Changing Ocean Chemistry: Impacts of Ocean Deoxygenation and Acidification from Benthic Iron Fluxes to Fisheries

Changing Ocean Chemistry: Impacts of Ocean Deoxygenation and Acidification from Benthic Iron Fluxes to Fisheries

Virtual

Ocean deoxygenation and acidification are impacting marine ecosystems, contributing to changes in ocean biogeochemical cycling and fisheries across the U.S. West Coast and northern Gulf of America/Mexico. Using spatially and temporally resolved observations, numerical modeling, and biogeochemical analyses, this seminar examines how changing ocean conditions influence processes from water-column oxygen dynamics to marine organisms. In the Santa Barbara Basin, observations of dissolved O₂ reveal persistent decadal hypoxic and anoxic conditions and changes in deep-water ventilation associated with high benthic iron fluxes (0.23–4.9 mmol m⁻² d⁻¹). Combining benthic iron flux measurements with numerical simulations demonstrates how iron availability can enhance surface primary production while contributing to feedbacks among iron, nitrogen, and oxygen cycling. In the northern Gulf of Mexico, we investigate how decadal changes in carbonate chemistry are associated with changes in otolith morphology in Red Snapper, an economically important fishery species. Our results demonstrated fluctuations in otolith size rather than a progressive trend with respect to dissolved inorganic carbon (DIC). These findings suggest that long-term trends in DIC and alkalinity (ALK) may influence otolith morphology, although variability in ocean chemistry and seasonal environmental conditions may also have cumulative effects on otolith density, mass, and volume. Together, these studies demonstrate how observations and modeling can link physical and biogeochemical variability to ecological responses across oceanic and coastal environments.