Polar Research (E-Journal)
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Glaciomarine sediments and suspended particulate matter, Weddell Sea Shelf, Antarctica
No full textSamples of glaciomarine sediments and suspended matter from the eastern and central Weddell Sea Shelf were collected during the Norwegian Antarctic Research Expedition (NARE) in 1978/79. Ice-rafted clastic materials are in general the main sediment sources. On the eastern shelf, biogenic materials are abundant (sponges and bryozoan debris), Fine-grained materials, clastic and bioclastic, are additionally supported as fecal aggregates and by currents. The composition of the bottom sediments shows only small variations laterally and within the profiles. Dissolution of the biogenic materials appears to be slight. The suspended matter is dominated by fine silt and clay particles of clastic, biogenic (mainly diatoms) and authigenic (Fe. Mg-rich silicates) origin. Metalliferous particles (Fe, Ti, Zn, Cr, Ni-rich) of possibly anthropogenic an4 or cosmic origin are observed. On the upper continental slope and the outer shelf the sedimentation rates are in the range of 2-5 cm/1OOO years, which are slightly higher than for the rest of the shelf. The bioclastic glaciomarine deposits grade southward into bioclastic free sediments, showing that glaciomarine deposits outside an ice shelf may form a sequence of alternating bioclastic-rich and bioclastic-free layers. Similarly, late Precambrian carbonate tillite sequences, especially in the case of thin carbonate layers interbedded with tillite layers, may reflect variations in glaciomarine facies rather than interglaciavglacial cycles
Glaciomarine sedimentation in a modern fjord environment, Spitsbergen
No full textBy means of high resolution acoustic profiling and correlation of echo character and sediment lithology, fjords in western and northern Spitsbergen are shown to be blanketed by a 5-20 m layer of acoustically transparent sediments consisting mainly of soft homogeneous mud with ice rafted clasts. Acoustically semi-transparent material is found on slopes and sills reflecting their coarser composition. The areal average depositional rate in the outer fjord is in the range of from 0.1 to l.Omm/year, increasing towards the glaciers. In Kongsfjorden, 5&100mm/year of muddy sediments is deposited at a distance of lOkm from the calving Kongsvegen glacier. Close to the ice front ( 4 . 5 km) coarser grained, interbedded (sanqmud) sediments are deposited. The main sediment sources are from settlement out of the turbid surface sediment plume, combined with various types of gravity flow (sediment creep, minor slides, and slumping). Material deposited from turbidity current is probably of minor importance. On shallow sills the sediments are remobilized by icebergs. The sediment adjacent to the ice front is reworked and compacted during surges, a common form of glacial advance for Spitsbergen glaciers. During the surge considerable amounts of coarse-grained sediment are deposited by meltwater in front of the ice margin
Introduction to a special section: winter terrestrial ecology in Arctic and alpine tundra
No full textI am very pleased to present this special section of articles on winter terrestrial ecology in Arctic and alpine tundra. This is a new and developing field of research, and has been hitherto little studied. Much is unknown about the ecology of the dark, cold period of the year, as traditionally ecologists have travelled to their field sites in summer, when the snow has melted and the plants, soils and invertebrates are more readily available to be studied. Arctic research in the summer is often challenging; Arctic research in the wintertime presents even greater obstacles. However, in tundra areas the long winter is an important determinant of the physical framework for living organisms, both during the winter itself and during the short growing season. Winter ecosystem respiration is an important contributor to the annual CO2 flux in the High Arctic, as shown in this issue in papers by Strebel et al. and Morgner et al., and values vary greatly between vegetation types. Carbon sink strength in the tundra is therefore overestimated if cold-season dynamics are not included, and estimates will be less biased at drier sites with little snow accumulation
Approaching the North: Norwegian and Russian foreign policy discourses on the European Arctic
No full textThe aim of this article is to identify Norwegian and Russian official foreign policy discourses on the European Arctic, and how perceived challenges are understood, framed and presented by the governments in their respective countries. The article makes use of discourse analysis to grasp how the Norwegian “High North” strategy is framed by the Norwegian government and, likewise, how the Russian approach to the European Arctic is framed by the Russian government. The empirical foundation is a study of primary texts such as white papers, official reports, speeches and strategies. We find that the Norwegian approach to the High North features in a powerful official discourse resulting from a robust and broad domestic discursive mobilization. The Russian approach is that of an increasingly assertive nation for which the zero-sum game and relative gains seem to be the main rationale, judging by the official discourse. The Russian approach is not as coherent or based on a broad discursive mobilization as in Norway’s case.We identify energy, security, the economy and the environment as key discursive nodal points that the foreign policy discourses of the two countries evolve around: we find that both countries regard the European Arctic’s potential as a future energy province to be the region’s most prominent aspect. The discourses show that energy is regarded to be of vital national interest, but the countries have differing perceptions on international cooperation. However, as the countries have some important common frames of references, a favourable climate for extended future cooperation could be further developed
