Effects of environmentally relevant polystyrene microplastics and cadmium on the development and reproduction of rare minnow (Gobiocypris rarus)

Microplastic pollution is widespread in the natural environment, and its enrichment, inherent adsorbability, and toxicity are key concerns in society. However, few studies of the effects of microplastic toxicity on the reproduction of fish have been reported. In this study, we investigated the effects of exposure to environmentally relevant concentrations of polystyrene microplastics (PS) and cadmium (Cd) alone and in combination for 28 days on the gonad development and reproduction of rare minnow (Gobiocypris rarus). Decreased condition factor, number of spawning events, number of eggs per spawning, and average hatching rate were detected in fish in the treatment groups. These changes were likely due to long-term oxidative stress and inflammation, which inhibited the development of gonads and further affected the reproduction function of rare minnow. The effects of treatment on oxidative stress, inflammation, and expression of genes related to gonad development differed between female and male fish in the treatment groups. PS alone exposure resulted in a significant reduction in the number of eggs per spawning and average hatching rate, but these effects were not observed in the Cd and PS + Cd groups. These results provide new insights into the ecotoxicological effects of microplastics in the natural environment.