Cross-basin analysis of freshwater ecosystem health based on a zooplankton-based Index of Biotic Integrity: Models and application

Abstract Quantitative evaluation of the aquatic ecosystem health is crucial to formulate policies about environmental water management and ecological restoration. However, it is often difficult to quantitatively compare or estimate the health of aquatic ecosystems for different watersheds. In this study, we developed a Freshwater Ecosystem Health Index (FEHI) based on a modified Zooplankton-based Index of Biotic Integrity (ZIBI) to address this difficulty. The ZIBI was developed based on the top six principal components (cumulative % = 88.6%) of 32 zooplankton community indicators. Then the ZIBI was transformed into the FEHI by using the arc-tangent function (to make FEHI fall into (0,1)). FEHI rating scales that were defined as (0,0.2), [0.2,0.4), [0.4,0.6), [0.6,0.8), [0.8,1) fall within bad, poor, fair, good, and excellent freshwater ecosystem health condition, respectively. Moreover, we established six estimation models of FEHI, respectively, directing at six situations that the available indicators are limited. The FEHI calculation and estimation models were then applied to evaluate three lakes and four river basins in eastern China. The results showed that the aquatic ecosystem health was good in areas that included rivers in Tongxiang plain, Meiliang Bay of Taihu Lake, rural area of Qinhuai River basin, Shahu Lake during Summer/Autumn. However, the aquatic ecosystem health was bad or fair in Xuanwu Lake (an urban shallow lake), the urban area of Qinhuai River basin, Huaihe basin, Yinghe basin, and Shahu Lake in winter. The FEHI will be a new and effective approach for quantitative evaluation/estimation of freshwater aquatic ecosystem health in eastern China.