Field observation on blue carbon dynamics in the Yatsushiro Sea considering influence of stratification

Recently, blue carbon, which is the carbon fixed by marine living organism has attracted attention as a new measure to mitigate climate change. In order to estimate the fixed amount of blue carbon, the partial pressure of CO2 (pCO2) in seawater is important. In this study, we carried out field observation in the Yatsushiro Sea and tried to reveal the actual dynamics of pCO2 in a coastal region. In addition, from observation in the conditions with different mixing condition, that is, strong stratification, weak one, and well-mixed, we tried to reveal the effects of stratification on pCO2 in seawater. As a result, it was confirmed that the effects of photosynthesis by flora and calcification by corals on the fluctuation of pCO2. Moreover, we revealed that the effect of photosynthesis of phytoplankton was concentrated in the surface layer. Furthermore, in the strong stratification period, it was suggested that pCO2 in seawater was able to be fluctuated due to the inflow of seawater from a coral habitats area.