Chronic poly(l-lactide) (PLA)- microplastic ingestion affects social behavior of juvenile European perch (Perca...

Juvenile perch were exposed to 2 % (w/w) poly(l-lactide) (PLA) microplastic particles (90-150 μm) in food pellets, or 2 % (w/w) kaolin particles, and a non-particle control food over 6 months. Chronic ingestion of PLA microplastics significantly affected the social behavior of juvenile perch, evident as a significantly increased reaction to the vision of conspecifics. PLA ingestion did not alter life cycle parameters, or gene expression levels. In addition to reactions to conspecifics, fish that ingested microplastic particles showed tendencies to decrease locomotion, internal schooling distance, and active predator responses. The ingestion of natural particles (kaolin) significantly downregulated the expression of genes related to oxidative stress and androgenesis in the liver of juvenile perch, and we found tendencies to downregulated expression of genes related to xenobiotic response, inflammatory response, and thyroid disruption. The present study demonstrated the importance of natural particle inclusion and the potential behavioral toxicity of one of the commercially available biobased and biodegradable polymers.