate stress,” said Hannah Stewart, co-author and coral conservation scientist. “Protecting these systems is not only important for the communities and biodiversity they support today, but also for the lessons they may provide about the future of coral reefs globally.”
The study also highlights a challenge unique to atolls: while they collectively form a reef network of global significance, they are spread across dozens of jurisdictions and many small island nations. That geographic dispersion can make them less visible in conservation agendas than large, centrally managed reef systems.
For many Pacific and Indian Ocean communities, however, atolls are far more than reef habitats. They are homes, sources of food security, cultural landscapes, and foundations of local economies.
“People who live on atolls have long understood the connection between healthy reefs, healthy islands, and healthy communities,” said Dolores deBrum Kattil, co-author and Executive Director of the Marshall Islands Conservation Society. “Recognizing the global importance of atoll reefs should go hand in hand with supporting the communities that depend on them.”
The authors emphasize that elevating atolls in coral reef conservation does not mean shifting attention away from places like the Great Barrier Reef or the Coral Triangle. Instead, they argue that conservation strategies should better reflect the full range of reef systems that make up the global coral reef estate.
“Protecting coral reefs at a global scale means protecting all major reef systems,” Wegmann said. “This study shows that atolls belong firmly in that category.”