Zooplankton in the water column from the surface to bottom was studied. Copepods were the dominating organisms. Average zooplankton biomass was about 5 g in 1000 m3 . The highest zooplankton density occurred between 300 and 600 m. The influence of the Scotia Front on the horizontal and vertical distribution of zooplankton is discussed.
Coarse-scale studies on chlorophyll a distribution in a region covering the Scotia Front zone showed an increased chlorophyll content and its deeper distribution at stations situated in the frontal zone. The sources of chlorophyll α were probably both the phytoplankton released from melting ice as well as spring bloom.
Net phytoplankton was studied in 10 stations situated west of Elephant Island along three transects located in the Scotia Front zone and in 2 stations situated in the eastern Bransfield Strait. Altogether 70 algal taxa were identified. Phytoplankton density and seston biomass were the highest in stations neighbouring the Scotia Front from the south. In the Scotia Front region Corethron criophilum was a dominant species. Phytoplankton community of the region is rather uniform, however the closer comparison of the phytoplankton species composition allowed to distinguish 4 stations groups. This division is concordant with the hydrological one. A different phytoplankton community was recorded in the eastern part of the Bransfield Strait.
Low concentrations of phytoplankton (average 2.5 x 104 to б.0 х 105 cells l-1) were found at ten stations surveyed in the region of the Weddell-Scotia Confluence. Phytoflagellates represented mainly by 1—3 μm picoplankton were prevalent among the algae, contributing 65—100% to the total numbers: this group is observed to dominate over diatoms in areas of intensive water mixing. Maximum concentrations of phytoplankton at one station, reaching down to 200 m, were due to a physical aggregation of cells by confluencing and downwelling waters. The average for the water column quantities of the same algal groups were nearly identical at most stations, but peak numbers occurred in the 0—75 m surface layer. Differences in diatom assemblages were associated with the complex hydrography of the WSC region.