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  • 11
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    Snowmelt modelling on signy island, South Orkney Islands (1998)
    Cambridge University Press
    Details
    Publication Date: 1998-01-01
    Description: The ability of the Utah energy-balance and snowmelt model (UEB) to simulate decline in snow water equivalent (SWE) at an extreme location was assessed. Field data were collected at Paternoster Valley, Signy Island, South Orkney Islands (60°43′S) during the austral summer of 1996–97. This is the first application of UEB in a maritime Antarctic site. UEB is a physically based snow melt model using a lumped snow-pack representation with primary state variables SWE and snow pack-energy content (U). Meteorological inputs are air temperature, wind speed, humidity, precipitation and total incoming solar and longwave radiation. The Paternoster Valley catchment was subdivided into eight non-contiguous terrain classes for sampling and modelling using a geographical information system (GIS). Simulations of SWE in each of these classes were compared พ with field observations. It is shown that initial U and snow-surface thermal conductance (Ks) affect model simulations. Good approximations of SWE depletion are obtained using measured incoming solar radiation to drive the model but there are shortcomings in the characterization of long wave radiation and sensible-heat fluxes.
    Print ISSN: 0260-3055
    Electronic ISSN: 1727-5644
    Topics: Geography , Geosciences
    Published by Cambridge University Press on behalf of International Glaciological Society.
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  • 12
    Electronic Resource
    Electronic Resource
    Physical, chemical and biological processes in Lake Vostok and other Antarctic subglacial lakes (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 414 (2001), S. 603-609 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Over 70 lakes have now been identified beneath the Antarctic ice sheet. Although water from none of the lakes has been sampled directly, analysis of lake ice frozen (accreted) to the underside of the ice sheet above Lake Vostok, the largest of these lakes, has allowed inferences to be made on lake ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/414603a
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  • 13
    Electronic Resource
    Electronic Resource
    Temporal plankton dynamics in an oligotrophic maritime Antarctic lake (2000)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 43 (2000), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈list style="custom"〉1The population density, diversity and productivity of the microbial plankton in an oligotrophic maritime Antarctic lake were studied for a 15-month period between December 1994 and February 1996.2In the lake, concentrations of nutrients and dissolved organic carbon were uniformly low, temperature varied over a small annual range of 0.1–3 °C, and the surface was ice-covered except during a period of approximately 6 weeks in summer.3The total of 57 morphotypes of protozoa observed during the study is a higher taxonomic diversity than previously reported from continental Antarctic lakes, but lower than that found in more eutrophic maritime Antarctic lakes. Likewise, planktonic abundance and productivity were lower than has been reported in other lakes on Signy Island, but generally higher than those of lakes on the Antarctic continent.4There were marked seasonal and interannual variations in planktonic population density.5Chlorophyll a concentrations ranged from undetectable to 4.2 µg L-1 and the greatest rate of primary productivity measured was 4.5 mg C m-3 h-1. The phytoplankton was dominated by small chlorophytes and chrysophytes, with phototrophic nanoflagellate abundance ranging from 1.1 × 103 to 1.2 × 107 L-1.6Bacterial densities of 3.6 × 108 to 1.9 × 1010 L-1 were recorded and bacterial productivity reached a peak of 0.36 µg C L-1 h-1. Numbers of heterotrophic nanoflagellates between 5.0 × 104 and 1.8 × 107 L-1, and of ciliates from undetectable to 1.1 × 104 L-1 were observed. Naked amoebae were usually rare, but occasionally reached peaks of up to 1.5 × 103 L-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00542.x
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  • 14
    Electronic Resource
    Electronic Resource
    A great lake under the ice (1996)
    [s.l.] : Nature Publishing Group
    Nature 381 (1996), S. 644-646 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] FOUR kilometres under the ice of central Antarctica is an enormous lake, 200 km long, covering an area of 14,000 km2, and in some places at least 500 m deep. These proportions are reported on page 684 of this issue1 by Kapitsa and colleagues. Lake Vostok, as it is now called, may be a unique ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/381644a0
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  • 15
    Electronic Resource
    Electronic Resource
    Depth-related changes in benthic diatom assemblages of a maritime Antarctic lake (1989)
    Springer
