Effect of Microplastics on Water Quality and Oreochromis Niloticus (Nile Tilapia) In Jakara River, Kano State, Nigeria
Abstract
Microplastic contamination has emerged as a significant threat to freshwater ecosystems globally, yet data from African water bodies remain critically limited. This study assessed the occurrence of microplastics and their effects on water quality and oxidative stress responses in Oreochromis niloticus from Jakara Reservoir, Kano State, Nigeria. Physicochemical parameters including temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), total dissolved solids (TDS), electrical conductivity, turbidity, pH, phosphate-phosphorus, and nitrate-nitrites were analyzed across four sampling sites (A-D). Microplastic polymers (PET, PP, PVC, PA, PS) were identified in both surface water and fish tissues (gills and liver) using FTIR spectroscopy. Oxidative stress biomarkers—superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (LPO)—were measured in gill and liver tissues. Results revealed significant spatial variation in water quality parameters, with several parameters exceeding FAO/WHO guidelines, particularly TDS (733.8±1.40 mg/L), electrical conductivity (1064±0.16 µS/cm), turbidity (38.9±0.001 NTU), nitrate-nitrites (11.50±0.74 mg/L), and phosphate-phosphorus (3.11±0.01 mg/L). Microplastic abundance in surface water ranged from 10-45 particles per site, with PET and PP being most prevalent. Fish from Site D showed the highest microplastic accumulation (35 particles in gills, 13 in liver). Significant oxidative stress was observed, with maximum SOD (4.65±0.78 U/mg prot.) and CAT (95.11±0.01 U/mg prot.) activities in gills at Site C, while liver LPO peaked at Site D (2.36±0.01 nmol/g). Correlation analysis revealed significant positive relationships between MPs and DO (r=0.794), turbidity (r=0.789), phosphate (r=0.711), and nitrate (r=0.732), with a strong negative correlation with TDS (r=-0.839). These findings demonstrate that microplastic pollution in Jakara Reservoir is associated with water quality degradation and oxidative stress in O. niloticus, posing risks to aquatic ecosystem health. It is therefore recommended that appropriate measures should be taken to curtail the menace that could disrupt this aquatic ecosystem in the long run.