Macroecological Studies, Morphometric and Parasite Fauna in Margaritifera Margaritifera in Coastal Zone of Niger Delta Bayelsa State

Abstract

A cross-sectional study on macroecology, morphometric and parasite fauna of M. maragritifera was carried out between the months of June to November, 2018. The aim was to determine the macroecology, morphometric and host-parasite relationship in M. magaritifera in Nun River Peremabiri, Southern Ijaw, Bayelsa State, Nigeria. A total of 442 mussels were sampled from Nun River using underwater diving. The morphometrics of the mussles involving shell length, shell height, shell breadth were measured using viernier caliper and the mass involving shell mass, total mass, and shell free dry mass were measured using weighing balance. The mussels were dissected and the various organs squashed and a wet mount carried out for parasite demonstration under light microscope. Physico-chemical analysis of the water sample was carried out each time the field was visited to determine the 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 seasons 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, 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. margaritifera occurred highest in November ∑-Pi Log Pi= -0.010, while the month of 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 = 1.22L0.14, W = 1.58L0.03, W = 1.81L0.11, W = 1.92L0.1, W = 1.91L0.136, W = 1.88L0.07 respectively. The slope “b” of regression across the months for growth determination using shell- weight (SL-W) relationship 0.03, 0.26, 0.68, 0.61, 0.59, and 0.59 were less than 3, showing a negative allometric pattern of growth. The values of ‘K’ obtained for the mussel were 0.001, 0.112, 0.295, 0.264, 0.256, and 0.256 correspondingly. The coefficient of determination (r2) of growth ranged between 0.007 (0.7%) and 0.401 (40.1%) variability for model and goodness of fit. Principal Component analysis of M. margaritifera showed a pronounced dimension in variability of morphological data (shell elongation 54.5% ellipsis category and shell inflation 45.4% Ellipsis category), (shell elongation - shell inflation 52.6% Ellipsis category and shell angle 47.4% Ellipsis category). Microscopic examination of the crushed digestive gland of M. margaritifera showed the presence of oocysts and gematocytes of Namatopsis sp. The parasite had a prevalence rate of 0.45 %, relative abundance of 2.00 and mean intensity of 009.