Studies on inter-relationships between phytoplankton and zooplankton in patchy distributional manner

本项目的主要目的是找出自然界中浮游植物和浮游动物的斑块分布，从而确定在不同种群密度下浮游植物和浮游动物之间的相互关系，这种关系可能因斑块的存在或不存在而在自然界中发生。所获得的数据可以总结如下。(1)通过连续拖曳朗赫斯特-哈迪浮游生物记录仪和散射-荧光-温度-深度记录仪，在不同海域记录了许多浮游植物和浮游动物在精细尺度上的斑片状分布。(2)草食性桡足动物摄食活动的昼夜节律在自然种群中被发现，节律随不同摄食/饥饿状态的变化幅度也被研究。由此可以推测桡足类垂直迁移的生态意义。桡足类垂直迁移使桡足类在表层周期性地遇到浮游植物斑块。(3)阐述了女川湾浮游植物、异养和混合养浮游纤毛虫的分布格局。尽管纤毛虫的游泳能力很弱，但每个物种似乎都保持着自己在水柱中的特定位置，这可能是由对浮游植物作为能量来源的依赖程度所控制的。

The main aims of this project are to figure out the patchy distributions of phytoplankton and zooplankton in nature and then determine the inter-relationships between phytoplankton and zooplankton at different population densities, which may occur in nature depending on the presence or absence of patches. The data obtained can be summarized as below.(1) Many instances of patchy distribution in fine scale of both phyto- and zooplankton in various sea areas were recorded by continuous towings of a Longhurst-Hardy Plankton Recorder and a Scatter-Fluorescence-Temperature-Depth Recorder.(2) Diel rhythms in feeding activity of herbivorous copepods were found in natural populations Magnitudes of the rhythm changing with different feeding/starving regimes was also examined. Then ecological significance of diel vertical migration of copepods, which makes copepods encounter periodically phytoplankton patches in the surface layer, could be speculated.(3) Distributional patterns of phytoplankton and heterotrophic and mixotrophic planktonic ciliates in Onagawa Bay were illustrated. Despite very weak swimming ability of the ciliates, each species seems to keep its specific position in water column which might be controlled by the degree of dependence on phtoplankton as a energy source.