太湖五里湖湖滨带浮游动物群落结构特征

湖滨带在保持物种多样性、拦截陆源污染物、净化水体等方面发挥着重要作用。选取经生态修复的五里湖湖滨带为研究对象,于2014年7月至2015年6月对该水域4个区域(A,B,C,D)浮游动物进行逐月采样,以探讨五里湖湖滨带浮游动物群落结构及其生态意义。结果表明,本次调查共鉴定出浮游动物104属207种,其中原生动物37属88种,轮虫38属76种,枝角类17属29种,桡足类12属14种,物种数最多出现在8月(63种),最少出现在2月(25种);岸型对物种数的影响表现为自然滩地型明显高于水泥护岸。浮游动物丰度和生物量均值分别为3 135.35个/L和2.38mg/L,原生动物和轮虫丰度是五里湖湖滨带浮游动物丰度主体,轮虫生物量是五里湖湖滨带浮游动物生物量主体。浮游动物群落结构的季节差异明显,枝角类丰度和生物量表现为春季最高,夏季最低,而浮游动物、原生动物、轮虫和桡足类丰度和生物量均为秋季最高,冬季或春季最低;空间格局上也存在较大差异,浮游动物及各类群丰度和生物量均表现为C区D区B区A区,整体呈现东五里湖高于西五里湖的趋势。浮游动物多样性指数及丰度对水质的分析表明,五里湖湖滨带水质为中污染,水体营养状态为轻度富营养。冗余分析表明,TN、DO、Chl-a及pH是影响浮游动物群落结构动态变化的重要环境因子。

Zooplankton Community Characteristics in the Lakeside Zone of Wuli Lake, Taihu Lake

Wuli Lake is a typical shallow urban lake in Wuxi City. Since March of 2004, an ecological restoration project has been ongoing in the lakeside zone of Wuli Lake. The lakeside zone (shoreline) of the lake plays an important role in maintaining species diversity, intercepting land-source pollutants and purifying water. In this study, we investigated the zooplankton community structure in the lakeside zone of Wuli Lake and assessed the water quality based on the results, aiming to provide data for assessing the ecological restoration and integrated improvement of the lakeside zone. The lakeside zone was divided into four areas: A, under treatment, desilting and restoration of aquatic vegetation; B, under treatment, sediment dredging and restoration of aquatic vegetation; C, wetland construction along the lakeshore; D residential. From July 2014 to June 2015, zooplankton samples were collected monthly at eight nearshore sites in Wuli Lake and water quality parameters were measured, including pH, dissolved oxygen (DO), turbidity (Tur), total phosphorus (TP), total nitrogen (TN), permanganate chemical oxygen demand (CODMn), chlorophyll-a (Chl-a), ortho-phosphate (PO43-), ammonia nitrogen (NH4+-N) and nitrite nitrogen (NO2--N). A total of 207 zooplankton species belonging to 104 genera were identified, consisting of 88 protozoa species (37 genera), 76 rotifer species (38 genera), 29 cladocera species (17 genera) and 14 copepod species (12 genera). The highest species richness occurred in August (63 species) and the lowest occurred in February (25 species). Natural bottomland had a more positive impact on species richness than cement revetment. The average zooplankton density and biomass were 3135.35 ind/L and 2.38 mg/L and protozoans and rotifers dominated total density, while rotifers dominated total biomass. The zooplankton community structure presented obvious seasonal differences. Cladocera density and biomass was highest in spring and lowest in summer, while the density and biomass of protozoa, rotifera and copepoda were highest in autumn and lowest in winter or spring. Spatially, zooplankton density and biomass in the eastern lake were higher than in the western lake, both following the same order, C>D>B>A, and presenting significant spatial differences. Based on the diversity indices and density of zooplankton, the water in Wuli Lake was polluted moderately and slightly eutrophic. Redundancy analysis revealed that TN, Chl-a, DO and pH were the important environmental factors affecting zooplankton community structure.