الخلاصة:
Water, a vital element, is the subject of careful attention throughout the world. His importance for the preservation of public health has led to extensive programs of monitoring. The objectives of the control of the quality of water intended for consumption are many and vary according to the means and the technical possibilities. In this context, the main objective of this study is the constitute baseline for further study of phytoplankton. Biggest dam of Algeria for the feeding and irrigation of six wilayas in the East. We have sought to describe these stands, essentially from the point of view of structure, abundance and dynamics. Determination of the taxonomic composition of these primary producers improves, in fact, knowledge of the biodiversity of the entire region. Our interest has also focused on the characterization of surface water quality via fourteen parameters, the establishment of physico-chemical and phytoplankton typologies specific to our study site and looking for possible links between the two compartments abiotic and biotic. Our results are based on data collected for twenty-four months from January 2015 to December 2016;at the level of eleven sampling points in surface area around the Beni Haroun dam in connection with wadis feed. The results show nutrient levels that are not yet alarming, but the situation is likely to worsen with the different levels of pollution continues to grow. On the basis of 88 samples, 72 taxons were identified belonging to 9 phytoplankton classes. The total species richness has highlighted a broad predominance of Cyanophyceae and Bacillariophyceae. The evolution of
densities.Total cell counts show significant seasonal variations in 2016 more than in 2015. The rainy season is of low algal productivity while the highest cell densities mark the summer seasons and fall. The indices of Shannon and of equitability reach the lowest values in the rainy season, diversity early spring due to the development of several species of Cyanophyceae, Diatoms, Chlorophyceae, Conjugatophyceae and Mediophyceae. In summer and autumn season, communities are at their most diverse. Abiotic elements have shown positive and / or negative affinities with the amount of phytoplankton biomass.
