A Link between The Kuroshio Extension, Marine Heatwaves, and Marine Ecosystems in the Gulf of Alaska

Abstract Marine Heatwave (MHW) events in the Northeast Pacific Ocean from 2014-2016 and 2019-present have had significant impacts on ocean life and livelihoods in the region. Numerous studies have linked these MHWs to known modes of climate variabilities. Using multiple datasets, here we show that the observed evolution of the 2012-2015 marine heatwave in the Gulf of Alaska (GOA) best correlates with the evolution of historical sea surface temperatures (SSTs) in response to large-scale variations in the Kuroshio Extension (KE) region. Further, we report the physical and biogeochemical changes during this MHW and their relation to these same KE variations. Based on these results we propose a link between large-scale KE variations and MHWs in the GOA. A link that further extends to the marine biogeochemistry and productivity in the region via KE-influenced modifications to mixed layer thickness. Our findings offer baseline guidance for understanding the biological implications of KE variations on the GOA and can aid in the formulation of climate-related fisheries policies on a local, regional, and global scale, both under current conditions and in response to future anthropogenic-induced changes in the KE.