The Bioassay of Macrobenthic Fauna in Nur Rud River in Nur Town

Determine and examine the distribution of the macrobenthos were studied in Nur Rud River monthly within one year (Jul. 2011 to Jun. 2012) from 7 sites in three replicates using Surber sampler with the cross-section 35×35 cm. Environmental indexes (debit, temperature and pH) were recorded in each site. In total, 7881 macrobenthos belonging to 7 orders of 21 families were detected. The most prevalent orders were Ephemeroptera (family Baetidea). Based on the results, water’s debit and temperature were significantly effective in density and diversity; and pH only affected the diversity of macrobenthos significantly, as the maximum and minimum densities were observed respectively in Feb.-Mar. and May-Jun. The maximum frequency of the macrobenthos pertained to site 1, the headstream of Nur Rud, and minimum frequency of the macrobenthos pertained to site 7, the place where the sewage of the sand mine enters the river. On average, maximum and minimum of Shannon-Wiener index were observed in Jun.-Jul. and Dec.-Jan.; Simpson index were observed in Feb.-Mar. and Jun.-Jul.; and Margalef index were observed in Oct.-Nov. and Jan.-Feb, respectively. Over one year, mean Shannon-Wiener index for species diversity, mean Simpson index for species dominance, and mean Margalef index for species richness were obtained as 1.35, 0.31, and 2.40, respectively. The quality of water in site 1 and site 4 was respectively high and moderate.