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Author Gleitz, M.; Rutgers v d Loeff, M.; Thomas, D.N.; Dieckmann, G.S.; Millero, F.J. url  openurl
  Title Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine Type Journal Article
  Year (up) 1995 Publication Marine Chemistry Abbreviated Journal Mar Chem  
  Volume 51 Issue 2 Pages 81-91  
  Keywords dissolved oxygen; inorganic compounds; summer; winter; nutrients (mineral); Antarctic zone; sea ice; brines; carbon; chemical composition; Psw; Weddell Sea; polar zones; polar regions; nutrients  
  Abstract During summer (January 1991) and winter (April 1992) cruises to the southern Weddell Sea (Antarctica), brine samples were collected from first year sea ice and analysed for salinity, temperature, dissolved oxygen and major nutrient concentrations. Additionally, the carbonate system was determined from measurements of pH and total alkalinity. During winter, brine chemical composition was largely determined by seawater concentration in the course of freezing. Brine temperatures ranged from -1.9 to -6.7 °C. Precipitation of calcium carbonate was not observed at the corresponding salinity range of 34 to 108. Removal of carbon from the total inorganic carbon pool (up to 500 µmol Ct kg?¹) was related to reduced nutrient concentrations, indicating the presence of photosynthetically active ice algal assemblages in the winter sea ice. However, nutrient and inorganic carbon concentrations did generally not reach growth limiting levels for phytoplankton. The combined effect of photosynthesis and physical concentration resulted in O? concentrations of up to 650 µmol kg?¹. During summer, brine salinities ranged from 21 to 41 with most values >28, showing that the net effect of freezing and melting on brine chemical composition was generally slight. Opposite to the winter situation, brine chemical composition was strongly influenced by biological activity. Photosynthetic carbon assimilation resulted in a Ct depletion of up to 1200 µmol kg?¹, which was associated with CO? (aq) exhaustion and O? concentrations as high as 933 µmol kg?¹. The concurrent depletion of major nutrients generally corresponded to uptake ratios predicted from phytoplankton biochemical composition. Primary productivity in summer sea ice is apparently sustained until inorganic resources are fully exhausted, resulting in brine chemical compositions that differ profoundly from those of surface waters. This may have important implications for pathways of ice algal carbon acquisition, carbon isotope fractionation as well as for species distribution in the open water phytoplankton.  
  Address  
  Corporate Author Thesis  
  Publisher Elsevier Science B.V. Place of Publication Amsterdam Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0304-4203 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number refbase @ admin @ Gleitz++1995 Serial 733  
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Author Thomas, D.N.; Lara, R.J.; Eicken, H.; Kattner, G.; Skoog, A. url  openurl
  Title Dissolved organic matter in Arctic multi-year sea ice during winter: major components and relationship to ice characteristics Type Journal Article
  Year (up) 1995 Publication Polar Biology Abbreviated Journal Polar Biol  
  Volume 15 Issue 6 Pages 447-483  
  Keywords sea ice; Arctic; Dom  
  Abstract Ice cores were collected between 10.03.93 and 15.03.93 along a 200 m profile on a large ice floe in Fram Strait. The ice was typical of Arctic multi-year ice, having a mean thickness along the profile of 2.56 ±0.53 m. It consisted mostly of columnar ice (83%) grown through congelation of seawater at the ice bottom, and the salinity profiles were characterized by a linear increase from 0 psu at the top to values ranging between 3 and 5 psu at depth. Distributions of dissolved organic carbon (DOC) and nitrogen (DON) and major nutrients were compared with ice texture, salinity and chlorophyll a. DOC, DON, dissolved inorganic nitrogen (DIN), NH?? and NO?? were present in concentrations in excess of that predicted by dilution curves derived from Arctic surface water values. Only NO?? was depleted, although not exhausted. High DOC and DON values in conjunction with high NH?? levels indicated that a significant proportion of the dissolved organic matter (DOM) was a result of decomposition/grazing of ice algae and/or detritus. The combination of high NH?? and NO?? points to regeneration of nitrogen compounds. There was no significant correlation between DOC and Chl a in contrast to DON, which had a positively significant correlation with both salinity and Chl a, and the distribution of DOM in the cores might best be described as a combination of both physical and biological processes. There was no correlation between DOC and DON suggesting an uncoupling of DOC and DON dynamics in multi year ice.  
