Wyniki wyszukiwania

Filtruj wyniki

  • Czasopisma
  • Autorzy publikacji
  • Słowa kluczowe
  • Data
  • Typ

Wyniki wyszukiwania

Wyników: 117
Wyników na stronie: 25 50 75
Sortuj wg:
Słowa kluczowe Arctic Svalbard crinoid Permian

Abstrakt

An early Permian (late Artinskian–Roadian) cladid crinoid (Catacrinidae gen. et sp. indet.) is reported for the first time from the V ø ringen Member of the Kapp Starostin Formation of Spitsbergen. The specimen is partly articulated and preserves a considerable part of its stalk and a complete cup, but only the proximal portions of its arms. Thus, it cannot be identified with any degree of certainty at the generic level. Despite this, our finding is important as it constitutes one of the youngest records of catacrinid crinoids to date and considerably extends the palaeogeographic distribution of this group.
Przejdź do artykułu

Abstrakt

Research on permafrost in the Abisko area of northern Sweden date from the 1950s. A mean annual air temperature of −3 #2;C in the Abisko mountains (i.e. 1000 m a.s.l.) and −1 #2;C beyond the mountain area at an altitude of around 400msuggests that both moun− tain and arctic permafrost occur there. Several geophysical surveys were performed by means of resistivity tomography (ERT) and electromagnetic mapping (EM). Wherever pos− sible the geophysical survey results were calibrated by digging tests pits. The results show that permafrost occurs extensively in the mountain areas, especially those above 900ma.s.l. and also sporadically at lower altitudes. At 400 m a.s.l. permafrost may be up to 30 m thick. Its thickness and extent are determined largely by the very variable local rock and soil con− ditions. Fossil permafrost is also likely to occur in this area.
Przejdź do artykułu

Abstrakt

The paper presents the first physicochemical and microbiological studies conducted in the northern area of Svalbard (Spitsbergen). Ten sediment samples were collected from the bottom of the longest fjord in the region, Wijdef jorden. Bottom sediments from ten lakes located along the shores of Wijdefjorden and Woodfjorden were also sampled. Organic matter content (LOI), water content, temperature, pH, and salinity of the sediments were determined. The quantity of aerobic bacteria cultured on various growth media at 4 ° C, 14 ° C, and 37 ° C ranged from 10 2 to 10 6 cfu/g of wet sediment mass, depending on the type of sampling station (fjord or lake). The number of bacteria did not co rrelate with organic matter content. Out of the 37 bacterial strains isolated from Wijdefjorden, 48% and 70% revealed ureolytic and proteolytic activity, respectively. The proportion of freshwater strains with ureolytic and proteolytic activity was 32% and 55%, respectively. Antibiotic resistance testing indicated that bacterial strains from the bottom sediments of the lakes were resistant to 8 antibiotics (out of the 18 investigated). Possible sources of this resistance are discussed. Using 16S DNA analysis, bacterial isolates from the lakes were identified as Pseudomonas sp., whereas frequently occurring strains in bottom sediment of the fjord were Pseudoalteromonas sp.
Przejdź do artykułu

Abstrakt

Candona rectangulata is an ostracod species common in cold (<15 ° C ) shallow freshwater Arctic water bodies. This species is useful in palaeolimnological studies because only few known autecological data can be applied in reconstructions of palaeoclimate. Particular attention was paid to the temperature, which is the basic factor determining the geo− graphic range of a species. In this study a wide tolerance of C. rectangulata to the temperature was demonstrated for the first time. Its high tolerance to the temperature changes seems to be based on induction of set of proteins belonging to the family of heat shock proteins. Using PAGE−SDS electrophoresis variation in the protein profile of non−model organism undergoing stress in the field (South Spitsbergen, near Stanisław Siedlecki Polish Polar Station) and in laboratory cultures was presented. These results could explain the eurythermic range of C. rectangulata and its good adaptation to the environmental conditions which normally do not exist in Arctic freshwater ponds.
Przejdź do artykułu

