Effects of vertical mixing on low trophic ecosystem in the Ulleung Basin, East Sea

Abstract

Ulleung basin (UB) in the southwestern East Sea shows relatively high primary productivity even in summer. The high productivity is probably associated with nutrient supply by vertical mixing, horizontal transport by ocean currents, or eddy-induced upwelling. In this study we investigated effects of vertical mixing on low trophic ecosystem in the UB using a one- dimensional physical-biological model (1D GOTM-ERSEM), focusing on timing and intensity of phytoplankton bloom. Stratification in the model was given by three different cases with different degree of reality. We found that proper representation of stratification plays a crucial role in timing of phytoplankton bloom by controlling nutrient supply in winter. However, the diatom, a dominant phytoplankton in spring bloom in the UB, was poorly simulated both in timing and strength of bloom, indicating importance of horizontal transport of silicate supply.y-induced upwelling. In this study we investigated effects of vertical mixing on low trophic ecosystem in the UB using a one- dimensional physical-biological model (1D GOTM-ERSEM), focusing on timing and intensity of phytoplankton bloom. Stratification in the model was given by three different cases with different degree of reality. We found that proper representation of stratification plays a crucial role in timing of phytoplankton bloom by controlling nutrient supply in winter. However, the diatom, a dominant phytoplankton in spring bloom in the UB, was poorly simulated both in timing and strength of bloom, indicating importance of horizontal transport of silicate supply.