AKIPRESS.COM - More than half a million hermit crabs have been killed after becoming trapped in plastic debris on two remote island groups, prompting concern that the deaths could be part of a global species decline, Guardian reports.

The pioneering study found that 508,000 crabs died on the Cocos (Keeling) Islands archipelago in the Indian Ocean, along with 61,000 on Henderson Island in the South Pacific. Previous studies have found high levels of plastic pollution at both sites.

Researchers from the Institute for Marine and Antarctic Studies (Imas) at the University of Tasmania, the Natural History Museum in London, and the community science organisation the Two Hands Project, found one to two crabs per metre squared of beach were being killed by litter.

They surveyed sites across four Cocos Islands and Henderson for open plastic containers, with the opening sloped upwards in a way that would prevent the crab from leaving, and counted the number of entrapped crabs in each. They then extrapolated their results across another 15 islands in the Cocos archipelago.

The problem is exacerbated as hermit crabs use the odour of recently deceased crabs to track down newly available shells, leading to multiple crabs becoming trapped in the same area – in one instance, 526 crabs were found in a single plastic container.