Quantitative analysis of planktonic biota of Owalla Reservoir, Osun State, Nigeria

Abstract

To provide baseline data on the phytoplankton flora and zooplankton fauna of Owalla Reservoir, Osun State, Nigeria, the planktonic community of the reservoir were examined. The research was conducted in seven sampling stations over the course of one annual cycle, from October 2012 to November 2013. Samples were taken every three months. 50 L of water were filtered through a 50 µm-mesh plankton net at the designated locations to get a net plankton sample. After reducing the volume of water to 30 ml, it was preserved in 5% formalin. Under a light compound microscope, the preserved net plankton samples were examined and both descriptive and inferential, were used to analyze the collected data. From the sample stations, 39 species of net zooplankton and 109 species of net phytoplankton were identified. Twelve species of Cyanophyta, eight species of Euglenophyta, three species of Dinophyta, two species of Rhodophyta, one species of Haptophyta, and twenty-two species of Bacillariophyta made up the phytoplankton flora. Respectfully, Rotifera > Cladocera > Copepoda > Insecta > Protozoa represented the zooplankton fauna. While zooplankton dropped approaching the dam area, the mean abundance of most phytoplankton groups increased along the reservoir's horizontal pattern of fluctuation. Additionally, the dry season was associated with a higher quantity of planktonic biota. In conclusion, Owalla Reservoir has a high biodiversity of phytoplankton and zooplankton, which is necessary for the survival of aquatic life and the production of fisheries.