  Address  
  Corporate Author Thesis  
  Publisher Springer-Verlag 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 D Approved no  
  Call Number refbase @ admin @ Thomas++1995 Serial 763  
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Author Gomez, I.; Wiencke, C.; Thomas, D.N. url  openurl
  Title Variations in photosynthetic characteristics of the Antarctic marine brown alga Ascoseira mirabilis in relation to thallus age and size Type Journal Article
  Year (up) 1996 Publication European Journal of Phycology Abbreviated Journal Eur J Phycol  
  Volume 31 Issue 2 Pages 167-172  
  Keywords photosynthesis: thallus: carbon fixation; growth curves; algae; age; Thalli; marine flora; Ascoseira mirabilis; Antarctica  
  Abstract Growth, photosynthesis, dark respiration, chlorophyll a (Chl a) content and dry weight were measured in 2- and 3-year-old plants of Ascoseira mirabilis (Ascoseirales), cultivated in the laboratory under changing daylengths which matched the seasonal variations in the Antarctic. Determinations were made in four thallus regions. Growth of A. mirabilis was seasonal, with higher rates in spring. Parameters such as net photosynthesis (P sub(max)), photosynthetic efficiency ( alpha ), both measured on a fresh weight (FW) basis, and dry weight content, showed significant age- and size-dependent variations. In contrast, no variations were observed in dark respiration, initial light-saturating point of photosynthesis (I sub(k)) and Chl a contents. P sub(max) had maximum values close to 16.5 mu mol O sub(2)/g super(1) FW/h in 2-year-old plants, whereas in 3-year-old plants maximum values of 8 mu mol O sub(2)/g FW/h were determined. The alpha -values reached maximum rates of 1.4 and 0.6 mu mol O sub(2)/g FW/h/( mu mol photons/m super(2)/s) in 2- and 3-year-old plants, respectively. Light compensation point (I sub(c)), dry weight ratios and Chl a contents varied significantly along the length of the blade. Maximum dry:fresh weight ratios were observed in the basal region, with values close to 18%. Distal regions of the 3-year-old plants had significantly higher dry weight content than 2-year-old plants (17.5% and 13%, respectively). Chl a concentrations increased towards the middle regions of the thallus to values close to 0.35 mg Chl a/g FW. The results indicate that some morpho-functional processes in A. mirabilis, especially net photosynthesis and photosynthetic efficiency, are governed by age of the plant, thereby reflecting differences in biomass allocation and size. Our data also confirm the previously demonstrated relationship between growth and seasonal physiological activity that allows A. mirabilis to survive under the low light conditions prevailing in the Antarctic.  
  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 0967-0262 ISBN Medium  
  Area Expedition Conference  
  Notes growth curves; size; Thalli; marine flora; thallus Approved no  
  Call Number refbase @ admin @ Gomez++1996 Serial 737  
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Author Weykam, G.; Thomas, D.N.; Wiencke, C. openurl 
  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
  Year (up) 1997 Publication Phycologia Abbreviated Journal Phycologia  
  Volume 36 Issue 5 Pages 395-405  
  Keywords Winter; Polar waters; Photosynthesis; Antarctic zone; Ice cover; Seaweeds; Light effects; Plant physiology; Growth; Palmariales; Gigartinales; Iridaea cordata; Palmaria decipiens; Ps; Antarctica  
  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.  
  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 0031-8884 ISBN Medium  
  Area Expedition Conference  
  Notes Marine Approved no  
  Call Number refbase @ admin @ Weykam++1997 Serial 767  
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Author Dieckmann, G.S.; Eicken, H.; Haas, C.; Garrison, D.L.; Gleitz, M.; Lange, M.; Nöthig, E.-M.; Spindler, M.; Sullivan, C.W.; Thomas, D.N.; Weissenberger, J. isbn  openurl
  Title A compilation of data on sea ice algal standing crop from the Bellingshausen, Amundsen and Weddell Seas from 1983 to 1994 Type Book Chapter
  Year (up) 1998 Publication Antarctic sea ice: Biological processes, interactions and variability Abbreviated Journal  
  Volume Issue Pages 85-92  
  Keywords Algae; Biomass; Ecology; Ice composition; Antarctica; Bellingshausen Sea; Amundsen Sea; Weddell Sea  
  Abstract Algal standing stock as chlorophyll a in sea ice was compiled from 448 cores collected during 13 U.S. and German research cruises to Antarctica between 1983 and 1994. The data have a high variability and show no clear relationships with other parameters such as core length. However, seasonal variations in standing stock are discernable. The authors recommend that due to the high variability in the data and inconsistency of sampling methods, the data be used with caution, since they do not represent all sea ice habitats. We provide the data due to the current need for such information for the parameterization of models.  
  Address  
  Corporate Author Thesis  
  Publisher American Geophysical Union Place of Publication Washington, DC Editor Lizotte, M.P.; Arrigo, K.R.  
  Language Summary Language Original Title  
  Series Editor Series Title Antarctic Research Series Abbreviated Series Title  
  Series Volume 73 Series Issue Edition  
  ISSN ISBN 0-87590-901-9 Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number refbase @ admin @ Dieckmann++1998 Serial 731  
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