Effects of ingestion of polyethylene microplastics on survival rate, opercular respiration rate and swimming performance of African catfish (Clarias gariepinus).

The study evaluated the impact of ingestion of microplastics on accumulation, survival, opercular respiratory rate (ORR), and swimming performance of Clarias gariepinus, the African freshwater catfish exposed to polyethylene microplastics. Juveniles were exposed for 4 days to 50-500 µm low-density polyethylene (LDPE) microplastics at four different concentrations (0.5, 1.0, 1.5, and 2.0 g/L). After 4 days of exposure, the concentration of microplastics in the gastrointestinal tract (GIT) of the fish increased with increasing concentrations of microplastics. Mean weights of microplastics in the GIT of the fish ranged from 0.0025 ± 0.001 g to 0.054 ± 0.01 g, suggesting that the fish were unable to detect and avoid ingesting the microplastics. No mortality was observed in all the treatment concentrations except in the highest concentration (2 g/L) where 10% mortality was observed. The results showed that ORR increased in a concentration and time-dependent manner. Compared with the control group, the swimming speed, travel distance and movement patterns of the fish exposed to microplastics were significantly reduced (p < 0.05). Therefore, this study helps understand the environmental impact of microplastics on C. gariepinus in freshwater environments.