University of Tehran/Springer International Journal of Environmental Research 1735-6865 6 1 2012 01 01 Cyanobacterium Microcystis aeruginosa Bloom in Aras Dam Reservoir 309 312 496 10.22059/ijer.2011.496 EN F. Mohebbi Iranian Artemia Research Center, P.O.Box 368. Urmia, Iran, A. Mohsenpour Azari Iranian Artemia Research Center, P.O.Box 368. Urmia, Iran M. Heidari Agricultural and Natural resources Research Center of West Azarbaijan, Urmia, Iran A. Asem Afagh High Education Center, Urmia, Iran Journal Article 2011 12 19 Occurances of cyanobacterial bloom typically appear in eutrophic lakes which either have been affected by anthropogenic nutrient loading or are naturally rich in nutrients. Microcystis blooms have been reported all over the world in freshwater ecosystems mainly due to increased population which results in increased the waste water production. The aim of this study was to recognize the basic reasons of Microcystis aeruginosa bloom in Aras reservoir. Water temperature, pH, DO, EC, TN, N-No2, N-No3, P-Po4, chl a and the number of Microcystis colonies were determined. The effects of these parameters on the microcystis increased growth was examined. Though we could not strictly relate a few other factors to this phenomenon, higher water temperature, pH and DO in the sampling site i.e. 27° C, 9.16 and 17.2 mg/L respectively, surely favored the M.aeruginosa bloom. In brief, preventing or reducing the nutrients flow into the reservoir should be considered as a priority in order to reduce Microcystis scum forming colonies. https://ijer.ut.ac.ir/article_496_b534ba68236ba543ae44b22bd110a1d6.pdf