Assessment of Kareh River Health Using multimetric Biological Index and Macrobenthos Communities

Kardeh River is one of the most important permanent rivers of Khorasan Razavi province Which supplies a large part of Mashhad's drinking and agricultural water. Multivariate analysis was used to find out the quality of Kardeh River in this study and to understand the impact of macroinvertebrates community structure drivers on ecosystem management. For this purpose, macroinvertebrates sampling was performed from four study stations during four seasons in 2018-2019, physical and chemical parameters also were measured. In this study, Of the Ephemeroptera, the total number of Caenidae and Baetidae families had the highest abundance (66 / 60 %). The results showed that the Index of Biotic Integrity varied from 3 to 1.1 and based on this biodiversity indicator, Kardeh River water quality was classified into three relatively good, poor and very poor quality classes. The Stream Invertebrate Grade Number Average Level index was classified into two categories: moderate pollution and severe pollution. Canonical Corrspondence Analysis also showed that nitrate, biochemical oxygen demand and chemical oxygen demand had the most effect on the distribution of macroinvertebrates at the study stations. In general, the Kardeh River water quality was poorly evaluated and among the study stations the station conditions were relatively better than the other stations. Therefore, among the available indices, multimetric indices are more reliable. However, these index should be calibrated according to the conditions of Iranian rivers.