RESUMEAu Cameroun, les rivières sont soumises à des perturbations physiques et chimiques qui sont à l'origine d'une dégradation croissante de la qualité d'eau. La présente étude évalue l'impact des caractéristiques physico-chimiques des eaux sur la distribution et l'abondance du phytoplancton et des macrophytes V. D. TAFFOUO et al. / Int. J. Biol. Chem. Sci. 11(4): 1766-1784, 2017 1767The impact of physico-chemical characteristics of water on the distribution of phytoplankton and macrophytes of Nkam River (Cameroon) ABSTRACTIn Cameroon, the rivers are subject to physical and chemical disturbances that are causing an increasing degradation of water quality. The present study was undertaken to assess the impact of the physico-chemical characteristics of water on the distribution and abundance of phytoplankton and macrophytes at the Nkam River. Floristic inventories were carried out on the basis of coefficient of abundance-dominance and sociability of Braun-Blanquet. The physical parameters [(pH, temperature, dissolved oxygen, electrical conductivity (COND) and total dissolved solid (TDS) were measured in situ. The chemical parameters (nitrates (NO 3 -), phosphates (PO 4 2-), biochemical demand in oxygen (DBO5) were analyzed at the Soils, Plants, Fertilizers and Water Laboratory of the Institute of Agronomic Research for Development, Yaoundé, Cameroon. 32 species of macrophytes were found in 19 families. The most abundant family was Poaceae (6 species) followed by Asteraceae (5). An inventory of the phytoplanckton found a total of 80 taxa distributed in 58 genera and 14 families. The Diatomophyceae was the most abundant with 25 taxa followed by the Cyanobacteriaceae (18)