Dr. Hjálmar Hátún
Senior research scientist
Faroe Marine Research Institute
University of the Faroe Islands
Research Interests: Focuses on the large-scale oceanic circulation in the subpolar North Atlantic and its impact on marine ecosystems. He has illustrated how the size and circulation intensity of the North Atlantic subpolar gyre regulates temperature, salinities, nutrient concentrations, the abundance key zooplankton species, stock sizes spawning distribution and feeding migration routes of pelagic fish stocks (blue whiting and mackerel), the breeding success of seabirds and the number of pilot whales. Hjálmar brings in large-scale indices like the gyre index to collectively discuss key trends in several components of this vast pelagic complex. In addition, he suggests that the adjacent shelf ecosystems should not be studied separately, but rather integrated in a bigger perspective which includes the oceanic waters connecting these shelves.
Traversing 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 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 which takes place 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. A consistent result from most climate models is reduced
winter convection due to global warming, and this is expected to have an especially severe impact on the North Atlantic Ocean primary production.