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Number of results: 217
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Abstract

The lakes and watercourses are habitats for various communities of cyanobacteria and algae, which are among the few primary producers in Antarctica. The amount of nutrients in the mineral-poor Antarctic environment is a limiting factor for the growth of freshwater autotrophs in most cases. In this study, the main aim was to assess the availability of mineral nitrogen for microorganisms in cyanobacterial mats in James Ross Island. The nitrate and ammonium ions in water environment were determined as well as the contents of major elements (C, N, P, S, Na, K, Ca, Mg, Al, Fe, Mn) in cyanobacterial mats. The molar ratios of C:N, C:P and N:P in mats were in focus. The growth of freshwater autotrophs seems not to be limited by the level of nitrogen, according to the content of available mineral nitrogen in water and the biogeochemical stoichiometry of C:N:P. The source of nutrients in the Ulu Peninsula is not obvious. The nitrogen fixation could enhance the nitrogen content in mats, which was observed in some samples containing the Nostoc sp.
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Abstract

Remains referred to Phorusrhacidae from the Cretaceous and Paleogene of the Antarctic Peninsula, and mainly known through informal and succinct descriptions, are reassigned here to other bird lineages recorded in the Antarctic continent. New records of ratites, pelagornithid birds, and penguins are added to the Upper Eocene avifauna of Seymour Island. Moreover, the original allocation for an alleged cursorial seriema−like bird from the Maastrichtian of Vega Island is refuted, and its affinities with foot−propelled diving birds are indicated. The indeterminate Pelagornithidae specimen represents the largest pseudo−toothed bird known so far. It is concluded that there is no empirical evidence for the presence of terror birds in Antarctica.
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Abstract

Many Antarctic marine benthic invertebrates are adapted to specific environ− mental conditions (e.g. low stable temperatures, high salinity and oxygen content). Changes caused by global climatic shifts can be expected to have significant impact on their physiol− ogy and distribution. Odontaster validus, an ubiquitous, omnivorous sea star is one of the “keystone species” in the Antarctic benthic communities. Laboratory experiments were car− ried out to study the effect of temperature rise (from 0 to 5#2;C) on some vital biological func− tions that sea stars must perform in order to survive in their environment. Parameters such as behavioural reaction of sea stars to food and food odour, locomotory performance and abil− ity to right were measured. Temperature increase significantly impaired the ability of O. validus to perform these functions (e.g. lowering the number of sea stars able to right, in− creasing time−to−right, reducing locomotory activity, weakening chemosensory reaction to food and food odour). At temperatures of 4 and 5#2;C a loss of motor coordination was ob− served, although at all tested temperatures up to 5#2;C there were single individuals perform− ing successfully.
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Abstract

The method of construction and division of dendrites proposed by Florek et al. (1951) was used for defining of the Antarctic biojjeographic areas. The affinity matrices of Knox and Lowry (1977) resulting from the analysis of the distribution of Antarctic Polychaeta and Amphipoda were taken as a basis for dendrite construction The results of the present analysis are compared with the conclusions of these authors and similarities and differences are discussed on the background of the hitherto published biogeographic divisions of Antarctica.
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Abstract

Macrozooplankton was collected at 63 stations by means of a Bongo sampler in the layer from the surface to a depth of 200 m. Wet formalin volume of siphonophors, polychaetes, pteropods, copepods, amphipods, euphausiids, chaetognaths, salps, and the remaining animals was determined; the distribution of major species was presented. Low diversity in macrozooplankton composition was observed in the study area. As far as biomass was concerned, salps predominated in the whole area; they occurred in exceptionally large quantities Large amounts of krill were also observed in some areas. Besides salps and krill, other euphausiids had the greatest share in the zooplankton; they were more abundant than copepods. Macrozooplankton biomass without salps and krill was low when compared with the values known from literature.
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Abstract

Adamussium jonkersi sp. nov. is described from the Late Oligocene Destruction Bay Formation, Wrona Buttress area, King George Island (South Shetlands), West Antarctica. The unit, characterized by volcanic sandstone, is a shallow marine succession deposited in a moderate- to high-energy environment. The thin-shelled pectinids, collected from the lower part of the unit, are preserved mostly as complete valves. Shell thickness, sculpture pattern and umbonal angle suggest a free-living, inactive swimming life habit.
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Abstract

