Over half a million tiny hermit crabs have been trapped and killed by the massive amounts of plastic debris on two remote island chains in the Indian and Pacific Oceans. The tragic mass mortality event has researchers fearing the worst on a global scale.
The discovery of 570,000 dead hermit crabs in the Indian Ocean’s Cocos (Keeling) Islands and the Pacific Ocean’s Henderson Island is just the latest sign of the growing crisis of plastic waste polluting our oceans, posing a grave threat to wildlife.
The first-of-its-kind study, published in Journal of Hazardous Materials, revealed that 508,000 crabs died in the Cocos archipelago along with 61,000 on Henderson Island. The crabs’ lives were likely claimed by the massive amount of plastic containers littering the area, whose openings are sloped upward in a manner that prevented them from climbing out once they had gone in.
Those involved in the study had been surveying the beaches of the islands for plastic waste before noticing a huge amount of open plastic containers filled with a mixture of both dead and alive hermit crabs.
Dr. Jennifer Lavers of the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS) said:
“We decided to do additional surveys across a range of sites of how many containers there were, including how many were open, how many were in a position likely to trap crabs, and how many contained trapped crabs.
These results are shocking but perhaps not surprising, because beaches and the vegetation that fringes them are frequented by a wide range of wildlife.”
The research was carried out by scientists from IMAS, the Natural History Museum in London, and community science group the Two Hands Project. Some of the leading scientists like Lavers had months ago sounded the alarm on the shocking extent to which the remote islands had become transformed into massive waste dumps due to the vast amounts of garbage—and primarily single-waste plastics—that make their way into our oceans.
In the study led by Lavers, researchers found that about 414 million pieces of plastic—including 977,000 shoes and 372,000 toothbrushes—had washed up on the Cocos Islands. Scientists believe that the amount of plastic waste washing up on such remote islands is a strong indicator of the total amount of debris in the ocean.
To make matters worse, because hermit crabs don’t have their own shells and instead inhabit empty ones, when they do find what they believe to be available shells they emit chemical signals that notify their fellow crabs, essentially drawing whole communities of the creatures to their deaths, explained Dr. Alex Bond of the Natural History Museum in London.
“This attracts more crabs that then fall into the containers and die, which then sends out more signals that say there are more shells available … Essentially, it’s a gruesome chain reaction.”
The blow to hermit crabs could be the start of a nasty chain reaction impacting marine life. In addition to forming an important part of maritime food chains, the scavengers also help clean island beaches and tropical forests while breaking down organic matter, spreading nutrients by aerating and fertilizing the soil, and dispersing seeds.
Researchers are stressing that their discovery of the hermit crabs’ fate should spark an urgent global investigation into the death rates of hermit crabs.