Microplastics appear to disrupt the ability of hermit crabs to choose a good home, suggesting pollution in the oceans may harm the species.
Up to 10 per cent of the plastics we use end up in the oceans. Much of it breaks down into tiny particles,聽known as microplastics, which are bad news for marine life. When ingested by filter feeders, fish and other organisms, they can have detrimental effects on health and reproductive success. But few studies have explored how microplastics might influence behaviour.
A key decision for hermit crabs is choosing when to abandon their shell and move into a new, bigger one. If microplastics in the water influence the crabs鈥� cognition you would expect them to take longer to move into a better shell and change shells less often.
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To test this idea, Andrew Crump and colleagues at Queen鈥檚 University Belfast took 64 hermit crabs from around the Antrim coast of Northern Ireland, half of which were left for five days in a 4 litre tank containing 50 grams of microplastics. The team removed each crab from its shell, gave it one that was 50 per cent too small, and placed it in an observation chamber with an empty shell of just the right size.
Crabs exposed to the microplastics were around half as likely to enter the new shell after 45 minutes as those not exposed. 鈥淢aybe microplastics reduced their ability to sense the shell,鈥� says Crump, who presented the research at a conference of the , Germany, last month.
The impact in the wild may not be as drastic as seen in the experiments, as the concentration of microplastics Crump and his team used was much higher than in the natural environment.
However, Yiftach Golov from Tel-Aviv University says that in the wild, microplastics absorb organic pollutants and heavy metals, which were not present in the study. 鈥淭hat would give even more striking results,鈥� he says.
