Evaluation of some Physicochemical Parameters and Benthic Macroinvertebrates of Ikere Gorge Reservoir in Oyo State, Nigeria

The physico-chemical parameters and benthic macroinvertebrates of Ikere Gorge Reservoir were studied to assess the impact of anthropogenic activities on this man-made lake by collecting surface water and benthic samples. Physico-chemical parameters were within the allowable limits of USEPA for fresh water bodies apart from conductivity (0.055 ± 0.002μS/cm) which was below standard. There were significant differences (p 0.05) in the mean values of DO, BOD, TDS, transparency, nitrate and sulphate between the sampling stations. A total of six genera (Chironomus, Melanoides, Cloeon, Bulinus, Bellamya and Hirudo) of benthic macro-invertebrates belonging to six orders (Diptera, Pelecypoda, Ephemeroptera, Heterobranchia, Caenogastropoa and Hirudinida) were recorded in the reservoir during the study. Pollution tolerant species including Melanoides tuberculata and Chironomus sp. dominated the benthic macroinvertebrates with a total number and percentage abundance of 674(56.88%) and 435(36.71%), respectively. Ikere Gorge Reservoir is relatively under stress due to dominance of indicators of pollution.