Exposure to polystyrene microplastics impairs gonads of zebrafish (Danio rerio)

Microplastic contamination poses a great threat to the health of aquatic species, which may affect their reproduction and result in ecological consequences. There is a need to further elucidate the potential impact microplastics can impose on aquatic species. In this study, the effects of exposure to polystyrene microplastics on reproductive organs, and the underlying response mechanisms, were investigated using zebrafish Danio rerio. After 21 days of continuous waterborne exposure, no significant difference was observed at the lower concentration of 10 μg/L. At concentrations above 100 μg/L, significantly enhanced reactive oxygen species (ROS) level was found in both male and female liver and gonads. At the concentration of 1000 μg/L, significantly increased apoptosis levels were observed in male testes, triggering increased expression of p53-mediated apoptotic pathways; histological alteration in the form of a significant decrease in testis basement membrane thickness was also observed. This study demonstrated that exposure to microplastics can induce molecular responses and histological alterations in fish gonads, implying potential adverse impact on fish reproductive organs. This work provided new insights on the reproductive damage microplastics can cause in fish and have implications in fields of freshwater ecology and environmental toxicology.