Planktonie material was taken in stratified hauls in the water column between King George and Elephant Islands, during the austral spring 1986. The species composition of Copepoda was diversified (abt. 50 taxa). Most frequent and abundant were M. gerlachei, C. acutus, R. gigas, small copepods of the family Pseudocalanidae and Cyclopoida. Interzonal Copepoda did not yet reach the euphotic zone; a comparatively low general copepod abundance and the advanced ontogenetic development in particular populations evidenced for the early spring phase of the planktonie community.
During the BIOMASS-SIBEX Antarctic expedition the distribution of Copepoda in three water layers (0—100, 100—300 and 300—500 m) in the Bransfield Strait and southern Drake Passage was studied. Altogether 46 taxa were recorded (Tabs. 1 and 2); the number of taxa increased with depth. Faunistic differences between the Drake Passage and the Bransfield Strait were observed. In some species the age-related splitting of the populations was registered (Figs. 2, 3 and 4). Young generations occupied usually the upper water layers.
The distribution of planktonic Ostracoda (Halocyprididae) was studied based on vertically-stratified zooplankton samples collected by hauling 200 p.m - mesh net by day and by night during two austral seasons: summer 1985/1986 and winter 1989, from the 1200 m deep Croker Passage off the Antarctic Peninsula. Seven species of Ostracoda were recorded: Alacia belgicae, Alacia hettacra, Melaconchoecia isocheira, Metaconchoecia skogsbergi, Boroecia antipoda, Disconchoecia aff. elegans and Proceroecia brachyaskos. The first three species, endemic to Antarctic waters, were predominant (about 90%). Generally Ostracoda were most numerous in 600-200 m layer in summer and in 1000-400 m layer in winter. In the investigated area there was a clear contrast between the abundance of Ostracoda during austral summer and scarcity during austral winter.
Zooplankton community composition, abundance and biomass from two polar localities – Kongsfjorden (Arctic) and Admiralty Bay (Antarctic) is compared. The community composition of zooplankton in both polar regions included similar taxonomic groups and the diversity at the species level was similar. Even though the overall species composition was different, some species were common for both ecosystems, for example Oithona similis, Microcalanus pygmaeus or Eukrohnia hamata. The abundance and biomass of the main zooplankton components (Copepoda) differed greatly between the two ecosystems, both being of an order of magnitude higher in Kongsfjorden than in Admiralty Bay. Kongsfjorden is situated at the border of two regions what induces high productivity with copepods playing an important role, and there is also a strong advection into the fjord. Admiralty Bay is adjacent to the homogenous Antarctic oceanic ecosystem; some advection into the bay occurs as an effect of tide and wind driven processes. Antarctic krill, which was not included in the present study, occupies most of the primary consumers niche and replaces copepods at the second trophic level.