人为活动对冈曲河大型底栖动物空间分布的影响

为监测人为活动对高海拔山区河流的影响，以香格里拉冈曲河为例，应用多维统计分析与排序分析，探讨大型底栖动物群落对人为活动的响应. 研究表明，冈曲河受到低浓度重金属污染，农业活动和水体富营养化程度相对较轻，总体水质状况符合国家地表水环境质量标准(GB3838—2002)Ⅰ，Ⅱ类水质标准. 聚类分析显示，大型底栖动物群落可分为4组:组Ⅰ(北支翁水河)与组Ⅱ(南支格咱河)采样点受人为活动的影响最轻；组Ⅲ采样点主要受开矿和农业活动影响；组Ⅳ采样点受重金属污染相对较重. 4组采样点在无度量多维标定法(NMS)排序轴上的分布差异明显，组Ⅰ与组Ⅱ采样点体现出空间分布差异，而人为活动主要影响组Ⅲ与组Ⅳ采样点. 随河级增加，底栖动物的群落结构除受到水深、河宽、水温、浊度和海拔高度等环境因子的影响外，组Ⅲ与组Ⅳ采样点影响底栖动物群落退化的主要因素为Cu，Pb和NO-₃-N. 石蛭科和毛缘蛾蚋为组Ⅰ采样点的指示种；叉襀和倍叉襀等敏感类群为组Ⅱ采样点的主要指示种；组Ⅲ的指示种为中耐污种短石蛾和蜉蝣，以及强耐污种寡毛类；涡虫为组Ⅳ采样点的指示种，表明涡虫具有较高的重金属污染耐受性. 

Effects of Anthropogenic Disturbance on the Spatial Distribution of Macroinvertebrate Communities in the Gangqu River of Shangrila

To evaluate the effects of anthropogenic disturbances on aquatic ecosystems of streams in high mountain areas, benthic macroinvertebrates were collected from the Gangqu Stream in Shangrila Gorge, China, and their response to anthropogenic disturbances was discussed using multiple statistical analysis and ordination analysis. The results show that the contamination of heavy metals was not seriously high at the sampling sites. Meanwhile, anthropogenic disturbances including farming, grazing, villages and town developments lightly affected the physio-chemical factors of the stream water;the water quality of sampling sites generally belonged to Grade Ⅰ or Grade Ⅱ Chinese Surface Water Standard(GB3838-2002). By applying cluster analysis, the sampling sites were clustered into four clusters according to the similarity of community composition. The north branch Wengshui stream (cluster Ⅰ) and south branch Gezan stream (cluster Ⅱ) had low level of human activities. The sampling sites of cluster Ⅲ were mainly affected by mining and farming. The sampling sites of cluster Ⅳ were heavily polluted by heavy metals. According to non-metric multi-dimensional scaling analysis (NMS), the four clusters were separated at the different areas at the ordination axes. The differences of spatial distribution were reflected between clusters Ⅰ and Ⅱ, whereas the differences of anthropogenic disturbances and contamination of heavy metals were discriminated from cluster Ⅲ to cluster Ⅳ. The variation of community compositions of macroinverterbates from the upstream to downstream areas were identified with water depth, stream width, water temperature, turbidity and altitude. The contamination of copper and lead and the enrichment of the nitrate dominated the separation of clusters Ⅲ and Ⅳ. Indicator value analyses were conducted to identify the indicator species for different clusters. Erpobdellidae sp. and Pericome sp. were the indicator species of cluster Ⅰ, and several sensitive species, including Nemoura sp., Amphinemura sp. etc., were the indicator species of cluster Ⅱ. Moderately tolerant species and tolerant species, including Brachycentrus sp., Ephemera sp. and Oligochaeta sp. dominated the species composition of cluster Ⅲ, and Dugesia sp. dominated the disturbed sampling sites of cluster Ⅳ. Thus, Dugesia sp. also reflected its characteristic of higher metal tolerance.