Circulation on the Western Antarctic Peninsula and implications for biological production

Andrea Piñones, Eileen E. Hofmann, Michael S. Dinniman, and John M. Klinck

Field observations from the U.S. Southern Ocean Global Ocean Ecosystem Dynamics Program showed that marine mammals and other predators concentrate in specific areas of the western Antarctic Peninsula (WAP) continental shelf. The relative contribution of circulation in producing these regions is investigated with Lagrangian particle tracking simulations that used a high-resolution version of the Regional Ocean Modeling System that included a dynamic sea-ice model and thermodynamically active ice shelves. Floats are released along the WAP outer and mid-shelf regions at a range of depths in different seasons. The simulated particle trajectories show preferred sites for cross-shelf exchange and onshelf intrusions, which correspond to areas where higher predator abundance is observed. These results suggest that circulation is potentially important in developing localized areas of high predator abundance perhaps through facilitating aggregation of prey and/or providing areas of enhanced nutrient availability and biological production. The trajectories of floats released along the southwestern portion of the model domain show inputs to the WAP shelf from the Bellingshausen Sea (BS) with a time scale that is consistent with the time required for krill eggs spawned in the BS to develop into larvae. These results suggest connectivity between WAP and BS krill populations.