Hermit crabs are making homes in plastic waste and it’s killing them

  Last updated December 18, 2019 at 2:13 pm

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An estimated half a million hermit crabs have been killed by plastic waste on some of the most remote islands in our oceans.


plastic waste_plastic pollution_hermit crabs

Hermit crabs are crawling into plastic bottles which they can’t climb out of. Credit: Institute for Marine and Antarctic Studies.




Why This Matters: Our plastic waste is slowly destroying even remote areas.




It’s known that plastic pollution has devastating effects on marine environments. Now, a first of its kind study shows the direct impact plastic pollution is having on hermit crabs on some of the most remote islands in our oceans.


A team of researchers, led by The Institute for Marine and Antarctic Studies (IMAS) estimates that more than 560,000 hermit crabs have been killed on the Cocos (Keeling) Islands in the Indian Ocean, and Henderson Islands in the Pacific, after being trapped in plastic debris.


The study, which is published in the Journal of Hazardous Materials, was carried out by the same researchers who previously revealed that Cocos and Henderson islands are littered with millions of pieces of plastic.




Deeper: Plastic waste has trashed one of Australia’s most remote islands




Plastic pollution is a deadly trap for crabs


The hermit crab study found that piles of plastic pollution on beaches create both a physical barrier and a series of potentially deadly traps for crabs.


IMAS’s Jennifer Lavers, who led the studies, says that while considerable attention had been given to plastic pollution in the marine environment, little research had been done into the risk that marine pollution poses to wildlife.


“When we were surveying debris on the islands, I was struck by how many open plastic containers contained hermit crabs, both dead and alive,” she says.


“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.


“Our calculations show more than 500,000 hermit crabs died from being trapped in containers on the Cocos (Keeling) Islands and 60,000 on Henderson island.


“These results are shocking but perhaps not surprising, because beaches and the vegetation that fringes them are frequented by a wide range of wildlife.




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“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.”


Cocos Keeling Islands plastic waste accumulation

Beach debris along the north side of Direction Island which is apart of the Cocos Keeling Island group. Credit: Silke Stuckenbrock


Hermit crab losses globally will impact ecosystems


Lavers says marine plastic is a problem worldwide, and comparable hermit crab losses on a global scale would have important implications for ecosystems.


“High concentrations of debris are now being encountered on beaches around the world, many of which are also home to hermit crabs that can be expected to interact with plastic pollution in the same way as those we studied.


“Hermit crabs play a crucial role in the health of tropical environments by aerating and fertilising soil, and dispersing seeds and removing detritus, as well being a key part of the marine ecosystem.


“Their population degradation is more than just a risk to the natural environment.


“They are also an important part of marine ecosystems that humans rely on for fishing, recreation and tourism, so ultimately the impacts may also be economic.


“Our study is the first to document the mortality of hermit crabs due to beach debris, but the broader global picture remains unknown,” Lavers explains.


The researchers do suggest that the mortality of hermit crabs on beaches across the world is likely to be substantial.


“Further investigation is required to inform a broader understanding of the scale and implications of their losses,” Lavers says.


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