西藏巴松错（湖）夏季浮游植物群落的水平和垂直分布

为揭示西藏巴松错浮游植物群落结构的水平和垂直分布特征及其与环境间的关系，于2020年7月对巴松错出入河流及其湖体15个采样点和湖中心B15采样点11个分层的浮游植物进行了调查，同时测定了水体相关理化指标。调查共采集水样275个，分析了浮游植物物种组成、细胞丰度、生物量和物种多样性等群落结构特征，并探讨浮游植物对水平和垂直环境梯度变化的响应。结果表明：（1）巴松错夏季共鉴定浮游植物167种，隶属于5门8纲20目29科66属，物种组成为硅藻-绿藻-蓝藻型；（2）在水平方向上，平均细胞丰度为1.8453×104 cells/L，平均生物量为0.0117 mg/L；在垂直方向上，平均细胞丰度为1.0055×104 cells/L，平均生物量为0.0061 mg/L；（3）巴松错夏季浮游植物群落结构水平分布较为均匀，群落复杂程度相对较高，较垂直分布更稳定；（4）RDA分析结果表明，EC是影响巴松错夏季浮游植物水平群落变异的主要环境因子，TUR是影响垂直变异的主要环境因子。本研究结果为进一步研究高寒湖泊生态系统提供了基础资料。

Horizontal and Vertical Distributions of the Summer Phytoplankton Community in Basomtso Lake of Xizang, China

In order to understand the horizontal and vertical distribution characteristics of phytoplankton community structure and its relationship with the environment the Lake Basomtso, Tibet, China, we investigated the stratified phytoplankton at 15 sampling sites and 11 sampling sites at B15 sampling site in the center of the Lake Basomtso in July 2020, and measured the related physical and chemical indexes of water bodies. A total of 275 water samples were collected to analyze phytoplankton community structure, including species composition, cell abundance, biomass and species diversity, and to explore the response of phytoplankton to changes in horizontal and vertical environmental gradients. The results showed that :(1) A total of 167 species of phytoplankton were identified in the Lake Basomtso, belonging to 5 phyla, 8 classes, 20 orders, 29 families, 66 genera. The species composition was bacillariophyta-chlorophyta-cyanophyta. (2) In the horizontal direction, the average cell abundance was 1.8453×104 cells/L, and the average biomass was 0.0117 mg/L. In the vertical direction, the average cell abundance was 1.0055×104 cells/L, and the average biomass was 0.0061 mg/L. (3) The horizontal distribution of phytoplankton community structure in the Lake Basomtso was relatively uniform, and the community complexity was relatively high, and the vertical distribution was more stable. (4) RDA analysis showed that EC was the main environmental factor affecting the variation of horizontal phytoplankton community in the Lake Basomtso, and TUR was the main environmental factor affecting the vertical variation of phytoplankton community in the Lake Basomtso. The results of this study provide basic data for further study of alpine lake ecosystem.