Results of an oceanographic survey along the edge of drifting pack ice in the area between Elephant Island and the South Orkney Islands are reported. The influence of sea ice on hydrological factors was very weak. It was not possible to develop oceanographic features characteristic for marginal sea-ice zones in the areas with well marked surface currents and dynamic hydrological conditions. The spatial distribution of chlorophyll was governed by water stability, although during our survey, areas with enhanced vertical stability could not be described in terms of a sea-ice edge influence.
The highest concentrations of algal cells (1.1 x l0 6 litre- 1 ) and of algal carbon (20 μg litre -1 ) were associated with a lens of ice melt water in the northeast of the study area. Phytoflagellates were dominant at all stations with greater numbers always in the 0 - 20 m surface layer and with the peaks of Cryptophyceae in the open waters and also near the ice edge east of 50° W. Picoplankton flagellates and monads (1.5-5.0 μ) were generally next in abundance and most important numerically in the near ice stations in the western part of the study area. Parasinophyceae were usually more abundant than Nitzschia cylindrus (Grunow) Hasle, the only common diatom species found mainly in the western near ice edge stations. The presence olN.cylindrus, dominant in the pack ice and in phytoplankton near the ice edge, shows that algae released from ice may act as an inoculum for the phytoplankton.
Chlorophyll a content and the density and species composition of algae were determined in drifting sea ice north of the Elephant Island (between 54-56°W and 60°30'—61°00'S) at the end of October 1986. In yellow-brownish pieces of brash ice the amount of chlorophyll α was on average 203.5 ± 149.9 mg m-3 at the density of algal cells of 255.7+137.8-103 in cm3. In not visibly discoloured ice the respective values were about 80 times lower, and in surface water about 700 times lower. 69 algal taxa were recorded in the samples, almost all of which were diatoms. Nitzschia cylindrus dominated in all the samples. A comparison of species composition in the investigated habitats revealed that the highest species similarities occurred between samples collected in discoloured ice, lower in the uncoloured ice and the lowest ones in water.
Four water masses were distinguished in the upper water layer between Elephant Island and the South Orkneys. Measurements of temperature, salinity, concentrations of dissolved oxygen and silicates were used for the analysis of the hydrological situation and to recognise the origin of water masses. For additional information, nitrates and chlorophyll concentrations were used. Drake Passage and Bransfield Strait waters occupied the western part of the investigated area, from surface to 150 m depth. Below, the Circumpolar Warm Deep Waters (CWDW) were found. The region east of 53.5°W was occupied by winter Weddell Sea water. Above this, a 45 m thin layer of summer modification of Weddell Sea Surface Water was found between 49°W and the South Orkneys. The highestchlorophyll α concentrations were found in this modified water.
Density, composition and domination structure of the sea ice microalgae in the Admiralty Bay (South Shetland Islands) were investigated in 1983. Algae were recorded both in discoloured and in colourless sea ice from June to October. The highest algae density, amounting to 5 x 105 cells in 1 cm3 was observed till the end of August, the diatoms Nitzschia cylindrus and N. curta being the dominant species. A total of 95 algal taxa. mostly diatoms, were recorded. Air temperature seems to be an important factor influencing the development of algae in sea ice.
During the spring of 1998 sympagic algae and meiofauna were studied in Ross Bay on the western coast of the Kane Basin between Ellesmere Island and Pim Island (Canada). Ice samples were collected by ice coring and the lowermost 2 cm sections were analysed. The sea-ice flora was composed of 59 taxa and was dominated by Nitzschia frigida, Navicula pelagica, Fragilariopsis oceanica and unidentified flagellates (over 60% of total number). Abundance of algae ranged from 1×109 to 3×109 cells per square meter. Sea-ice meiofauna was composed of Nematoda and Harpacticoida and was strongly dominated by nematodes (99.76%). Total sympagic meiofauna abundance ranged from 37.5×103 to 146.1×103 ind. and biomass from 2.88 to 8.83 mg C per m2. There was no clearly marked patchiness in the horizontal distribution of sympagic algae and meiofauna.
Altogether 105 algal taxa were identified including 101 diatom species. Chaetoceros criophilus was dominant in the western part of the study area influenced by waters from the Bellingshausen Sea. Corethron criophilum was abundant in the Weddcll Sea water mass found to the east of 53.5°W meridian. Nitzschia cylindrus common in the ice-melt samples was dominant in only two net phytoplankton collections obtained at the ice-edge zone. Additional samples from Admiralty Bay, at King George Island revealed the dominance of Chaetoceros socialis and the presence of many tychoplankton species. Very few diatom cells were found in the open waters of the Bransfield Strait which combined with the presence of krill, suggested intensive grazing by herbivores. The unstable waters of the Weddell-Scotia Confluence area contained little phytoplankton except for a station dominated by Phaeocystis pouchetii. Greater cell densities were related to warm, lower salinity Weddell Sea water of summer modification found in the surface layer east from 49°W.
