Author(s): Lin HAO; Zhaolin SUN; Yasuyuki MARUYA; Satoshi WATANABE; Shinichiro YANO

Linked Author(s): Shinichiro Yano

Keywords: Hypoxia, River discharge, Climate change, Ariake sea

Abstract: Numerous studies have highlighted the profound impact of climate change-induced shifts in precipitation patterns on river and marine ecosystems. Ensemble-Based Climate Scenarios indicate an escalation in the frequency and intensity of flooding events, leading to heightened discharges from urban areas into the estuary. Increased river discharge lowers salinity, reinforcing the halocline and intensifying vertical stratification, which limits oxygen transport and exacerbates hypoxia near the seafloor. The Ariake Sea, located on Kyushu Island in western Japan, is a vital estuarine region influenced by freshwater. It is crucial for sustaining fisheries and seaweed production but suffers from severe hypoxia. This study used a large ensemble climate simulation database (d4PDF), which provides regional downscaling simulations for Japan, to assess the potential for hypoxia events during the rainy season. Historical simulation climate data from d4PDF were input into a coupled three-dimensional hydrodynamic model (Delft3D-FLOW) and a lower-trophic ecosystem model (Delft3D-WAQ) to simulate dissolved oxygen (DO) dynamics in the Ariake and Yatsushiro Seas. The results reveal a correlation between the severity of hypoxia and the likelihood of flood exceedance, with hypoxia primarily occurring in summer. This highlights the urgent need for effective adaptation measures to mitigate climate change impacts on marine ecosystems and ensure the sustainability of fisheries.

DOI: https://doi.org/10.64697/IAHR-APD2024_P180

Year: 2024