Abstrakt

This paper presents distribution and properties of soils within the Fuglebekken catchment in neighbourhood of the Polish Polar Station in Hornsund, SW Spitsbergen (Svalbard Archipelago). The present study describes 8 representative soil profiles out of 34 profiles studied for the whole catchment. Soils of the Fuglebekken catchment show initial stage of their formation because of very slow rate of chemical and biological weathering in Arctic climate conditions . Uplifted marine terraces of the Fuglebekken catchment are characterized by domination of Haplic Cryosols which ar e related to stony and gravelly parent material (reworked marine sediments). Such soils constitute of 17% of the studied area. Turbic Cryosols forming characteristic micro−relief occur on flat surfaces and gentle slopes. Such soils (covering 7% of the catchment) are formed from loamy parent material. Along streams Hyperskeletic Cryosols (Reduc taquic) and Turbic Histic Cryosols occur. The last two soil units (constituting 11% of the catchment) are mantled by continuous and dense vegetation cover (especially mosses) due to high content of water rich in nutrients flowing from colonies of sea birds located on slopes of Ariekammen and Fugleberget. The studied soils are generally characterized by shallow occurrence of permafrost ( i.e. at 30–50 cm), high content of pebbles, sandy or sandy loam texture, and neutral or s lightly alkaline reaction. Soils occurring along streams and near colonies of sea birds show higher content of nutrients (N and P) in comparison with other soils and are covered by more dense vegetation. This indicates important impact of bird guano on chemical composition of soil solution and fertility of such soils.
Przejdź do artykułu

Abstrakt

We assessed culturable soil microfungal diversity in various habitats around Hornsund, Spitsbergen in the High Arctic, using potato dextrose agar ( PDA) medium. Thermal growth classification of the fungi obtained was determined by incubating them in 4 ° Cand 25 ° C, permitting separation of those with psychrophilic, psychrotolerant and mesophilic characteristics. In total, 68 fungal isolates were obtained from 12 soil samples, and grouped into 38 mycelial morphotypes. Intergenic spacer regions of these morphotypes were sequenced, and they represented 25 distinct taxonomic units, of which 21 showed sufficient similarity with available sequence data in NCBI to be identified to species level. Soil under ornithogenic influence showed the highest species diversity, including sequences assigned to Mortierella macrocystis, M. elongata, Mortierella sp., Cudoniella sp., Varicosporium elodeae , Beauveria bassiana , Geomyces pannorum , Penicillium sp. and Atradidymella muscivora . Fourteen taxa were classified as psychrophilic, seven mesophilic, and four psychrotolerant.
Przejdź do artykułu

Abstrakt

The paper presents the results of a study of cyanobacteria and green algae assemblages occurring in various tundra types determined on the basis of mosses and vascular plants and habitat conditions. The research was carried out during summer in the years 2009–2013 on the north sea−coast of Hornsund fjord (West Spitsbergen, Svalbard Archipelago). 58 sites were studied in various tundra types differing in composition of vascular plants, mosses and in trophy and humidity. 141 cyanobacteria and green algae were noted in the research area in total. Cyanobacteria and green algae flora is a significant element of many tundra types and sometimes even dominate there. Despite its importance, it has not been hitherto taken into account in the description and classification of tundra. The aim of the present study was to demonstrate the legitimacy of using phycoflora in supplementing the descriptions of hitherto described tundra and distinguishing new tundra types. Numeric hierarchical−accumulative classification (MVSP 3.1 software) methods were used to analyze the cyanobacterial and algal assemblages and their co−relations with particular tundra types. The analysis determined dominant and distinctive species in the communities in concordance with ecologically diverse types of tundra. The results show the importance of these organisms in the composition of the vegetation of tundra types and their role in the ecosystems of this part of the Arctic.
Przejdź do artykułu

Abstrakt

The mesostigmatid mite Vulgarogamasus immanis (Berlese, 1904) is reported in Svalbard for the first time. The gamasid mite community of Svalbard is amongst the best known of invertebrate groups of the archipelago due to recent revisions based on fresh sampling campaigns. Nonetheless, a hitherto unrecorded species of gamasid mite was recently found along the strandline in Barentsburg. This record brings the total gamasid mite inventory of Svalbard to 23 species. The current inventory of Svalbard is bedeviled with synonyms and misidentifications. Nevertheless, resolving these confusions and maintaining an accurate and updated species inventory is of prime importance in understanding the ecology of this region. Especially in a period of rapid environmental change.
Przejdź do artykułu

