Evaluateation of water quality of Ghareh-Aghaj River(Fars province ,Iran)

Macrobenthos can serve as a bioindicator for natural or anthropogenic environmental changes. Ghareh-Aghaj River is one of the most important rivers in Fars province that supply potable, agricultural and industrial water. This study aimed to investigate the changes of macrobenthos in different months and stations for one year from September 2018 to August 2019 to determine the water quality of Ghareh-Aghaj River in Fars province. For this purpose, 10 stations were selected from 190 kilometers of river length and sediment samples collected once every 45 days. Identifications were done using binocular stereomicroscope and benthic identification keys. BMWP, ASPT and Shannon Wiener indices were used to evaluate water quality. From the midstream zone to the Persian Gulf (stations 7 to 10) has severe pollution. These stations are surrounded by extensive farmlands that use pesticides and herbicides in a large scale, resulting agricultural runoff containing a variety of contaminants flowsinto the river. In addition, in the downstream stations, especially in ​​Kavar (Station 7), the effluent of sand mines flows into the river, which has caused a severe change in the ecosystem of the lake. According to the results, the water quality of Ghareh-Aghaj River is relatively badand placed in the category of moderate to severe polluted.