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Author |
Thomas, D.N. |
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Title |
Frozen Oceans – The floating world of pack ice |
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Book Whole |
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Year |
2004 |
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Abstract |
Pack ice is a layer of frozen seawater on the top of the polar oceans, varying in thickness from a few centimetres to tens of metres. It is an ephemeral feature, not just of polar regions but also of seas such as the Baltic, Caspian and Sea of Okhotsk. At its maximum extent it covers 13% of the Earth's surface area, making it one of the major biomes on the planet.For many years seen as an obstacle to trade and a threat to human life, the ice itself is now perceived to be vulnerable as we come to realize the dangers posed by global warming. Sea ice not only dominates polar regions but is also central to global ocean circulation as well as global climate patterns. Every year the formation, consolidation and subsequent melt of millions of square kilometres of ice influence the whole of the ocean's ecosystems.This is the first book to offer the general reader access to a remote frozen habitat which has for so long fascinated explorers, writers and scientists. During the harsh polar winter the surface of the ocean freezes up, forming a temporary ice layer called pack ice, or sea ice. This gives rise to a spectacular floating world which for a number of months each year becomes home to a wealth of plant and animal life. The wonderful colour photographs of life on, in and under the ice help draw the reader into this superb account of an extreme environment. Guaranteed to capture the imagination.The author is a veteran of six expeditions to the Arctic and Antarctic, and this book is packed with photographs taken in the course of his journeys. His lively and readable text conveys his excitement at the dangers and possibilities of life on the ice. He provides an in-depth background to the whole ecosystem of sea ice, its living communities and the structure of the ice itself. The level of accurate scientific detail will satisfy anyone looking for a reliable, up-to-date overview of this topic. |
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Publisher |
Natural History Museum |
Place of Publication |
London |
Editor |
Coyne, C. |
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0-565-09188-3 |
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Call Number |
refbase @ admin @ Thomas2004 |
Serial |
756 |
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Author |
Thomas, D.N.; Baumann, M.E.M.; Gleitz, M. |
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Title |
Efficiency of carbon assimilation and photoacclimation in a small unicellular Chaetoceros species from the Weddell Sea (Antarctica): Influence of temperature and irradiance |
Type |
Journal Article |
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Year |
1992 |
Publication |
Journal of Experimental Marine Biology and Ecology |
Abbreviated Journal |
J Exp Mar Biol Ecol |
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Volume |
157 |
Issue |
2 |
Pages |
195-209 |
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Keywords |
photosynthesis; Psw; Weddell Sea; Chaetoceros; temperature effects; irradiance; light effects; acclimation; respiration; carbon fixation; low temperature; polar waters; Antarctica; water temperature |
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Abstract |
It is well established that Antarctic phytoplankton and sea-ice algae are able to thrive at low temperatures and it has been proposed that a reduction in respiration may be important in enabling them to do this. This possibility was studied in an Antarctic clone of a small unicellular Chaetoceros species isolated from the Weddell Sea (Antarctica), using comparative measurements of C assimilation during long- and short-term incubation series over a range of temperatures (-1.5 to 4 °C) at two irradiances (5 and 55 µmol m?²/s). Even though doubling times varied considerably, the total amount of C assimilated per cell per generation time was similar at each of the temperature and light conditions. However, over one cell cycle, significant respiratory C losses were determined by divergences in C assimilation patterns between cumulative and long-term incubations at both light intensities at 0 and 4 °C. At -1.5 °C, insignificant C losses were recorded. No significant extracellular release of dissolved organic material (DOC) was observed. |
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Elsevier Science B.V. |
Place of Publication |
Amsterdam |
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0022-0981 |
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Call Number |
refbase @ admin @ Thomas++1992 |
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757 |
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Author |
Thomas, D.N.; Dieckmann, G.S. |
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Title |
Biogeochemistry of Antarctic sea ice |
Type |
Journal Article |
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Year |
2002 |
Publication |
Oceanography and Marine Biology: An Annual Review |
Abbreviated Journal |
Oceanogr Mar Biol Annu Rev |
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Volume |
40 |
Issue |
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Pages |
143-169 |
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Keywords |
Sea ice; Biogeochemistry; Nutrients (mineral); Dissolved gases; Dissolved organic matter; Ps; Antarctic Ocean |
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Abstract |
