Study on Stracture, Abundance and Ecology of Phytoplankton with Emphasis on Characteristics of Dominant Species in Shahid Rajaee Resevoir (Mazandaran)

The Shahid Rajaee dam has been constructed on Tajan River in the south of Sari city. High probability of algal bloom occurrence in the dams and its negative effects on economic, social activities and human health in the area indicate to the importance of algal studies (determination of abundance and structural community of phyoplankton) in this dam. Sampling was carried out in May, June, July, Agust, September, November and February at the reservoir in 2011-2012. Result showed that 107 species identified in 53 genus and 8 divisions of phytoplankton. Bacillariophyt and Pyrrophyta formed more than %90 of phytoplankton abundance. Three species namely Cyclotella meneghiniana Kuetzing,1844 ¡Ceratium hirundinella (Mueller) Dujardin, 1841 and Goniaulax polyedra Stein, 1883 showed tendensy to form mass density and showed higher bloom potential with compare to the other species in this area. Abundance of C. meneghiniana Kuetzing in warm months was significantly higher than cold months (p