Polar Research (E-Journal)
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Environmental changes during the Paleocene—Eocene Thermal Maximum in Spitsbergen as reflected by benthic foraminifera
No full textThe study deals with environmental changes during the Paleocene-Eocene Thermal Maximum (PETM) and its background conditions in Spitsbergen through analysis of benthic foraminiferal assemblages (FA) in a section drilled in the Paleogene Central Basin. The impact of this extreme global warming occurs here in prodelta shelf mudstones composing the lower part of the Gilsonryggen Member (Frysjaodden Formation). The start of the PETM perturbation is marked by a faunal turnover, in which the medium-diversity circumpolar Reticulophragmium assemblage was replaced by a low-diversity Trochammina fauna. During the hyperthermal period, benthic foraminiferal diversity decreased severely, while the dominance of small-sized taxa with epifaunal morphology strongly increased. This low-diversity fauna occurs in sediments with a reduced thorium/uranium ratio (proxy for oxygenation) and kaolinite enrichment (proxy for high humidity). The faunal changes were thus caused by the combined effects of hypoxic and hyposaline conditions in a stratified water column, due to extreme warming with its accompanying intensified hydrologic cycle. The PETM acme coincides with the maximum flooding surface (MFS) of the Gilsonryggen depositional sequence, composed of the Gilsonryggen Member and the overlying Battfjellet and Aspelintoppen formations. The transgressive phase of the sequence was initiated by local tectonics, while the eustatic sea-level rise of the PETM was superimposed on this transgression.Keywords: PETM; foraminifera; faunal turnover; diversity decrease; sequence stratigraphy(Published: 25 July 2013)To access the supplementary material for this article, please see Supplementary files in the column to the right (under Article Tools)Citation: Polar Research 2013, 32, 19737, http://dx.doi.org/10.3402/polar.v32i0.1973
Tetraploids do not form cushions: association of ploidy level, growth form and ecology in the High Arctic Saxifraga oppositifolia L. s. lat. (Saxifragaceae) in Svalbard
No full textSaxifraga oppositifolia L. is a common circumpolar plant species that displays considerable morphological and genetic variation throughout its range. It is mainly diploid, but tetraploids are reported from several regions. The growth form varies from prostate to cushion-shaped, and the plant thrives in wet snow beds as well as on dry ridges. This variation has triggered the curiosity of many researchers, but as yet, no one has explained the observed morphological variation using ecological and/or genetic factors. However, the ploidy level has rarely been taken into account. This is the first study that demonstrates a significant correlation between ploidy level, ecology and growth form in S. oppositifolia. We successfully analysed 193 individuals of S. oppositifolia from 15 locations in Svalbard to investigate possible relationships among growth forms (prostrate, intermediate and cushion), ecological factors (vegetation and soil characteristics) and ploidy level. Results from flow cytometry reported 106 diploids, eight triploids and 79 tetraploids. Tetraploids almost exclusively showed prostrate growth, while the diploids displayed all three growth forms, evidence that growth form is at least partly genetically determined. Our analyses of environmental and vegetation data in relation to ploidy level indicated overlapping niches, but the tetraploids showed a narrower niche, and one shifted towards more benign habitats characterized by higher pH, higher soil temperatures and higher cover of vascular plants. The latter may suggest that tetraploids are slightly better competitors, but less hardy. Thus, autopolyploidy in S. oppositifolia has expanded the ecological amplitude of this species complex.Keywords: Autopolyploidy; flow cytometry; morphotypes; habitat segregation; purple saxifrage(Published: 6 June 2013)To access the supplementary material for this article, please see Supplementary files in the column to the right (under Article Tools)Citation: Polar Research 2013, 32, 20071, http://dx.doi.org/10.3402/polar.v32i0.2007
Review of Sea ice–an introduction to its physics, chemistry, biology and geology, edited by David N. Thomas & Gerhard S. Dieckmann
No full textTo my knowledge, there is (as yet) no university course producing 'sea ice scientists' in the way that there are university programmes for young oceanographers, glaciologists and so on
Photogrammetric methods applied to Svalbard glaciers: accuracies and challenges
