以鲢、鳙放养为主的武山湖后生浮游动物群落结构特征

Metazooplankton Community Structure in Wushan Lake Stocked Densely with Planktivorous Filter-feeding Bighead and Silver Carp

武山湖是紧邻长江的通江型富营养湖泊。为了解该湖在以鲢、鳙放养为主的情况下后生浮游动物结构特征,于2017年9月至2018年8月对其后生浮游动物群落结构特征开展了监测。结果表明,武山湖共采集浮游动物61种(属),其中轮虫24种,枝角类23种和桡足类14种;优势种共有13种,其中轮虫12种和桡足类1种。轮虫丰度全年有11个月占比超过70%,而桡足类和枝角类全年占比均较小。就生物量而言,轮虫全年有10个月占比超过80%,但桡足类生物量占比在实施冬季捕捞期间即12月、1月和2月占比分别为20.1%、79.2%和51.8%,明显比其他月份高,表明减少鲢、鳙能够减缓浮游动物被捕食压力。冗余分析结果显示温度、叶绿素a和pH是影响武山湖浮游动物群落结构的关键因子。研究结果表明武山湖后生浮游动物以小型轮虫为主,枝角类和桡足类数量少且仅为小型种类。

Wushan Lake is a highly eutrophic,shallow lake connected to the Yangtze River by channel,and a national wetland park.In order to study metazooplankton structural characteristics in the lake stocked densely with silver carp(Hypophthalmichthys molitrix)and bighead carp(Aristichthys nobilis),we conducted a field survey on the metazooplankton community and lake trophic status from September 2017 to August 2018.A total of 61 metazooplankton species(genera)were identified including twenty-four species of Rotifer,twenty-three species of Copepods and fourteen species of Cladocera.Thirteen dominant species including twelve species of Rotifer and one species of Copepods were observed.The percentage of Rotifer of the total abundances was more than 70%in 11 months of the year,while Copepods and the Cladocera abundance accounts for a small percentage of the year.The percentage of Rotifer of the total biomass was more than 80%in 10 months of the year.However,the percentage of Copepods increased after winter-fishing,constituting 20.1%,79.2%and 51.8%of the total biomass in December,January and February,respectively.Redundancy analyses showed that temperature,Chl a and pH were important factors determining the structures of metazooplankton communities.Our results showed that the metazooplankton were mainly Rotifers and the size of Cladocera and Copepods is small in Wushan Lake.