Trophic transfer of microplastics does not affect fish personality

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Microplastics are ubiquitous in the marine environment. Their small size makes them bioavailable to a range of organisms and studies have reported ingestionacross the food chain. Few studies have demonstrated physical transfer of microplastics between organisms, and no research has assessed the ecological impacts of transferred microplastics and contaminants over different trophic levels. Contaminants associated with plastics can alter animal behaviour; thus, exploring changes in behaviour may be fundamental in understanding ecosystem effects of microplastics. This study explored the effects of microplastics and associated contaminants through the food chain in the marine intertidal zone. We exposed beach hoppers, Platorchestia smithi, to environmentally relevant concentrations of microplastics and then fed them to Krefft's frillgobies, Bathygobius krefftii, ray-finned fish that inhabit shallow coastal ecosystems. We tested fish personality to see whether there were any changes that could be attributed to trophic transfer of microplastics, as even subtle changes in behaviour can have cascading effects on other organisms and the wider ecosystem. Exploring behavioural changes in response to contaminant exposure is a developing area in ecotoxicology due to its increased sensitivity compared with the traditional LD50 approach. While gobies readily ingested contaminated beach hoppers, we detected no effect of microplastic trophic transfer on fish personality relative to control groups. While chronic exposure studies assessing a suite of behaviours are required, it is possible that the transfer of microplastics via trophic interactions does not provide an additional exposure pathway for contaminants through the food web.