Water masses in Kangerlussuaq, a large fjord in West Greenland: the processes of formation and the associated foraminiferal fauna
No full textThe water masses in Kangerlussuaq (Søndre Strømfjord) in West Greenland were studied during both a summer and a winter field survey. In order to obtain an improved understanding of the relationship between the physical oceanography and modern foraminiferal assemblage distributions, conductivity–temperature–density measurements were carried out in connection with sediment surface sampling along a transect through the 180 km long fjord. The exchange between the inner part of Kangerlussuaq (275 m deep) and the ocean is restricted by an almost 100 km long outer, shallow part. Our study shows that the water mass in this inner part is almost decoupled from the open ocean, and that in winter the inner part of the fjord is ice covered and convection occurs as a result of brine release. These processes are reflected in the foraminiferal assemblage, which consists of a sparse agglutinated fauna, indicative of carbonate dissolution. A monospecific, calcareous assemblage (Elphidium excavatum forma clavata) occurs in the innermost, shallow part, which is strongly influenced by sediment-loaded meltwater during the summer. The outer, shallow part of the fjord is dominated by strong tidal mixing, and in summer the density of the incoming water does not exceed the bottom water density in the inner fjord. The foraminiferal assemblage here reflects high bottom water current velocity and an influence of water with relatively high salinity. Kangerlussuaq can be regarded as a modern analogue for ice-proximal environments in the Quaternary, with a strong seasonal forcing caused by freshwater run-off and sea-ice formation
Review of Recent mammals of Alaska, by S.O. MacDonald and J.A. Cook
No full textBilled as a summary monograph, this book is more precisely a catalogue of all mammals that have been documented in Alaska during the past 10 000 years, fronted by an introduction to mammalian collections in Alaska, and a short overview of Alaskan biogeography, and summarized in a set of appendices. In between these two segments are 116 1–2-page species accounts, each of which includes a brief summary of the taxonomy, distribution, abundance and status. In creating this text, the authors have summarized a great deal of detailed information gleaned from a thorough combing of both peerreviewed and grey literature. However, the aim of the book is centred less around describing the basic biology and ecology of Alaskan mammals, than on introducing the readers to the archived specimens that exist in museum collections. This focus reflects the training and expertise of the two authors, both of whom have spent their careers affiliated with natural history collections: S.O. MacDonald worked as a curator at the at the University of Alaska Museum (UAM) from 1979 to 1984, and is now curator in the Mammals Division of the Museum of Southwestern Biology (MSB) at the University of New Mexico, whereas J.A. Cook was the Curator of Mammals at UAM from 1990 to 2001, and now fills that role at MSB. Cook, MacDonald and their students have conducted extensive field collections in Alaska, and throughout their careers have advocated strongly that natural history collections are valuable research tools. This book serves as a summary of their work, and as a plea for continued efforts in these areas
Holocene sedimentary rocks in Mathiesondalen, central Spitsbergen, Svalbard
No full textHolocene lithified sediments of glacial and glaciofluvial origin have been found in environments where carbonate cementation is a present-day process. The rocks occur as well cemented tillites, conglomerates. coarse sandstones and breccias, indicating a complex depositional pattern within a limited area. Both clasts and carbonate cement are mainly derived from underlying Carboniferous and Permian sequences which form the bedrock of this area
Foraging strategy of little auks under divergent conditions on feeding grounds
No full textA dual foraging strategy (long versus short trips) has been described for some species of seabirds, such as petrels, albatrosses (Procellariiformes) and penguins (Sphenisciphormes). Such a strategy has recently been reported for little auks (Alle alle) from the central coast of west Spitsbergen, Svalbard. This has been explained as a response to poor trophic conditions close to the breeding colony, and better conditions further away (150 km). In the present study, we investigated the foraging strategy of little auks in Hornsund, southern Spitsbergen, during two seasons with contrasting oceanographic conditions. During 2004, foraging conditions for little auks were good: cold Arctic waters rich in profitable high-energy food were dominant in their feeding grounds. Conversely, during 2006 there was a great influx of warm Atlantic water in the feeding area, inducing poor foraging conditions. In both seasons we examined the pattern of foraging trip lengths automatically with a video camera (both adults from four nests in each year), and by direct non-stop observation of 20–54 individually marked birds. Our results showed that the dual strategy and the ratio of short and long trips were consistent, regardless of the conditions in the feeding grounds. This suggests that the strategy is inherent and may be crucial for the self-maintenance of adults