雅鲁藏布江谢通门江段浮游生物资源现状及其季节动态

为加强对高原河流浮游生物的群落结构的了解，对雅鲁藏布江中游的浮游生物进行定性和定量分析，调查其资源现状和季节变化，并探究浮游生物的丰度与环境因子的相关性。分别于2008年10月（秋季）、12月（冬季）和2009年3月（春季）、8月（夏季）在西藏雅鲁藏布江中游谢通门江段选取4个采样点进行浮游生物资源现状调查。本次调查共检出浮游植物6门、74属、107种，以硅藻门最多（31属、63种），其次为绿藻门（22属、23种）和蓝藻门（22属、23种），黄藻门（22属、23种）、裸藻门（22属、23种）和金藻门（22属、23种）较少。浮游植物的密度和生物量以秋季最高，分别为7.758×105个/L 和3.402 mg/L；夏季最低，分别为2.088×105个/L和1.281mg/L；共检出浮游动物3门、47属、54种，以原生动物和轮虫居多，罕见枝角类和桡足类。浮游动物的密度和生物量以秋季最高，分别为526.5 个/L和0.055 mg/L；冬季最低，分别为125.1 个/L和0.004 mg/L。研究表明，雅鲁藏布江谢通门江段浮游生物的种类数和现存量呈现明显的季节差异，主要与透明度和水温等环境因子相关。

Resource Status and Seasonal Variation of Plankton in the Xaitongmoin Reach of Yarlung Zangbo River

The Yarlung Zangbo River is the longest plateau river in China, the highest major river in the world and its geography is very rugged. Study of the plankton community has been rare because sampling is difficult, so there are no comprehensive reports on the resource status and seasonal variation of plankton in the main stem. To better understand the plankton community structure and provide basic data for conserving biodiversity in high altitude rivers, we carried out the first plankton community investigation in the middle reach of the Yarlung Zangbo River. The resource status and seasonal variation of plankton were analyzed based on qualitative and quantitative analysis and the relationship between plankton abundance and environmental factors was explored. Plankton sampling in the Xaitongmoin reach of the Yarlung Zangbo River was carried out at two sampling sites in October and November, 2008 , and March of 2009 (sites 1, 2) , and August of 2009 (add sites 3, 4). Environmental factors were also measured; longitude and latitude, altitude, water temperature, transparency, flow velocity and pH. A total of 107 phytoplankton species (74 genera, 6 phyla) were observed. Phytoplankton was dominated by Bacillariophyta(31genera, 63species), followed by Chlorophyta(22genera, 23species) and Cyanophyta(15genera, 15species), while Xanthophyta(3genera, 3species), Euglenophyta(2genera, 2species) and Chrysophyta(1genera, 1species) were rare. Phytoplankton density and biomass were the highest in autumn (7.758×105cells/L and 3.402mg/L). The lowest density and biomass were in summer (2.088×105cells/L and 1.281mg/L). A total of 54 zooplankton species (47 genera, 3 phyla) were observed. Protozoans and rotifers were the dominant taxa, while cladocerans and copepods were rare. The density and biomass of zooplankton were highest in autumn (526.5 ind/L and 0.055mg/L) and lowest in winter (125.1 ind/L and 0.004 mg/L). Species richness and biomass of plankton displayed obvious seasonal variations in the Xaitongmoin reach of the Yarlung Zangbo River, primarily related to the ecological factors of transparency and water temperature.