Plastic leachates induce appetitive response in the helmet crab Telmessus cheiragonus

Plastic has now been widely recognized as a prevalent, ubiquitous and consistently increasing source of pollution. The extent of this pollution is such that plastics are now considered as a threat to both terrestrial and aquatic environments, the economy and human well-being on a global scale. Beyond the widely acknowledged ingestion and subsequent damages related to the ingestion of plastic debris, a growing body of literature focuses on the various effects of plastics additives that are released in seawater, including on the chemosensory abilities of a range of invertebrates such as gastropods, mussels, hermit crabs, fish and seabirds. In this context, the objective of the present work was to assess the effects of leachates from conventional polymers (polypropylene (PP), polyethylene (PE) and polyamide (PA)), bio-sourced and biodegradable polymers (polylactic acid, PLA) and surgical masks on the feeding responsiveness of the helmet crab Telmessus cheiragonus. Using a sponge feeding assay, we show that PP and PE leachates did not impact T. cheiragonus feeding response. In contrast, leachates from PA, PLA and masks stimulated a feeding response similar to the one elicited by the chemical cues of a prey. Interestingly, the response to both leachates and prey cues did not exhibit any significant difference with the response to prey cues only. These results indicate a polymer-specific effect of plastic leachate on T. cheiragonus feeding response and an absence of any synergistic or antagonistic effects with the chemical cues from a prey. The observed short-term effects of plastic leachates are discussed in the context of their potential long-term implications on the ecology of T. cheiragonis in particular and decapods in general.