基于大型底栖动物完整性指数评价深圳茅洲河生态状况

对受人类活动强烈影响、几乎不存在常规参照点的城市河流开展生态评价存在很多困难。本研究以深圳市茅洲河为例,通过调查河流大型底栖无脊椎动物及水环境指标,用水体理化指标聚类法确定参照组、受损组样点,构建底栖完整性指数(Benthic index of biotic integrity, B-IBI)评价河流生态状况。研究发现：虽然茅洲河水环境质量整体较差,聚类分析仍然能将水质相对较好和较差的样点分成不同组。虽然底栖动物以颤蚓和摇蚊等耐污种为主,但底栖动物总分类单元数和集食者分类单元数对水环境变化较敏感。用这两个参数构建的B-IBI对各点的生态状况进行评价表明：12个位于干、支流上游或水库出水口附近的样点生态状况达到“好”等级；B-IBI主要受氮、磷营养盐、COD、溶解氧浓度的影响。建议参照 “好”等级样点的生态状况确定茅洲河现阶段修复目标,并以水质提升作为当前首要修复任务。

Ecological Condition Assessment of Maozhou River at Shenzhen City Based on the Benthic Index of Biological Integrity

Ecological assessment of urban rivers is difficult because the extensive impacts resulting from human activities makes it difficult to find suitable reference sites. In this investigation, Maozhou River, the largest river in Shenzhen City was selected for a case study. A benthic index of biological integrity (B-IBI) was developed and then used to evaluate the ecological status of the river, and the environmental factors affecting the B-IBI were analyzed. Development of the B-IBI was based on an investigation of benthic invertebrates and water physicochemical parameters at 34 sites in the Maozhou River in late March and early April of 2018, with 11 main stem sites and 23 tributary sites. Cluster analysis of water physicochemical parameters was used to identify reference sites and disturbed sites. Sixteen benthic metrics indicating diversity, community composition, tolerance and functional feeding groups were calculated and screened for inclusion in the benthic index of biotic integrity (B-IBI). Water quality was poor at most surveyed sites and the benthic invertebrate community was composed of 62 taxa and dominated by pollution-tolerant species such as Tubifex sp. and Chironomus sp.. Although benthic communities were generally degraded, the total number of benthic taxa and the number of collector-gatherers were sensitive to environmental conditions and the B-IBI was constructed using these two metrics. The average B-IBI score for all sites was 45.80 and there was a significance difference between reference and disturbed sites, with an average score of 73.67 for reference sites and 35.75 for disturbed sites. Based on the B-IBI scores, the ecological condition of the 34 sites were grouped into three levels: good, medium and poor. Conditions at 12 sites, located in the upper reaches of the main stem and tributaries and near the reservoir outlet, were classified as good, while conditions at the other sites were classified as medium or poor. B-IBI scores were primarily affected by nitrogen, phosphorus, COD and DO concentrations. We recommend using environmental and ecological conditions at Maozhou River sites classified as good as the restoration reference for degraded sites, and improvement of water quality as the most urgent task for restoration projects. This study improves our understanding of the current ecological status of Maozhou River and provides a reference for the ecological evaluation of other urban rivers.