Potential impacts of microplastic ingestion: Oxidative stress level in commercial fish from the Lagos Lagoon, Nigeria

Abstract

The presence of microplastics (MPs) in aquatic systems and the tissues of commercially available fish species poses risks and potential impacts on human health. While MPs have been reported in the surface water, benthic sediment, and edible fish species in the Lagos Lagoon, the possible effects of these contaminants on fish species have been lacking. This study aimed at providing vital information on MP contamination in the Lagos lagoon and highlighting the probable effects on the visceral organs of four fish species, Tilapia (Orechromis niloticus, n=16), Silver catfish (Chrysichthys nigrodigitatus, n=16), African knifefish (Gymnarchus niloticus, n=16) and African catfish (Clarias gariepinus, n=16). Gill, stomach, and liver of the sample specimen were examined for MP contamination and oxidative stress. MP accumulation in all the fish species differed but was detected in all tissues. The most abundant MP type was fibers (64%), followed by fragments (24%). Polyethylene, polychloroprene, polypropylene, and polystyrene were detected by Fourier transform infrared spectroscopy. Oxidative stress analysis of the fish tissues revealed significantly high antioxidant activities (p ≤ 0.05) and lipid peroxidation levels in the microplastic-contaminated tissues. Although this study highlights the possible effects of microplastics on wild fish species, extensive research is necessary to elucidate the cause-effect relationship of environmentally relevant microplastics on fish tissues to conduct as well as report associated risk assessments