上海水源地毗邻湖库浮游植物群落结构的季节变化及其影响因子

Seasonal changes of phytoplankton community structure and its influencing factors in lakes and reservoirs adjacent to water sources in Shanghai

为改善城市水源地及毗邻水域的水质管理,2019年11月至2020年11月分别在青草沙水库中央沙水域和金泽水库南白荡水域开展了4个季度的采样调查.运用综合营养状态指数(TLI(∑))对水体营养状态等级进行综合评估,并采用主成分分析(PCA)、冗余分析(RDA)和相关性分析等方法研究了浮游植物群落特征与环境因子的关系.结果表明:中央沙和南白荡水域TLI(∑)范围分别为57.5~59.0、54.1~56.1,2个水体均处于轻度富营养状态;两者分别鉴定出浮游植物7门104属184种、8门96属172种;蓝藻门是中央沙水域全年浮游植物构成的主要门类,其次为硅藻门、绿藻门,而南白荡浮游植物群落结构季节性演替明显,优势门类由硅藻门/隐藻门蓝藻门隐藻门/硅藻门变化,浮游植物细胞密度季节平均值变化范围分为3.00×10^(7)~1.61×10^(8) cells/L、4.29×10^(6)~6.59×10^(7) cells/L;鉴定出2个水体浮游植物的优势类群分别有4门17属、5门13属,中央沙水域全年的主要优势类群为假鱼腥藻属(Pseudanabaena)和长孢藻属(Dolichospermum),而南白荡春冬季的主要优势类群为小环藻属(Cyclotella)、隐藻属(Cryptomonas)和蓝隐藻属(Chroomonas),夏秋季主要优势类群为假鱼腥藻属、平裂藻属(Merismopedia)和微囊藻属(Microcystis);中央沙水域浮游植物群落结构变化主要与总氮、总磷、水温等环境因子有关,而南白荡主要与水温、总溶解性盐等环境因子有关,水体流通性差异对此起关键作用.

In order to improve water quality management for urban water sources and their adjacent waters,sample were collected in Zhongyangsha Reservoir and Lake Nanbaidang in four seasons from November 2019 to November 2020.The comprehensive trophic level index(TLI(∑))was used to assess the trophic state levels of water bodies,and the relationship between the characteristics of phytoplankton communities and environmental factors were studied using principal component analysis(PCA),redundancy analysis(RDA)and correlation analysis.It is shown that the TLI(∑)ranged over 57.5-59.0 and 54.1-56.1 for Zhongyangsha Reservoir and Lake Nanbaidang,respectively,and both water bodies were in a mildly eutrophic state.The phytoplankton species were identified with 184 species of 7 phyla and 104 genera,and 172 species of 8 phyla and 96 genera in Zhongyangsha Reservoir and Lake Nanbaidang,respectively.Cyanophyta was the major group throughout the year in the Zhongyangsha Reservoir,followed by Bacillariophyta and Chlorophyta,while the seasonal succession of the phytoplankton community structure in Lake Nanbaidang changed mainly from Bacillariophyta/Cryptophyta-Cyanophyta-Cryptophyta/Bacillariophyta.The seasonal mean density of phytoplankton was 30.0 million-161 million cells/L and 4.29 million-65.9 million cells/L.The dominant species of phytoplankton in the Zhongyangsha Reservoir and Lake Nanbaidang were identified as 4 phyla and 17 genera,and 5 phyla and 13 genera,respectively.The main dominant species in Zhongyangsha Reservoir were Pseudanabaena and Dolichospermum throughout the year,while in Lake Nanbaidang the main dominant species were Cyclotella,Cryptomonas and Chroomonas in spring and winter,and Pseudanabaena,Merismopedia and Microcystis in summer and autumn.The results also indicated that the changes in the structure of the phytoplankton community in Zhongyangsha Reservoir were mainly related to environmental factors such as total nitrogen,total phosphorus,and water temperature,while in Lake Nanbaidang changes were mainly related to water temperature,total dissolved solids etc.,and the differences in water circulation played a key role.