Benthic macro-invertebrates of Asejire reservoir, Southwest Nigeria

Abstract

A survey of the benthic macro-invertebrate fauna of Asejire Reservoir, Southwest Nigeria was carried out for two years to provide information on the occurrence, distribution and abundance of the benthic macro-invertebrates of the reservoir. Twenty sampling stations were established in the reservoir and sediment samples were collected from each station at bimonthly intervals using an improvised Van-veen grab. Data obtained was subjected to descriptive statistics and various biodiversity indices. A total of 364,351 individual macro-invertebrate specimens were collected. The fauna comprised of twenty-eight species. These was composed of the class Insecta (13 spp), Gastropoda (9 spp) and Bivalvia (2 spp), while Arachnida, Malacostraca, Hirudinea and Gordiadea comprised one species each. Potadoma moerch (32.9%), P. freethi (18.3%) and Melanoides tubaculata (9.0%) were the dominant species accounting for more than 60% of the recorded individuals’ species while the least occurring species were Sphaerium sp (0.2%) and Hydracarina sp (0.4%). Asejire Reservoir can be inferred to be rich quantitatively and qualitatively in benthic macro-invertebrate fauna based on occurrence and abundance of species recorded during this study.