Antarctic sea ice at its maximum extent in winter covers 40% of the Southern Ocean in a frozen layer, on average, 1 m thick. Sea ice is not solid, rather it is an ice crystal matrix permeated by a labyrinth of brine filled channels and pores in which life thrives. Organisms are constrained by a set of physicochemical factors quite unlike anything they encounter in the plankton from where they are recruited. Because sea ice is increasingly viewed as a suitable proxy for life in previous periods of the Earth's history, and even for astrobiology, it is pertinent that the physicochemical constraints acting upon sea-ice biology are better understood. The, largely microbial, network that develops in the ice itself imparts a unique chemistry that influences the nature and chemical composition of biogenic material released from the ice. This chemistry can result in the export of material to the sediments with distinctive chemical signatures that are useful tools for reconstructing past sea-ice cover of the oceans. This review synthesises information on inorganic nutrient, dissolved organic matter and dissolved gases from a variety of Antarctic ice habitats. |
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Taylor & Francis |
Place of Publication |
London |
Editor |
Gibson, R.N.; Barnes, M.; Atkinson, R.J.A. |
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ISSN |
0415254620 |
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Notes |
Review; Marine |
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no |
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Call Number |
refbase @ admin @ Thomas+Dieckmann2002 |
Serial |
758 |
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Author |
Thomas, D.N.; Dieckmann, G.S. |
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Title |
Antarctic sea ice – a habitat for extremophiles |
Type |
Journal Article |
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Year |
2002 |
Publication |
Science |
Abbreviated Journal |
Science |
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Volume |
295 |
Issue |
5555 |
Pages |
641-644 |
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Keywords |
Microorganisms; Sea ice; Ecosystems; Polar zones; Antarctic zone; Epontic organisms; Sea ice ecology; Antarctic sea ice; Marine microorganisms; Marine ecosystems; Bacteria; Algae; Psychrophilic bacteria; extremophiles; Ps; Antarctica |
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Abstract |
The pack ice of Earth's polar oceans appears to be frozen white desert, devoid of life. However, beneath the snow lies a unique habitat for a group of bacteria and microscopic plants and animals that are encased in an ice matrix at low temperatures and light levels, with the only liquid being pockets of concentrated brines. Survival in these conditions requires a complex suite of physiological and metabolic adaptations, but sea-ice organisms thrive in the ice, and their prolific growth ensures they play a fundamental role in polar ecosystems. Apart from their ecological importance, the bacterial and algae species found in sea ice have become the focus for novel biotechnology, as well as being considered proxies for possible life forms on ice- covered extraterrestrial bodies. |
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American Association for the Advancement of Science |
Place of Publication |
Washington, DC |
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ISSN |
0036-8075 |
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Notes |
Review |
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no |
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Call Number |
refbase @ admin @ Thomas+Dieckmann2002_2 |
Serial |
759 |
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Author |
Thomas, D.N.; Gleitz, M. |
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Title |
Allocation of photoassimilated carbon into major algal metabolite fractions: Variation between two diatom species isolated from the Weddell Sea (Antarctica) |
Type |
Journal Article |
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Year |
1993 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
13 |
Issue |
4 |
Pages |
281-286 |
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Keywords |
carbon fixation; metabolites; biomass; Nitzschia curta; Chaetoceros; Psw; Weddell Sea |
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Abstract |
Distribution of photoassimilated carbon into major metabolite classes differed between two Antarctic diatom species, Nitzschia curta and a small unicellular Chaetoceros sp.. Time course uptake studies (over 54 h) revealed that¹?C allocation appeared to be equilibrated after approximately 8 h at light saturated photosynthesis. During short term dark periods (6 h), polysaccharides as well as low-molecular-weight compounds were catabolised to sustain protein synthesis in the dark, whilst lipid reserves were not mobilised for this process. Experiments with these two species were conducted at 0 and -1.5 degree C, although no difference in the distribution of radiolabel was measured between the two temperatures. It is hypothesised that under near-optimal conditions fast growing species are characterised by a high carbon turnover associated with a rapid flow of newly assimilated carbon into polymeric compound classes. On the other hand, slower growing species (such as N. curta) may store a significant amount of surplus carbon in the low-molecular-weight metabolite fraction. Species specific preferences were observed when comparing the accumulation of radiolabel into the lipid pools. |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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ISSN |
0722-4060 |
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Notes |
Bibliogr.: 48 ref.; Marine |
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no |
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Call Number |
refbase @ admin @ Thomas+Gleitz1993 |
Serial |
760 |
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