太湖流域平原水网区底栖动物完整性健康评价

基于75个采样点的底栖动物监测数据,应用生物完整性的理论和方法,对太湖流域平原水网区进行水生态健康评价. 以采样点环境所承受的干扰程度为标准,确定参照点13个、受损点62个. 对涉及底栖动物群落丰富度、组成、耐污能力及摄食功能的21个候选指数进行分布范围、判别能力及相关性分析,筛选出有较强预判能力且相对独立的6个核心指数构成B-IBI(底栖动物完整性指数)健康评价体系,包括总分类单元、软体动物分类单元、Shannon-Wiener多样性指数、前3位优势分类单元相对丰度、BI指数、滤食者相对丰度. 通过比值法统一各指数的量纲,以参照点B-IBI值的25%分位数作为健康基准值,运用四分法划分B-IBI健康分级标准:B-IBI≥2.84,为健康；2.13≤B-IBI<2.84,为亚健康；1.42≤B-IBI＜2.13,为一般；0.71≤B-IBI＜1.42,为差；B-IBI＜0.71,为极差. 应用B-IBI对太湖流域平原水网区进行健康评价,结果显示:太湖东部、南部沿岸湖区以及太湖上游水库健康状况相对较好,总体处于健康或亚健康水平；太湖北部三湾、西部湖区较差,基本处于差或极差水平；太湖上游洮滆水系生态状况也不容乐观,从上游至下游沿程呈逐步恶化趋势；京杭大运河的监测断面均表现为极差水平. B-IBI健康评价结果与基于水质及富营养化评价的结果高度吻合, 但今后仍需加强该评价体系的标准化及本土化等方面的研究. 

A Preliminary Benthic Index of Biotic Integrity (B-IBI) for Bioassessment of the Plain Waterway Network of Taihu Basin

A preliminary Benthic Index of Biotic Integrity (B-IBI) was developed to assess the health status of aquatic ecosystem in the plain waterway network of Taihu Basin. Totally 21candidate metrics were used to describe structure and function of macroinvertebrate assemblages from 13reference sites and 62impaired sites. The candidate metrics were evaluated by distributing range analysis, discriminatory power analysis and Pearson correlation analysis. The final B-IBI included total taxa number, molluscan taxa number, Shannon-Wiener index, percentage of three most-dominant taxa, biotic index and percentage of the filter-group. Finally, the scoring criteria of B-IBI were normalized based on the quadrisection system, and these scores were interpreted as excellent (≥2.84), good (2.13-<2.84), moderate (1.42-<2.13), poor (0.71-<1.42) and very poor (<0.71). The results showed a relatively good heath for the southern-and-eastern lakeshores and the Daxi reservoir, and a poor health for the northern-and-western ones and its upstream river networks.The B-IBI can well differentiate the impaired sites from the reference ones, by giving a significant negative linear response to a gradient of chemical anthropogenic disturbances. In future, more works should be focused on strengthening standardization and localization of B-IBI for local government and managing agencies.