Lichens of relict penguin colonies and sites affected by active penguin colonies were investigated in Victoria Land, Ross Sea sector, continental Antarctica. A total of 17 coastal sites, seven in northern and ten in southern Victoria Land, have been investigated across 7 ° of latitude from 71 ° to 78 ° S. Altogether 40 taxa of lichens have been identified. Four of the recorded species are new to the Antarctic – Caloplaca erecta , C. soropelta , C. tominii and Physcia tenella ; two species are new to the Victoria Land area – Lecania nylanderiana and Lecanora polytropa . The first lichen records from Beaufort Island are also provided. Data presented here expand the knowledge on the occurrence, diversity and distribution of Victoria Land lichens.
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Abstract

The tarsometatarsus, a compound bone from the lower leg in birds, is the most important skeletal element in fossil penguin taxonomy, especially in the case of early members of this group. However, any attempt to go beyond the problem of mere classification obviously requires the better understanding of osteological traits under consideration. This in turn touches on the issue of interplay between bone and concomitant soft−tissue structures, such as muscles, tendons and vessels. This paper focuses on the more holistic comprehension of the tarsometatarsal section of the Eocene penguin foot, based on the analysis of the myology and the vascular system of its modern counterparts. A number of graphical reconstructions are provided with a discussion of the role of the hypotarsus and inter− metatarsal foramina.
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Abstract

This paper presents a unique case study and methodology for measurements of the bedload transport in the two, newly created troughs at the forefield of the Baranowski Glacier: Fosa and Siodło creeks. The weather conditions and the granulometric analysis are presented and discussed briefly. Rating curves for the Fosa and Siodło creeks are presented for the first time for this region. Changes of the bedload transport as well as water discharge and water velocity at both creeks are investigated. The hysteresis for the relationships between rate of bedload transport and water discharges were identified showing that for both creeks for the higher water levels a figure of eight loop may be easily recognized. Moreover, a new method for the calculation of bedload transport rate, based on the weighted arithmetic mean instead of the arithmetic mean, is proposed.
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Abstract

The Antarctic Peninsula region has experienced a recent cooling for about 15 years since the beginning of the 21st century. In Livingston Island, this cooling has been of 0.8°C over the 12-yr period 2004–2016, and of 1.0°C for the summer average temperatures over the same period. In this paper, we analyse whether this observed cooling has implied a significant change in the density of the snowpack covering Hurd and Johnsons glaciers, and whether such a density change has had, by itself, a noticeable impact in the calculated surface mass balance. Our results indicate a decrease in the snow density by 22 kg m-3 over the study period. The density changes are shown to be correlated with the summer temperature changes. We show that this observed decrease in density does not have an appreciable effect on the calculated surface mass balance, as the corresponding changes are below the usual error range of the surface mass balance estimates. This relieves us from the need of detailed and time-consuming snow density measurements at every mass-balance campaign.
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Abstract

Different chromosomal forms of Deschampsia antarctica Desv. (Poaceae), including diploids (2n=26), hypotriploid (2n=36–38) and a genotype with an occasional occurrence of B chromosome (2n=26+0-1B) that originated from southern marginal populations (Argentine Islands region, maritime Antarctic) were studied using molecular cytogenetic, morphometric and biochemical methods. FISH analysis revealed variations in the number of rDNA sites between the diploid and hypotriploid plants. The genome size varied among plants with a different chromosome number and was on average 10.88 pg/2C for diploids and 16.46 pg/2C for hypotriploid. The mean values of leaf length of plants grown in vitro varied within a range of 5.23–9.56 cm. The total phenolic content ranged from 51.10 to 105.40 mg/g, and the total flavonoid content ranged from 1.22 to 4.67 mg/g. The amount of phenolic compounds did not differ significantly between the genotypes, while a variation in the flavonoid content was observed for L59 and DAR12. The diploids did not differ significantly among each other in terms of the number of rDNA loci, but differed slightly in their genome size. The individuals of DAR12 carrying B chromosome were similar to other diploids in terms of their genome size, but statistically differed in leaf length. The hypotriploid had both a greater number of rDNA sites and a larger genome size. No statistical correlations were observed between the genome size and leaf length or genome size and accumulation of phenolic and flavonoid compounds. The results of this study suggest that D. antarctica plants from the southern edge of the range are characterised by the heterogeneity of the studied parameters.
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Abstract

