Microplastic Bioaccumulation and its Systemic Effects in Labeo rohita: From Cellular Damage to Behavioural Disruption

Microplastics (MPs) are emerging contaminants of global concern due to their potential to disrupt physiological and biochemical functions in aquatic organisms. This study investigated the effects of polyethylene (PE) microplastics on Labeo rohita, a commercially important freshwater carp. Fingerlings (25 ± 2 g) were exposed to 0 (control), 1, 3, and 5 mg/L PE microplastics for 60 days, followed by a 30-day recovery period in clean water. Microplastic accumulation was quantified in gill, liver, and intestine, and impacts on tissue biochemistry (carbohydrates, proteins, lipids), antioxidant enzyme activities (SOD, CAT, GST), micronucleus formation, and behavioural responses were assessed. Results revealed dose-dependent reductions in carbohydrate, protein, and lipid levels, significant decreases in antioxidant enzyme activities, and a marked increase in micronuclei frequency at higher concentrations, indicating oxidative stress and genotoxicity. During recovery, proteins and carbohydrates largely returned to baseline, whereas lipid content, antioxidant enzymes, and micronucleus frequencies showed partial restoration, especially at higher exposure levels. These findings demonstrate that PE microplastics induce metabolic disruption, oxidative stress, and genomic instability in L. rohita, with recovery being incomplete at elevated concentrations, highlighting potential ecological and aquaculture risks.