Polar Research (E-Journal)
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Heat conservation during cold exposure in birds (vasomotor and respiratory implications)
No full textThe mechanisms by :vhich peripheral circulation and respiration serve in maintaining thermal homeostasis in birds living in cold climates are reviewed. Three types of arteriovenous heat exchanger (an elaborate rete, asimple rete, and a venue comirantes system) are found in the legs of birds. The anatomical differences between the different types of A-V associations are described, and the regulation of peripheral blood flow, in respect to maximal heat conservation and prevention of tissue damage, is discussed. A nasal temporal counter current heat exchanger, lowering the temperature of the expired air to values considerably below the body temperature, is the most important mechanism for minimizing the respiratory heat and water loss. In addition, a decreased ventilatory requirement, caused by a changed respiratory pattern and an increased parabronchial oxygen extraction, lowers the amount of air ventilated relative to the amount of oxygen uptake. Thus, the relative loss of heat and water is reduced
Clay mineral cycles identified by diffuse spectral reflectance in Quaternary sediments from the Northwind Ridge: implications for glacial–interglacial sedimentation patterns in the Arctic Ocean
No full textA Quaternary record of fine-grained sediment composition is used to investigate Arctic Ocean climate variability on glacial–interglacial time scales. Diffuse spectral reflectance data from sediment core P1-92AR-P25 from the Northwind Ridge, north of Alaska, demonstrates cyclic variations in mineralogy. Varimaxrotated R-mode factor analysis of down-core data revealed three major mineralogical assemblages, which were then compared with the content of manganese, a proxy for basin ventilation, and thus glacial–interglacial cycles. Results indicate that factor 1, a smectite + chlorite clay assemblage, was delivered to the core site during interglacials, either by fluvial discharge or sea-ice drift from Siberian rivers or inflow from the Bering Sea. Factor 2, an illite + goethite assemblage, is related to glacial periods, and was probably transported from the Laurentide Ice Sheet by icebergs or meltwater. Factor 3, glauconite, might have been sourced from the North Slope region of Alaska during deglacial intervals, or from dolomites associated with Laurentide iceberg-discharge pulses. The observed variations in sediment source and transport mechanisms arise from glacial–interglacial changes in sea level, the size of the terrestrial ice sheets surrounding the Arctic Ocean, the extent of sea-ice cover and altered atmospheric circulation. The reconstructed glacial– interglacial circulation patterns from the Late Quaternary show some similarity with modern circulation changes presumably related to the monthly- to decadally-fluctuating Arctic Oscillation. However, because the Arctic Oscillation operates on much shorter time scales, further research is necessary to better understand the driving mechanism for the changes observed over glacial– interglacial cycles, and the potential role of ocean–atmospheric interaction
Late Jurassic/Early Cretaceous phosphates of Nordvik, North Siberian Basin
No full textLate Jurassic and Early Cretaceous calcite-rich phosphate (fluor/hydroxy apatite) concretions in the North Siberian basin (Nordvik) have been analysed. Their mineralogical and geochemical (major, trace and rare earth element) characteristics are presented in a sedimentological context. Low oxygen conditions prevailed along large parts of the seafloor of this wide epicontinental sea. In the Nordvik region this, in combination with slow and very fine-grained clastic sedimentation, and high algal production, resulted in the formation of phosphatic concretions. The concretions mainly consist of microcrystalline to ultracrystalline apatite and calcite, with traces of sphalerite, pyrite, kaolinite, quartz and albite. The clastic composition of the concretions is comparable with the surrounding Nordvik shales. Dysoxic–anoxic conditions in the last precipitating pore-water phases (early diagenetic) are reflected in enrichments in, for example, vanadium, uranium and the rare earth elements in the concretions
Colonization of the polar willow Salix polaris on the early stage of succession after glacier retreat in the High Arctic, Ny-Ålesund, Svalbard
No full textThe polar willow (Salix polaris), predominant in the late successional stage in deglaciated areas of Ny-Ålesund, Svalbard, is rarely found in the early stage, when purple saxifrage (Saxifraga oppositifolia) dominates. To elucidate the pattern and the mechanism of successional change from the Saxifraga stage to the Salix stage, we examined the distribution pattern, size structure and habitat conditions of a colonizing Salix population in the seral stage where Salix was invading Saxifraga-dominated sites. The present distribution pattern and aerial photographs taken in the past suggest that Salix colonization at this site commenced within the last 70 years. We found 115 Salix individuals (22 male, 13 female and 80 unknown) in a 30 m ¥ 30 m quadrat on the seral stage. Although the largest individual had a size of 2000 cm2 (length ¥ maximum width), the majority (84%) of individuals were smaller than 100 cm2. The seedling size distribution, as inferred from the leaf scar number, indicated that annual recruitment was slight. Of the individuals observed about 75% had colonized bare ground; only four individuals grew within Saxifraga colonies. No significant difference was found in soil characteristics (water content, and carbon and nitrogen concentrations) between the seral stage and the earlier stage prior to colonization by Salix. These results suggest that difficulties in seed production, germination and/or seedling establishment of Salix, rather than soil formation by preceding species (Saxifraga), limits the early-stage colonization by Salix
Review of Health of Antarctic wildlife: a challenge for science and policy, edited by Kerry R. Knowles & Martin J. Riddle
