It is estimated that more than 500,000 hermit crabs died after they were trapped in debris on two island groups, and a global decline could take place. That’s due to plastic pollution.
A team of researchers concluded that 508,000 crabs died in the Cocos Islands archipelago in the Indian Ocean, while another 61,000 died on Henderson Island, which can be found in the South Pacific. Previous research found a concerning level of plastic pollution in both regions.
The mixed team of researchers from the Institute of Marine and Antarctic Studies at the University of Tasmania and the Natural History Museum from London that the pollution killed one out of two crabs per square meter.
A survey across four Cocos Islands and Henderson revealed the existence of open plastic containers with the opening pointed upwards in a manner that blocked the crab from leaving. The scientists counted the number of trapped crabs and extrapolated the data across 15 islands spread across the Cocos archipelago.
Plastic pollution threatens crabs in the Indian Ocean
The issue is complicated by the fact that hermit crabs will rely on the smell released by recently released crabs to track down new shells that can be occupied. Several crabs will get stuck in the same place. For example, 526 crabs were encountered in a single plastic container.
Hermit crabs don’t have their shells and will occupy free ones as long as they fit. When they die, a chemical is released, signaling that a shell is available. In some cases, this can lead to a lethal chain reaction.
These crabs play an important role in tropical areas since they disperse seeds and contribute to the fertilization of soils. A sharp decline could affect many ecosystems, and some may vanish altogether.
While the results are quite grim, they are not surprising as it was inevitable that some land creatures will be affected by plastic pollution.