Antarctic plants experience UV−B stress and for their survival they have been showing various adaptive strategies. The first line of defence is to screen UV−B radiation before it reaches the cell, then to minimize damage within the cells through other protective strategies, and finally to repair damage once it has occurred. A fifteen days experiment was designed to study lichen: Dermatocarpon sp. and Acarospora gwynnii under natural UV and below UV filter frames in the Indian Antarctic Station Maitri region of Schirmacher Oasis, East Antarctica. Changes in UV absorbing compounds, total phenolics, total carotenoids and chlorophyll content were studied. The change in total phenolics and total carotenoid content was significant in both Dermatocarpon sp. and A. gwynnii indicating that the increase in UV absorbing compounds, total phenolics and total carotenoid content act as a protective mechanism against the deleterious effect of UV−B radiations, whereas the change in chlorophyll content was not significant in both lichen species.
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Abstract

Rock glaciers are lobate or tongue-shaped landforms which consist of rock debris and have either an ice core or an ice-cemented matrix. Characteristics such as the landscape setting, morphology, material and current geomorphological state are universally used to classify rock glaciers. In Antarctica, rock glaciers have only been surveyed on the Antarctic Peninsula, Ellsworth Mountains and in Victoria Land. This paper presents the first data on the identification and description of rock glaciers in the Jutulsessen nunataks, Dronning Maud Land, East Antarctica. The rock glaciers in the Jutulsessen exhibit a variety of morphologies and states. Our data suggests that the rock glaciers in Brugdedalen and Jutuldalen are active, while the features at Vassdalen and Grjotlia are considered inactive, and a feature at Grjotøyra is considered relict. The described rock glaciers do not fit into existing classification systems and appear to be different to alpine, Arctic and Andean rock glaciers. They further present examples that fit both the ‘glaciogenic’ and ‘permafrost’ development theories.
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Abstract

Populations of Antarctic hairgrass Deschampsia antarctica Desv. from King George Island exhibit variation in many traits. The reason for that is not evident and could be addressed to variable environmental conditions. Obviously, phenotypic variation could be due to stable or temporal changes in expression pattern as the result of adaptation. Stable changes could be due to mutations or site DNA methylation variation that modified expression pattern. Recently, metAFLP approach was proposed to study such effects. A variant of methylation sensitive AFLP (Amplified Fragment Length Polymorphism), based on the isoschizomeric combinations Acc65 I/ Mse I and Kpn I/ Mse I was applied to analyze the sequence and site DNA methylation differences between two D. antarctica populations exhibiting morphological dissimilarities. Both DNA sequence mutations and site methylation pattern alternations were detected among and within analyzed populations. It is assumed that such changes might have originated as the response to environmental conditions that induced site methylation alternations leading to phenotypic variation of D. antarctica populations from South Shetland Islands.
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Abstract

New echinoid material from the Oligocene Chlamys Ledge Member (uppermost part of the Polonez Cove Formation) on King George Island, West Antarctica, includes the “regular” echinoid Caenopedina aleksandrabitnerae sp. n. and poorly preserved spatangoids, here tentatively identified as members of the genus Abatus . Caenopedina aleksandrabitnerae sp. n. is characterized by fully tuberculate genital plates, which sets it apart from most other species in the genus, by the uneven periproctal margin which indicates that periproctal plates were incorporated into the apical disc, and by moderately wide interambulacral plates with a height/width ratio of 1:3. Among the modern Caenopedina species it is closest to the Australian and New Zealand representatives, which is in contrast to previous reviews of Cenozoic Antarctic echinoid faunas that suggested limited relationship to the Australasian region. This is the first record of Caenopedina from Antarctica; it considerably extends its historical distribution to the south.
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Abstract

