基于微生物生物完整性指数的城市河道生态系统健康评价

生物完整性指数(index of biotic integrity,IBI)已被广泛运用于河流生态系统的健康评价.然而,目前基于微生物的IBI评价方法很少,针对城市河道的相关研究更是缺乏.本研究采用Illumina高通量测序技术,对浙江省内5条城市河道的微生物群落多样性及组成进行了分析.通过典型相关分析(canonical correlation analyses,CCA)和Spearman相关性分析水质对微生物组成的影响,明确受水质变化影响显著的微生物类群,与特定功能菌群一并作为备选指标.对备选指标进行分布范围、判别能力及Pearson相关性分析,筛选出香农多样性指数、微生物分类单元数、疣微菌门相对丰度、绿菌门相对丰度和分支杆菌属相对丰度等参数指标,初步构建了适合浙江城市河道的微生物生物完整性指数(microbiome index of biotic integrity,M-IBI)指标体系.采用比值法对生物指标计分,评价结果显示:总计22个样点中,9个样点为"健康"等级,占总样点的40. 9%;10个样点为"亚健康"等级,占总样点的45. 5%; 2个样点为"一般"等级,占总样点的9. 1%; 1个样点为"较差"等级,占总样点的4. 5%.各采样点M-IBI值可有效反映水体受干扰程度,且与水质状况基本吻合(R=0. 753,P 0. 01),表明M-IBI可以较合理地评价城市河道生态系统健康状况.

Assessment of Ecosystem Health of an Urban River Based on the Microbe Index of Biotic Integrity (M-IBI)

The index of biotic integrity (IBI) has been widely used in river ecosystem health assessment. However, few studies have reported the application of microbial communities in ecosystem health assessment so far, especially for urban rivers. In this study, the Illumina high-throughput sequencing technique was applied to analyze the microbial community diversity and composition of five urban rivers selected in Zhejiang Province. Canonical correlation analyses (CCA) and Spearman correlation analysis were used to evaluate the relationship between each taxonomic group and the water quality properties to select the most sensitive taxonomic groups as candidate indexes. The functional metrics, including the relative abundance of pathogenic bacteria, pollutant-degrading bacteria, and nutrient cycling bacteria were also selected as candidate indexes. Based on the distribution range, discriminatory power, and Pearson''s correlation analysis for candidate indexes, five metrics, including the Shannon-index, the number of microbial phyla, the relative abundance of Verrucomicrobia, Chlorobi, and Mycobacterium were selected to establish a biotic integrity index of microbes (M-IBI) evaluation system. A ratio score system was used to get metrics into a uniform score for all sampling points, and the results showed that among the urban river samples studied, most of them (40.9%) were at "Great" level, 45.5% were at "Good" level, 9.1% were at "Moderate" level, and 4.5% were at "Bad" level. The index of M-IBI effectively discriminated the least, medium, and highly impaired sampling points and provided a good match with the water quality (R=0.753, P<0.01), indicating that the M-IBI has potential as an index to evaluate the health of urban river ecosystems.