Spatial and temporal variability of zooplankton was studied during five summers (2004–2008) in the Dumont d’Urville Sea, east Antarctica. The species recorded, based on the catch of a 500 µm-mesh Bongo net, were typical of southern continental shelf communities in Antarctica, including Euphausia crystallorophias, polychaetes, pteropods and biomass-dominant copepods. There was a strong degree of temporal variation in abundance, possibly related to the thickness and extent of the sea ice cover during each spring prior to the surveys. Total mean abundance was highly variable between years, with a minimum of 961 ind. 1000 m-3 in 2004 (range 65–3407 ind. 1000 m-3) and a maximum of 15,627 ind. 1000 m-3 in 2005 (range 5109–33,869 ind. 1000 m-3). Spatially, within each year, abundances were also variable, and there were no uniform patterns in abundance from year to year. Water column physical characteristics (temperature and salinity) were relatively constant and did not contribute substantially to variation between the years. It is likely that variation in zooplankton distribution was largely related to a combination of localised features, such as the thickness and extent of sea ice cover, the position and extent of the Mertz Polynya, local wind conditions and bathymetric features. |