    Polar biology 9 (1989), S. 525-532 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The epiphytic diatoms of filamentous matforming algae in Sombre Lake, Signy Island, South Orkneys, Antarctica were examined in a field study from January to March 1987. Results reveal 1) a shallow shelf assemblage, dominated by Fragilaria spp, with high percentages of empty frustules, and low numbers of viable cells and, 2) a mid-depth zone containing the most luxuriant epiphytic growth dominated by Achnanthes minutisima Kütz., Synedra rumpens var. familiaris (Kütz) Hust., and Cymbella minuta Hilse ex Rabenh., and 3) a deep water assemblage with low numbers of actively growing cells, dominated by Stauroneis anceps var. hyalina M. Perag. et Brun. in Hérib. The comparison of methods and their impact on ecological interpretation is discussed together with a consideration of the principal factors potentially influencing community structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261037
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  • 16
    Electronic Resource
    Electronic Resource
    Transmission electron microscope analysis of virus-like particles in the freshwater lakes of Signy Island, Antarctica (2000)
    Springer
    Polar biology 23 (2000), S. 657-660 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water samples from a range of fresh-water Antarctic lakes on Signy Island (South Orkney Islands: 60°45′S, 45 °38′W) were examined for the presence of virus-like particles (VLPs) during the 1998/1999 field season. It was discovered that VLPs were ubiquitous, morphologically diverse and abundant, with high concentrations ranging from 4.9 × 106 ml−1 to 3.1 × 107 ml−1. Likely hosts include bacteria, cyanobacteria and eukaryotic algae. In addition, an unusually large virus morphotype was observed with a head diameter 370 × 330 nm and a tail 1.3 μm long.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000000152
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  • 17
    Electronic Resource
    Electronic Resource
    Temporal patterns of primary production in a large ultra-oligotrophic Antarctic freshwater lake (1997)
    Springer
    Polar biology 18 (1997), S. 363-370 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A large ultra-oligotrophic Antarctic freshwater lake, Crooked Lake, was investigated between January 1993 and November 1993. The water column supported a small phytoplankton community limited by temperature, nutrient availability and, seasonally, by low photosynthetically active radiation. Chlorophyll a concentrations were consistently low (〈1 g l−1) and showed no obvious seasonal patterns. Production rates were low, ranging from non-detectable to 0.56 g C l−1 h−1, with highest rates generally occurring towards the end of the austral winter and in spring. The pattern of carbon fixation indicated that the phytoplankton was adapted to low light levels. Chlorophyll a specific photosynthetic rates (assimilation numbers) ranged from non-detectable to 1.27 gC (g chlorophyll a)−1 h−1. Partitioning of photosynthetic products revealed carbon incorporation principally into storage products such as lipids at high light fluxes with increasing protein synthesis at depth. With little allochthonous input the data suggest that lake dynamics in this Antarctic system are driven by phytoplankton activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050201
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  • 18
    Electronic Resource
    Electronic Resource
    Patterns of energy storage in Pseudoboeckella poppei (Crustacea, copepoda) from two contrasting lakes on Signy Island, Antarctica (1989)
    Springer
    Hydrobiologia 172 (1989), S. 183-191 
    Details
    ISSN: 1573-5117
    Keywords: Antarctic lakes ; copepod ; lipid ; phytoplankton ; triacylglycerol ; wax ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The copepod Pseudoboeckella poppei (Daday) (Calanoida, Centropagidae) was sampled from Sombre and Heywood Lakes on Signy Island, Antarctica (60° S, 45° W) between January 1984 and March 1985. Sombre Lake is clear and oligotrophic with little phytoplankton and a bottom sediment low in organic content. By contrast Heywood Lake is turbid and mesotrophic; a substantial phytoplankton develops in summer and the bottom sediments are comparatively rich in organics. Both lakes freeze over for much of the year, forcing the copepods to adopt a benthic feeding strategy over winter. Adult Pseudoboeckella feed on phytoplankton when this is available, but also on detritus, diatoms and short algal filaments stirred up from the sediment. In Heywood Lake, male copepods show a smooth seasonal trend in lipid content with lipid being synthesised in early summer and utilised in late summer and winter. The summer increase in lipid content is associated with an increase in dry weight. Female lipid contents show evidence of two peaks of egg production. In Sombre Lake both male and female copepods increase in size during summer and show a wider range of lipid contents than in Heywood Lake; it is likely that this is due to the poorer winter feeding conditions which necessitate the synthesis of a much larger store of reserves during the summer. In contrast to marine calanoid copepods, lipid stores are exclusively triacylglycerol with no trace of wax ester.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00031621
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