Impacts of polystyrene microplastics on the behavior and metabolism in a marine demersal teleost, black rockfish (Sebastes schlegelii)

After nano- (0.5 μm) or micro- (15 μm) polystyrene (PS) microplastics exposure, the behavior, metabolism and energy reserve in marine demersal fish (Sebastes schlegelii) were evaluated. The behavior of fish was accurately recorded by video behavior tracking technology. Results showed that changes in behavior (e.g. cluster, the reduction of swimming speed and range of movement) were significantly greater in 15-μm PS-exposed fish, which may affect hunting behavior and exploration competence. Oxygen consumption and ammonia excretion of fish was significantly greater in 15-μm PS treatment than in 0.5-μm PS treatment, suggesting respiration and metabolism stress. Moreover, the abnormal behavior, respiration and ammonia excretion of PS-exposed fish had recovered modestly. In addition, abnormal symptoms of bile, liver and lumen of intestine were detected in 15-μm PS exposure. Importantly, the growth and gross energy of fish were reduced in 15-μm PS exposure than 0.5-μm PS exposure. Both 0.5-μm and 15-μm PS exposures led to significantly lower protein and lipid contents, suggesting energy reserve and nutrition quality reduction of fish. Overall, microplastics had the negative impact at greater levels than nanoplastics. Altered behavior, energy reserve and nutritional quality of fish indicated the potential risk on biological functions, the development of fishery and food safety.