ABSTRACT
The sediment characterization and evaluation of benthic macroinvertebrates community in Obazuwa lake was carried out for 6 months across 3 stations from March 2019 through August 2019. The heavy metals of the sediment were analyzed and studied and they include, Iron (Fe) (597.20–3219.80 mg/kg), Copper (Cu) (4.00 – 43.50 mg/kg), Manganese (Mn) (22.50 –55.60), Lead (Pb) (0.15 – 4.00 mg/kg), Cadmium (Cd) (0.00–0.30 mg/kg), and Zinc (Zn) (22.49–107.50mg/kg) and also the Particle size distribution and Organic content (% organic carbon and % organicmatter) were also analyzed. A total of 9 macro-invertebrate taxa were encountered during the study period which comprises: 2 species of Coleoptera accounted for 78%, 1 species of Ephemeroptera accounted for 8%, 1 species of Hemiptera accounted for 1%, 2 species of Diptera accounted for 8%, 1 species of Oligochaeta accounted for 2%, 1 species of Mollusca accounted for 2%, 1 species of Amphibia accounted for 1%. The species richness for the three stations using Margalef’s index showed that station 2 had the highest species richness (1.443) and station 3 had the lowest (1.251). Shannon Weiner’s index showed that station 3 had the highest diversity (1.169), followed by station 2 (0.6931), then station 1 (0.664). The evenness index showed that maximum evenness was in station 2, and minimum in station 1 (0.2775). Coleoptera was found to be highly positively correlated with Iron (Fe) (0.623). Ephemeroptera was found to be positively correlated with Iron (Fe) (0.496). Mollusca was found to be highly positively correlated with Lead (Pb) (0.685). Factors which influenced the abundance and distribution of the benthic macroinvertebrates includes the nature of the water body, habitat richness and stability, immediate substrate of occupation, the heavy metal composition, anthropogenic activities, tropic condition, resource partitioning and predation.
