望虞河西岸湖荡群浮游植物群落与水环境因子的关系

为了解过水型湖荡群浮游植物群落与水质变化特征,探究望虞河西岸湖荡群浮游植物时空分布及其环境影响因子,基于生物多样性分析、Pearson线性相关性分析、冗余分析(RDA)方法,于2018年9月—2019年7月对望虞河西岸湖荡群(宛山荡、嘉凌荡、鹅真荡、漕湖)的浮游植物和水环境因子进行采样调查分析,结果表明：①四个湖荡水质均处于GB3838—2002《地表水环境质量标准》V类~劣V类水平,超标指标为TN和COD_Cr,春季优于其他季节。 ②湖荡群共鉴定浮游植物8门68属152种(含变种、变形),其中硅藻门、绿藻门、蓝藻门最多；主要优势种包括小球藻(Chlorella vulgaris)、梅尼小环藻(Cyclotella meneghiniana)、颗粒直链藻(Melosira granulata)、铜绿微囊藻(Microcystis aeruginosa)、阿氏浮丝藻(Planktothrix agardhii)等；年均生物量为13.48 mg/L,年均藻细胞密度为15.25×10^₆ cells/L；湖荡群浮游植物多样性指数呈秋高夏低趋势,处于中污染型至重污染型的过渡状态,其中Shannon-Wiener多样性指数多介于2~3之间,Pielou均匀度指数为0.5~0.8,Margalef丰富度指数处于1~2之间。 ③Pearson相关性分析与RDA分析结果表明,影响浮游植物的主要环境因子为WT(水温)、NH_4⁺-N和NO_3^--N。 研究显示,望虞河西岸湖荡群浮游植物空间分布不均、季节特征明显,与太湖相比,优势种相近且多样性指数较好,但湖荡群水质较差,建议持续监测并加强针对性措施。

Relationship Between Phytoplankton Community and Water Environment Factors

The Wangyu River basin, connecting Yangtze River and Taihu Lake, is a typical flood plain river-lake network and it plays an important role in improving the water quality of Taihu Lake and the surrounding area. In this study, we explored the characteristics of phytoplankton community structure in the western lake group of Wangyu River, including phytoplankton biomass, density, diversity, dominant species, and the spatiotemporal distribution. The primary environmental factors affecting the phytoplankton community were determined by Pearson correlation analysis (PCA) and redundancy analysis (RDA). The aim was to provide theoretical evidence and data to support water quality monitoring, scientifically based water diversion and ecological conservation of the lake group and river-lake network. Seasonal investigation of phytoplankton and water environmental factors in the lake group (Wanshan Lake, Jialing Lake, Ezhen Lake and Caohu Lake) was carried out at 19 sampling sites from September 2018 to July 2019. Results show that: (1) Water quality in the four lakes met or violated Class V standards (environmental quality standards for surface water: GB3838-2002), and water quality in spring was better than in other seasons. The environmental parameters at excessive levels were TN and CODCr. (2) A total of 152 phytoplankton species (varieties, variants) from 68 genera of 8 phyla were identified, dominated by Diatoms, Chlorophyta and Cyanobacteria. Dominant species included Chlorella vulgaris, Cyclotella meneghiniana, Melosira granulata, Microcystis aeruginosa and Planktothrix agardhii. The average annual phytoplankton biomass and density in the lakes were 13.48 mg/L and 15.25×106 cells/L. The ranges of the Shannon-Wiener diversity, Pielou evenness and Margalef richness indices of the phytoplankton community were, respectively, 2-3, 0.5-0.8 and 1-2, and tended to be higher in autumn and lower in summer. Phytoplankton biodiversity indicated water quality in the lakes ranged from moderately to heavily polluted. RDA and PCA indicated that water temperature, NH4+-N and NO3--N were the primary environmental factors affecting phytoplankton community structure. The spatial distribution of phytoplankton in the lake group was uneven and the seasonal differences were obvious. In conclusion, the dominant species of phytoplankton in the lake group were similar to those in Taihu Lake, but phytoplankton diversity indices were better and water quality was worse. Therefore, we suggest continuous monitoring of water quality in this group of lakes and using appropriate measures for improving water quality.