Major Nutrient Fronts in the Northeastern Atlantic: From the Subpolar Gyre to Adjacent Shelves

Diatom-dominated spring blooms in the northeastern Atlantic, both in the open ocean and on adjacent shelves, become silicate-limited every spring/summer. We here review the fertilizing silicate fluxes from the large subpolar gyre source, across the major oceanic Subarctic Front and further across shelf edge and tidal mixing fronts and onto adjacent shelves. As a case study, we illustrate potential linkages between the open ocean dynamics and the primary production, fish larvae abundances and seabird breeding success within the Faroe shelf ecosystem. The “boosting effect” of vigorous winter convection occurring every 5–8 years is illustrated, and we also discuss the pre-bloom silicate decline, which has taken place throughout the entire subpolar North Atlantic since the early 1990s. Reduced winter convection due to global warming is projected by most climate models, and this is expected to have severe impact on the North Atlantic Ocean primary production.