摘要：Karoon River is the main source of drinking, industrial and agricultural utility in Ahwaz city. Protozoans are useful indicators for river water pollution. The aim of this study was to identify and enumerate Dominant protozoans in Karoon Water River, Ahwaz city. In this descriptive study, we took samples from 3 points of karoon river in Ahwaz city boundaries (upstream- uptake point for water treatment plant, middle and downstream) in two seasons (dry and wet). Samples prepared and examined by optic microscope. The results showed 6 species of mastigophora and ciliophora. Most prevalent species were Monosiga fusiformis, Bodocaudatus ، Cercomonas Longicauda، Cercomonas Crassicauda، Tetramitus descissus And Stalked Ciliate. The seasonal variation difference was statistically significant. Minimum concentration was in January (less than 1 cell /lit) and maximum was in October (1600 cell/ lit). The average concentration of protozoans was 129.68 cells/ lit. Protozoans in 3 sampling stations were statistically different, where in 2 and 3 stations Bodocaudatus, Cercomonas Longicauda, Cercomonas Crassicauda, and Tetramitusdescissus were dominant. Identified protozoan species indicate pollution of Karoon River by sewage discharge.
