Investigation of benthic macroinvertebrate in Gheshlagh and Gaveh River (Kurdistan Province) based on the Hilsenhoff Biological Index (HFBI)

Large invertebrates are known as biological indicators of their living environments. The present study was carried out in line with the quality monitoring studies of Zhaveh dam, which was constructed on the two branches of Gheshlagh and Gaveh River (Kurdistan Province). The purpose of this study was to investigate the large invertebrates in the river in order to determine the density and abundance of different large invertebrates and the quality of river water based on Hilsenhoff biological index. Large invertebrates sampling was done seasonally from autumn 2020 to summer 2021(4 seasons) at 5 stations with 3 replications. Samples were fixed with 70% ethyl alcohol and isolated, counted and counted in the laboratory. Large invertebrates were identified using a stereomicroscope and a valid key. The Hilsenhoff biological index was determined based on the presence of samples at each station. The results of the study of large invertebrates in different seasons and during one year showed that organisms belonging to 10 families from 5 order belonging to Hirudinea, Insecta, Crustacea, Oligochaeta and Bivalvia. Results showed that the highest abundance belonged to station 5 (34%) and lowest abundance belonged to station 2 (7%). The highest value of Hilsenhoff index was observed in spring (7.45) and the lowest value of this index was related to autumn (6.79). According to the HFBI Biological index, the water quality was classified as very poor and highly polluted due to its proximity to the effluent outlet of the treatment plant and further investigations are suggested for any exploitation.