[Accumulation and Clearance of Polystyrene Microplastics in Brine Shrimp and the Responses of Microbiome and Metabolism].

To investigate the accumulation kinetics of microplastics （MPs） with different characteristics in zooplankton and the related biological effects, the accumulation and clearance of polystyrene microplastics （PS-MPs） with different concentrations and particle sizes in brine shrimp （Artemiasaline） were analyzed under different nutritional conditions. The responses of microbial communities and metabolic functions in brine shrimp were revealed using the combination methods of microbiome and metabolome. The results showed that the accumulation and clearance rate of PS-MPs in brine shrimp increased with the increase in exposure concentrations, showing a concentration-dependent manner. On the contrary, the accumulation and clearance of PS-MPs in brine shrimp were negatively correlated with their particle sizes. The nutritional condition did not alter the accumulation kinetics of PS-MPs in brine shrimp, indicating that short-term feeding may have had no effect on the uptake and clearance of PS-MPs in brine shrimp. Compared to that in the control, exposure to PS-MPs significantly enhanced the diversity of the microbial community in brine shrimp. The proportions of Proteobacteria and Acinetobacter were increased by 0.4 folds and 12.3 folds, respectively, whereas the proportions of Firmicutes and Bacillus were decreased by 43% and 86%, respectively. This finding indicates that PS-MPs may have caused an imbalance of the bacterial community in brine shrimp by inhibiting the beneficial bacteria and stimulating the harmful bacteria, thus disrupting the metabolic function in brine shrimp. In addition, exposure to PS-MPs resulted in a production of 2 311 different metabolites in brine shrimp and mainly disrupted the pyrimidine metabolism and the biosynthesis of dermal sulfate/chondroitin sulfate in brine shrimp, leading to toxicity in the shrimp. The accumulation and biological effects of MPs with different characteristics in zooplankton may further affect the stability of aquatic systems, leading to unpredictable ecological risks.