Removing Rats Helps Atoll Reefs Keep Pace With Sea Rise
Lancaster University researchers link rat removal and seabird presence on Indian and Pacific Ocean islands to faster reef and sand growth.
Updated on Nov. 4, 2026 in Environmental
Live Poll
Should your community spend money removing invasive rats to protect coastal islands?
Researchers measured reef growth, sand production, and root growth on 28 islands in the Indian and Pacific Oceans. Lagoon reefs beside rat-free islands rose about 0.23 inches (5.9 millimeters) a year, 1.8 times as fast as reefs beside rat-infested islands.
Why it matters
Many atoll islands have lost native forest to coconut plantations and most bird colonies have disappeared after ship-borne rats ate seabird eggs and chicks. The findings suggest that restoring these islands could help reefs and shorelines respond to rising seas.
Lagoon reefs beside rat-free islands rose an estimated 0.23 inches (5.9 millimeters) a year, 1.8 times faster than beside rat-infested islands. Reefs around seabird islands produced 2.3 to 2.8 times as much sand, though the reef and sand figures come only from six Chagos Archipelago islands.
The players
Lancaster University
A public research university in England whose researchers conducted the study measuring reefs, sand, and roots on 28 islands.
The details
Seabirds feed at sea up to 620 miles (1,000 kilometers) from their nesting islands and deposit nitrogen-containing guano, which the researchers linked to more photosynthesis and limestone skeleton build-up in nearby corals. Parrotfish scrape coral and excrete it as sand, and the team found sand production rose sharply near seabird islands.
Timeline
Projected sea-level rise for the central Indian Ocean is about 0.24 inches (6 millimeters) a year by 2100 if the world warms by 2°C (3.6°F).
Some atoll reefs are projected to keep pace with rising seas through the end of this century.
Fine root measurements on Tetiaroa forest plots were taken over two years.
Big Picture
Rats have been removed from about 1,000 islands worldwide, and this study adds evidence that such eradication efforts can strengthen the natural defenses islands have against rising seas. The findings connect island restoration to coastal protection in a way earlier conservation work had not measured directly.
Restoring seabird populations and removing invasive rats could help atoll shorelines and reefs keep pace with rising seas, which matters for island communities that depend on reefs for protection. The sand and reef gains described here are measured over years, so the benefits are long-term rather than immediate.
The takeaway
Protecting seabird colonies and removing invasive rats can help atoll islands build reefs and sand that buffer shorelines against rising seas. Supporting island restoration is one practical way to strengthen coastal resilience over the coming decades.
Further reading
For more on how island ecosystems respond to environmental change, explore the Environmental section.
Live Poll
Should your community spend money removing invasive rats to protect coastal islands?
