Two shallow ponds at Cape Evans, Ross Island, were sampled at 1–2 week intervals, during winter freezing throughout the winter and during the subsequent melt period, to examine the physical and chemical conditions imposed on the biota during the year. Liquid water was first detected at the base of the ponds in late December. During the main summer melt period conductivities were less than 10 mS cm−1 with maximum daily temperatures around 5°C. The bottom waters became increasingly saline during freezing and water temperatures decreased below 0°C; by June the remaining water overlying the sediments had conductivities >150 mS cm−1 and temperatures of −13°C. Calcium carbonate, then sodium sulphate precipitated out of solution during early freezing. The dominant nitrogen species was dissolved organic-N which reached 12 g m−3 in Pond 1 just prior to final freeze up. The organic and inorganic forms of nitrogen and dissolved reactive phosphorus increased with increasing conductivity in the ponds. The behaviour of particulate-N and particulate-P mirrored that of chlorophyll a with a peak in March-April and a second higher peak just before final freeze-up. This study provides clear evidence that organisms which persist throughout the year in Antarctic coastal ponds must be capable of surviving much more severe osmotic, pH, temperature and redox conditions than those measured during the summer melt. Deoxygenation, pH decline and H2S production, however, point to continued respiratory activity well into the dark winter months.

Based on two complete years of marine ecological surveys (1981-82 and 1984-85) carried out in the Hornsund fjord on southern Spitsbergen (77"N), the seasona1 variation of physical and biological processes is presented. Physical parameters reflect the strong seasona1ity of sun radiation, while water sa1inity and temperature fluctuate within a narrow range. Concentrations of nutrients and suspended matter depend on meltwater discharge from glaciers and snow cover thickness. The breeding period of most marine invertebrate species is strongly related to the phytoplankton bloom which peaks in May. Ringed seal and polar bear occurrences are directly related to sea ice conditions. Both species are most numerous in Hornsund during March-April. Sea birds which nest in huge colonies along the Hornsund coasts arrive in April-May and leave by August-September except for Fulmars and Briinnich's Guillemots which were observed year-round.

Based on two complete years of marine ecological surveys (1981‐82 and 1984‐85) carried out in the Hornsund fjord on southern Spitsbergen (77N), the seasonal variation of physical and biological processes is presented. Physical parameters reflect the strong seasonality of sun radiation, while water salinity and temperature fluctuate within a narrow range. Concentrations of nutrients and suspended matter depend on meltwater discharge from glaciers and snow cover thickness. The breeding period of most marine invertebrate species is strongly related to the phytoplankton bloom which peaks in May. Ringed seal and polar bear occurrences are directly related to sea ice conditions. Both species are most numerous in Hornsund during March‐April. Sea birds which nest in huge colonies along the Hornsund coasts arrive in April‐May and leave by August‐September except for Fulmars and Brünnich's Guillemots which were observed year‐round.

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