Polish Polar Research

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.

In this paper, the recent ice regime variations in the Kara Sea have been described and quantified based on the high-resolution remote sensing database from 2003 to 2017. In general, the Kara Sea is fully covered with thicker sea ice in winter, but sea ice cover is continuously declining during the summer. The year 2003 was the year with the most severe ice conditions, while 2012 and 2016 were the least severe. The extensive sea ice begins to break up before May and becomes completely frozen at the end of December again. The duration of ice melting is approximately twice than that of the freezing. Since 2007, the minimum ice coverage has always been below 5%, resulting in wide open-waters in summer. Furthermore, the relevant local driving factors of external atmospheric forcing on ice conditions have been quantitatively calculated and analyzed. Winter accumulated surface air temperature has been playing a primary role on the ice concentration and thickness condition in winter and determining ice coverage index in the following melt-freeze stage. Correlation coefficients between winter accumulated temperature and ice thickness anomaly index, the ice coverage anomaly index, duration of melt-freeze stage can approach -0.72, -0.83 and 0.80, respectively. In summer, meridional winds contribute closely to summer ice coverage anomaly index, with correlation coefficient exceeding 0.80 since 2007 and 0.90 since 2010.

Nothofagaceae fossil leaves and an associated palynoflora from Late Cretaceous sediments of Vega Island, eastern Antarctic Peninsula, are presented. The leaves are described as Nothofagus sp. 1 and Morphotype LDB 1, and come from the Snow Hill Island (late Campanian-early Maastrichtian) and the López de Bertodano (late Maastrichtian) formations, respectively. The palynoflora obtained from levels immediately above and below the Nothofagus sp. 1 and in the same horizon as the Morphotype LDB 1, included terrestrial and marine elements. In the palynoflora associated with Nothofagus sp. 1, conifers are dominant and pollen grains with Nothofagus affinity are represented by four species: Nothofagidites kaitangataensis (Te Punga) Romero 1973 and Nothofagidites senectus Dettmann and Playford 1968, which belong to the ancestral pollen type, as well as Nothofagidites dorotensis Romero 1973 and Nothofagidites sp. of the brassii-type. Cryptogamic spores, marine dinoflagellate cysts and algae, among others, are part of the assemblage. The palynoflora associated with the Morphotype LDB 1 also contains abundant conifer and angiosperm pollen grains with N. dorotensis as the only Nothofagus species recorded. Marine dinoflagellate cysts are scarce while fungi and phytodebris are common elements. The joint presence of marine and non-marine palynomorphs supports a probable nearshore environment at time of deposition for both units. Pollen and spore evidence suggests a mixed conifer and angiosperm forest, with Podocarpaceae and Nothofagus as the main components, and ferns, lycopods, and mosses in the understory. This forest developed under temperate and moist conditions during the middle Campanian-Maastrichtian.

The phytotoxic effects of fluoride and its derivatives on the seeds and seedlings of the Colobanthus apetalus and Colobanthus quitensis were studied. This is a first study to evaluate the influence of sodium fluoride (NaF) on the morphophysiological and biochemical processes on two Colobanthus species. The influence of various concentrations of NaF (9 mM, 19 mM, 29 mM) on the germination capacity and germination rate of seeds, seedlings growth and the proline content of plant tissues was analyzed under laboratory conditions (20/10°C, 12/12 h). The seeds of C. apetalus were collected from a greenhouse, whereas the seeds of C. quitensis were collected in Antarctica and in a greenhouse (Olsztyn, Poland). The tested concentrations of NaF did not suppress the germination of C. apetalus seeds, but the germination of C. quitensis seeds was inhibited. Sodium fluoride mainly inhibited root growth of C. apetalus and C. quitensis. In both analyzed species, the free proline content of seedlings increased significantly under exposure to NaF. The results of this study clearly indicate that C. apetalus and C. quitensis are highly resistant to NaF stress.

Microbes living in the polar regions have some common and unique strategies to respond to thermal stress. Nevertheless, the amount of information available, especially at the molecular level is lacking for some organisms such as Antarctic psychrophilic yeast. For instance, it is not known whether molecular chaperones in Antarctic yeasts play similar roles to those from mesophilic yeasts when they are exposed to heat stress. Therefore, this project aimed to determine the gene expression patterns and roles of molecular chaperones in Antarctic psychrophilic Glaciozyma antarctica PI12 that was exposed to heat stress. G. antarctica PI12 was grown at its optimal growth temperature of 12ºC and later exposed to heat stresses at 16ºC and 20ºC for 6 hours. Transcriptomes of those cells were extracted, sequenced and analyzed. Thirty-three molecular chaperone genes demonstrated differential expression of which 23 were up-regulated while 10 were down-regulated. Functions of up-regulated molecular chaperone genes were related to protein binding, response to a stimulus, chaperone binding, cellular response to stress, oxidation, and reduction, ATP binding, DNA-damage response and regulation for cellular protein metabolic process. On the other hand, functions of down-regulated molecular chaperone genes were related to chaperone-mediated protein complex assembly, transcription, cellular macromolecule metabolic process, regulation of cell growth and ribosome biogenesis. The findings provided information on how molecular chaperones work together in a complex network to protect the cells under heat stress. It also highlights the evolutionary conserved protective role of molecular chaperones in psychrophilic yeast, G. antarctica, and mesophilic yeast, Saccharomyces cerevisiae.