Effects of Polystyrene Microplastics on Behavioural Response and Histopathology of Carassius auratus

The contamination of aquatic ecosystems by plastic waste is a major environmental challenge worldwide. Microplastics are small plastic particles having size ranging from 1 µm to 5 mm. Their ingestion has been detected in many aquatic organisms. In this study, the aim is to investigate behavioural responses and histopathological changes in the gills and gut of goldfish (Carassius auratus) following exposure to 10 mg/L of Polystyrene microplastics (PS-MPs, size: -5 um) for 28 days. Histopathological alterations were observed in the gills and intestine of the treated group. Significant alterations detected in the gills of the treated group include lamellar aneurysm as well as lamellar deviation, along with protrusion of the secondary lamellar epithelium and fusion of secondary lamellae. In the intestine, structural damage observed included broken villi, muscularis mucosa, and submucosa, along with enlarged goblet cells and detached epithelial layers. The behavioural changes observed in the treated group illustrated signs of distress, lethargic movement, and lack of appetite. Additionally, the fish showed impaired buoyancy control, making it difficult for them to maintain an upright orientation as well as positional control within the water column. The research revealed the physiological dysfunction resulting in fish by toxic effects of PS-MPs.