雅鲁藏布江流域底栖动物多样性及生态评价

雅鲁藏布江起源于喜马拉雅山,是世界上海拔最高的河流之一,是流经我国西藏境内重要的国际河流,其河流生态系统具有特殊地貌及生态条件。研究该流域底栖动物多样性分布特征及其影响因子,是科学评价该区域河流生态系统健康状况,实现资源可持续开发利用的基础。2009年10月—2010年6月期间,以底栖动物作为指示物种,对雅江流域干支流及堰塞湖的14个采样断面进行河流生态评价。采用Alpha及Beta生物多样性指数分别指示局部采样河段及全区域的底栖动物多样性。对采样断面底栖动物组成分析发现:14个采样断面共采集到底栖动物110种,隶属57科102属。雅江干流底栖动物种类数最高为29,平均为19。支流年楚河种类数为17。支流拉萨河,尼洋河,帕龙藏布的最高种类数分别为25,33,36;平均种类数分别为21,21,22,生物多样性普遍高于干流。整个流域中底栖动物平均种类数相差不大,但种类组成和密度相差较大。调查区域的Beta多样性指数β高于低海拔地区的相似的山区河流,说明雅江流域内底栖动物群落差异性高于正常海拔地区。对14个采样断面的物种组成进行除趋势对应分析表明:影响雅江流域底栖动物多样性的主要因素为河型,河床阻力结构,堤岸结构,水流流速。保持稳定的阶梯-深潭结构和自然堤岸结构,以及适宜的流速有利于保护雅江河流生态。

Research on assemblage characteristics of macroinvertebrates in the Yalu Tsangpo River Basin

The Yalu Tsangpo River, the highest river in the world, originating from the Himalayas, is the most important international river in Tibet. Compared with rivers in normal elevation areas, the aquatic ecosystem of the Yalu Tsangpo River is unique due to its special topography and ecological conditions. Research about the macroinvertebrates in relation to environments is an important basis for scientific assessment of river ecology and sustainable utilization of water resource in the Yalu Tsangpo River. Field investigations were conducted at 14 sampling sections by using macroinvertebrates as indicators to assess the river ecology of the Yalu Tsangpo River during October 2009 - June 2010. Several alpha diversity indices were used to assess biodiversity of the sampled sections. A beta diversity index was calculated to evaluate the biodiversity of the whole sampled river reaches. From analyses of the assemblage composition of all samples, altogether 110 taxa of macroinvertebrates, belonging to 57 families and 102 genera, were identified from the Yalu Tsangpo River Basin. The maximum and average values of macroinvertebrate taxa richness in the main channel of the Yalu Tsangpo River were 29 and 19, respectively. The taxa richness in the tributary Nianchu River, was lower than that in the main channel. The maximum values of taxa richness in the tributaries: Lhasa, Niyang, and Palong Tsangpo rivers were 25, 33, and 36, respectively; and the average values were 21, 21, and 22, respectively, which were higher than those in the main channel. For different sampling sections, no large variance existed in taxa richness, while taxa composition and density of macroinvertebrates were very different. The beta diversity index of the Yalu Tsangpo River, was much higher than that in normal elevation rivers, indicating much higher heterogeneity of macroinvertebrates in the Yalu Tsangpo River. Macroinvertebrate assemblages of the 14 sections were clustered using Detrended Correspondence Analysis (DCA). The ordination diagram indicated that the main factors impacted macroinvertebrate assemblages of the Yalu Tsangpo River were river pattern, riverbed structures, bank structures, and flow conditions. Keeping stable step-pool systems, natural bank structures, and suitable flow velocity is in favor of conservation of river ecology of the Yalu Tsangpo River.