ABSTRACT
The physical and chemical parameters and evaluation of benthic macroinvertebrates of Owan River, Delta State, Nigeria was carried across three (3) stations showing the wet and dry seasons. Macroinvertebrates were sampled using modified kick sampling techniques. The results from the river showed that water temperature ranged between (28-28.5 °C), air temperature (21-28 °C), Depth (5.00-8.88m), Flow velocity (0.70-0.9m/s), Biochemical Oxygen Demand (0.60-2.30mg/L), Dissolved Oxygen (0.00 – 3.00 mg/L), pH (6.40-6.7), Turbidity (14- 39.0 NTU), Nitrate (2.61- 12.91 mg/L) and Sulphate (6.00- 2.3 mg/L). Physical and chemical parameters were within the allowable limits of USEPA for fresh water bodies. The overall taxa composition, distribution and abundance of macrobenthic invertebrates collected during the study period is presented in 27 taxa comprising of 236 individuals were recorded during the study. Haplotaxida accounted for 6.7%, Ephemeroptera accounted for 12.29%, Decapoda accounted for 2.9%, Hemiptera accounted for 1.69%, Hymenoptera accounted for 0.85%, Diptera accounted for 8.47%. Shannon Weiner’s index was used to calculate general diversity and showed that Station 3 had the highest diversity (2.215) followed by station 2 (2.119) and station 3 (1.209). The evenness index showed that maximum evenness was in station 3 (0.7632) and the minimum in station 1 (0.4786). From the coefficient correlation analysis, it was observed that the distribution and abundance of some benthic macroinvertebrates by changes in some physico-chemical parameters. 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.
