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Author |
Thomas, D.N.; Lara, R.J.; Haas, C.; Schnack-Schiel, S.B.; Dieckmann, G.S.; Kattner, G.; Nöthig, E.-M.; Mizdalski, E. |
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Title |
Biological soup within decaying summer sea ice in the Amundsen Sea, Antarctica |
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Book Chapter |
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Year |
1998 |
Publication |
Antarctic sea ice: Biological processes, interactions and variability |
Abbreviated Journal |
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Pages |
161-171 |
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Keywords |
Marine biology; Algae; Ice composition; Pack ice; Decomposition; Ecology; Nutrient cycle; Antarctica; Amundsen Sea |
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Abstract |
In late February 1994, during the ANT XI/3 expedition of R/V Polarstern, ice cores from perennial sea ice were sampled in the Amundsen Sea in areas of dense pack ice. The ice was largely rotten, and a conspicuous feature was the occurrence of thick gaps and voids, often filled with a dark brown slush comprised of loose ice chunks and crystals. These interior ice assemblages were at depths between 1.0 and 1.5 m in 3 to 4 m thick ice floes, and had remarkably rich interior ice algal assemblages (<= 377 µg Chl a L?¹) which were in turn a food source for unusually large numbers of foraminifers (<= 1262 individuals L?¹), the calanoid copepod Stephos longipes (<= 163 individuals L?¹) and harpacticoid copepods (<= 168 individuals L?¹). Analysis of inorganic nutrients (nitrate, phosphate, ammonium, nitrite, and silicate) and dissolved organic carbon (DOC) showed that these were sites of high nutrient supply coupled with high rates of nutrient regeneration. |
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Publisher |
American Geophysical Union |
Place of Publication |
Washington, DC |
Editor |
Lizotte, M.P.; Arrigo, K.R. |
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Series Title |
Antarctic Research Series |
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Series Volume |
73 |
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ISBN |
0-87590-901-9 |
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Call Number |
refbase @ admin @ Thomas++1998 |
Serial |
764 |
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Author |
Thomas, D.N.; Mock, T. |
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Title |
Life in frozen veins – coping with the cold |
Type |
Journal Article |
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Year |
2005 |
Publication |
The Biochemist |
Abbreviated Journal |
Biochemist |
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Volume |
27 |
Issue |
1 |
Pages |
12-16 |
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Keywords |
adaptation; Antarctic; Arctic; low temperature; micro-organism; sea ice |
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Abstract |
Every autumn a fundamental transition occurs in the surface waters of Polar Oceans. The surface waters of millions of square kilometres freeze to form an ice layer that varies from a few centimetres through to several metres thick, and which effectively separates the ocean from the atmosphere above. Ice made from seawater is a porous, semi-solid matrix permeated by a labyrinth of brine channels and pores, and within these a diverse microbial assemblage, including viruses, archaea, bacteria, flagellates and unicellular algae can thrive. These assemblages can reach such high abundances that the ice becomes a rich coffee colour. The microbial assemblages are in turn a rich food source for grazing proto- and zooplankton, especially in winter when food in the water column is scarce. |
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Biochemical Society |
Place of Publication |
London |
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no |
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Call Number |
refbase @ admin @ Thomas+Mock2005 |
Serial |
765 |
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Author |
Thomas, D.N.; Papadimitriou, S. |
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Title |
Biogeochemistry of sea ice |
Type |
Book Chapter |
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Year |
2003 |
Publication |
Sea ice – an introduction to its physics, chemistry, biology and geology |
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Volume |
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Issue |
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Pages |
267-302 |
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Blackwell Science Ltd |
Place of Publication |
Oxford |
Editor |
Thomas, D.N.; Dieckmann, G.S. |
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ISBN |
0-632-05808-0 |
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no |
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Call Number |
refbase @ admin @ Thomas+Papadimitriou2003 |
Serial |
766 |
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Author |
Weykam, G.; Thomas, D.N.; Wiencke, C. |
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Title |
Growth and photosynthesis of the Antarctic red algae Palmaria decipiens (Palmariales) and Iridaea cordata (Gigartinales) during and following extended periods of darkness |
Type |
Journal Article |
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Year |
1997 |
Publication |
Phycologia |
Abbreviated Journal |
Phycologia |
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Volume |
36 |
Issue |
5 |
Pages |
395-405 |
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Keywords |
Winter; Polar waters; Photosynthesis; Antarctic zone; Ice cover; Seaweeds; Light effects; Plant physiology; Growth; Palmariales; Gigartinales; Iridaea cordata; Palmaria decipiens; Ps; Antarctica |
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Abstract |
Physiological and developmental responses during and following long-term exposure to darkness were investigated in the Antarctic red algae Palmaria decipiens and Iridaea cordata. Thalli were kept in darkness for a period of 6 mo, simulating winter sea ice cover. Subsequently, they were grown illuminated under seasonally fluctuating Antarctic daylengths. During darkness, P. decipiens, an Antarctic endemic, rapidly lost its ability to photosynthesize although chlorophyll a content remained fairly constant. The amount of floridean starch decreased gradually in the dark, with a sudden drop simultaneous with the development of new blades. After reexposure to light there was a rapid increase in photosynthetic oxygen production, whereas the rate of carbon assimilation increased more slowly, resulting in high apparent photosynthetic quotients. The increase in growth rate showed a close relation to carbon assimilation, suggesting that carbon is utilized first for growth, then for floridean starch accumulation. In contrast to P. decipiens, the photosynthetic rate of the Antarctic cold-temperate I. cordata was still about half of the initial rate after a dark period of 6 mo, i.e. the alga maintained functionality of its photosynthetic apparatus during winter. After reexposure to light there was a continuous increase in specific growth rate due to increasing photosynthetic activity. Iridaea cordata also accumulated floridean starch during summer, although in smaller amounts than P. decipiens. Together with the ability to photosynthesize, starch accumulation facilitates survival during extended dark periods in winter. The early development of blade initials and the rapid increase in photosynthetic capability after illumination may permit P. decipiens to use the period of high water transparency optimally in Antarctic spring. Iridaea cordata seems better able to survive prolonged dark periods in areas with less predictable light conditions. Both physiological patterns are well suited to the highly seasonal light conditions in Antarctica. |
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0031-8884 |
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Notes |
Marine |
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no |
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Call Number |
refbase @ admin @ Weykam++1997 |
Serial |
767 |
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Author |
Thomas, D.N.; Dieckmann, G.S. (eds) |
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Title |
Sea ice – an introduction to its physics, chemistry, biology and geology |
Type |
Book Whole |
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Year |
2003 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Keywords |
zoology; sea ice |
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Abstract |
Sea ice, which covers up to 7% of the planets surface, is a major component of the worlds oceans, partly driving ocean circulation and global climate patterns... |
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Publisher |
Blackwell Science Ltd |
Place of Publication |
Oxford |
Editor |
Thomas, D.N.; Dieckmann, G.S. |
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0-632-05808-0 |
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no |
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Call Number |
refbase @ user @ Thomas+Dieckmann2003 |
Serial |
845 |
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