Bryozoans were found in upper Cenozoic diamictite debris that crops out at the southwestern tip of Cape Lamb, Vega Island. The diamictite is the youngest deposit on the island and richly composed of foraminifers, brachiopods and scallops. The foraminifera assemblage recovered from the Cape Lamb diamictite and 87 Sr/ 86 Sr isotopic age obtained from the pectinid Adamussium colbecki in the nearby locality of Terrapin indicates a Pleistocene age for this deposit. The main goal of this contribution is to present a bryozoan assemblage of Microporella stenoporta Hayward et Taylor, Hippothoa flagellum Manzoni, Ellisina antarctica (Kluge), Micropora notialis Hayward et Ryland and an indeterminate crisiid constituting the first record of these bryozoan taxa in Cenozoic diamictites of the Antarctic Peninsula.
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Abstract

The loose, small zooecia of the cheilostome bryozoans have been discovered in the lowermost part of the La Meseta Formation on Seymour (Marambio) Island. They systematically include the representatives of Beanidae Canu et Bassler, Catenicellidae Busk, Savignyellidae Levinsen, and Calwelliidae MacGillivra y. The bryozoan assemblage is comprised of separate, small−sized internal moulds dominated by distinct, boat−shaped zooecia belonging to Beania , scarce, unizooidal internodes tentatively included into a ditaxiporine catenicellid ? Vasignyella , and representative of the family Savignyellidae. A few branched segments composed of multiserial zooecia arranged back to back were tentatively incorporated into ? Malakosaria . Beania , marks the oldest fossil record, whereas representatives of Savignyellidae along with ditaxiporine catenicellid and ? Malakosaria are for the first time reported from Antarctica. The relationship between the taxonomic composition, colony growth−patterns rep− resented by membraniporiform/petraliform, catenicelliform and cellariform, along with associated biota and sedimentary structures of the La Meseta Formation implies nearshore environment, with considerable wave action, and warm climatic conditions.
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Abstract

Palaeostresses inferred from brittle mesostructures in the southern Wright Peninsula show a stress field characterized by compressional, strike−slip and extensional regime stress states. The compressional stress ( s 1 ) shows a main NW−SE direction and the extensional stress ( s 3 ) shows a relative scattering with two main modes: NE−SW to E−W and NW−SE. The maximum horizontal stress ( s y ) has a bimodal distribution with NW−SE and NE−SW direction. The compressional orientation is related to subduction of the former Phoenix Plate under the Antarctic Plate from the Early Jurassic to the Early Miocene. Extensional structures within a broad−scale compressional stress field can be related to both the decrease in relative stress magnitudes from active margins to intraplate regions and stretching processes occurring in eastern Adelaide Island, which develop a fore−arc or intra−arc basin from the Early Miocene. Stress states with NW−SE−trending s 1 are compatible with the dominant pattern established for the western Antarctic Peninsula. NW−SE orientations of s 3 suggest the occurrence of tectonic forces coming from fore−arc extension along the western Antarctic Peninsula.
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Abstract

In this study, selected heavy metals resistant heterotrophic bacteria isolated from soil samples at the Windmill Islands region, Wilkes Land (East Antarctica), were characterized. Phylogenetic analysis revealed affiliation of isolates to genera Bacillus , Lysinibacillus , Micrococcus and Stenotrophomonas . The strains were found to be psychrotolerant and halotolerant, able to tolerate up to 10% NaCl in the growth medium. The Minimum Inhibitory Concentration of the seven heavy metals Cr, Cu, Ni, Co, Cd, Zn, and Pb was deter − mined in solid media for each bacterial strain. Gram−positive Vi−2 strain and Gram−negative Vi−4 strain showed highest multiply heavy metals resistance, and Vi−3 and Vi−4 strains showed multi−antibiotic resistance to more than a half of the 13 used antibiotics. Plasmids were detected only in Gram−negative Vi−4 strain. The bacteria were able to produce different hydrolytic enzymes including industrially important proteases, xylanases, cellulases, and b −glucosidases. High heavy metals resistance of the Antarctic bacteria suggests their potential application for wastewater treatment in cold and temperate climates. Highly sensitive to Cd and Co ions Vi−1, Vi−5 and Vi−7 strains would be promising for developing biosensors to detect these most toxic heavy metals in environmental samples.
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Abstract

