The Effects of Different Concentrations of Microplastics on the Physiology and Behavior of Sebastes schlegelii

This study investigated the toxic effects of 0-1 mg/L polystyrene microplastics (0.5 μm) on juvenile Sebastes schlegelii through a 24-day indoor exposure experiment. The results showed that the exposure group of ≥ 0.1 mg/L induced significant physiological damage, and the liver antioxidant system showed dynamic imbalance (SOD activity first increased and then decreased, CAT activity was inhibited by 30-50%), and the accumulation of lipid peroxidation product MDA reached 200%; Immunosuppression manifests as a 20-35% decrease in lysozyme activity and a significant increase in the concentrations of pro-inflammatory cytokines TNF - α and IL-6; The survival rate of the high concentration group (1 mg/L) decreased to 82%, and the weight gain rate decreased by 40%. At the behavioral level, the contradictory response induced by microplastics was revealed for the first time: individual swimming speed decreased by 35-50% (significantly correlated with 30% inhibition of acetylcholinesterase activity, P<0.05), while at the population level, defensive clustering was quantified by nearest neighbor distance (NND) and inter individual distance (IID), showing a 40% reduction in IID in the high concentration group, (P<0.05). But the group polarity (PP) decreased by 50% (P<0.05), and the exposed motor coordination was severely impaired. The results indicate that microplastics, at concentrations ≥ 0.1 mg/L, simultaneously disrupt individual functions and group behavioral adaptability through a dual mechanism of oxidative damage and neurotoxicity.