Investigation of the effects of environmental factors on diversity and distribution patterns of macroinvertebrates communities Zarin-Gol River Golestan province

Benthic organisms in the aquatic environment plays an important role in aquatic nutrition, movement, rotation of food in aquatic ecosystem and the conversion of organic matter to mineral ones. The purpose of present study was biological monitoring of Zarin Gol river. This study carried out in Golestan province using macrobenthic invertebrates' population as it sample. Macro benthic invertebrate samples were collected by Surber sampler (900 cm2) of 12 sampling stations with 3 replicates in two seasons: winter and spring. Totally, 6192 individuals of benthic organism were identified consist of 31 families and 9 order. Three dominant populations of abundance were Ephemeroptera (%37), Trichoptera (%23.45) and Diptera (Simulidae (%16) and Chironomidae (%12.4)). Maximum total density in all sampling periods was in stations 2 (7944.44 ind/m2) (downstream under the agriculture activity). Population biological indices value and abundance of sensitive organisms decreased from upstream to downstream, while the abundance of resistance organisms increased. The human activities effect on abundance and distribution of macro invertebrates and reduction of water quality in Zarin Gol River.