Rat Removal Speeds Atoll Reef Growth, Study Finds
Research on 28 islands suggests reefs could partly keep pace with sea-level rise, though the work is research-stage.
Updated on Nov. 4, 2026 in Environmental
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Lancaster University researchers measured reef growth, sand production and root growth on 28 islands in the Indian and Pacific Oceans, finding that removing invasive rats is linked to faster reef growth and more sand. The findings are from a research study, not an established or deployed intervention.
Why it matters
Rats that arrived on ships eat seabird eggs and chicks, and most atoll bird colonies are gone as a result, which weakens the natural supply of nutrients and sediment that keeps low islands and reefs building. The study ties rat removal to reef and island processes at a scale that could inform how atoll nations plan against rising seas.
The measurements rest on field data from the Chagos Archipelago and Tetiaroa, with reef rise rates 1.8 times faster beside rat-free islands and sand output 2.3 to 2.8 times higher near seabird colonies. The study does not yet show how far these ratios hold on other atolls, and the reef and sand estimates come from only six islands.
The players
Lancaster University
A United Kingdom research university whose researchers conducted the island, reef and root measurements in this study.
The details
Seabirds feed at sea up to 620 miles (1,000 kilometers) from the island where they nest and deposit nitrogen-containing guano there, and that nutrient input appears to fuel the growth of corals and reef algae. Parrotfish scrape coral and excrete it as sand, so more fish and more coral translate into more sand. Corals near seabird islands photosynthesized more and laid down more limestone skeleton, which let the team estimate reef build-up rates.
Timeline
Projections extend through the end of this century, with 2100 used as the benchmark year for central Indian Ocean sea-level rise.
Fine root measurements on Tetiaroa forest plots were taken over a two-year period.
The Tech Race
Rat eradication on islands has been pursued as a conservation tool for years, and this study adds a coastal-geology measure to that body of work. It positions island restoration as a possible complement to engineered coastal defenses, though the evidence so far comes from a limited set of atolls.
The findings are research-stage and do not yet translate into a deployed program or availability for communities. Island managers and conservation groups would be the first to apply rat-removal results, and no timeline for broader implementation has been announced.
The takeaway
Watch whether follow-up measurements extend the reef and sand findings beyond the six Chagos islands and five Tetiaroa islands studied. The projection that some atoll reefs could keep pace with rising seas through the end of this century is the claim most worth testing against future data.
Further reading
For broader context on how ecosystems respond to human-introduced species, explore the Environmental section.
Source note: This article includes information reported by Earth.
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