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Author Herborg, L.-M.; Thomas, D.N.; Kennedy, H.; Haas, C.; Dieckmann, G.S. url  openurl
  Title Dissolved carbohydrates in Antarctic sea ice Type Journal Article
  Year 2001 Publication Antarctic Science Abbreviated Journal Antarct Sci  
  Volume 13 Issue 2 Pages 119-125  
  Keywords Doc; Mcho; Pcho; sea ice; bacteria; carbon cycling; diatoms; dissolved organic carbon; monocarbohydrates; polycarbohydrates  
  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.  
  Address  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number refbase @ admin @ Herborg++2001 Serial 743  
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Author Kattner, G.; Thomas, D.N.; Haas, C.; Kennedy, H.; Dieckmann, G.S. url  openurl
  Title Surface ice and gap layers in Antarctic sea ice: highly productive habitats Type Journal Article
  Year 2004 Publication Marine Ecology Progress Series Abbreviated Journal Mar Ecol Prog Ser  
  Volume 277 Issue Pages 1-12  
  Keywords Antarctic sea ice; Gap layers; Biogeochemistry; Particulate organic matter; Dissolved organic matter; Chlorophyll a; Nutrients  
  Abstract Biogeochemical investigations of the upper layers of sea ice were made on layered summer ice floes collected from the Weddell Sea, Antarctica, from mid-February to March 1997. The surface layers had a clearly defined bottom layer immediately overlying a gap filled with seawater. Generally the gap covered rotten sea ice below. Using differences in algal biomass, mostly in the bottom layer of the surface ice overlying the gap, the floes were classified as low, moderate or high biomass. In addition, a floe with a re-frozen gap layer was studied. In the floes with the highest biomass, particulate organic carbon (POC) and nitrogen (PON) reached concentrations of up to 6000 µMC and 600 µMN in the bottom layer. In the upper part of the surface ice layer and the gap water, particulate and dissolved organic matter concentrations (POM, DOM) were clearly lower. High concentrations of POM were generally accompanied by high values of DOM although POM values generally exceeded DOM. All C and N contents of organic matter were significantly correlated. In gap waters, POM was low but still clearly higher than in the surrounding seawater, whereas DOM was in the range of seawater concentrations. Most POC/PON and C/chlorophyll a ratios pointed to an actively growing algae community, whereas the higher and more variable DOC/DON ratios reflected the various sources influencing DOM composition. Nitrate and silicate closely followed the signature of salinity, reaching in some gap water samples values similar to seawater concentrations. In some samples, in particular from the upper part of the surface ice layer, nitrate was totally exhausted. The distribution of the regenerated nutrients ammonium and phosphate was totally different from that of nitrate and silicate, reaching values of up to 15.9 and 9.08 µM, respectively. The bottom ice layer of the floe with the re-frozen gap layer had a high biomass similar to that of the high-biomass ice floe. DOC concentrations were lower, and DON maximum was not clearly linked with DOC maximum, but instead was associated with high ammonium and phosphate concentrations. The significant correlations between POM and DOM as well as between nitrate and silicate and between the regenerated nutrients ammonium and phosphate indicate that the gap-layer floes are semi-enclosed, highly productive habitats that still maintain high biomass during freezing. They are ubiquitous in the Antarctic pack-ice zone and important features that support high algae standing stocks.  
