中海における2006年春・夏季の赤潮収束過程

The red tide of dinoflagellate, Prorocentrum minimum occurred in Lake Nakaumi (southwestern Japan) in spring 2006. The patterns of phytoplankton changes in species compositions and abundance were investigated from 5 April, the mid-term of red tide to 9 August 2006. The red tide of Proro. minimum finished on 24 May 2006. The dominant composition of Lake Nakaumi had changed from dinoflagellate to diatom via cyanophyceae. It is considered that the main causes of these transitions are consumption of surface nutrient by red tide algae and nutrient inflow from land by the huge precipitation around the Lake Nakaumi. On the other hand, the red tide of Proro. minimum deposited through the halocline. The large abundance of these deposited algae probably caused the anoxic zone in the bottom layer of Lake Nakaumi