Transport and retention of zooplankton in northern George VI Sound, Antarctic Peninsula

Ryan Dorland, Meng Zhou, and Kendra Daly

Northern George VI Sound exhibits a rich mesoscale circulation pattern replete with coastal currents and eddies during austral fall 2001. The circulation pattern determined from a combination of direct current and hydrographic data and the zooplankton distribution from an Acoustic Doppler Current Profiler and net tows suggest significant transport across the entrance of northern George VI Sound and retention of zooplankton near the George VI Ice Shelf. A cyclonic gyre within Marguerite Bay is the likely source of zooplankton supply to the region. Surface coastal current intrusions, driven by wind forcing and baroclinic pressure gradients, steer nearly one-third of the water volume transport of this gyre into the sound. Zooplankton and micronekton were entrained in coastal currents and mesoscale eddies and aggregated within the sound. Net tows confirm the presence of larval stage Euphausia superba and abundant copepods contributing to the acoustic backscattering signal. The influence of diel migration on the transport calculation is discussed and the impacts of the transport and retention to higher trophic levels in the region are explored. Results emphasize the coupling between mesoscale physical features and zooplankton distributions at high latitudes.