Composition, Diversity and Spatio-Temporal Variation of Zooplankton in Small Dam Lakes of Northern Côte d’Ivoire

Abstract

This study investigates the composition, diversity and spatio-temporal variation of zooplankton communities in five small reservoirs located in northern Côte d’Ivoire. Zooplankton sampling was conducted between June 2016 and June 2018 during both dry and rainy seasons using a 20-µm plankton net, while physicochemical parameters were measured simultaneously. A total of 74 zooplankton taxa were identified, dominated by Rotifera (51 species), followed by Cladocera (13 species) and Copepoda (5 taxa). Taxonomic richness was generally higher during the rainy season, whereas zooplankton density showed contrasting seasonal patterns among reservoirs. Higher densities were recorded during the dry season in Mambiandougou, Torla and Noumousso, while Sambakaha and Korokara exhibited higher abundances during the rainy season. Canonical correspondence analysis revealed that zooplankton distribution was mainly structured by electrical conductivity, total dissolved solids, dissolved oxygen and pH. The dominance of indicator genera such as Brachionus, Keratella and Filinia reflects high trophic levels. Despite their geographical proximity, the reservoirs exhibit distinct ecological functioning, driven by local environmental conditions and seasonal dynamics. Zooplankton therefore proves to be a relevant bioindicator for assessing the ecological quality of small tropical reservoirs.