Projected thermal stress and regional vulnerability of Manila clam production in Korean waters under climate change scenarios

Abstract

The Manila clam (Ruditapes philippinarum) is one of the commercially valuable bivalves, but climate change poses a growing threat to its survival and production. This study analyzed projected changes in thermal stress conditions for Manila clams across seven coastal sites in the Korean Peninsula using CMIP6 model simulations under four SSP scenarios in years 2030, 2050, 2075, and 2100. We defined vulnerable conditions as sustained periods of eight or more consecutive days with water temperatures exceeding 26 °C, based on previous thermal threshold researches. Our analysis revealed distinct regional and temporal patterns in thermal stress vulnerability. Northern sites, particularly Wonsan Bay (39.18°N), showed relative stability until 2050 under moderate scenarios (SSP1-2.6, SSP2-4.5), while the most southern site, Geoje (34.76°N), exhibited the longest high temperature periods across all scenarios. Statistical analysis demonstrated significant temporal trends (p < .001) and regional differences (p < .001) in vulnerable days over all sites. The number of high-temperature days increased significantly from 2030 to 2075, with most pronounced changes during 2050–2075 (mean increase 16.14 days, p < .001) over all sites. The Yellow Sea sites showed greater absolute numbers of high-temperature days but less sensitivity to climate change compared to the East Sea sites, likely due to reduced influence from the Kuroshio Current. In consideration of the regional environmental impact of future climate change, we propose the adaptation strategies to support the sustainable production of clams including shifting the cultivation area to the northern region, developing heat-resistant species, adjusting farming calendars to avoid peak heat periods, and implementing deep-sea water cooling systems.