f Farahani - Academic Center for Education, Culture and Research, Kharazmi Branch, Tehran, Iran
r Ramezannejad Ghadi - Department of Biology, Faculty of Science, Golestan University, Gorgan, Iran
m Masoudi - Academic Center for Education, Culture & Research (ACECR) Mazandaran, Iran
a Mokhlesi - Academic Center for Education, Culture and Research, Kharazmi Branch, Tehran, Iran

Our present study include Seasonal variations of phytoplankton of water body in Karaj River and its relation with physico-chemical parameters of the water body to establish the occurrence of the various phytoplankton throughout the year. Seasonal variations in phytoplankton composition were studied at 12 stations chosen on Karaj River between September 2009 and August 2010. A total 52 taxa of phytoplankton were identified, belonging Bacillariophyta, Chlorophyta, Cyanophta, Dinophyta, and Cryptophyta divisions. Bacillariophyta by genera of Navicula, Nitzschia, Cymbella, Achnanthes, Amphora and Fragilaria were the most abundant group at all stations. Microcystis spp. and Spirulina spp. of cyanophyta were observed to be sub-dominant. Some species of phytoplankton occurred continuously during the study period. This work demonstrates changes in phytoplankton diversity and expresses the possibilities of using these minute organisms as an indicator in biomonitoring system to determine the quality of water body

Algal Flora; Seasonal variation; Karaj River; Iran