Rat eradication on Palau's Ulong Island sparks rapid reef and fish recovery
A year after invasive rats were removed from Ulong Island in Palau, researchers observed a surge in seabird activity, a rise in leaf nitrogen and a 183% increase in fish biomass on nearby reefs.
In 2024, invasive rats were eradicated from Ulong Island in the Republic of Palau as part of the Island-Ocean Connection Challenge. Monitoring by Island Conservation and the Scripps Institution of Oceanography showed that within a year seabird activity surged, with Bridled Tern calls up 286% and other species increasing by roughly 50% compared to the control island Ngeruktabel. The return of birds, including the endangered Palau Ground Dove, has led to greater guano deposition, raising leaf nitrogen by about 80% at a reef site.
Correspondingly, total fish biomass around Ulong jumped 183%, signaling enhanced reef productivity. Researchers highlighted the speed of these changes as unexpected, underscoring the tight link between terrestrial restoration and marine health. The study provides the first experimental proof that seabird-driven nutrient flows can rapidly revive coral reef ecosystems.
Why it matters
It shows that fixing land-based threats can quickly boost nearby ocean health, offering a model for coastal conservation worldwide.
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