THE DISTRIBUTION OF ANTARCTIC DIATOMS IN THE WEDDELL SEA DURING AUSTRAL WINTER

As part of the AMERIEZ (Antarctic Marine Ecosystem Research at the Ice Edge-Zone) program, water samples were collected and analyzed for dia tom species composition along 40 degrees W and 48 degrees W transects normal to a rapidly moving ice edge during mid-austral winter. The ove rall abundance of living diatoms was low; integrated estimates down to 150 m ranged from 1.06 x 10(8) to 6.03 x 10(8) cells m(-2). On both t ransects, we found a significantly higher number of living diatom cell s in the open water compared to samples collected underneath the sea i ce, although the sea ice was moving rapidly. Diversity was low; both F ragilariopsis cylindrus and Fragilariopsis spp. together accounted for an average of 59% of the total living diatoms at each station, indivi dually averaging 29%. The distributional patterns of the dominant diat om taxa were closely related to the presence of the ice cover. The res ults of our study emphasize the low phytoplankton abundance during the austral winter season and the paucity of resting spores in the Antarc tic flora.