Physico-chemical assessment of Lotic Nun River, and Abundance of its Margaritifera margaritifera

A cross-sectional study on lotic Nun River Peremabiri, Bayelsa State, Nigeria was carried out between the months of June to November, 2018. The aim was to determine the physico-chemical parameters of the River and its mussel abundance. A total of 442 mussels were sampled for the study. Physico-chemical analysis was carried out on the water sample to determine the depth, water velocity, turbidity, hydrogen ion concentration (pH), biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO) and alkalinity, phosphate and nitrate. The pH range recorded in this study was (7.530 – 8.990). Turbidity value obtained in wet season was (3.32 NTU) and (0.010 NTU) for dry season. The alkaline concentrations for wet and dry seasons were 180.3 mg/L and 181.37 mg/L respectively. Dissolved oxygen for wet and dry seasons were 2.654 mg/L and 3.16 mg//L, while the concentration obtained for nitrate in wet and dry season were 0.896 (mg/L) and 1.838 mg/L likewise. Biological oxygen demand (BOD) recorded in wet and dry season were 78.32 mg/L and 81.55 mg/L correspondingly. The chemical oxygen demand (COD) obtained in wet and dry seasons were 159.35 mg/L and 126.35 mg/L respectively. The COD/BOD ratio obtained for wet and dry season were 2.03 and 1.54 likewise, while the phosphate concentration obtained was 0.0065 mg/L and 0.0082 mg/L for wet and dry seasons. Also, the nitrogen concentration recorded for wet season and dry season were 0.202 mg/L and 0.2185 mg/L respectively. Diversity in M. magaritifera occurred highest in November (∑-Pi Log Pi= -0.010), while the month July had the least diversity (∑-Pi Log Pi= -0.133) at (P> 0.05). Growth performance index showed November had the oldest M. margaritifera recorded (66 yrs) and June had the least age recorded (3 yrs). The length-weight of the mussel for the month June – November were, W = 1.22L^0.14, W = 1.58L^0.03, W = 1.81L^0.11, W = 1.92L^0.1, W = 1.91L^0.136, W = 1.88L^0.07 respectively.

Key words: Physico-chemical parameters, Abundance, growth performance in index.