International Science Community Association International Research Journal of Environmental Sciences 2319-1414 9 4 2020 10 22 Assessment of the Temporal and Spatial Variability in the Phytoplankton Dynamics of a Tropical Alkaline-saline Lake Simbi, Kenya 14 23 EN K.M. Harishma 1 Division of Forest Botany, Kerala Forest Research Institute, Peechi 680 653, Kerala, India S. Sandeep 2 Division of Forest Botany, Kerala Forest Research Institute, Peechi 680 653, Kerala, India V.B. Sreekumar 3 Division of Soil Science, Kerala Forest Research Institute, Peechi 680 653, Kerala, India Gwambene Brown 1 Marian University College, Bagamoyo, Tanzania Opiyo Stephen Balaka 1 Department of Natural Resources and Environmental Sciences, Faculty of Agriculture and Natural Resources Management, Kisii University, P.O Box 408-40200, Kisii, Kenya > Research Paper 2020 3 29 2020 10 22 This study evaluated the phytoplankton dynamics of abundance, species composition and diversity across spatial and temporal scales in Lake Simbi for the period between December 2018 and May 2019. This was necessary, considering the significance of phytoplankton communities in this lake for conservation and ecological role. Sampling was done on a monthly basis for 6 months at six fixed stations systematically selected. A total of 84 phytoplankton species were identified comprising of Cyanophyceae (36 species), Chlorophyceae (25 species), Bacillariophyceae (11 species), Zygnematophyceae (4 species), Dinophyceae (3 species) and Euglenophyceae (3 species). Although, the Cyanophyceae family still dominated in Lake Simbi, a shift in the species composition was realized and this can be probably attributed to the changes in the water quality regime of the lake. The results showed a high phytoplankton density in the lake due to its eutrophic nature. However, reduced abundance of the cyanobacterial species, especially Spirulinaspecies on which flamingos feed and the subsequent dominance of the toxin producing Microcystis species might have contributed to the decline of the flamingo population. All the phytoplankton characteristics of density and diversity indices evaluated in Lake Simbi exhibited no significant spatial and temporal variations. Generally, activities that help to improve and maintain ecosystem integrity need to beadopted by all stakeholders to promote sustainability of all aquatic resources in Lake Simbi. Copyright@ International Science Community Association