Abstrakt

Hansbreen, a medium size tidewater glacier in Southern Spitsbergen (Svalbard) is one of the most intensively studied glaciers in the Arctic. This work presents new digital elevation models of its surface and basal topography based on data collected during GPS/GPR campaigns conducted in the spring seasons of 2005 and 2008, as well as on other recent topographic/bathymetric sources. The mean thickness of the glacier is calculated as 171 m and its volume is estimated to be 9.6 (±0.1) km 3 . The main feature of the bedrock morphology is a vast depression that is overdeepened below sea level and extends as far as 11 km upstream from the glacier front. This depression is divided into four individual basins by distinct sills that are related to the main geological/tectonic features of the area. The bedrock morphology affects considerably the glacier’s surface topography. The influence of bedrock and surface relief on the subglacial drainage system geometry is discussed. Vast depressions on the glacier surface favor concentration of meltwater and development of moulin systems.
Przejdź do artykułu

Abstrakt

The diversity of cyanobacterial assemblages from various microhabitats in the Arctic area of Petuniabukta, Billefjorden, central Svalbard, was described. The present article contains the introductory common review of the cyanobacterial diversity and ecological data concerning main habitats, while the characteristics of individual taxonomic groups will be presented in following specific studies. Eight distinct main habitats were recognized, which differed in their species composition and especially the dominant species. More than 80 morphospecies were registered during our investigation, but only about 1/3 of them could be assigned to known and described taxa. The others require additional analyses based on modern taxonomic methods (the polyphasic approach ). The composition of cyanobacterial micro flora was comparable with assemblages in coastal Antarctica. The diversity of unicellular and colonial morphotypes (36 taxa) was higher tha n other groups. The number of filamentous species without heterocytes and akinetes, with 30 species, and heterocytous types, with only 20 species, were similar in both of these ecosystems. These numbers will be surely changed in the future, but the overall proportion of different groups will likely stay the same. In contrast to the limited species diversity, simple filamentous aheterocytous species were dominant and formed massive populations. Fewheterocy tous taxa, mostly grouped within the genus Nostoc ( N. commune –complex), were dominant in tundra soils.
Przejdź do artykułu

Abstrakt

Pigments (chloropigments-a and carotenoids) in sediments and macroalgae samples, collected in Hornsund, in July 2015 and July 2016, were analysed (HPLC) in this work. In spite of the aerobic conditions and the periodic intensive solar irradiation in the Arctic environment, neither of which favour pigment preservation in water column and surface sediments, our results indicate that these compounds can provide information about phytoplankton composition, primary production and environmental conditions in this region. The sum of chloropigments-a, a marker of primary production, in the Hornsund sediments varied from 0.40 to 14.97 nmol/g d.w., while the sum of carotenoids ranged from 0.58 to 8.08 nmol/g d.w. Pheophorbides-a and pyropheophorbides-a made up the highest percentage in the sum of chloropigments-a in these sediments, supplying evidence for intensive zooplankton and/or zoobenthos grazing. Among the carotenoids, fucoxanthin and its derivatives (19'-hexanoyloxyfucoxanthin and 19'-hexanoyloxy-4-ketofucoxanthin) contributed the highest percentage, which points to the occurrence mainly of diatoms and/or haptophytes in the water. The pigment markers show that the input of macroalgae to the total biomass could be considerable only in the intertidal zone.
Przejdź do artykułu

Abstrakt

This article describes the morphological characteristics of the populations of green alga, Tetraspora gelatinosa , growing in the stressful Arctic conditions (77 ° 00’22” N, 015 ° 32’54.33” E). We present the first detailed morphological characteristics of this species from such a high latitude. Populations from both stagnant and flowing waters were studied. Depending on the type of habitat, their mucilaginous colonies (thalli) have different shapes, but the structure, size and the placement of the vegetative cells, akinetes and ameboid forms, as well as the pseudocilia morphology of both populations, were very similar. Literature data on the distribution of T. gelatinosa indicate that it is a cosmopolitan species. Our data are compared with some characteristic features of this species growing in different geographical and climatic zones. No significant differences were found in the morphology of the colonies compared, nor in the location and the inner structure of cells. How − ever, there were slight differences in cell size between the populations from warm and cold zones.
Przejdź do artykułu