  Address  
  Corporate Author Thesis  
  Publisher Inter-Research Place of Publication Oldendorf/Luhe Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0171-8630 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number refbase @ admin @ Kattner++2004 Serial 745  
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Author Kennedy, H.; Thomas, D.N.; Kattner, G.; Haas, C.; Dieckmann, G.S. url  openurl
  Title Particulate organic matter in Antarctic summer sea ice: concentration and stable isotopic composition Type Journal Article
  Year 2002 Publication Marine Ecology Progress Series Abbreviated Journal Mar Ecol Prog Ser  
  Volume 238 Issue Pages 1-13  
  Keywords Pom; Anarctic sea ice; ice microalgae; carbon isotopic composition  
  Abstract The chemical and isotopic data from sea ice collected over a wide area of the Weddell Sea, Antarctica, during the austral summer/early autumn illustrate the range of environmental conditions under which ice algae grow. A range of ice types and features were sampled including intact and layered ice floes and surface ponds. Sea ice communities were found in all these environments but the highest biomasses were found either at the base of ice floes, or in the interior of layered floes with quasi-continuous horizontal gaps at or shortly below the water level. In the layered floes, particulate organic carbon (POC) measured in the ice layer immediately overlying the gap water (280 to 6014 µmol dm?³) was in excess of what would be predicted if algal growth had occurred in a closed environment. The chemical composition of the gap water was strongly affected by biological activity in the overlying ice, which acts as a physical support for the algae retained within its matrix. The lowest range of POC (27 to 739 µmol dm?³) conformed to predictions of algal growth in a closed system and samples were collected from the interior of ice floes where there was essentially no potential for nutrient exchange. The surface ponds displayed nitrate (NO³?) exhaustion and total dissolved inorganic carbon (?CO?) reductions consistent with nutrient limited algal growth. The stable carbon isotopic composition of the particulate organic matter (POM) across all habitat types sampled (?¹³CPOC -10.0 to -27.3?) displayed a wide range but was much less variable than the range of POC concentrations might have implied. The assumption that the highest biomass of algae in sea ice will result in the most positive ?¹³CPOC values cannot be generally applied. The isotopic composition of dissolved inorganic carbon (?¹³C?CO?) in gap waters and surface ponds varied from 0.15 to 3.0? and was shown to be commensurate with the changes predicted from NO³? deficits caused by algal growth.  
  Address  
  Corporate Author Thesis  
  Publisher Inter-Research Place of Publication Oldendorf/Luhe Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0171-8630 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number refbase @ admin @ Kennedy++2002 Serial 746  
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Author Schnack-Schiel, S.B.; Dieckmann, G.S.; Gradinger, R.; Melnikov, I.A.; Spindler, M.; Thomas, D.N. url  openurl
  Title Meiofauna in sea ice of the Weddell Sea (Antarctica) Type Journal Article
  Year 2001 Publication Polar Biology Abbreviated Journal Polar Biol  
  Volume 24 Issue 10 Pages 724-728  
  Keywords Sea ice biota; Foraminifera; Antarctic sea ice; Sea ice; Meiofauna; Community composition; Meiobenthos; Antarctic zone; Juveniles; Psw; Weddell Sea; Antarctica  
  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.  
  Address  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Heidelberg Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0722-4060 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number refbase @ admin @ Schnack-Schiel++2001 Serial 751  
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Author Schnack-Schiel, S.B.; Thomas, D.N.; Haas, C.; Dieckmann, G.S.; Alheit, R. url  openurl
  Title The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica Type Journal Article
  Year 2001 Publication Antarctic Science Abbreviated Journal Antarctic Sci  
  Volume 13 Issue 2 Pages 150-157  
  Keywords copepods; Drescheriella glacialis; sea ice; seasonality; Stephos longipes  
  Abstract In January to March 1997, a RV Polarstern cruise that transected the Weddell Sea resulted in samples being taken in thick pack ice in the south-eastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled over a wide geographic area during late summer/early autumn. Common features of the first warm period was the occurrence of surface ponds, and that many floes had quasi-continuous horizontal gaps, underlying a layer of ice and metamorphic snow. With the onset of cold air temperatures in late February the gaps rapidly refroze. The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water, while in the gap water copepodids, mainly stages CI-CIII in summer and CII-CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats and was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gapwater, but predominated in the refrozen gaps.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0954-1020 ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number refbase @ admin @ Schnack-Schiel++2001_2 Serial 753  
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