Effects of sub-mesoscale eddy on the lower-trophic level marine ecosystem in the East China Sea

Research Summary

　The lower-trophic level marine ecosystem in the Kuroshio region of the East China Sea (ECS) during summer generally shows typical subtropical features, i.e., small size pico-phytoplankton such as cyanobacteria dominates in the euphotic layer under the oligotrophic condition due to the stable stratification. It is also known that such stable physical and chemical conditions are often disturbed by the Kuroshio frontal eddy. We observed sub-mesoscale frontal eddies with about 25km diameters at the subsurface layer and the change of phytoplankton community associated with passing of eddies where the dominant groups quickly changed from pico-phytoplankton to micro-phytoplankton. These changes from the oligotrophic ecosystem to the eutrophic ecosystem were caused by the upwelling and horizontal advection of nutrient-rich subsurface water associated with the passing of eddies. However, the details of biogeochemical and ecosystem responses to the physical perturbations with eddies are still not clear. In this study, we will conduct comprehensive observations including various physical and biogeochemical parameters in the Kuroshio region of the ECS and numerical simulations using the latest lower-tropic level marine ecosystem model for understanding of the interactions between physical and biogeochemical processes.

The lower-trophic level marine ecosystem in the Kuroshio region of the East China Sea

Principal Investigator：

Naoki Yoshie

Senior assistant professor, Division of Coastal Oceanography,

Center for Marine Environmental Studies, Ehime University,Biogeochemistry