Abstrakt

Hornsund and Kongsfjorden are two similar-sized Arctic fjords on the West coast of Spitsbergen. They are influenced by cold coastal Arctic water (Hornsund) and warmer Atlantic water (Kongsfjorden). Environmental conditions affect the timing, quantity, spatial distribution (horizontal and vertical) of spring and summer blooms of protists as well as the taxonomic composition of those assemblages. Here, we compile published data and unpublished own measurement from the past two decades to compare the environmental factors and primary production in two fjord systems. Kongsfjorden is characterized by a deeper euphotic zone, higher biomass and greater proportion of autotrophic species. Hornsund seems to obtain more nutrients due to the extensive seabird colonies and exhibits higher turbidity compared to Kongsfjorden. The annual primary production in the analysed fjords ranges from 48 g C m-2 y-1 in Kongsfjorden to 216 g C m-2 y-1 in Hornsund, with a dominant component of microplankton (90%) followed by macrophytes and microphytobenthos.
Przejdź do artykułu

Abstrakt

A 6 km long stretch of the coast of Calypsostranda between Skilvika and Josephbukta, situated on the western side of Recherchefjorden, was investigated. It is made of an accumulative marine terrace at a height of 2–8 m a.s.l. (terrace 1) and width of 40–180 m, divided by a cliffed section in the frontal moraines of Renardbreen. From the character and intensity of changes, the area was divided into 6 zones. The aim was to analyse the dynamics of changes within coastal zone from 1936 to 2007 and to characterise the influence of various morphogenetic factors (marine, fluvial, cryospheric). The important element of this study has been to determine sources and directions of sediment transport. The dynamics of changes of coastal zone in the Calypsostranda region was established from archival maps and precise GPS measurements for the periods: 1936–1960, 1960–1990, 1990–2000, 2000–2005, 2005–2006, 2006–2007. Comparing the extension of shoreline between 1936 and 2007 showed that there was more erosion than accumulation. Nearly 110 000 m 2 of the area of terrace 1 decreased, whereas about 77 000 m 2 appeared. The net balance for 1936–2007 was about −32 700 m 2 , on average over the whole length of the shoreline, it re − treated by 5.7 m (0.08 m a −1 ). The cease of sediment delivery in the extramarginal sandur fans area of Renardbreen caused intensification of marine processes, that made the shore − line retreat by over 100 m. Continuing sediment delivery from the Scottelva catchment, with contribution of material from erosion of the north end of the shoreline studies, caused the aggradation of coastal zone by over 60 m near its mouth.
Przejdź do artykułu

Abstrakt

Hørbyebreen surged in the 19th or early 20th century, as suggested by geomorphological evidences and looped medial moraines. In this study, we investigate its wide−spread geometry changes and geodetic mass balance with 1960 contour lines, 1990 and 2009 digital elevation models, in order to define the present−day state of the glacier. We also study its thermal structure from ground−penetrating radar data. Little is known about the glacier behaviour in the first part of the 20th century, but from its surge maximum until 1960 it has been retreating and losing its area. In the period 1960–1990, fast frontal thinning (2–3 m a −1 ) and a slow mass build−up in the higher zones (~0.15 m a −1 ) have been noted, resulting in generally negative mass balance (−0.40 ± 0.07 m w. eq. a −1 ). In the last studied period 1990–2009, the glacier showed an acceleration of mass loss (−0.64 m ± 0.07 w. eq. a −1 ) and no build−up was observed anymore. We conclude that Hørbyebreen system under present climate will not surge anymore and relate this behaviour to a considerable increase in summer temperature on Svalbard after 1990. Radar soundings indicate that the studied glacial system is polythermal, with temperate ice below 100–130 m depth. It has therefore not (or not yet) switched to cold−bedded, as has been suggested in previous works for some small Svalbard surge−type glaciers in a negative mass balance mode.
Przejdź do artykułu

