Abstract: In order to evaluate the ecological health condintion of the upper reaches of Zhanghe River, an adapted benthic index of biotic integrity (B-IBI) was developed in 2015. Macro-invertebrates were sampled at 12 monitoring stations which were grouped into two condition categories (reference and impaired stations) according to the level of degradation. A total of 47 benthic macroinvertebrates taxa were identified, including aquatic insects 33 taxa (including Chironomidae 16), Mallusca 8, Annalida 3 and Crustacea 3 taxa. Aquatic ecosystem healthy assessment was researched using Benthic Index of Biotic Integrity (B-IBI). Eighteen candidate biological metrics in 4 categories based on macro-invertebrate assemblages were chosen, and value distribution, discriminatory power and pearson correlation were analysed. Meanwhile, total taxa and percentages of (Crustacea + Mollusca) %, tolerant taxa % and predators % were screened out to form a B-IBI index system for the upper reaches of Zhanghe River. Assessment results using B-IBI showed that in the whole watershed, 5 of sampling stations were in "healthy" and "sub-healthy" state, 3 were in "fair" state, and 4 were in "poor" or "very poor" state. Discussion about the ecological condition and B-IBI evalution results of the whole watershed was conducted.

Key words: upper reaches of Zhanghe River, benthic macro-invertebrates, benthic index of biotic integrity, ecological health assessment