The Water Quality of the Shahid Rajaee Reservoir (Mazandaran-Iran): Based on Phytoplankton Community

Shahid Rajaee reservoir (SRR) is one of the main reservoirs located in Mazandaran province. There is no published data of algal study and water quality deduction based on biotic parameter in this area. Therefore, SRR was chosen to study the water quality and water pollution based on the phytoplankton community. Samples were collected at four stations during the 6-month sampling occasions (June, July, August, September, November 2012 and February 2013). Results showed that the water quality of selected sampling stations based on the phytoplankton communities (Shannon-Weiner diversity index H′, 0.92–1.37) were classified as slightly polluted to polluted. The H′ values reflected excellent quality in June (2.80) and February (2.77), whereas the lowest quality was obtained in August (0.58). Based on the saprobic index values, the reservoir was categorized as β-mesosaprobic class (moderate organic loading) except in August which was under α-mesosaprobic to β-mesosaprobic (critical organic loading) classification. The water quality condition derived from the trophic classification (based on chlorophyll-a concentration) varied from good to poor class at different sampling months and stations. Based on the results obtained, the risk of pollution and water quality degradation was more noticeable at station 2 and during July and August 2012. In order to prevent the occurrence of eutrophication and algal bloom, it is necessary to conduct regular monitoring and human activities surrounding the SRR and the river tributaries should be monitored.