洞庭湖后生浮游动物群落结构及水质生物学评价

Community Characteristics and Bioassessment of Metazooplankton in Dongting Lake

为了解洞庭湖后生浮游动物群落结构、影响因素,客观评价洞庭湖水生态环境质量,为支撑长江流域水生态考核工作提供一定的科学依据,在2019年对洞庭湖16个断面的后生浮游动物开展了3次调查,分别为3月(枯水期)、6月(平水期)和9月(丰水期),并同步监测了12项环境参数。结果表明洞庭湖后生浮游动物样品中共检出2门26属,其中轮虫为9属,枝角类12属,桡足类为5属。洞庭湖后生浮游动物的平均密度为84.4个·L^(-1),其中轮虫占84.3%,桡足类占13.3%,枝角类占2.4%。东洞庭湖后生浮游动物密度最高,其次为南洞庭湖、入湖口、西洞庭湖和洞庭湖出口。洞庭湖后生浮游动物优势种是广生多肢轮虫(Polyarthra vulgaris)、暗小异尾轮虫(Trichocerca pusilla)、螺形龟甲轮虫(Keratella cochlearis)以及无节幼体(Nauplius)。轮虫对水体营养水平的响应相对比较显著,东洞庭湖营养状态明显高于其它湖区。洞庭湖富营养化导致了后生浮游动物群落结构的小型化,后生浮游动物可以作为湖泊水环境变化的指示性生物。Canonical correspondence analysis(CCA)分析表明叶绿素a、总氮、总磷和透明度是影响洞庭湖后生浮游动物分布的主要影响因素,与国内大多数湖泊浮游动物的影响因素较为一致。采用Shannon-Wiener多样性指数和Pielou均匀度指数对洞庭湖进行生物评价,结果显示洞庭湖为轻污染,用后生浮游动物对洞庭湖水生态状况进行评价较为合适。

In order to understand the community structure and influencing factors of metazooplankton in Dongting Lake,evaluate the water ecological environment quality of Dongting Lake,and provide a certain scientific basis for supporting the assessment of water ecology in the Yangtze River Basin.We conducted three surveys of metazooplankton in 16 sections of Dongting Lake,respectively in March(dry season),June(normal season)and September(wet season),and monitored 12 environmental parameters simultaneously in 2019.The results showed that the metazooplankton community belonged to 2 phyla and 26 genera,including Rotifera 9 genera,Cladocera 12 genera,Copepoda 5 genera.The average density of metazooplankton was 84.4 ind·L^(-1),with Rotifera as the most dominant class(accounted for 84.3%of the total density),followed by Copepoda(13.3%)and Cladocera(2.4%).On the spatial distribution,the density of metazooplankton was highest in East Dongting lake,followed by South Dongting lake,estuary,West Dongting Lake and lakeoutlet.The dominant species of metazooplanktonin were Polyarthra vulgaris,Trichocerca pusilla,Keratella cochlearis,Bosmina sp.and nauplius.The response of rotifers to water nutrient level was relatively significant,and the nutrient status of East Dongting Lake was significantly higher than that of other lakes.Eutrophication of Dongting Lake resulted in the miniaturization of metazooplankton community structure,metazooplankton can be used as indicators of lake water environment changes.Canonical correspondence analysis(CCA)showed Chlorophyll A,total nitrogen,total phosphorus and transparency were the key factors controlling the community structure of metazooplankton,it is consistent with the influence factors of zooplankton in most lakes in China.The shannon-Wiener diversity index and Pielou evenness index were used to evaluate the water quality of Dongting Lake,the results showed that the water quality of Dongting Lake was light pollution,it is suitable to evaluate the water ecological status of Dongting Lake by metazooplankton.