摘要：The present research is a study on water quality and benthic macro invertebrate in Gorganrood River, a South Eastern Caspian Sea . The research was carried out at six sampling sites and the abundance and diversity of benthos were monitored along the length of river from 2007 to 2008. Fourteen families included under different groups such as Annelida, Mollusca and Insecta were recorded in the present investigation. The greatest number of species were recorded at 1st station and the least number was at 6th station. Low macro invertebrate abundance was observed during spring as a result of heavy rainfall and flood and generally in all lowest section because of high value of nitrogen and other nutrients. Water physicochemical parameters such as Phosphate, Nitrate, TPS and others were measured and water quality were studied through different indices such as saprobic system, Helsinhoff (FBI), BMWP and the results were compared and evaluated by physical and chemical parameters. The result indicated that the water quality in the up stream and the middle were good to fair, but the down stream qualities were poor at all sites.
