Trophic transfer and bioaccumulation of nanoplastics in Coryphaena hippurus (Mahi-mahi) and effect of depuration

Ocean plastic pollution is a global concern, exacerbated by the distinctive physiochemical characteristics of nanoplastics (NPs), making it crucial to study the impacts on marine animals. While most studies focus on the impacts of waterborne NP exposure, trophic transfer is another key transport mechanism that may also provide insight into the potential transfer of NPs to humans through the food chain. This study investigates polystyrene NP transfer to Coryphaena hippurus (mahi-mahi) larvae, a widely consumed fish and significant marine predator, during the early life stage. Using a two-step food chain, Brachionus plicatilis (rotifers) were exposed to NPs, and subsequently fed to C. hippurus larvae, with exposure durations ranging from 24 to 96 h. Significant NP transfer was observed via the food chain, varying with exposure duration. A depuration study over 72 h, simulating environmental intermittent NP exposure, revealed substantial NP excretion but also notable retention in the larvae. Biodistribution analysis indicated that most NPs accumulated in the gut, with a significant portion remaining post-depuration and some translocating to other body parts. Despite no significant effects on body length and eye diameter during this short study period, histopathological analysis revealed intestinal tissue damage in the larvae.