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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 |
Type |
Book Chapter |
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Year  |
1998 |
Publication |
Antarctic sea ice: Biological processes, interactions and variability |
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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 |
Series Issue |
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Edition |
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ISSN |
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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 |
Giannelli, V.; Thomas, D.N.; Haas, C.; Kattner, G.; Kennedy, H.; Dieckmann, G.S. |
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Title |
Behaviour of dissolved organic matter and inorganic nutrients during experimental sea-ice formation |
Type |
Journal Article |
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Year |
2001 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
Ann Glaciol |
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Volume |
33 |
Issue |
1 |
Pages |
317-321 |
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Abstract |
It is well established that during sea-ice formation, crystals aggregate into a solid matrix, and dissolved sea-water constituents, including inorganic nutrients, are rejected from the ice matrix. However, the behaviour of dissolved organic matter (DOM) during ice formation and growth has not been studied to date. DOM is the primary energetic substrate for microbial heterotrophic activity in sea water and sea ice, and therefore it is at the base of the trophic fluxes within the microbial food web. The aim of our study was to compare the behaviour of DOM and inorganic nutrients during formation and growth of sea ice. Experiments were conducted in a large indoor ice-tank facility (Hamburg Ship Model Basin, Germany) at -15°C. Three 1 m³ tanks, to which synthetic sea water, nutrients and dissolved organic compounds (diatom-extracted DOM) had been added, were sampled over a period of 5 days during sea-ice formation. Samples were collected throughout the experiment from water underlying the ice, and at the end from the ice as well. Brine was obtained from the ice by centrifuging ice cores. Inorganic nutrients (nitrate and phosphate) were substantially enriched in brine in comparison to water and ice phases, consistent with the processes of ice formation and brine rejection. Dissolved organic carbon (DOC) was also enriched in brine but was more variable and enriched in comparison to a dilution line. No difference in bacteria numbers was observed between water, ice and brine. No bacteria growth was measured, and this therefore had no influence on the measurable DOC levels. We conclude that the incorporation of dissolved organic compounds in newly forming ice is conservative. However, since the proportions of DOC in the brine were partially higher than those of the inorganic nutrients, concentrating effects of DOC in brine might be different compared to salts. |
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International Glaciological Society |
Place of Publication |
Cambridge |
Editor |
Intl. Symp. on Sea Ice and its Interaction with the Ocean, A. and B., Fairbanks, Alaska(USA), 19-23 Jun 2000, |
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Edition |
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ISSN |
0260-3055 |
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Call Number |
refbase @ admin @ Giannelli++2001 |
Serial |
732 |
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Author |
Haas, C.; Thomas, D.N.; Bareiss, J. |
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Title |
Surface properties and processes of perennial Antarctic sea ice in summer |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of Glaciology |
Abbreviated Journal |
J Glaciol |
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Volume |
47 |
Issue |
159 |
Pages |
613-625 |
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Keywords |
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Abstract |
Ice-core and snow data from the Amundsen, Bellingshausen and Weddell Seas, Antarctica, show that the formation of superimposed ice and the development of seawater-filled gap layers with high algal standing stocks is typical of the perennial sea ice in summer. The coarse-grained and dense snow had salinities mostly below 0.1ppt. A layer of fresh superimposed ice had a mean thickness of 0.04-0.12 m. Gap layers 0.04-0.08 m thick extended downwards from 0.02 to 0.14 m below the water level. These gaps were populated by diatom standing stocks up to 439 ?g L?¹ chlorophyll a. We propose a comprehensive heuristic model of summer processes, where warming and the reversal of temperature gradients cause major transformations in snow and ice properties. The warming also causes the reopening of incompletely frozen slush layers caused by flood-freeze cycles during winter. Alternatively, superimposed ice forms at the cold interface between snow and slush in the case of flooding with negative freeboard. Combined, these explain the initial formation of gap layers by abiotic means alone. The upward growth of superimposed ice above the water level competes with a steady submergence of floes due to bottom and internal melting and accumulation of snow. |
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Publisher |
International Glaciological Society |
Place of Publication |
Cambridge |
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ISSN |
0022-1430 |
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Notes |
IPØ/Tvärrminne |
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no |
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Call Number |
refbase @ admin @ Haas++2001 |
Serial |
742 |
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Author |
Herborg, L.-M.; Thomas, D.N.; Kennedy, H.; Haas, C.; Dieckmann, G.S. |
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Title |
Dissolved carbohydrates in Antarctic sea ice |
Type |
Journal Article |
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Year |
2001 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarct Sci |
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Volume |
13 |
Issue |
2 |
Pages |
119-125 |
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Keywords |
Doc; Mcho; Pcho; sea ice; bacteria; carbon cycling; diatoms; dissolved organic carbon; monocarbohydrates; polycarbohydrates |
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Abstract |
Concentrations of dissolved monocarbohydrates (MCHO) and polycarbohydrates (PCHO) were analysed in a variety of ice habitats from summer Weddell Sea sea ice (surface ponds, ice cores, gap layers and platelet ice). The dissolved organic carbon (DOC) pool in these habitats was also measured and the contribution of carbohydrate to this pool was assessed. The DOC concentrations within all sea ice habitats were high compared to surface seawater concentrations with values up to 958µMC being measured. Total carbohydrates (TCHO) were highest in the ice cores and platelet ice samples, up to 3 1% of the DOC pool, a reflection of the high algal biomass in these two habitat classes. TCHO in the other habitats ranged between 10% and 29% of DOC. The ratios of MCHO to PCHO varied considerably between the ice habitats: in surface ponds and ice cores MCHO was 70% of the TCHO pool, whereas in gap layers and platelet ice there were lower PCHO concentrations resulting in MCHO being 88% of TCHO. |
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no |
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Call Number |
refbase @ admin @ Herborg++2001 |
Serial |
743 |
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Author |
Schnack-Schiel, S.B.; Dieckmann, G.S.; Gradinger, R.; Melnikov, I.A.; Spindler, M.; Thomas, D.N. |
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Title |
Meiofauna in sea ice of the Weddell Sea (Antarctica) |
Type |
Journal Article |
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Year |
2001 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
24 |
Issue |
10 |
Pages |
724-728 |
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Keywords |
Sea ice biota; Foraminifera; Antarctic sea ice; Sea ice; Meiofauna; Community composition; Meiobenthos; Antarctic zone; Juveniles; Psw; Weddell Sea; Antarctica |
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Abstract |
Sea-ice meiofauna was studied during various cruises to the Weddell Sea. Foraminifers dominate (75%) the sea-ice community in terms of numerical abundance while turbellarians dominate (45%) in terms of biomass. Distribution of organisms is patchy and varies considerably between cruises but also between sampling sites within one cruise. The bulk of the meiofauna is concentrated in the lowest parts of the sea ice, especially during winter and autumn. However, in porous summer sea ice, sympagic organisms also occur in high densities in upper and intermediate layers of sea ice. Proto- and metazoans associated with Antarctic sea ice include organisms actually living in sea ice, as well as those on the underside of floes and in the underlying water. The sea-ice habitat serves as a feeding ground, as well as an important nursery for juveniles, providing energy-rich food resources. The ice also constitutes a shelter from predators. |
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Publisher |
Springer |
Place of Publication |
Heidelberg |
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ISSN |
0722-4060 |
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no |
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Call Number |
refbase @ admin @ Schnack-Schiel++2001 |
Serial |
751 |
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