Etude des peuplements des cyanobactéries au niveau des eaux du barrage Mexa -EL TARAF

Abstract

Our study focused on the inventory and identification of cyanobacteria inhabiting the waters of the dam Mexa (Fl-Tarf) and determination of physicochemical characteristics may cause of control the growth of cyanobacteria, and the assessment of level of eutrophication The dam was sampled from ló April to 5 May 2011 at three stations. The results of measurements of physical-chemical parameters of water show a variation throughout the study period and the 3 stations. These have a correlation with the density of cyanobacteria. The chlorophyll (a) identified is consistent with the densities of listed cyanobacteria. They also indicate that this dam are in the category of mesotrophic to eutrophie (based on dates). The observation of morpho-anatomical cyanobacteria collected in the dam Mexa we identified only i genus, belonging to two subgroups Chroscoccales and Oscillatoriales potentially toxic: Microcystis sp. Based on the criteria proposed by Komarek and Komarkova (2002). 3 morpho-species were identified namely: M. Jos aquae, M. aerugenosa, M.botrys. Monitoring the evolution of average densities of species of the genus Microcystis identified shows the clear predominance of the species Microcystis aerogenosa. The culture of all samples, except for the first exit (there is an absence of cyanobacteria), shows a good development on solid and liquid medium BGIL. Microscopic observation of these cultures revealed the presence of the genees Microcystis spp., Lyngbwa spp. Pseudoanabaena spp., Spirulina spp.. Microcystis spp.