玄武湖挺水植物区与敞水区浮游甲壳动物昼夜水平迁移初探

DIEL HORIZONTAL MIGRATION OF CRUSTACEAN ZOOPLANKTON BETWEEN THE MACROPHYTES AND OPEN WATER IN LAKE XUANWU

浮游甲壳动物昼夜垂直迁移(DVM)是深水湖泊中的一种常见的现象,在浅水湖泊中,没有明显的下层滞水层为浮游甲壳动物提供避护所,浮游甲壳动物的垂直迁移活动不明显。但浅水湖泊挺水植物的存在为浮游甲壳动物提供了区别于敞水带的生境,结合理化、浮游植物和鱼的因素,对浅水湖泊玄武湖挺水植物区与敞水区浮游甲壳动物的昼夜水平迁移进行了研究。结果得出:浅水湖泊玄武湖中理化环境(如温度、溶解氧和pH)在荷花区、敞水区、荷花区与敞水区的交界区差异不大,对浮游甲壳动物的昼夜水平迁移不起主导作用。荷花区的浮游植物在质量和数量上低于敞水区,浮游甲壳动物在夜间捕食压力小的情况下会向敞水区移动。敞水区、交界区浮游甲壳动物在白天被捕食的风险要大于荷花区,因而白天时间浮游甲壳动物会迁移到荷花区聚集。

Diel vertical migration （DVM） of the crustacean zooplankton is a common phenomena in deep lake. In the shallow lake, the backwater is lacked which functions as a refuge for crustacean zooplankton and diel vertical migration （DVM） of the crustacean zooplankton couldn＇t appear. However,the macrophyte in the shallow lake offers a refuge area for crustacean zooplankton from the open water. Combining to the factors of physics and chemistry,phytoplankton and fish, the study researched the diel horizontal migration of crustacean zooplankton between the macrophytes and open water in a shallow lake （Lake Xuanwu）. Results of the present study on Lake Xuanwu showed that the physical and chemical factors such as temperature,dissolve oxygen and pH were not very different and hadn＇t a dominant effect to the crustacean zooplankton migration among the lily vegetation area, open water and their boundary area. In the nights, crustacean zooplankton migrated to open water which might be that the number and biomass of phytoplankton in the water of lily vegetation area were lower than that in the boundary and open water areas. As the risk that crustacean zooplankton were preyed by fish in open water was high, crustacean zooplankton were found to migrated to the lily area in the daytime.