Seasonal to tidal variability in currents, stratification and acoustic backscatter in an Antarctic ecosystem at Deception Island

The annual cycle of the marine ecosystem of a semi-enclosed bay at Deception Island, Antarctica, was studied with moorings and cruises from March 1999 to November 2000. Moored observations of water temperature, currents and acoustic Doppler profiler (ADP) backscatter amplitude were made during the experiment. A camera and anemometer monitored winds and ice cover from the northern ridge. We estimate that water parcels inside Deception Island have a mean residence time of 2.4 years, and a 1% volume exchange occurs over each tidal cycle. Seasonal and diurnal processes dominated water temperature and current variability. ADP backscatter amplitude was consistent with the diel migration of zooplankton.