Seasonal Change of Community Structure and Abundance of Macrobenthos in Roudan River

The macrobenthos community on the Roudan River and its relationship to its physical and chemical environment are described. The sampling design consisted of 3 stations and with 3 replicate in four seasons. The Roudan is a long central river that drains a vast central part of Iran and is constrained by the transport of sediments from the mountain and land. Sixteen species were collected in the three stations. It was highly dispersed within the flooding water and dominated in density by highly diversified insects. During these periods in three stations, along the river, the turbid, but enriched by exports from adjacent mudflats and detritus was colonized by a large and abundant macrobenthos community that was dominated by by Chironomus and Paraleptophtebia belonging to order Diptera and Ephemeroptera respectively. The limnaea belonging the order Lymnaeidae and classes of Gastropoda was dominant in station 2 due to the presences of higher grass in riverside and less turbidity of the river in this part of the river. Besides of the macrobenthos of the clasess Insecta and Gastropoda which was dominant in all the sampling station and in different season, the macrobenthos of the groups of Maxillopoda, Secernentea, Arachnida, Malacostraca are also observed and recorded.