Application of biological index in assessment of the impacts of ecological engineering on river ecosystem health

The species and community structure characteristics of benthic macroinvertebrate play an important role in assessment of water quality and ecosystem health in rivers and lakes as environmental assessment indices. Linzhuanggang river, which located in Taihu Lake basin in China, was taken as an example in this study for assessment of the impacts of ecological engineering on water quality, habitat of aquatic life and ecosystem health. It the assessement, we applied Benthic-Index of Biotic Integrity (B-IBI), Shannon-Weiner Index (SWI), Biotic Index (BI). The community structure, biological density, dominant species and sensitive species of benthic macroinvertebrate varied remarkably after ecological engineering construction. B-IBI, SWI and BI changed from 1.72 ("worse-healthy"), 3.50 ("clean") and 7.8 ("middle polluted") to 2.71 ("inferior-healthy"), 4.00 ("clean") and 6.0 ("clean") respectively. The quantities of sensitive species and biological density of benthic macroinvertebrate in ecological reaches were superior to those in natural controlled reaches. The results showed that ecological engineering was beneficial to improve water quality and habitat for aquatic life, so as to restore damaged river ecosystem.