Polish Polar Research

Bowseria arctowskii gen. et sp. nov., a new organic-walled monothalamous (single-chamber) foraminiferan is described from samples collected in Admiralty Bay (King George Island, West Antarctica) at 100- 200 m water-depth (mwd). The species is characterized by a large (1- 2 mm) elongate theca with a single terminal aperture. Molecular phylogenetic analyses, based on partial small subunit rDNA sequences, indicate that the new species belong to a clade of single-chambered foraminifers that branch as a sister group to the multi-chambered textulariids and rotaliids. The most closely related to the new species is an undetermined allogromiid from under the Ross Ice Shelf.

An investigation of cyanobacterial microflora in the northern, deglaciated part of James Ross Island in the NW part of the Weddell Sea, Antarctica , was conducted during the Antarctic summer season 2005-2006. Five main types of habitats with dominant cyanobacterial assemblages were analyzed (soils, seepages, streams, wetted rocky walls and lakes), and main ecological variables were measured (pH, temperature, intensity of global radiation, conductivity and nutrients), as a background for further ecological and ecophysiological studies. The definable traditional cyanobacterial morphospecies were identified.

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.

Ornithogenic tundra developing near large seabird colonies with its dense vegetation creates sites for foraging, hiding and breeding of herbivores. Grazing, trampling and faeces deposition are considered as the most important ways that vertebrate herbivores influence the plants. Excrement deposition level informs us on the intensity of grazing i.e. foraging ground attractiveness. We have compared vertebrate herbivores’ faeces deposition (biomass) in the vicinity of big colonies of piscivorous (kittiwake Rissa tridactyla and Brünnich’s guillemot Uria lomvia) and planktivorous (little auk Alle alle) seabirds and the control area was in Hornsund, SW Spitsbergen. Much higher level of faeces deposition was recorded nearby seabird colonies as compared to the control area. These finding points out that vertebrate herbivores concentrate and feed more intensively on rich ornithogenic pastures. Number of herbivores and their faeces deposition level recorded nearby planktivorous seabird colony were greater as compared to those found nearby the colony of piscivores. The highest number of geese (Branta bernicla and Anser brachyrhynchus) and of their faeces biomass were found near the colony of planktivorous little auk, where distinct gradient in faeces deposition level along the colony-seashore axis was recorded. Reindeers Rangifer tarandus were observed in considerable numbers near the little auk colony, and were not recorded at all near cliff-nesting sites of kittiwakes and guillemots. Total deposition of excrements produced by geese was generally higher if compared to reindeers.

The buoyant hypopycnal flow of brackish water and suspended sediment transport and settling were studied in two sub-polar fjords: the glacial Kongsfjörden and the outwash (non-glacial contact) Adventfjörden, Svalbard . The data presented indicates faster water mixing on the tidal flat in comparison to the englacial runoff, which leads to faster horizontal density gradients decreases in the non-glaciated fjord. The fast settling of particles in the narrow zone of the steep slope at the edge of the tidal flat leads to the removal of 25% of the surface suspended sediment. The rapid settling is due to increasing salinity, decreasing velocity, and flocculation of fine particles. The fast settling of suspended particulate matter (SPM) in the tidal flat area causes sediment redeposition and resuspension followed by sediment transport along the bottom with hyperpycnal flows. This leads to grain sorting in the fjord head. In contrast, at the glacier front, SPM is transported farther into the fjord, where tidal pumping and water mixing lead to the removal of 71% of total SPM. The fjords investigated represent two different sedimentological regimes. In the glaciated Kongsfjörden, the buoyant hypopycnal flow of brackish water is the main sediment transporting factor. In the non-glacial Adventfjörden, hyperpycnal flows transport sediment along the bottom.

The Hornsund region is characterised by a topoclimatic variation, which results principally from the local orography, the vicinity of open sea and the two contrasting environments: non-glaciated and glaciated. The specific types of atmospheric circulation determine the local thermal differences. The west coast is characterised by the most favourable thermal conditions, where air temperature is largely determined by foehn processes. The temperature at the Baranowski Station is 0.8°C higher on average than that of the Polish Polar Station on the northern shore of Hornsund . The temperature in the northern shore of the fjord happens to be higher than that on the west coast, which is attributed to the NW cyclonic inflow of cool Arctic air masses. During intermediate weather, when ground frost-thaw takes place, the northern shore of Hornsund is warmer by 0.5°C ; whereas, during moderately frosty weather, it is warmer by 0.2°C than the west coast. The differences result from the effect of the warmer fjord waters on the surrounding air temperature. During moderately warm weather, more favourable conditions occur near the Baranowski Station, expressed by the mean temperature difference of 0.9°C. The greatest temperature difference of 1.5°C on average is normally recorded during warm weather.