3种不同营养水平的河流浮游植物群落结构及其与环境因子的相关性

为了更好地了解人类活动干扰下，河流水质和浮游植物群落结构的变化情况以及河流生态系统的演变过程，于2019年6月对贵州境内3种不同营养类型的河流（锦江河、湘江河和南明河）进行调查。研究了3条河流的理化因子、浮游植物种类组成及密度，结合冗余分析（RDA）研究了它们之间的关系，并应用聚类分析法研究3条河流浮游植物的空间分布特征。结果表明：水体富营养化程度排序为南明河>湘江河>锦江河，3条河流的综合营养指数分别为61.76、48.76和36.05。锦江河共有浮游植物6门19属21种，其中硅藻门种类最多，占总种数的57.14%；湘江河共有浮游植物6门34属43种，其中硅藻门和绿藻门种类最多，分别占总种数的41.86%和37.21%；南明河共有浮游植物6门32属46种，其中硅藻门和绿藻门种类最多，分别占总种数的39.13%和32.61%，锦江河、湘江河、南明河水体中浮游植物细胞数的平均值分别为12.66×10⁵、38.66×10⁵、132.61×10⁵个/L。浮游植物细胞密度与溶解氧呈显著正相关（P<0.05），浮游植物细胞密度与电导率、溶解性总固体、盐度、总氮、总磷、氨氮、硝酸盐氮也呈显著正相关（P<0.01）。锦江河的电导率、盐度、溶解性总固体和营养盐含量最低，南明河的最高。此外，聚类分析显示3条河流的浮游植物群落按结构特征可分为两大类。这表明，随着人类活动的加强，河流的电导率、盐度、溶解性总固体、营养盐含量升高，浮游植物的细胞密度增加，其群落结构会由硅藻门占优势，逐渐转变为蓝藻门占优势。

Phytoplankton's community structure and its relationships with environmental factors in three rivers with different nutrition levels

In order to know more about the change of water quality, phytoplankton''s community structure and the evolution of river ecosystem by human activities. In June 2019, the phytoplankton samples and water samples were collected from 21 locations in three rivers with different nutrition levels, which included Jinjiang River, Xiangjiang River and Nanming River. Physicochemical factors, species composition and abundance of phytoplankton were studied, and combined with the result of Redundancy analysis (RDA) studied the relationship of these indexs, the spatial distribution characteristic of phytoplankton was analyzed using the clustering analytical method simultaneously. The results showed that the eutrophication level of the three rivers were in order of Nanming River > Xiangjiang River > Jinjiang River, the comprehensive trophic level index (TLI) of the three rivers were 61.76, 48.76 and 36.05, respectively. Twenty-one species of 19 genera in 6 phyla phytoplankton were found in Jinjiang River, in which Bacillariophyta was the predominant species, and accounted for 57.14% of the total species. Forty-three species of 34 genera in 6 phyla phytoplankton were found in Xiangjiang River, in which Bacillariophyta and Chlorophyta were the predominant species, accounted for 41.86% and 37.21% of the total species respectively. Forty-six species of 32 genera in 6 phyla phytoplankton were found in Nanming River, in which Bacillariophyta and Chlorophyta were the predominant species, accounted for 39.13% and 32.61% of the total species respectively. The cell density of phytoplankton in water sample of Jinjiang River, Xiangjiang River and Nanming River were 12.66×10⁵ cells/L, 38.66×10⁵ cells/L, and 132.61×10⁵ cells/L, respectively. The cell density of phytoplankton was positive correlation with dissolved oxygen (P<0.05), and it was positive correlation with conductivity, total dissolved solids (TDS), salinity, total nitrogen, total phosphorus, ammonia nitrogen, and nitrate nitrogen (P<0.01). The conductivity, salinity, TDS, and nutrient concentration in Jinjiang River were the lowest, however, these indexes in Nanming River were the highest. The result from hierarchical cluster analysis showed that community structures of phytoplankton in the three rivers were different, and these samples were divided into two groups, in which the samples of Jinjiang River and Xiangjiang River were one group, the samples of Nanming River were the other group. These studies suggested that with the intensifying of human activity, the conductivity, salinity, TDS, nutrient concentration and phytoplankton abundance in rivers increased, the abundance of Bacillariophyta decreased, otherwise, the abundance of Cyanophyta increased.