Effect of Qezel Kosar rainbow trout (Oncorhynchus mykiss) farm effluent on some abiotic and biotic characteristics in Daryasar River, Mazandaran Province

The aim of this study was to assess the impact of trout farm effluent on some physicochemical and characteristics biotic indices in Daryaser River (Mazandaran Province). Sampling of water and macrobentic fauna were done in 5 stations (control, in before influent of farm; and other stations include; in 35, 125, 400 and 750 m after effluent were selected in two weekly in summer, 2011. Results showed that farm effluent was not significant difference in many physicochemical parameters (P>0.05) except nitrate and phosphate parameters in before and after farm effluent. An assessment of biotic indices indicates the health of the Daryasar River. It seems, for low production capacity of the farm and its suitability management, the drainage into Daryasar River has little adverse effects on water health and chemical quantities are in the scope of national standards for effluent discharge in surface water.