No full textUse of digital images is expanding as a tool for glacier monitoring, and smallformat time-lapse cameras are increasingly being used for glacier monitoring of fast-flowing glaciers. Stereoscopic imagery is preferable since it yields direct displacement results but stereo photogrammetry has more requirements regarding geometry in set-up and control points, as well as the additional cost of another complete camera system. We investigate a combination of methods to achieve satisfactory control of accuracy with resulting significant day-to-day velocity variations ranging from 1.5-4 m day-1 made at a distance of 2 km. Validation of results was made by comparing different methods, partly using the same image material, but also in combination with aerial and satellite images. Monoscopic results can also be used to gain continuity in a stereo data set when geometry or visibility is poor. We also explore the use of ordinary photographs taken from airliners for compilation of orthoimages as a potential low cost method for detection of sudden changes. The method, showing some tens of metres accuracy, was verified for monitoring velocities and front positions during a glacier surge and was also used to validate monoscopic timelapse images.Keywords: Photogrammetry; time-lapse; orthoimage; mono- and stereoscopic; surge; velocity(Published: 12 June 2012)Citation: Polar Research 2012, 31, 18671, http://dx.doi.org/10.3402/polar.v31i0.1867
The algal vegetation in the outer part of Isfjorden, Spitsbergen: revisiting Per Svendsen’s sites 50 years later
No full textThe benthic algal vegetation was investigated at two different sites in the outer part of Isfjorden, Svalbard, during 27-29 July 2007. One exposed site at Kapp Linne´ and one sheltered site in Ymerbukta were sampled both in the littoral and sublittoral zones. A total of 83 different taxa were recorded, 81 from the sublittoral and 40 from the littoral zone. The sublittoral zones at the two sites did not differ much in terms of the taxa recorded, but the number of species in the littoral differed between the two sites: Kapp Linne´ had 39 while only five species were found in Ymerbukta. The results are compared to a survey made by Per Svendsen in 1954 and 1955 in order to seek any changes in the diversity. Even though the number of species is difficult to compare directly, we registered a higher species number than Svendsen did 50 years ago. The difference seemed more pronounced in the littoral zone than in the sublittoral. Possible explanations for the differences between the two investigations are discussed. Two species not previously recorded in Svalbard, Antithamnionella floccosa and Litosiphon laminariae, were registered.Keywords: Arctic; Svalbard; long-term changes; algal diversity(Published: 26 March 2012)Citation: Polar Research 2012, 31, 17538, DOI: 10.3402/polar.v31i0.1753
Environmental monitoring and management proposals for the Fildes Region, King George Island, Antarctica
No full textThe Antarctic terrestrial environment is under increasing pressure from human activities. The Fildes Region is characterized by high biodiversity, but is also a major logistic centre for the northern Antarctic Peninsula. Different interests, from scientific research, nature conservation, protection of geological and historical values, station operations, transport logistics and tourism, regularly overlap in space and time. This has led to increasing conflict among the multiple uses of the region and breaches of the legal requirements for environmental protection that apply in the area. The aim of this study was to assess the impacts of human activities in the Fildes Region by monitoring the distribution of bird and seal breeding sites and recording human activities and their associated environmental impacts. Data from an initial monitoring period 200306 were compared with data from 200810. We observed similar or increased levels of air, land and ship traffic, but fewer violations of overflight limits near Antarctic Specially Protected Area No. 150 Ardley Island. Open waste dumping and oil contamination are still major environmental impacts. Scientific and outdoor leisure activities undertaken by station personnel are more frequent than tourist activities and are likely to have a commensurate level of environmental impact. Despite the initial success of some existing management measures, it is essential that scientific and environmental values continue to be safeguarded, otherwise environmental impacts will increase and the habitat will be further degraded. We argue that the Fildes Region should be considered for designation as an Antarctic Specially Managed Area, a measure that has proven effective for environmental management of vulnerable areas of the Antarctic.Keywords: human impact; Antarctic; Fildes Region; environmental management; Antarctic Specially Managed Area; protected area(Published: 18 May 2012)Citation: Polar Research 2012, 31, 18206, http://dx.doi.org/10.3402/polar.v31i0.1820
Review of Climate change in the polar regions, by John Turner & Gareth J. Marshall
No full textIn this ambitious, cross-disciplinary volume, British Antarctic Survey scientists John Turner and Gareth Marshall synthesize what is known about climate change in the Arctic and Antarctic and compare the changes that have occurred in the two polar regions. The authors examine recent changes in light of those that have taken place over the course of the last million years, and tackle the difficulties involved in teasing apart natural from anthropogenic change. The book is arranged in eight sections: an introduction; polar climate data and models; high-latitude climates and mechanisms of change; the last million years; the Holocene; the instrumental period; predictions for the next 100 years; and a summary.(Published: 12 March 2012)Citation: Polar Research 2012, 31, 17512, DOI: 10.3402/polar.v31i0.1751
Trampling on maritime Antarctica: can soil ecosystems be effectively protected through existing codes of conduct?
