Source Biogeochemistry

The Salish Sea’s biogeochemistry is tightly linked to the Pacific Ocean waters that flow in through Juan de Fuca Strait. These inflows vary from year to year in both volume and chemical makeup, with important consequences for temperature, oxygen, nutrients, and the carbon system. In this project, we used a decade of high-resolution model output from LiveOcean combined with Lagrangian particle tracking to determine which Pacific water masses contribute to Salish Sea inflow, how their contributions vary over time, and what that means for key biogeochemical constituents. We paired model results with observations of tracers not included in the model, such as dissolved phosphate, dissolved silica, and a suite of trace metals, to characterise the distinct properties of each source water mass. Our results show that deep water masses control nutrient supply through volume changes, while surface waters—particularly from the southern shelf—drive interannual variability in oxygen and carbonate chemistry due to both property and volume changes. Understanding how changing Pacific source waters drive variability in coastal systems is essential for anticipating and managing future risks. 

Beutel, B; Allen, S.E. , Xiong, J., Maldonado, M. (2025). Impact of water mass dynamical and property variability on the inflow of a semi-enclosed sea. Submitted to Biogeosciences.