A Study on Phytoplankton in the Lake of Sanandaj Dam1

The lake of Sanandaj dam is located within the territory of Sanandaj city,in the longitude coordinates of 46° 33' and the northern width of 55° 20', in the upstream of Banidar village and over Komasi river. The field activity of this research was seasonal and was carried out for one year from June 2015 to June 2016. Considering the size of the lake, five stations were set up in the lake. Phytoplankton was sampled from three surface layers, the middle layer, light absorbing layer and the layer near the bed of the lake.Phytoplankton specimens were immediately recorded with 4% formalin fixation (fixed) and then examined and identified under microscope with a magnification of 10X, 20X and 40X. The results of the study on the composition and species diversity of phytoplankton showed that 54 species existed in the lake. In this study, six groups of phytoplankton including: Bacillariophyta, Chrysophyta, Pyrophyta, Cyanophyta, Chlorophyta and Euglenophyta with 20, 1, 9, 6, 16, and 2 species were identified. The seasonal analysis of species diversity of phytoplankton revealed that in spring, summer, autumn and winter, respectively, 23, 25, 25 and 18 species were recorded.The highest species variation belonged to summer and autumn with 25 species. In addition, exploring the demographic changes of 6 phytoplankton groups in the lake indicated thatthe highest and lowest densities of phytoplankton respectively with an average of 3750000 ± 239793 and 127481 ± 90656 belonged to autumn and summer.