Investigation of Microplastics Contamination in African Catfish Clarias gariepinus and Nile Tilapia Oreochromis niloticus Fish Species in Owe River Ile-Oluji, Ondo State, Nigeria

Abstract

The primary aim of this study is to investigate the presence of microplastics (MPs) contamination in surface water and two fish species (Clarias gariepinus and Oreochromis niloticus) in Owe River. One Litre (1 L) of water samples were collected from four different locations along the river in triplicates, samples were digested to remove organic matters. Eighteen (18) numbers of fishes were collected for each species. Samples collected were dissected and the guts excised were digested with 10% Potassium hydroxide and 10% Hydrogen Peroxide. Both digested water and fish samples were filtered using 0.45µm membrane through a vacuum filtration apparatus. The filter papers were then observed under digital microscope (1600X RoHS China) for MPs identification.  MPs were classified into colours and shapes. A total of 104 items was found in the gut of both fish species with an average of 4.33 ± 1.71 and 1.44 ± 0.70 items/individual for Clarias gariepinus and Oreochromis niloticus respectively. Fiber was seen to be dominant in fish species compared to other MPs shapes identified.The abundance of MPs in the water samples ranged from 203 ± 50.64 to 724.33 ± 129.89 Items/L with a total of 1898± 198.34 Items/L. Most of the recovered MPs from river water samples were fragments. Attenuated total reflectance– Fourier transform infrared (ATR – FTIR) spectroscopic analyses led to the identification of four (4) plastic polymer types, with polyethylene (PE) and polypropylene (PP) jointly constituting 82 % of the plastic particles. The enormous anthropogenic activities and indiscriminate disposal of plastic themed wastes along the river course are notably contributing factors to the MPs contamination of Owe River. A serious monitoring of waste disposal and necessary mitigation process is advised.