【摘要】 2013年8月1日19∶00至2日18∶00,通过间隔1 h的定量采样,研究南昌市典型城市湖泊月亮湖中浮游动物(轮虫、枝角类和桡足类)的昼夜垂直分布规律。结果表明,月亮湖共发现浮游动物20种,其中轮虫16种,枝角类1种,桡足类3种;剪形臂尾轮虫(Brachionus forficula)、桡足类无节幼体(Copepoda Nauplii)和迈氏三肢轮虫(Filinia maior)为优势物种,分别占总捕获数量的48.27%、15.75%和11.11%。浮游动物主要类群和优势物种的Morisita指数均大于1,说明月亮湖中的浮游动物群落呈聚集分布。密度垂直分布和平均滞留深度分析结果显示,浮游动物垂直分布昼夜差异明显,夜间(19∶00-05∶00),浮游动物先聚集于月亮湖中层,01∶00后逐渐迁移到表层;白天(06∶00-18∶00),浮游动物逐渐从表层向中层和底层迁移;主要类群中轮虫、枝角类和桡足类的迁移均表现为夜间上升、白天下降、傍晚再上升,轮虫和桡足类的迁移幅度小于枝角类。优势种剪形臂尾轮虫和无节幼体的昼夜垂直迁移表现为夜升昼降,至傍晚再上升;迈氏三肢轮虫昼夜垂直分布差异显著(P<0.05),但昼夜垂直迁移活动不明显。相关分析表明,水温、p H值和溶解氧对月亮湖浮游动物的垂直分布和迁移活动有显著影响。更多还原

【Abstract】 Zooplankton typically display diel vertical migration and this study characterized the vertical distribution and migration of Rotifera,Cladocera and Copepoda in Yueliang Lake,a small( 3 hm2),shallow( average2. 0 m),urban reservoir in Nanchang City,Jiangxi Province. From 19 ∶ 00,August 1 to 18 ∶ 00,August 2,2013,zooplankton was collected each hour at three depths( 0. 5,1. 5,2. 5 m) at three sites. Physiochemical factors( water depth,p H,dissolved oxygen,conductivity,Chlorophyll a and turbidity) were determined at the three depths,each time a sample was collected. Variation of zooplankton densities and physiochemical factors at each depth was analyzed using one-way ANOVA. The correlation between zooplankton density and physicochemical factors was analyzed by Pearson correlation coefficients. A total of 20 species of zooplankton( 16 Rotifera,1 Cladocera and 3 Copepoda) were observed. The dominant species were Brachionus forficula( 48. 27%),Copepoda nauplii( 15. 75%) and Filinia maior( 11. 1 %). Morisita indices of the primary zooplankton groups and dominant species were > 1,indicating that the zooplankton community aggregated by depth. The vertical distribution and mean residence depth( D) of zooplankton varied significantly between day and night. Zooplankton aggregated in the middle layer at night( 19 ∶ 00- 05 ∶ 00) and gradually migrated to the surface layer after 01 ∶ 00 am. During the day( 06 ∶ 00- 18 ∶ 00),zooplankton gradually migrated from the surface layer to the middle and lower layers. Rotifera,Cladocera and Copepoda,the primary zooplankton groups,all ascended to the surface layer at night and descended to the lower layer during the day,but the migration range of Rotifera and Copepoda was smaller than that of Cladocera. The migration characteristics of the dominant species( Brachionus forficula and Copepoda nauplii)were consistent with their groups. The vertical distribution of Filinia maior was significantly different among the three water layers( P < 0. 05),but diel vertical migration was not obvious. Pearson correlation coefficients show that water temperature,p H and dissolved oxygen significantly influenced the diel distribution and vertical migration of zooplankton in Yueliang Lake. Our study will provide a scientific basis for assessing shallow urban lakes and contribute to the on-going research in aquatic ecology.更多还原