大淀湖综合治理后浮游动物群落结构特征研究

Research on the community structure of zooplankton after comprehensive treatment in Lake Dadianhu, Shanghai

摘要:

大淀湖于2005、2006年进行了清淤改造并采取了水体生态恢复措施。为评价水体生态整治效果，于2006年9月至2007年8月对大淀湖综合治理后浮游动物群落变化状况进行了逐月采样监测。结果共发现浮游动物72属149种，其中原生动物45属80种、轮虫20属61种、枝角类5属6种、桡足类2属2种。原生动物中优势属种为变形虫（Amoeba sp.）、球形砂壳虫（Difflugia globulosa）等，轮虫优势种为针簇多肢轮虫（Polyarthra trigla）、异尾轮虫（Trichocerca stylata）等，各季优势种组成不同。浮游动物年均生物量和密度为9.48 mg/L和12.15*10⁴ ind/L，春季最高, 达10.51 mg/L和13.10*10⁴ ind/L。生物量和密度所占比例均以原生动物最高(98.02%，83.55%)，其次是轮虫(1.99%，12.79%)，枝角类和桡足类很少，桡足类年平均密度和生物量仅9.5 ind/L和0.11 mg/L，枝角类仅0.32 ind/L、0.01 mg/L。年均Shannon-Weiner指数轮虫为2.30，原生动物为1.91，枝角类和桡足类都小于0.5。枝角类和桡足类在浮游动物群落密度和生物量组成中所占比例非常低，生物多样性指数也很低，这是大淀湖生态治理后浮游动物群落结构呈现的主要特征。尽管调查期间水质为Ⅲ~Ⅵ类水，但从浮游动物生物量来看，水体属富营养型；从多样性指数来看属α-β中污型。广义加性模型(GAM)分析表明浮游动物生物量与叶绿素a浓度、硝态氮相关性显著。

Abstract:

A comprehensive treatment was made in Lake Dadianhu(Shanghai) to desilt and restore ecological system during 2005 and 2006. A series of investigations on the dynamics of zooplankton community structure were made to evaluate the treatment from Sep.2006 to Aug.2007, monthly sampled. The investigations explored species diversity, density, biomass of zooplankton and the correlation between zooplankton and environmental facts. 149 species of zooplankton were recorded including 80 species of Protozoa, 61 species of Rotifer, 2 species of Cladoceran and 2 species of Copepods. Amoeba sp.and DiffLugia globulosa were the dominant species of Protozoan while Polyarthra trigla and Trichocerca stylata were the dominant species of Rotifer. However, the dominant species changed in different seasons. The annual average density and biomass of zooplankton in Lake Dadianhu were 13.10*10⁴ ind/L and 10.51 mg/L, respectively. The highest density and biomass emerged in spring (13.10*10⁴ ind/L, 10.51 mg/L). The highest proportion of density and highest proportion of biomass in the zooplankton community were both the proportion of Protozoan (98.02%, 83.55%) and the second was the rotifer (1.99%, 12.79%), Cladocera and Copeoda were low. The annual average density and biomass of Cladocera were 9.5 ind/L and 0.11 mg/L while the Copeoda were 0.32 ind/L and 0.01 mg/L. The average annual ShannonWeiner index of Rotifer was 2.30 and Protozoan was 1.91while Cladocera and Copeoda were both below 0.5. The characteristic of zooplankton community structure of Lake Dadianhu after treatment was that the proportion of density and biomass of Cladocera and Copeoda in the zooplankton community was very small and diversity index of them was small, too. The water quality was Ⅲ-Ⅵ grade classified by GB3838-2002 while it was eutrophic assessed by the biomass of zooplankton and α-β mesosaprobity by the index of ShannonWeiner. GAM analysis showed that the correlation between zooplankton biomass and chlorophyll a or nitrate nitrogen was significant.