No full textSoil trampling is one of the most obvious direct negative human impacts in Antarctica. Through a range of experiments and field studies based on quantitative physical (soil penetration resistance) and biological (collembolan abundance) indicators, we evaluate the current codes of conduct relating to the protection of Antarctic soils from the consequences of pedestrian impacts. These guidelines include using, where available, established paths that cross vegetation-free soils. However, the effectiveness of this strategy is highly dependent on context. Limited intensity use - below 100 foot passes per year - produces small changes at the soil surface that can recover relatively rapidly, suggesting that the dispersal of activity across wider corridors may be the most appropriate option. However, for paths with a higher use level and those located in steep-sloped sites, it is desirable to define a single track, following stony or bouldery surfaces wherever possible, to keep the disturbed area to a minimum. It is clear that both environmental conditions and expected use levels must be taken into account in determining when and where it is more appropriate to concentrate or disperse human activities. Even though they may have performed satisfactorily to date, the increasing pressure in terms of numbers of visits for certain sites may make it necessary to revise existing codes of conduct.Keywords: Trampling impacts; environmental monitoring; low impact practices; soil resilience; soil penetration resistance; collembolan abundance(Published: 28 December 2012)Citation: Polar Research 2012, 31, 10888, http://dx.doi.org/10.3402/polar.v31i0.1088
A surge of the glaciers Skobreen-Paulabreen, Svalbard, observed by time-lapse photographs and remote sensing data
No full textWe present observations of a surge of the glaciers SkobreenPaulabreen, Svalbard, during 2003-05, including a time-lapse movie of the frontal advance during 2005, Advanced Spaceborne Thermal Emission (ASTER) imagery and oblique aerial photographs. The surge initiated in Skobreen, and then propagated downglacier into the lower parts of Paulabreen. ASTER satellite images from different stages of the surge are used to evaluate the surge progression. Features on the glacier surface advanced 2800 m over 2.4 yr, averaging 3.2 m/day, while the front advanced less (ca. 1300 m) due to contemporaneous calving. The surge resulted in a lateral displacement of the medial moraines of Paulabreen of ca. 600 m at the glacier front. The time-lapse movie captured the advance of the frontal part of the glacier, and dramatically illustrates glacier dynamic processes in an accessible way. The movie documents a range of processes such as a plug-like flow of the glacier, proglacial thrusting, incorporation of old, dead ice at the margin, and calving into the fjord. The movie provides a useful resource for researchers, educators seeking to teach and inspire students, and those wishing to communicate the fascination of glacier science to a wider public.Keywords: Glacier surge; time-lapse movie; Skobreen; Paulabreen; Svalbard(Published: 12 November 2012)To access the supplementary material to this article please see Supplementary Files in the column to the right (under Article Tools).Citation: Polar Research 2012, 31, 11106, http://dx.doi.org/10.3402/polar.v31i0.1110
A preliminary synoptic assessment of soil frost on Marion Island and the possible consequences of climate change in a maritime sub-Antarctic environment
No full textLocated in the sub-Antarctic, Marion Island (46˚ 54' S, 37˚ 45’ E) has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic process occurring on the island and this paper aims to understand the synoptic weather circulation pattern associated with summer soil frost occurrence in a sub-Antarctic environment. Preliminary results from automated microclimate measurements in the interior of Marion Island show that summer soil frost is dependent on Antarctic air mass circulation. This occurs exclusively during post-cyclonic airflow after the passage of a cold front connected to a mid-latitudinal cyclone and subsequent ridging in of the South Atlantic Anticyclone behind the cold front, or when a series of low pressure systems passes over the island. The duration and intensity of soil frost cycles are dependent on the duration of post-cyclonic Antarctic air mass circulation. Summer soil frost on Marion Island is driven by a complex interaction between the latitudinal position of the passing cyclone, the latitudinal position of the ridging anticyclone as well as the trajectory of the air mass circulation. The data suggest that predicted trends in synoptic climate change in the sub-Antarctic may lead to non-linear responses in soil frost dynamics.Keywords: Marion Island; climate change; synoptic weather; soil frost; sub-Antarctic; air mass circulation(Published: 22 March 2012)Citation: Polar Research 2012, 31, 17626, DOI: 10.3402/polar.v31i0.1762