Plankton community structure and dynamics versus physical structure from Terra Nova Bay to Ross Ice Shelf (Antarctica).

During the austral summer 1997/1998, an oceanographic cruise was carried out on a large-scale grid in the Ross Sea. In this contribution, we focused our attention on the coastal area from the Terra Nova Bay (TBN) polynya to the eastern edge of the Ross Ice Shelf (RIS). We analyzed picoplankton, nanoplankton and microplankton fractions, with particular regard to heterotrophy versus autotrophy and the size-based partitioning of living carbon. Plankton dynamics were closely associated with hydrological features: (1) diatom blooms were confined to the ice-edge TNB polynya, (2) Phaeocystis dominance was confined to the lower salinity surface waters, diluted by the RIS and the Drygalsky Ice Tongue, (3) heterotrophic communities prevailed in the warmer surface waters of the Drygalsky basin, where most of the living carbon was associated with tintinnids (namely Codonellopsis gaussi). Phaeocystis distribution suggested that low salinities may be the main driving force in enhancing their develo