江苏省太湖流域大型底栖无脊椎动物完整性业务化评价指数构建

Development of an Operational Benthic-Index of Biotic Integrity (B-IBI) for Assessing Water Ecological Health of Taihu Basin in Jiangsu Province,China

为支撑流域水生态目标的业务化管理,提高水生态监测和评价的可操作性,突破物种分类鉴定的技术瓶颈,以大型底栖无脊椎动物为研究对象,在江苏省太湖流域布设120个采样点,于2013年1—3月、7—8月和10—11月开展3次监测。以最小干扰为参照状态,对涉及物种丰度、物种多度组成、耐污能力和摄食类群的72个候选指数进行分布范围、判别能力及相关性分析,结合指数获取的便利性及物种分类的难易程度,最终筛选出3个核心指数构成大型底栖无脊椎动物完整性业务化评价指数,其中湖荡、河流和水库的指数为软体动物分类单元数、优势分类单元相对多度和BMWP指数,溪流的指数为ETO分类单元数、前三位优势分类单元相对多度和BMWP指数。经验证,业务化指数与环境梯度有较好的响应关系,且可操作性强,具备开展业务化应用的前景。但目前的流域水生态目标管理尚处于摸索阶段,技术体系还须在业务化过程中不断修正和完善。

For sustaining the management of aquatic eco-health at the watershed scale, it is urgent to reduce the dependence on taxonomic identification of species and improve the maneuverability of aquatic biomonitoring and bioassessment, then samples of benthic macroinvertebrates were collected three times at 120 sampling sites in Taihu basin of Jiangsu province. Twenty-nine sampling sites were located in Taihu Lake, and the number of sites in other lakes, rivers, reservoirs and streams were 20, 40, 15 and 16, respectively. The three investigations were conducted in the periods from January to March, from July to August and from October to November in 2013. An operational benthic index of biotic integrity(B-IBI) was developed to assess the health status of aquatic ecosystem. Totally 72 candidate metrics for richness, composition, tolerance and feeding measures were used to describe structure and function of macroinvertebrate assemblages from reference sites and impaired sites. The candidate metrics were evaluated by distributing range analysis, discriminatory power analysis, Pearson correlation analysis, and the requirements analysis for taxonomic identification and professional skills. The final operational B-IBI for lakes, rivers and reservoirs included molluscan taxa number, percentage of top-three-dominant taxa and biological monitoring working party(BMWP), which was composed of ETO(Ephemeroptera, Trichoptera and Odonata) taxon number, percentage of most-dominant taxa and BMWP for streams. It was proved that the B-IBI, which was transformed to improve maneuverability, could well differentiate the impaired sites from the reference ones, by giving a significant negative response to a gradient of anthropogenic disturbances. However, the environmental management of aquatic ecology was still in the exploratory stage in China and more works should be focused on constantly revising and perfecting the technique system of aquatic biomonitoring and bioassessment for local government and managing agencies in future with the goal of offering an important foundation for water environmental management as taking the objective from the water quality to aquatic eco-health.