Distribution spatio-saisonnière des cyanobactéries le long du cours d'eau, la Lobo, haut Sassandra (Daloa, Côte d'Ivoire)

Spatio-seasonal Distribution of the Cyanobacteria along the river stream, Lobo Haut Sassandra (Daloa, Ivory Coast). Cyanobacteria populations were studied through in situ records along the Lobo River, source of drinking water supply for the 261,789 inhabitants of the city of Daloa in Ivory Coast. .This environment is characterized by a an average depth of 5 m and an average temperature of 30ºC. This river is mostly influenced by human activities that favour the growth of aquatic plants by enrichment in nutrients. The nitrate concentration varied between 0 and 1.54 mg.l -1(NO3-) and phosphate concentration ranged from 0.001 to 0.71 mg.l-1 (PO43-). The analyzes of biological parameters carried out in six stations between September 2013 and June 2014 identified 13 taxa of cyanobacteria with a dominance of Oscillatoria sp. (OSSP) and Pseudanabaena sp. (PSSP) genera each representing 11%. Very little difference was observed between the cyanobacterial populations of each station. They proliferated more in the dry season than in the rainy season. The species Aphanocapsa sp. (APSP) presented a maximal density of 24.10³ cells. ml-1 on St5 station in dry season whereas in the rainy season it was only 5.10³ cells .ml-1 at the same location