A comparative analysis of biotic indices using macroinvertebrates to assess water quality in Mobarakabad River, Golestan Province

Biotic indices for water quality monitoring are useful tools for assessing the health of rivers and lakes. The aim of this study was to compare biotic indices using benthic macroinvertebrate to evaluate the water quality of Mubarakabad River, Minudasht, Golestan Province. Macroinvertebrate samples were collected seasonally from 4 stations in three replications using a Surber sampler with a coverage area (900 cm2) in 2020. A total of 2828 specimens of macroinvertebrate identified and classified into 8 orders and 12 families, of which Diptera with 4 families was the most diverse group of macroinvertebrate and the highest frequency belonged to Chironomidae (46.99%) and then Baetidae (22.52%). Spring with 39% had the highest and winter with 12% had the lowest frequency. The highest distribution of macroinvertebrate was obtained in station 4 (33%) and the lowest in station 1 (19%). The studied indicators were: 1) EPT (percent of Ephemeroptera, Plecoptera and Trichoptera); 2) BMWP (Biological Monitoring Work Party System); 3) ASPT (Average Score per Taxon); 4) HFBI (Hilsenhoff Family Biotic Index); and 5) the Shannon-Wiener and Simpson index. According to the cluster analysis of macroinvertebrate distribution among the stations, it showed two separate groups. The results of biotic indices showed that the Hilsenhof, BMWP and ASPT are suitable for assessing the water quality of the Mubarakabad River. Finally, water quality was assessed as good condition for the upstream station and poor condition for the downstream station. The results of a combination of biotic indices showed that stations located in rural and agricultural areas are more polluted than upstream stations and control and management of pollutant sources is necessary to protect the study area.   .