When it comes to moving home, hermit crabs are experts, often swapping shells for the optimal abode. But now researchers have found that exposure to microplastics disrupts this key behaviour. The finds are the latest to suggest such pollution could be having an impact on the world’s marine creatures. “Usually a so-called ‘normal’ hermit crab will always want to go for the better shell,” said Dr Gareth Arnott, co-author of the new research from Queen’s University Belfast, adding such shells are typically those of sea snails.
Arnott and his colleagues placed 29 female hermit crabs in a tank containing seawater, seaweed and 4mm-diameter polyethylene beads, at a concentration akin to levels found in the environment. Another 35 female hermit crabs were placed in a similar tank, but without the polyethylene beads. The team found that 25 of the crabs who had not been exposed to the microplastics explored the optimal-sized shells, with 21 of the crabs – 60% – taking up residence in them. By contrast, crabs that had been exposed to microplastics took longer to begin such exploration and far fewer did so: just 10 made contact with the optimal-sized shells and only nine – 31% of the group – moved home. This suggests exposure to microplastics affects the shell selection behaviour of hermit crabs,
the team say, indicating that pollution could be affecting cognition.
“We hypothesize that either some aspect of the polyethylene is getting into them to affect their decision making, or else it is an indirect effect that the presence of the plastic in the tank might be influencing their feeding behaviour, for example,” Arnott said. He added that the study only looked at hermit crabs, and it will be important to explore whether the behavioural changes observed in the laboratory are seen in the wild and have real-world implications.
Source: Guardian
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