If hermit crabs became extinct, it would be a problem. They play an essential role in tropical environments because they disperse seeds and fertilize the soil. A decline in hermit crabs could have a significant impact on surrounding ecosystems.
Unfortunately, researchers discovered over half a million dead hermit crabs that died after getting trapped in plastic containers on two remote islands; Henderson and Cocos. Experts fear that these deaths could be part of a global species decline.
Previous studies have found high levels of plastic pollution at the Cocos Islands archipelago in the Indian Ocean and Henderson Island in the South Pacific. Researchers wanted to investigate these islands to see how marine life was dealing with the plastic situation. They discovered one to two dead crabs per square meter of the beach.
The researchers involved include the community science organization “the Two Hands Project,” the Natural History Museum in London, and the Institute for Marine and Antarctic Studies (IMAS) from the University of Tasmania.
The team surveyed sites across four Cocos Islands and Henderson island for plastic containers that have the opening faced upwards. When the plastic container is with its opening to the sky, it acts as a perfect trap to the crab because once it’s in, it can’t get out. They counted the number of entrapped crabs, then they concluded their results across an additional 15 islands in the Cocos archipelago.
The hermit crabs use the odor of recently deceased crabs to track down available shells. Little do these crabs know, they’re falling into a trap. Multiple crabs become stuck in the same plastic container at times. For example, the researchers found 526 crabs in a single plastic container. That’s a lot of crabs!
Dr. Alex Bond, one of the report’s researchers, said:
The problem is quite insidious, really, because it only takes one crab. Hermit crabs do not have a shell of their own, which means that when one of their compatriots die, they emit a chemical signal that basically says there’s a shell available, attracting more crabs. Essentially it is this gruesome chain reaction.
Around 414 million pieces of debris were found on the beaches and vegetation of the Cocos Islands and and 38 million pieces on Henderson Island. It’s no surprise that the study found 508,000 dead crabs on the Cocos Islands, along with 61,000 on Henderson Island.
Dr. Jennifer Lavers, who led the study, said:
These results are shocking but perhaps not surprising. It is inevitable that these creatures will interact with and be affected by plastic pollution, although ours is one of the first studies to provide quantitative data on such impacts.
The researchers highlight that their findings show the drastic measures of the situation at hand and the need for an urgent investigation into the death rate of hermit crabs around the world.
