This paper includes a check-list of Recent Svalbard marine ostracods based on published sources and on diploma theses as well as some new studies. This is the first study of this group of crustaceans from Hornsund. A total of 41 species belonging to 12 families were collected at 55 sampling stations from dredged sediments. Seven species are reported for the first time from the Svalbard Archipelago. Polycope orbicularis Sars is the most abundant species in the present fauna. Species compositions of Hornsund and the Liefdefjorden are seen to have the highest similarity (S = 50.6).

The material discussed in this paper was collected in the Drake Passage and Bransfield Strait (Antarctica) within the framework of the BIOMASS-SIBEX programme. Samples were collected by hauling Nansen nets verticaly through the 100 — 0, 300—100 and 500 — 300 m layers in December 1983 and January 1984. Of the six species recorded — Metaconchoecia isocheira, Alacia hettacra, Alacia belgicae, Metaconchoecia skogsbergi, Boroecia antipoda and Discoconchoecia off. elegans — the first three, endemic to Antarctic waters — were predominant (92.9%). Ostracoda were found most abundantly in the eastern part of the study area — between Elephant Island and South Orkney Islands, and in the south-western part of Bransfield Strait. Their vertical distribution depended on the hydrological conditions. Ostracoda were most numerous in the 500—300 m and 300 — 100 m layers; very few were recorded in the 100—0 m surface layer.

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.

Candona rectangulata is an ostracod species common in cold (<15 ° C ) shallow freshwater Arctic water bodies. This species is useful in palaeolimnological studies because only few known autecological data can be applied in reconstructions of palaeoclimate. Particular attention was paid to the temperature, which is the basic factor determining the geo− graphic range of a species. In this study a wide tolerance of C. rectangulata to the temperature was demonstrated for the first time. Its high tolerance to the temperature changes seems to be based on induction of set of proteins belonging to the family of heat shock proteins. Using PAGE−SDS electrophoresis variation in the protein profile of non−model organism undergoing stress in the field (South Spitsbergen, near Stanisław Siedlecki Polish Polar Station) and in laboratory cultures was presented. These results could explain the eurythermic range of C. rectangulata and its good adaptation to the environmental conditions which normally do not exist in Arctic freshwater ponds.

The ostracod fauna were examined from the Kapp Starostin Formation sequences (Upper Permian) from West Spitsbergen (Svalbard). The ostracod taxa are mainly confined to 3 superfamilies: Kirkbyacea, Healdiacea and Bairdiacea. 11 taxa are identified. One new species, Kindlella bellsundi is proposed. The ostracod assemblage dominated by kirkbyacean taxa is related to open shelf marine environment.

Ostracods from Admiralty Bay on King George Island (South Shetland Islands) represent 29 podocopid species, belonging to 19 genera, one cladocopid and six myodocopid species. They were recovered from Recent marine and/or glacio-marine sediment samples from water depths of up to 520 m. These ostracods constitute a variable assemblage, which is overall typical for the Antarctic environment. Shallow-water assemblages tend to be more variable in terms of frequencies and species richness than deep-water assemblages. The later are low in numbers and remain relatively high diversities. Overall, no linear relation between ostracod assemblage-composition and environmental features analyzed was recognized.

Deep−sea benthic Ostracoda (Crustacea) in Icelandic waters are poorly known. Here we report deep−sea ostracode assemblages from the multiple core (MUC) and the epibenthic sledge (EBS) samples collected from Icelandic waters by the first cruise of the IceAGE (Icelandic Marine Animals: Genetics and Ecology) project. Samples from shelf − −edge and lower−bathyal working areas are examined. The results show (1) distinct MUC and EBS faunas due to the large difference in mesh size of MUC and EBS; and (2) distinct shelf−edge and lower−bathyal ostracode faunas. Such remarkable faunal turnover from shelf to bathyal depths is similar to the faunal turnovers reported from depth transects in the adjacent regions of the western North Atlantic Ocean, the Greenland Sea, and the North Sea, but, at the same time, there are certain differences in the faunal composition between the Icelandic waters and these adjacent regions. In addition, we illustrate many Icelandic deep−sea ostracode species with high−resolution scanning electron microscopy and composite all−in−focus stereomicroscopic images for the first time. These results provide important basic information on deep−sea ostracode research and biogeography of this important region connecting North Atlantic proper and Nordic Seas.

Tonnacypris glacialis (G.O. Sars, 1890) is a meiobenthic species widely distributed in Arctic freshwater lakes. Field study of its life cycle as well as the laboratory experiments showed clearly that only one generation of this ostracod species occurs during the vegetation season, and that the condition necessary for the next generation to appear is eggs freezing.

Four Ostracoda species belonging to one family, Halocyprididae, were found in plankton material collected from the Scotia Sea and off the King George Island (the Antarctic) during the austral summer 1988/1989. Alacia belgicae, A. hettacra and Metaconchoecia isocheira were dominant making up to nearly 99% of all Ostracoda. The horizontal distribution was modified by variability of hydrological conditions. The higher concentrations of chlorophyll a and phytoplankton, which were found in the mid- and eastern parts of the Scotia Sea, coincided with the highest densities of Ostracoda. The influence of ice pack presence in the Scotia Sea upon the higher abundance of Ostracoda in the period investigated in comparison with the earlier studies was distinctive. A vertical distribution analysis confirmed that the three above-mentioned endemic species were most abundant in the mesopelagial. The population structures of A. belgicae, A. hettacra, and M. isocheira were analysed. The presence of the youngest stage of A. belgicae in the Scotia Sea confirmed the beginning of reproduction of this species at that time. The vertical distribution patterns of A. hettacra and M. isocheira populations were similar, although their age structures in comparison with A. belgicae differ significantly. This was consistent with their higher “mean population stage” values.