Plankton assemblages in Alape river, Igbokoda in Ilaje local government area of Ondo state, Nigeria

The knowledge of plankton species composition and distribution to time and space are of great importance as reduction in plankton populations could lead to food unavailability for higher trophic levels (fish) in aquatic ecosystems. Phytoplankton are the most important primary producers and biological indicators in aquatic ecosystems. This study assessed plankton composition in Alape River, Ondo State. Water samples were collected from January to June 2022 from station I and II, were transported to the laboratory for qualitative and quantitative analysis of the monthly occurrence, distribution and abundance of phytoplanktons species. The results showed that annual mean percentage composition of different groups of phytoplankton contributed nearly 29.39% of chlorophyceae, 12.68% of bacillariophyceae, 46.4% of myxophyceae and 11.53% of euglennineae in Station I and 23.20% of chlorophyceae, 21.60% of bacillariophyceae, 33.60% of myxophyceae and 21.60% of euglennineae in Station II. The annual mean percentage composition of different groups of zooplankton showed that rotifera contributed 25.56%, cladocera 22.22%, copepoda 27.41% and protozoa 24.81% in Station I while rotifera contributed 25.56%, cladocera 22.22%, copepoda 27.41% and protozoa 24.81% in Station II. Thus, the study concluded that the dominance of plankton species such as phytoplankton (chlorophyceae, bacillariophyceae, myxophyceae and euglinae) and Zooplankton (cladocera, rotifera, copepoda and protozoa) as strongly showed that the river is eutropic. The study provides important baseline data on the composition and distribution of zooplankton in the Alape River, which can be used for future comparative studies and to monitor changes in the zooplankton community over time. There is a need for increased public awareness of the importance of plankton in aquatic ecosystems