An Arctic Strait of Two Halves: The Changing Dynamics of Nutrient Uptake and Limitation Across the Fram Strait

The hydrography of the Arctic Seas is being altered by ongoing climate change, with knock-on effects to nutrient dynamics and primary production. As major pathway exchange between Atlantic, Fram Strait hosts two distinct water masses in upper column, northward flowing warm saline Atlantic Waters east, southward cold fresh Polar Surface Water west. Here, we assess how physical processes control using nitrogen isotope data collected during 2016 2018. In Waters, a weakly stratified column shallow nitracline reduce limitation. To west, Water, limitation greater because stronger stratification inhibits resupply from deeper lateral nitrate supply central waters low. A historical hindcast simulation ocean biogeochemistry 1970 2019 corroborates these findings highlights strong link depth winter mixing, which shoaled response local reduction sea-ice formation. Overall, find that while eastern currently experiences seasonal replenishment high production, loss sea ice continued atmospheric warming has potential inhibit deep mixing limit production future.