Abstrakt

The identification of macroalgal beds is a crucial component for the description of fjord ecosystems. Direct, biological sampling is still the most popular investigation technique but acoustic methods are becoming increasingly recognized as a very efficient tool for the assessment of benthic communities. In 2007 we carried out the first acoustic survey of the littoral areas in Kongsfjorden. A 2.68 km2 area comprised within a 12.40 km2 euphotic zone was mapped along the fjord's coast using single- and multi-beam echosounders. The singlebeam echosounder (SBES) proved to be a very efficient and reliable tool for macroalgae detection in Arctic conditions. The multibeam echosounder (MBES) was very useful in extending the SBES survey range, even though it's ability in discriminating benthic communities was limited. The final result of our investigation is a map of the macroalgae distribution around the fjord, showing 39% macroalgae coverage (1.09 km2) of investigated area between isobaths -0.70 m and -30 m. Zonation analysis showed that most of the studied macroalgae areas occur up to 15 m depth (93%). These results were confirmed by biological sampling and observation in key areas. The potential of acoustic imaging of macrophytes, and a proposed methodology for the processing of acoustic data, are presented in this paper along with preliminary studies on the acoustic reflectivity of macroalgae, also highlighting differences among species. These results can be applied to future monitoring of the evolution of kelp beds in different areas of the Arctic, and in the rest of the world.
Przejdź do artykułu

Abstrakt

The rapidly changing Arctic provides excellent opportunities for investigating primary succession on freshly deglaciated areas. Research on the Gåsbreen foreland (S Spitsbergen) traced the succession of particular groups of organisms and species, particularly lichens and bryophytes, and determined the effect of selected abiotic factors on this succession. Fieldwork in 2008, employed a continuous linear transect of phytosociological relevés (1 m2) along the foreland. Data analysis allowed to distinguish five different succession stages and three types of colonisers. Canonical correspondence analysis and a permutation test showed that distance from the front of the glacier and fine grain material in the substrate mostly influenced the distribution and abundance of vegetation, and the steepness of the moraine hills affected the colonisation process, mainly in the older part of the marginal zone.
Przejdź do artykułu

Abstrakt

The archipelago of Svalbard in the European High Arctic lies on the convergence of the Palaearctic and Nearctic flora and fauna and contains elements of both regions. The island of Hopen is located in the south east of the archipelago within the path of the cold south−westerly flowing East Svalbard Current originating in the Arctic ocean and flowing along the north Russian coast. This current is postulated as a colonization route of the invertebrate fauna of Svalbard. Few reports of the terrestrial invertebrates of Hopen exist and none of the mite suborders Oribatida or Mesostigmata. With the taxonomic confusion existing in the inventories of this important region of the Arctic, new sampling campaigns with species identified by modern taxonomic principles and with material deposited in accessible museums and collections are essential. Identified mites included six species of oribatid mites with Diapterobates notatus dominating, and five species of Mesostigmata with Zercon forsslundi forming the dominant species. None of the species collected was a new record for Svalbard and all have wide circumpolar, Palaearctic or Holarctic distributions. Dispersal to Svalbard from northern Russia is hence neither supported nor rejected. The expected oribatid and mesostigmatid diversity of the island is greater than observed from the limited sampling described here.
Przejdź do artykułu

Abstrakt

A 2.5−metre−long marine core from Isvika bay in Nordaustlandet (80 ° N, 18 ° E) was AMS 14 C dated and analysed for its sedimentological and magnetic parameters. The studied record was found to cover the entire Holocene and indicates major turnovers in the palaeohydrography and sedimentary depositional history. The area was deglaciated at around 11,300 BP. The early Holocene has indications of rapid melting of glaciers and frequent deposition of ice−rafted debris (IRD). The climatic optimum terminated with a probable glacier re−advance event occurring ca. 5800 cal BP. This event caused the deposition of a diamicton unit in Isvika bay, followed by a shift towards a colder and a more stratified hydrographic set − ting. The reduction in IRD indicates gradual cooling, which led to the stratification of the bay and eventually to more persistent fast sea−ice conditions by 2500 cal BP. For the last 500 years, Isvika has again been seasonally open.
Przejdź do artykułu

Abstrakt

A significant limit to current understanding of cold coast evolution is the paucity of field observations regarding development of rocky coastlines and, in particular, lack of precise recognition of mechanisms controlling rock coast geomorphology in polar climates. Results are presented from a pilot survey of rock resistance using Schmidt Hammer Rock Tests (SHRT) across the recently deglacierized Nordenskioldbreen forefield and coastal zone, in central Spitsbergen, Svalbard. The aim is to improve understanding of the effects of rock weathering on high latitude coasts. SHRT across a field of roches moutonnées of metamorphic rocks, uncovered from ice over the last century and exposed to the operation of littoral processes, demonstrated significant relationships between rock surface resistance and distance from present shoreline, distance from the ice cliff as well as thickness of the snow cover. Sites closest to the present−day shoreline were characterized by lower resistance in comparison with more inland locations. The result support models that advocate intensification of weathering processes in cold region coastal settings.
Przejdź do artykułu