The climatic change on King George Island (KGI) in the South Shetland Islands, Antarctica, in the years of 1948–2011 are presented. In the reference period, a statistically significant increase in the air temperature (0.19 ° C/10 years, 1.2 ° C in the analysed period) occurred along with a decrease in atmospheric pressure (−0.36 hPa/10 years, 2.3 hPa). In winter time, the warming up is more than twice as large as in summer. This leads to decrease in the amplitude of the annual cycle of air temperature. On KGI, there is also a warming trend of daily maximum and daily minimum air temperature. The evidently faster increase in daily minimum results in a decrease of the diurnal temperature range. The largest changes of air pressure took place in the summertime (−0.58 hPa/10 years) and winter (−0.34 hPa/10 years). The Semiannual Oscillation pattern of air pressure was disturbed. Climate changes on KGI are correlated with changing surface temperatures of the ocean and the concentration of sea ice. The precipitation on KGI is characterised by substantial variability year to year. In the analysed period, no statistically significant trend in atmospheric precipitation can be observed. The climate change on KGI results in substantial and rapid changes in the environment, which poses a great threat to the local ecosystem.
At the northern border of pack ice the study on chlorophyll a content, density of cells, species composition and domination in samples from the drifting ice floes and from brash ice was carried out. 102 taxa of algae were found in the pack ice. In the study area algal taxa were rather uniformly distributed. In different ice layers the qualitative composition of diatom assemblages was similar and usually the diatom Nitzschia cylindrus was dominant and most frequent. Chlorophyll a content (from 0.12 to 334.5 mg m-3) and the density of cells (from 0.3 to 362 x l0 6 cm) varied strongly in various habitats. Ice floes near the northern pack ice border contained low values of chlorophyll a (mean value 0.50 ±0.28 mg m-3) . However, brash sea ice originating from ice floes, contained 142.4 ±117.5 mg m-3 of chlorophyll α in visibly discoloured and 30.1 ±24.3 mg m~3 of chlorophyll α in not visibly discoloured parts on average. The range of chlorophyll α content and the presence of characteristic species allow to distinguish brash sea ice infiltration assemblage of diatoms.
Eight samples of the ice algae were collected from the annual ice in Tikhaia Bay, Hooker Island, Franz Josef Land. Species composition included 58 diatoms (and some Navicula, Nitzschia and other Pennatophyceae unidentified species), 2 dinoflagellates, 2 chrysophyceans, 1 chlorophycean, 1 cyanophycean and possible dinoflagellate and chrysophycean cysts. The maximum quantity was 132300 cells/l. In 4 samples Aulacoseira granulatu prevailed, in other samples Nitzschia frigida, N. cylindrus, Rhizoclonium sp. and dinoflagellate cysts dominated. Xanthiopyxis polaris found by Gran (1904) in Arctic sea ice and referred to the diatoms is, possibly, the dinoflagellate cyst. On the whole, the ice community consisted of benthic and planktonic-benthic species of mainly marine and brackishwater-marine pennate diatoms, their resting stages, freshwater unicellular algae and marine chlorophycean.
This article comprises an analysis of the variability of meteorological conditions on Kaffiøyra (NW Spitsbergen, Svalbard) in 2013–2017 in connection with atmospheric circulation and the extent of sea ice. The obtained results were compared with the results of observations made at the Ny-Ålesund station. Due to the situation of the area in the polar region and the large amount of clouds, especially in summer, the annual sum of incoming solar radiation was small, amounting to an average of 2,237.8 MJ.m-2 per year. The mean air temperature in the considered period was -2.0°C. Its extreme values ranged from 15.2°C to -23.8°C. In the annual course, the highest mean temperature occurred in July (6.5°C), and the lowest in March (-7.8°C). The mean relative humidity of air was high (83%). The prevailing wind directions were from south and north sectors and this coincided with the orientation of Forlandsundet. The mean wind speed was 3.6 m.s-1. In the summer season in 1975–2017, a statistically significant air temperature increase was observed, reaching 0.28°C/10 years. The high variability of local weather conditions was caused mainly by atmospheric circulation and the impact of sea ice was much smaller in comparison.