The development of megasporocytes and the functional megaspore formation in Deschampsia antarctica were analyzed with the use of microscopic methods. A single archesporial cell was formed directly under the epidermis in the micropylar region of the ovule without producing a parietal cell. In successive stages of development, the meiocyte was transformed into a megaspore tetrad after meiosis. Most megaspores were arranged in a linear fashion, but some tetrads were T-shaped. Only one of the 60 analyzed ovules contained a cell in the direct proximity of the megasporocyte, which could be an aposporous initial. Most of the evaluated D. antarctica ovules featured monosporic embryo sacs of the Polygonum type. Approximately 30% of ovules contained numerous megaspores that were enlarged. The megaspores were located at chalazal and micropylar poles, and some ovules featured two megaspores - terminal and medial - in the chalazal region, or even three megaspores at the chalazal pole. In those cases, the micropylar megaspore was significantly smaller than the remaining megaspores, and it did not have the characteristic features of functional megaspores. Meiocytes and megaspores of D. antarctica contained polysaccharides that were detectable by PAS-reaction and aniline blue staining. Starch granules and cell walls of megasporocytes, megaspores and nucellar cells were PAS-positive. Fluorescent callose deposits were identified in the micropylar end of the megasporocytes. During meiosis and after its completion, thick callose deposits were also visible in the periclinal walls and in a small amount in the anticlinal walls of megaspores forming linear and T-shaped tetrads. Callose deposits fluorescence was not observed in the walls of the nucellar cells.
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Abstract

Sedimentological study of the three geographically separated outcrops of bottom− sets of a single lava−fed delta (Pliocene) in the James Ross Island (Antarctica) allows recognition of six lithofacies. Deposits of traction currents, deposits of volcaniclastic debris flows and products of such flows transformations (both l ow− and high−density turbidity currents) and glacigenic deposits (subaqueous de bris flows and traction/turbidity currents) were all recognised. Existence of submarine proglacial environment formed prior to formation of volcaniclastic deposits partly covering the subaqueous slopes of volcano is supposed. The principal role of mass flow processes was recognised and explained by relative steep slopes of the lava−fed delta. The distribution of lithofacies significantly differs in the individual outcrops. These variations in sedimentary succession an d also in thickness of volcaniclastic deposits of “bottomsets” of the single lava fed delta suggest principal role of local conditions and paleogeography for development and preservation of this part of delta depositional system. Moreover proximal and distal setting can be followed and direct vs . more distant relation to over−riding lava−fed delta supposed. The sedimentary succession terminated by foresets of hyaloclastite breccia.
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Abstract

The order Passeriformes is the most successful group of birds on Earth, however, its representatives are rare visitors beyond the Polar Front zone. Here we report a photo−documented record of an Austral Negrito ( Lessonia rufa ), first known occurrence of this species in the South Shetland Islands and only the second such an observation in the Antarctic region. This record was made at Lions Rump, King George Island, part of the Antarctic Specially Protected Area No. 151 (ASPA 151). There is no direct evidence of how the individual arrived at Lions Rump, but ship assistance cannot be excluded.
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Abstract

Henryk Arctowski Station, the research station of the Polish Academy of Science in Admiralty Bay, King George Island, West Antarctica, is one of the most heavily visited bases in Antarctica. Between the seasons 1991/92 and 1996/97, 12884 tourists were recorded. A specially designed tourist trail was marked to divert visitors toward alternative attractions, not only the station buildings. Tourist management goals include: environmental protection, minimising waste and pollution, respecting the rules relating to protected areas, and prohibition of collections and souveniring.
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Abstract

The paper provides information on oceanobiological expeditions to the Antarctic organized by Polish Academy of Sciences. The scope of research of five expeditions is described and main achievements of Polish Antarctic studies are summarized.
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Abstract

In the plankton samples collected with a Bongo net besides Euphausia superba the following species of the Euphausiacea were found:. £. frigida, crystallorophias, E. triacantha and T. macrura. The most aboundant and most frequently caught species was T. macrura equally distributed throughout the research area. The species E. frigida also occurred regularly though in much smaller numbers. E. triacantha occurred sporadically, mainly in the western part of the research region, and E. crystallorophias only at two stations in the Bransfield Strait. Some aspects of the biology and ecology of the mentioned above species are presented in this study.
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