The effect of Rainbow trout fish farms effluents on macroinverebrate communities and water quality of Peredanan river (West Azarbajan)

Today, the multi purpose use of the potential of water resources is considered with the construction of Rainbow trout farms upstream of permanent rivers in order to make optimal use of these resources and increase employment. The direct entry of the effeluent of theses pools into the water of these rivers can affect their water quality. The aim of this study was to determine the effect of rainbow trout farm waste water on benthic macroinvertebrate of Peredanan River(West AzarbaijanProvince) in 2015 using Hilsenhoff biotic index. Sampling was performed seasonally from 6 sites including entrance, exit, and 4 sites with 700 m distance intervals from first farm (700, 1400, 2100 and 2800 m). Some important physicochemical factors such as TDS, pH, DO,EC and water temperature were determined. Four divisions, four orders and 14 families from macroinvertebrates were identified. The results showed that Shironomidae had the highest density. Site 1 indicated very good water quality during the study period, whears site 2 on the exit of farm had the lowest quality than other sites. Hilsenhoff index for the river was 1.99 which indicated that Peredanan river water quality was excellent. This showed there are no organic pollutents in the river. The lowest and highest Hilsenhoff was observed in site 4 (1.74) and site 2 (2.44), respectively. On the other hand, this index was lowest in spring (1.79) and highest in autumn (2.15). The apropeiate rate of the index on the farest site (1400 m from exit) may be due to higher self filteration capacity which resulted in waste water dilution and decrease in any unwanted effects.