| |
Records |
Links |
|
Author |
Mock, T.; Dieckmann, G.S.; Haas, C.; Krell, A.; Tison, J.-L.; Belem, A.L.; Papadimitriou, S.; Thomas, D.N. |
|
| |
Title |
Micro-optodes in sea ice: a new approach to investigate oxygen dynamics during sea ice formation |
Type |
Journal Article |
| |
Year |
2002 |
Publication |
Aquatic Microbial Ecology |
Abbreviated Journal |
Aquat Microb Ecol |
|
| |
Volume |
29 |
Issue |
3 |
Pages |
297-306 |
|
| |
Keywords |
Fragilariopsis cylindrus; Oxygen; Methods; Micro-optodes; Sea ice; Biogeochemistry; Diatoms; Algae; Chlorophyll; Photosynthesis; Salinity effects; Sea water; Marine ecosystems; Chlorophylls; Dissolved oxygen; Gases; Epontic environment; Electrodes; Sensors; Brines; Ice-water interface; Ice formation; Bacillariophyceae |
|
| |
Abstract  |
Oxygen micro-optodes were used to measure oxygen dynamics directly within the microstructure of sea ice by freezing the sensors into the ice during its formation. The experiment was conducted in a 4 m³ mesocosm filled with artificial seawater and inoculated with a unialgal culture of the common Antarctic ice diatom Fragilariopsis cylindrus (Bacillariophyceae) to a final chlorophyll a (chl a) concentration of 11 µg 1?¹. Ice growth was initiated 7 d after inoculation by reducing the air temperature to -10 plus or minus 2 degree C and terminated 17 d later. The final ice thickness was 27 cm. One optode was frozen into grease ice and 2 others into the skeletal layer of the growing ice sheet. Increasing oxygen concentrations during ice crystal formation at the water surface and the ice-water interface revealed a strong inclusion of oxygen, which was either physically trapped and/or the result of photosynthesising diatoms. The major portion of oxygen was present as gas bubbles due to super-saturation as a result of increasing salinity and oxygen production by diatoms. An increase in salinity due to a concurrent decrease in ice temperatures during subsequent sea ice development reduced the maximum concentration of dissolved oxygen within brine. Thus, dissolved oxygen concentrations decreased over time, whereas gaseous oxygen was released to the atmosphere and seawater. The sensors are a significant advance on more conventional microelectrodes, because the recordings can be temperature and salinity compensated in order to obtain precise measurements of oxygen dynamics with regard to total (dissolved and gaseous) and dissolved oxygen in sea ice. Optodes do not consume oxygen during measuremnet over a long period under extreme conditions, which is another advantage for long-term deployment in the field. |
|
| |
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 |
0948-3055 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
Marine |
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Mock++2002 |
Serial |
749 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Thomas, D.N. |
|
| |
Title |
Frozen Oceans – The floating world of pack ice |
Type |
Book Whole |
| |
Year |
2004 |
Publication |
|
Abbreviated Journal |
|
|
| |
Volume |
|
Issue |
|
Pages |
|
|
| |
Keywords |
|
|
| |
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. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
Natural History Museum |
Place of Publication |
London |
Editor |
Coyne, C. |
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
|
ISBN |
0-565-09188-3 |
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Thomas2004 |
Serial |
756 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Weykam, G.; Thomas, D.N.; Wiencke, C. |
|
| |
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 |
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 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Thomas, D.N. |
|
| |
Title |
Photosynthetic microbes in freezing deserts |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Trends in Microbiology |
Abbreviated Journal |
Trends Microbiol |
|
| |
Volume |
13 |
Issue |
3 |
Pages |
87-88 |
|
| |
Keywords |
|
|
| |
Abstract |
Polar deserts are not devoid of life despite the extreme low temperature and scarcity of water. Recently, patterned stone fields – caused by periglacial activity – have been surveyed in the Arctic and Antarctic. It was found that the productivity of the cyanobacteria and algae (hypoliths) that colonise the underside of the stones is strongly related to the pattern of the stones. The hypolith assemblages were in some cases as productive as lichens, bryophytes and plants that resided nearby. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
Elsevier Science B.V. |
Place of Publication |
Amsterdam |
Editor |
|
|
| |
Language |
English |
Summary Language |
English |
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0966-842X |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Thomas2005 |
Serial |
755 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Underwood, G.J.C.; Aslam, S.N.; Michel, C.; Niemi, A.; Norman, L.; Meiners, K.M.; Laybourn-Parry, J.; Paterson, H.; Thomas, D.N. |
|
| |
Title |
Broad-scale predictability of carbohydrates and exopolymers in Antarctic and Arctic sea ice |
Type |
Journal Article |
| |
Year |
2013 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc Natl Acad Sci U S A |
|
| |
Volume |
110 |
Issue |
39 |
Pages |
15734-15739 |
|
| |
Keywords |
Antarctic Regions; Arctic Regions; Biopolymers/*analysis; Carbohydrates/*analysis; Ice Cover/*chemistry; Models, Chemical; Molecular Weight; Solubility; algae; biogeochemistry; global relationships; microbial |
|
| |
Abstract |
Sea ice can contain high concentrations of dissolved organic carbon (DOC), much of which is carbohydrate-rich extracellular polymeric substances (EPS) produced by microalgae and bacteria inhabiting the ice. Here we report the concentrations of dissolved carbohydrates (dCHO) and dissolved EPS (dEPS) in relation to algal standing stock [estimated by chlorophyll (Chl) a concentrations] in sea ice from six locations in the Southern and Arctic Oceans. Concentrations varied substantially within and between sampling sites, reflecting local ice conditions and biological content. However, combining all data revealed robust statistical relationships between dCHO concentrations and the concentrations of different dEPS fractions, Chl a, and DOC. These relationships were true for whole ice cores, bottom ice (biomass rich) sections, and colder surface ice. The distribution of dEPS was strongly correlated to algal biomass, with the highest concentrations of both dEPS and non-EPS carbohydrates in the bottom horizons of the ice. Complex EPS was more prevalent in colder surface sea ice horizons. Predictive models (validated against independent data) were derived to enable the estimation of dCHO concentrations from data on ice thickness, salinity, and vertical position in core. When Chl a data were included a higher level of prediction was obtained. The consistent patterns reflected in these relationships provide a strong basis for including estimates of regional and seasonal carbohydrate and dEPS carbon budgets in coupled physical-biogeochemical models, across different types of sea ice from both polar regions. |
|
| |
Address |
School of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, United Kingdom |
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
National Academy of Sciences |
Place of Publication |
Washington, DC |
Editor |
|
|
| |
Language |
English |
Summary Language |
English |
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0027-8424 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
PMID:24019487; PMCID:PMC3785782 |
Approved |
no |
|
| |
Call Number |
refbase @ user @ |
Serial |
17491 |
|
| Permanent link to this record |