No full textClimate change and disease, among other factors, play an important role in the regulation and evolution of animal populations through the differential survival of individuals (Holmes 1996; Harvell et al. 2002). The study and monitoring of disease is important because diseases are likely to be spread more rapidly now than in the recent past because of increased globalization and rapid humaninduced climate change (Daszak et al. 2000; Ward & Lafferty 2004). Antarctic wildlife offers a unique opportunity to study disease spread in terms of globalization and climate change because: (1) Antarctic animals are increasingly exposed to humans and other disease vectors, such as introduced species; and (2) there is strong evidence of climatic changes in and around Antarctica (Mayewski et al. 2009), which together may affect the composition and virulence of pathogens or increase the overlap between Antarctic and other seabirds and their parasites (e.g., Kovats et al. 2001)
Review of Greetings from Spitsbergen: tourists at the eternal ice, 1827–1914, by John T. Reilly
No full textThis finely produced but maddeningly inconsistent work seeks to explore a segment of Svalbard’s history through a largely pictorial examination of the vessels that carried tourists to the archipelago. The book has the pleasant feel of an essential family scrapbook (indeed, some scrapbook pages from early tours of Svalbard are reproduced here in their entirety), and it is because of this feel that it is easier to overlook the flaws in a work destined to take its place in the library of every Svalbardian.(Published: 1 January 2010)Citation: Polar Research 2011, 30: 5912 - DOI: 10.3402/polar.v30i0.591
Review of Explorer: the life of Richard E. Byrd, by Lisle A. Rose
No full textWith his Hollywood good looks, Commander’s stripes, boyish humility, overweening faith in the righteousness of American technological progress, and bags of cash from some of America’s most reactionary Republican businessmen, Richard Evelyn Byrd in the late 1920s stepped neatly into the role of globally recognized polar superstar, a magnificently tricky job made vacant by Roald Amundsen’s chivalric disappearance north of Tromsø during the Italia catastrophe of 1928. In a geographic world soon to be taken over by science bureaucrats in national directorates and emerging research institutions, Byrd, a naturally sensitive and deep thinker, self-reinvented as a muscular man of action, became a final bastion of the fading cult of polar personality
Recent spatial development of Svalbard strandflat vegetation over a period of 31 years
No full textVegetation succession was analysed at the forefields of two glaciers in Svalbard over an interval of 31 years (1975–2006). In 1975, 85 sampling sites were positioned along transects extending from the coastline to the glacier fronts: botanical observations were made at each sampling site. This protocol allowed us to carry out new observations in 2006 under the same conditions. Thus, it was possible to undertake a botanical assessment of species and taxa, and to see how the vegetation has changed with reference to a typology established by coupling correspondence analysis and ascending hierarchical classification. Vegetation succession at the sampling sites was also measured by using vectors positioned in the multidimensional space of correspondence analysis. In this way, the changes over the interval between seven vegetation types were plotted and mapped, and the colonization process was calibrated and dated against a series of reference stages, mainly since the end of the Little Ice Age
Effects of disturbance on geese in Svalbard: implications for regulating increasing tourism
No full textTourism in the Arctic archipelago of Svalbard, Norway, has increased significantly in the last decade. Cruise ships make landings all around the archipelago, and there are numerous snowmobile, boat and hiking excursions. We describe disturbance effects on the three geese species that breed in Svalbard: the pink-footed goose (Anser brachyrhynchus), the barnacle goose (Branta leucopsis) and the light-bellied brent goose (Branta bernicla hrota). All three are regarded as highly vulnerable to disturbance. Behavioural responses by geese to humans on foot were analysed by estimating the distances at which geese become alerted, the escape flight distances and the length of escape flights, during pre-nesting, nesting and brood-rearing periods. We evaluate the consequences of human intrusion on the reproductive success in breeding colonies. During all three phases, pink-footed geese responded at longer ranges, and flew/ran longer distances, than both brent and barnacle geese: when disturbed on the nest site, both male and female pink-footed geese flew far away, resulting in a high rate of nest loss to avian predators (35%), compared with the 4 and 0% losses among barnacle and brent geese, respectively. During brood rearing, families of pink-footed geese escaped at an average distance of 1717 m, compared with distances of 620 and 330 m for brent and barnacle geese, respectively. Even though bird sanctuaries have been established on several islets, with no human access during nesting, many core areas for the three species remain without restrictions, such as islets used by brent geese and slopes and valleys with nesting pink-footed geese, broodrearing areas and moulting grounds for non-breeding geese. We propose regulations of human access to goose concentration areas, and address the need to better protect these significant areas. We also discuss the need for further research on the vulnerability of geese to human activity
Pleomorphism in the Antarctic flagellate Pyramimonas gelidicola (Prasinophyceae, Chlorophyta)
No full textSpecies of the genus Pyramimonas (Prasinophyceae) are a common, widespread, but minor component of the Antarctic marine phytoplankton. They are often associated with the seasonal sea-ice environment. Pyramimonas gelidicola (McFadden, Moestrup & Wetherbee, 1982) was isolated from the water column of a saline Antarctic lake, and observations on the organism’s life history as it grew in unialgal cultures were made. The alga proved to be pleomorphic: capable of producing several morphologically distinct life stages. We recorded motile single-celled quadriflagellates that formed two statistically distinct size classes, a rare uniflagellate cell-type, and aggregations of quadriflagellate cells, multilobed forms and an encystment stage. Multilobed forms and cell aggregations, never before observed in an Antarctic Pyramimonas species, are presumed to be growth medium-induced morphotypes. Multilobed forms contained an equal number of nuclei and lobes, suggesting that they are the product of asexual reproduction. Some of the morphotypes we report here may never be observed under natural field conditions, but the potential for this alga to alternate between morphotypes is clearly demonstrated