Development and application of IBI based on fish to assess the river's health in the East Tiaoxi River

Index of biological integrity (IBI) based on fish to assess the river health in the East Tiaoxi River was established in this study. Two IBI systems and assessment criteria were established due to sampling sites being from two different eco-regions. The sampling sites from the tributaries in the upper reaches of East Tiaoxi were in the eco-zone of evergreen broad-leaf forest between Zhejiang Province and Fujian Province, and IBI in the tributaries was established including species richness (M1), percentage of species in the Balitoridae to species richness (M5), percentage of endemic species to species richness (M6), Shannon-Wiener's diversity index (M7), percentage of invertivores to abundance (M13), percentage of herbivores to abundance (M14) and percentage of intolerant species to abundance (M16). The sampling sites from the middle-lower reaches of East Tiaoxi River were in the Eco-zone of agriculture area in urban and suburban in the Yangtze River Delta, and IBI in the middle-lower reaches was established including species richness (M1), percentage of species in the Gobiidae to species richness (M4), percentage of endemic species to species richness (M6), Shannon-Wiener's diversity index (M7), percentage of species inhabit in the up layer to species richness (M8), percentage of species inhabit in the middle-up layer to species richness (M9), percentage of herbivores to abundance (M14), percentage of species spawn in shells to species richness (M21), abundance (M22) and percentage of DELT to abundance (M23). The status of river health was categorized into five levels, such as 'healthy', 'fair', 'poor', 'very poor' and 'no fish'. Two IBIs were applied to assess the 45 observation sites in the East Tiaoxi River in 2010 and 2011. The results showed that the river's health was mainly at the status of 'fair' and 'poor'. By contrast in 2011, the observation sites of 'healthy' and 'fair' decreased by 1 and 2 sites than those in 2010, respectively. Meanwhile, the observation sites of 'poor', 'very poor' and 'no fish' increased by 1 site than those in 2010, respectively.