湟水河流域秋季大型底栖动物群落结构及关键影响因子识别

为了解湟水河流域大型底栖动物群落结构特征并识别影响其空间分布的关键环境因子，于2020年9月对湟水河流域25个样点进行了大型底栖动物和环境因子调查采样。结果显示，本次共采集并鉴定出大型底栖动物109（属）种；聚类分析（Bray-Curtis距离）结果显示，依据大型底栖动物群落结构相似性，湟水河25个样点在空间上可以分为3组：第1组样点主要分布在中上游支流，该组指示物种为朝大蚊属1种（Antocha sp.）；第2组样点分布比较广泛，中上游干、支流均有，该组的指示物种为四节蜉属1种（Baetis sp.），第3组样点主要分布在中下游干流，该组指示物种为瑞士水丝蚓（Limnodrilus helveticusi）。大型底栖动物的物种丰度、香农威纳指数、Margalef丰富度指数、四节蜉属1种和瑞士水丝蚓的相对丰度在上下游和干支流之间的空间差异性较大。冗余分析（RDA）结果表明栖息地评分、电导率、亚硝态氮、总磷、浊度和水深是影响湟水河大型底栖动物的关键环境因子。湟水河水生态保护修复策略应当更多地关注次生盐化和营养盐污染防治以及水土保持来提升流域水生态健康状况。

Autumn Macroinvertebrate Community Structure and Identification of Key Environmental Factors in the Huangshui River Basin

In this study, we characterized the autumn macroinvertebrate community structure in the Huangshui River basin and identified the key environmental factors affecting spatial distribution, aiming to provide a reference for restoring the aquatic ecology of Huangshui River. Macroinvertebrate and aquatic environmental parameters were measured at 25 sampling sites (8 mainstream sites and 17 tributary sites) in the Huangshui River basin in September 2020. A total of 109 macroinvertebrate species (genus) were identified, including 4 phyla, 7 classes, 14 orders and 41 families, with absolute dominance of Arthropoda taxa (81.7%). The 25 sampling sites were divided into three groups according to similarity of macroinvertebrate community structure, based on Bray-Curtis distance. Group 1 included 8 sites distributed primarily in the upper and middle tributaries, with the indicator species Antocha sp.; Group 2 included 13 sites that were widely distributed in the upper and middle mainstream and tributaries, with the indicator species Baetis sp.; Group 3, with 4 sites primarily distributed in the middle and lower mainstream, with the indicator species Limnodrilus helveticusi. Species richness, Shannon-Weiner and Margalef indices, and the relative abundance of Baetis sp. and Limnodrilus helveticusi were very different between the upper and lower reaches and between the mainstream and tributaries. Redundancy analysis (RDA) shows that habitat, conductivity (TDS), nitrite (NO2-), total phosphorous (TP), turbidity and water depth were the key environmental factors affecting macroinvertebrates in the Huangshui River basin. Restoring aquatic ecology in the Huangshui River basin will require improved prevention and control of secondary salinization and nutrient pollution and strengthening soil and water conservation, based on a strategy of water quality protection and ecological restoration.