基于浮游植物生物完整性指数的湖泊生态系统评价——以2012年冬季太湖为例

依据2012年12月对太湖29个样点和同一地理区划4个湖、库的浮游植物和环境变量的监测结果,应用生物完整性理论和方法,构建冬季太湖浮游植物生物完整性指数,评价冬季太湖水生态健康质量。采用干扰程度最小系统法定义筛选确定参照点,对51个候选参数进行分布范围筛选、判别能力分析、参数间相关性分析,获得了太湖枯水期P-IBI指数的6个构成参数:总分类单元数、硅藻门分类单元%、细胞Simpson指数、细胞密度、硅藻门细胞密度%和绿藻门个体密度%。采用比值法统一各参数的量纲,累加后得到枯水期太湖P-IBI分值,并划分健康评价标准。应用P-IBI对冬季太湖水生态进行评价,8个参照点中1个点位评价结果为健康其余7个为亚健康;25个受损点中,2个点位为亚健康,9个点位为一般,12个点位为差,2个点位为极差。太湖总体受到了不同程度的人为干扰,东太湖湖区水生态状况最好,评价结果多为亚健康或一般;竺山湖、贡湖、东部沿岸和西部沿岸次之;南部沿岸和湖心区最差,湖心区有2个点位评价结果为极差。与冬季太湖P-IBI指数显著相关的水化学因子是氨氮和总磷含量。

Preliminary study on phytoplanktonic index of biotic integrity (P-IBI) assessment for lake ecosystem health: a case of Taihu Lake in Winter, 2012

A preliminary phytoplanktonic index of biotic integrity (P-IBI) was developed to evaluate the ecosystem health of Taihu Lake in winter by means of the data that were collected from 29 sites in Taihu Lake and 4 sites in similar lakes or reservoirs in December 2012. The method of the least disturbed condition was used to find the reference sites. Fifty-one metrics were examined stepwise in the distribution analysis, discriminating power analysis, and redundancy analysis to obtain the core metrics. The final P-IBI included the total taxa number, Bacillariophyta taxa number (%), the Simpson diversity index of cells, cell density, Bacillariophyta cell density(%), and Chlorophyta individual density (%). These metrics were transformed into uniform scores using the ratio score method, and a P-IBI value was obtained by summing up the scores. According to the P-IBI assessment, 8 reference sites included 1 healthy site, and the rest were subhealthy; 2 of 25 impaired sites were subhealthy, while 9 were good-to-fair, 12 were fair, and the other 2 sites were poor. East Taihu Lake was best in terms of the health condition in the entire Taihu Lake, while the central region was the worst. The health conditions in other regions (Zhushan Lake, Gong Lake, eastern lakeshore, and western lakeshore) were intermediate, meaning relatively poor conditions. Our results suggest that ammonia nitrogen and total phosphorus are the major factors that correlate significantly with the P-IBI score for Taihu Lake in winter.