长江和澜沧江源区夏季浮游植物分布特征研究

在全球气候变化和人类活动的影响下，长江和澜沧江源区水生态环境问题日益突出，而浮游植物是水生态系统的物质循环和能量流动的重要环节，为了解长江和澜沧江源区浮游植物资源现状，本研究对比了2012 ~ 2016年长江和澜沧江源区干支流浮游植物特征，并采用冗余分析（RDA）揭示了浮游植物群落结构与9种环境因子间的关系。结果表明长江源区共鉴定出浮游植物4门44种（属），其中蓝藻门5种（属），绿藻门9种（属），硅藻门29种（属），隐藻门1种（属），当曲和直门达2014年的浮游植物种类数最多，为18种，五道梁2012年种类数最少，为6种。长江源区浮游植物密度变化范围为2.53×104 ~ 94.00×104 ind/L，最小值出现在2015年的当曲样点，最大值为2016年的唐古拉山样点。长江源区Shannon多样性指数、Margalef丰富度指数和Pielou均匀度指数变化范围分别为0.86 ~ 3.34、0.34 ~ 0.96、0.33 ~ 0.83，最小值为2012年的五道梁样点。澜沧江源区共鉴定出浮游植物4门32种（属），其中蓝藻门5种（属），绿藻门6种（属），硅藻门20种（属），隐藻门1种（属），扎曲2014年鉴定出种类数最多，为14种。澜沧江源区浮游植物密度变化范围为2.23×104 ~ 38.64×104 ind/L，最小值为扎那曲（2015年），最大值为囊谦（2012年）。澜沧江源区Shannon、Margalef、Pielou三种多样性指数变化范围分别为0.86 ~ 3.21、0.36 ~ 0.78、0.25 ~ 0.91。长江和澜沧江源区总体上浮游植物密度较低，水体处于贫营养状态，浮游植物均匀度指数较高，种类分布较为均匀，群落结构较稳定。温度、浊度、流速和含沙量是影响长江和澜沧江源区浮游植物群落结构的主要环境因子。

Distribution of the Summer Phytoplankton Community in Source Regions of the Yangtze River and Lancang River

Phytoplankton is an important part of the material cycle and energy flow of the water ecosystem. To understand the current status of phytoplankton resources in the source region of the Yangtze River and Lancang River, this study compared the characteristics of phytoplankton in the source region of the Yangtze River and Lancang River from 2012 to 2016, and revealed the relationship between phytoplankton community structure and 9 environmental factors through Redundancy Analysis (RDA). The results showed that a total of 44 species (genus) of phytoplankton in 4 phyla were identified source region of the Yangtze River, including 5 species (genus) of Cyanophyta, 9 species (genus) of Chlorophyte, 29 species (genus) of Diatoms and 1 species (genus) of Cryptophyta, Dangqu and Zhimenda had the largest number of phytoplankton species (genus) in 2014, with 18, and Wudaoliang had the least number of species in 2012, with 6. The density of phytoplankton in the source area of the Yangtze River varies from 2.53×104 ~ 94.00×104 ind/L, the minimum value was the Dangqu sample site in 2015, and the maximum value was the Tanggula Mountain sample site in 2016. The Shannon diversity index, Margalef richness index, and Pielou evenness index in the source area of the Yangtze River ranged from 0.86 to 3.34, 0.34 to 0.96, and 0.33 to 0.82, respectively, and the minimum was the Wudaoliang sample site in 2012. A total of 32 species (genus) in 4 phyla of phytoplankton were indentified in the source area of the Lancang River, including 5 species (genus) of Cyanophyta, 6 species (genus) of Chlorophyta, 20 species (genus) of Diatoms, and 1 species (genus) of Cryptophyta, Zhaqu identified the largest number of species in 2014, with 14. The range of phytoplankton density in the source area of the Lancang River was 2.23×104 ~ 38.64×104 ind/L, the minimum was Zanaqu (2015), and the maximum was Nangqian (2012). The three diversity indexes of Shannon, Margalef and Pielou in the source area of the Lancang River ranged from 0.86 to 3.21, 0.36 to 0.78, and 0.25 to 0.91, respectively. In the source region of the Yangtze and Lancang River, the density of phytoplankton was generally low, indicating that the water bodies were all in an oligotrophic state. The Pielou index of phytoplankton was high, resulted the species distribution was relatively uniform, and the community structure was stable. Temperature, turbidity, flow velocity and sand content were the main environmental factors affecting the structure of phytoplankton communities in the source regions of the Yangtze and Lancang Rivers.