Abstrakt

This paper presents a detailed study of melting processes conducted on Hansbreen - a tidewater glacier terminating in the Hornsund fjord, Spitsbergen. The fieldwork was carried out from April to July 2010. The study included observations of meltwater distribution within snow profiles in different locations and determination of its penetration time to the glacier ice surface. In addition, the variability of the snow temperature and heat transfer within the snow cover were measured. The main objective concerns the impact of meltwater on the diversity of physical characteristics of the snow cover and its melting dynamics. The obtained results indicate a time delay between the beginning of the melting processes and meltwater reaching the ice surface. The time necessary for meltwater to percolate through the entire snowpack in both, the ablation zone and the equilibrium line zone amounted to c. 12 days, despite a much greater snow depth at the upper site. An elongated retention of meltwater in the lower part of the glacier was caused by a higher amount of icy layers (ice formations and melt-freeze crusts), resulting from winter thaws, which delayed water penetration. For this reason, a reconstruction of rain-on-snow events was carried out. Such results give new insight into the processes of the reactivation of the glacier drainage system and the release of freshwater into the sea after the winter period.
Przejdź do artykułu

Abstrakt

The Ebbabreen ice−cored moraine area is covered with a sediment layer of up to 2.5 m thick, which mostly consists of massive diamicton. Due to undercutting by lateral streams, debris flow processes have been induced in marginal parts of this moraine. It was recognized that the sedimentology of deposits within the deposition area of debris flows is the effect of: (1) the origin of the sediments, (2) the nature of the debris flow, and (3) post−debris flow reworking. Analysis of debris flow deposits in microscale (thin sections) suggests a common mixing during flow, even though a small amount of parent material kept its original structure. The mixing of sediments during flow leads to them having similar sedimentary characteristics across the deposition area regardless of local conditions ( i.e. slope angle, water content, parent material lithology). After the deposition of sediments that were transported by the debris flow, they were then reworked by a further redeposition process, primarily related to meltwater stream action.
Przejdź do artykułu

Abstrakt

In this study, weather conditions causing warm waves in north−western Spits − bergen, exemplified by Ny− Å lesund station, were analyzed. Between 1981 and 2010, 536 days with the maximum temperature exceeding 8.3 ° C (the value of 95 percentile) were selected. 37 warm waves, which altogether lasted 268 days, were identified. A typical feature of pressure pattern causing warm waves was the appearance of positive anomalies of both the sea level pressure and the height of isobaric surface 500 hPa in the Euro−Atlantic sector of the Arctic. This indicates a presence of high−pressure systems in this region. Extremely warm days appeared more often with the circulation from the eastern than the western sector. Longer and warmer heat waves occurring in the last decade of the analyzed period may be considered as a sign of climate warming, which has a significant impact on environment, i.e. reduction in area and thickness of glaciers, reduction of permafrost and snow cover, changes in biodiversity, etc . The increase in the air temperature and more frequent occurrence of heat waves may encourage development of tourism in polar areas, potentially causing further changes in the environment.
Przejdź do artykułu

Abstrakt

This paper describes in detail the phe notypic traits of the newly discovered Leptolyngbya sieminskae sp. n. (Cyanobacteria). The species was found at two islands of the Svalbard archipelago (Spitsbergen and Nordaustlandet) in habitats which differed in humidity, water sources and altitude. The research was conducted at two fjords: on the southern side of Spitsbergen – Hornsund (77 ° N, 015 ° E) and the north−west side of Nordaustlandet – Murchisonfjord (80 ° N, 018 ° E). Although Leptolyngbya sieminskae was found in different latitudes no significant morphological differences were found between the specimens from both sites. The only visible difference is in the thickness of filaments and sheaths.
Przejdź do artykułu

Ta strona wykorzystuje pliki 'cookies'. Więcej informacji