Water quality assessment and genotoxicity in fishes of Karamana River, Kerala, India: An insight of microplastic pollution.

Microplastics are emerging pollutants of global concern, and their widespread presence poses a serious threat to aquatic and terrestrial ecosystems. The current study investigated water quality and the presence of microplastics in the water and native fish samples of the Karamana river, Kerala, India. Water quality was analyzed using various physicochemical parameters, including dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and more. Microplastics isolated from water and native fish samples were characterized using Fourier-Transform Infrared (FTIR) spectroscopy. DNA damage in the fish liver and gill cells was assessed using the comet assay (single-cell gel electrophoresis). The water quality assessment revealed that metals in water were within the acceptable limit, reduced DO, increased BOD, and COD, which indicated river water ecosystem in hypoxic conditions, and the higher level of the most probable number (MPN) index confirms the presence of coliforms in this river. The microplastics isolated from the water and native fish samples were in fibers, fragments, film, pellets, and foams in nature. The abundance of microplastics in the river confirms the load of microplastic pollution, which varies among the sites. FTIR spectroscopy analysis confirmed the presence of microplastic polymers such as polyethylene, polypropylene, polystyrene, polyamide, polyoxymethylene, and polyester in the water and native fish samples of the Karamana river. The increased % tail DNA in the liver and gill cells of the fish inhabitants of the Karamana river compared with the control fish, indicated the DNA damage; this could be due to the microplastics in that aquatic ecosystem.