Water Mass Assemblages and Nutrient Dynamics in Nares Strait: A Multiyear Perspective

Abstract Nares Strait is a critical gateway for the export of Arctic waters and nutrients toward the North Atlantic. Yet, the fine‐scale structure, variability, and long‐term evolution of its water masses and nutrient concentrations remain poorly characterized. Here, we combine almost two decades of high‐resolution hydrographic and biogeochemical data (2006–2024) to resolve the spatial and temporal variability in nutrient availability and water mass (WM) properties across this key arctic gateway. Using unsupervised clustering and tracer‐based diagnostics, we identify three dominant WM regimes shaped by Arctic and Atlantic influences, glacial inputs, and internal mixing. Our analysis reveals net freshening and nutrient shifts across all major water masses, including a doubling of nutrient concentrations in the arctic upper halocline as well as significant freshening of Polar Mode Water and Baffin Bay Polar Water properties. This multidecadal analysis provides crucial insights into the complex drivers of hydrographic and nutrient changes, enhancing our ability to predict how Arctic productivity will evolve.