Coastal warming heightens direct impacts of seawater temperature on nutrients near aquaculture farms in Korea

Abstract

The potential roles of temperature and phytoplankton in nutrient cycling throughout the water column were investigated nearby aquaculture farms. Using the convergent cross mapping (CCM), we examined the relative strength of phytoplankton and temperature effects on nutrients. High δ¹⁵N values of particulate organic matter in the inner bay were detected compared to those in the outer bay. δ¹⁵N values >5 ‰ throughout the bay indicate that nitrogen influxes from the aquaculture farms are the critical nitrogen source in the study region. Our CCM models revealed that temperature positively and strongly affected the potential regeneration of nutrients, associated with PO₄^3- while phytoplankton utilized nutrients as soon as available. The temperature-driven nutrient regeneration was higher in the bottom layer than that in the surface layer, indicating that temperature was a more important controlling factor in nutrient fluxes from the surface sediments.

Keywords: Aquaculture; Coastal warming; Convergent cross mapping (CCM); Nutrients; Regeneration.