Assessment of Aquatic Ecological Health of Rivers in Zhangye City Based on Benthic Macroinvertebrate Index of Biological Integrity

[Objective] As a vital ecological barrier in Northwest China, the river ecosystem health of Zhangye City is of critical importance to regional ecological security. This study aims to provide a comprehensive understanding of the aquatic ecological health of rivers in Zhangye City across different seasons. [Methods] A survey of benthic macroinvertebrates was conducted in 2023 at 136 sampling sites along seven rivers in Zhangye City. The benthic macroinvertebrate-based index of biological integrity (B-IBI) system for rivers in Zhangye City was constructed by selecting 23 candidate biological parameters from five categories that increased in sensitivity with the level of disturbance. B-IBI values of each river were then calculated for different seasons to evaluate their ecological health. [Results] A total of 159 benthic species were identified across both the wet and dry seasons. These species belonged to 5 phyla, 8 classes, 17 orders, and 51 families. Arthropods were the dominant taxa in both seasons, particularly Baetis sp. and Orthocladius sp. The analysis revealed significant differences in benthic macroinvertebrate communities between the dry and wet seasons across rivers in Zhangye City (r=0.09,p