青弋江流域大型底栖动物群落结构及水质评价

Macroinvertebrate community structure and water quality assessment in the Qingyi River Watershed

研究河流大型底栖动物群落结构特征及水环境质量对水生态的保护与修复具有重要意义。以青弋江流域为研究对象,于2020年9月进行了大型底栖动物及水体理化因子的调查,采用相对重要性指数、生物多样性指数及Jaccard相似性系数分析了大型底栖动物群落结构特征,运用丰度/生物量比较曲线法及冗余分析法探究了底栖动物群落受到的干扰程度及其主要影响环境因子,最后利用水生态环境质量综合指数对河流水质进行评价。研究结果表明:(1)共采集鉴定大型底栖动物61种,隶属于3门6纲17目,平均丰度为265.9个/m^(2),平均生物量41.6 g/m^(2)。相对重要性指数分析显示,日本沼虾(Macrobrachium nipponensis)、中国圆田螺(Cipangopaludina chinensis)、羽摇蚊(Chironomus plumosus)及扁蜉(Ecdyrus)为群落中的主要优势种。(2)由群落相似性分析知,Jaccard相似性系数较低,调查点位之间存在较强的空间异质性。(3)冗余分析表明,电导率、氨氮浓度及流速是影响底栖动物群落结构的主要环境因子。(4)生物指数分析结果显示该流域水质为轻度污染或中度污染,与水质理化因子评价存在较大差异。综合考虑生物及非生物因子的水生态环境质量综合指数模型计算结果显示,流域整体水环境质量偏好,但部分采样点已受到干扰或处于污染状态,与ABC曲线分析及优势种分析基本一致,评价结果更具科学性及可靠性。

It is of great significance to study the community structure of macrobenthos and the water quality for protection and restoration of aquatic ecology. Taking the Qingyi River Basin as the research object, a survey of macrobenthos and physicochemical factors of the water body was carried out in September 2020. It analysed the structural characteristics of the macrobenthic community by means of the relative importance index, the biodiversity index and the Jaccard similarity coefficient. It investigated the extent of disturbance to the benthic community and the main environmental factors that affect it, by applying the comparative abundance/biomass curve method and redundancy analysis. Finally, the comprehensive index of water ecological environment quality was used to evaluate the river water quality. The results showed that(1) 61 species of macrobenthos were collected and identified in the Basin, which belonged to 3 phyla, 6 classes and 17 orders. The average density was 265.9 ind/m^(2)while the average biomass was 41.6 g/m^(2). The main dominant species which were shown in the index of relative importance in the community were Macrobrachium nipponensis, Cipangopaludina chinensis, Chironomus plumosus, and Ecdyrus.(2) The Jaccard similarity coefficient was low due to the analysis of community similarity, with a strong spatial heterogeneity between the investigation sites.(3) The main environmental factors-conductivity, ammonia nitrogen concentration and flow velocity-influenced the community structure of macrobenthos by the redundancy analysis.(4) The biological index analysis results indicated that the water quality in the basin was lightly or moderately polluted, which varied significantly from the assessment of the physical and chemical factors of water quality. The comprehensive water and ecological quality index model calculations, which integrated biotic and abiotic factors, suggested an overall water and environmental quality preference for the basin. But some sampling points have been disturbed or polluted, which was basically consistent with the abundance-biomass comparison curves analysis and the dominant species analysis, in which the result of evaluation was more scientific and reliable.