Author(s): Lin Hao; Zhaolin Sun; Yasuyuki Maruya; Shinichiro Yano; Satoshi Watanabe
Linked Author(s): Shinichiro Yano
Keywords: Hypoxia; River discharge; Climate change; Ariake Se
Abstract: Numerous studies have highlighted the profound impact of climate change-induced shifts in precipitation patterns on river and marine ecosystems. Climate change projections indicate an escalation in the frequency and intensity of flooding events, leading to heightened discharges from urban areas into the estuary. This surge in river discharge diminishes salinity levels, disrupts the halocline, and hinders the vertical transfer of dissolved oxygen (DO) from surface layers to the seabed, exacerbating hypoxia near the seafloor. The Ariake Sea, located on Kyushu Island in western Japan, is a vital estuarine region influenced by freshwater (ROFI). 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 Sea. The results indicate a relationship between the severity of hypoxia and the probability of flood exceedance, with hypoxia predominantly occurring frequently in July and August each year. This underscores the critical necessity for implementing effective adaptation measures to mitigate the effects of climate change on marine ecosystems and promote fisheries’ sustainability.
Year: 2024