Planktonic flora and fauna of Opa Reservoir wetlands, Obafemi Awolowo University, Ile-Ife, Nigeria

Abstract

Abstract Background Wetlands are transition zones between aquatic and terrestrial environments of Opa Reservoir Obafemi Awolowo University, Ile-Ife, Nigeria, threatened by increase in agricultural practices and urbanization within the catchment area. A critical appraisal of the current ecological integrity of the wetlands using planktonic composition and community structure which are formidable to sustaining wetlands is essential, hence this study. Result A total of 104 plankton species comprises of 68 species of phytoplankton and 36 species of zooplankton were recorded from the wetlands. In each sampled location and during the sampling period, Bacillariophyta had the highest occurrence among the phytoplankton, while Rotifera recorded the highest occurrence among the zooplankton. Generally, Synedra ulna and copepod (cyclopoid) Nauplius, respectively, were the most common phytoplankton and zooplankton recorded during the period of study. Analyses also showed that the phytoplankton had a higher species occurrence and abundance (65.3% and 98.18%, respectively) than the zooplankton (34.6% and 1.82%, respectively). Diversity indices (Shannon–Wiener, Margalef, and Simpson) analyses of both plankton groups revealed that the wetlands were generally polluted. Conclusion The study concluded that the ability of the wetlands to support and maintain a balanced adaptive community of plankton with species composition and diversity is being eroded due to anthropogenic activities in the wetland areas. This could have some ecological and socioeconomic implications considering the fact that they are intrinsically a part of the adjoining reservoir which provides many ecosystem services.