城市新建湖泊浮游动物群落结构特征及其驱动因素——以南通紫琅湖为例

Structural characteristics and driving factors of zooplankton community in a newly-built urban lake:a case of Zilang Lake in Nantong

城市新建湖泊具有生态系统不稳定、受人类活动干扰强度大、水体流动性差等特点。浮游动物作为水域生态系统的重要组成部分,对湖泊生态系统的健康和稳定有重要作用,因此探究其群落结构形成机制对城市新建湖泊生态系统的合理构建和水质保护具有重要意义。本研究以城市新建湖泊——江苏南通紫琅湖为例,于2019年1月至2020年10月对浮游动物群落特征及其驱动因子进行了研究。共鉴定浮游动物61种(轮虫39种,枝角类11种,桡足类11种),优势种12种(轮虫11种,桡足类1种);三大类群的丰度和生物量差异显著,均为轮虫>桡足类>枝角类,其中轮虫的丰度为(1 468.9±367.0)ind./L,占比达97.2%,生物量为(1 762.6±442.0)μg/L,占比达88.2%,为浮游动物群落丰度和生物量最大的贡献类群,表明紫琅湖浮游动物群落整体呈现小型化特征。冬春季的优势种更替率最大(R=60.0%),春夏季的优势种更替率最低(R=18.2%)。紫琅湖浮游动物多样性季节变化明显,且多样性阈值评估显示紫琅湖浮游动物多样性较低,整体处于“一般”水平。生物多样性指数对水质状况的评估结果显示,紫琅湖春季、夏季和秋季的水质状况处于α-中污型,冬季处于多污型。Spearman相关性分析和冗余分析表明浊度、叶绿素a、总磷是紫琅湖浮游动物群落特征形成的主要驱动因素。

In recent years,newly-built urban lakes have gradually become an important part of urban ecosystems with the development of social economy and the acceleration of urbanization. However,newly-built urban lakes are often characterized by unstable ecosystem,large intensity of interference by human activities and poor water fluidity due to their short construction time. Zooplankton as an important part of the aquatic ecosystem,plays an important role in the health and stability of lake ecosystem. It is important and meaningful to explore the formation mechanism of structural characteristics of zooplankton community for the rational construction of lake ecosystem and water quality protection in newly-built urban lakes. In order to provide effective strategies for the rational construction of the ecosystem and water quality protection in newly-built urban lake,we explored the structural characteristics of zooplankton community and the main environmental driving factors in Zilang Lake in Nantong,Jiangsu from January 2019 to October 2020. A total of 61 zooplankton species(including 39 species of rotifers,11 species of cladoceras and 11 species of copepods) were identified in this study,in which 12 species were dominant species(including 11 species of rotifers,1 species of copepods). There were significant differences in the abundance and biomass of the three zooplankton groups,which were rotifers>copepods>cladoceras. The abundance and biomass of rotifer accounted for 97. 2% and 88. 2%,respectively,indicating that the zooplankton community structure in Zilang Lake tended to miniaturization. There were seasonal differences in the composition of dominant species. The seasonal replacement rate(R)of dominant zooplankton species in Zilang Lake was significantly different,and the replacement rate between winter and spring was the highest(R=60. 0%),followed by autumn and winter(R=44. 4%),while the lowest replacement rate was between spring and summer(R=18. 2%). The diversity threshold index assessment showed that the degree of zooplankton diversity in Zilang Lake was low(Dy=0. 96),and the overall diversity of zooplankton was at the "general" level. The results of biodiversity index assessment on the water quality showed that the water quality of Zilang Lake in spring,summer and autumn was in the α-medium pollution type,and it was in the multi-pollution type in winter. Spearman rank correlation analysis and redundancy analysis(RDA)analysis results showed that turbidity,chlorophyll a and total phosphorus were the main driving factors affecting the formation of zooplankton community characteristics in Zilang Lake.