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Author |
Krell, A.; Schnack-Schiel, S.B.; Thomas, D.N.; Kattner, G.; Zipan, W.; Dieckmann, G.S. |
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Title  |
Phytoplankton dynamics in relation to hydrography, nutrients and zooplankton at the onset of sea ice formation in the eastern Weddell Sea (Antarctica) |
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Journal Article |
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Year |
2005 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
28 |
Issue |
9 |
Pages |
700-713 |
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Keywords |
Weddell Sea; Asf; Hydrography; Phytoplankton; Seasonal change; Community composition; Primary production; Zooplankton |
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Abstract |
The quantitative and qualitative distribution of phytoplankton was investigated along five North–South transects in the eastern Weddell Sea during the transition from late autumn to winter. Relationships with the regional hydrography, progressing sea ice coverage, nutrient distribution and zooplankton are discussed and compared with data from other seasons. To the north of the Antarctic Slope Front (ASF) a remnant temperature minimum layer was found above the primary pycnocline throughout summer. Surface waters had not entirely acquired typical winter characteristics. While temperature was already in the winter range, this was not the case for salinity. Highest biomass of phytoplankton, with the exception of the first transect, was found in the region adjoining the ASF to the north. Absolute chlorophyll a (Chl a) concentrations dropped from 0.35 to 0.19 µg/1. Nutrient pools exhibited a replenishing tendency. Ammonium concentrations were high (0.75–2 µmol/1), indicating extensive heterotrophic activity. The phytoplankton in the ASF region was dominated by nanoflagellates, particularly Phaeocystis spp.. North of the ASF the abundance of diatoms increased, with Fragilariopsis spp., F. cylindrus and Thalassiosira spp. dominating. Community structure varied both due to hydrographical conditions and the advancing ice edge. The phytoplankton assemblage formed during late autumn were very similar to the ones found in early spring. A POC/PON ratio close to Redfield, decreasing POC concentration and a high phaeophytin/ Chl a ratio, as well as a high abundance of mesozooplankton indicated that a strong grazing pressure was exerted on the phytoplankton community. A comparison between primary production (PP) in the water column and the sea ice showed a shift of the major portion of PP into the ice during the period of investigation. |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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0722-4060 |
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Isi:000231421200006 |
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Call Number |
refbase @ admin @ Krell++2005 |
Serial |
747 |
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Author |
Hulatt, C.J.; Thomas, D.N. |
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Title |
Productivity, carbon dioxide uptake and net energy return of microalgal bubble column photobioreactors |
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Journal Article |
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Year |
2011 |
Publication |
Bioresource Technology |
Abbreviated Journal |
Bioresour Technol |
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Volume |
102 |
Issue |
10 |
Pages |
5775-5787 |
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Keywords |
*Bioreactors; Carbon Dioxide/*metabolism; Energy Metabolism; Equipment Design; Microalgae/growth & development/*metabolism; Photochemistry |
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Abstract |
This work examined the energy return of Chlorella vulgaris and Dunaliella tertiolecta cultivated in a gas-sparged photobioreactor design where the power input for sparging was manipulated (10, 20, and 50 Wm(-3)). Dry weight, organic carbon and heating values of the biomass were measured, plus a suite of variables including Fv/Fm and dissolved oxygen. A model for predicting the higher heating value of microalgal biomass was developed and used to measure the energetic performance of batch cultivations. High power inputs enhanced maximum biomass yields, but did not improve the energy return. Cultivation in 10 Wm(-3) showed up to a 39% higher cumulative net energy return than 50 Wm(-3), and increased the cumulative net energy ratio up to fourfold. The highest net energy ratio for power input was 19.3 (D. tertiolecta, 12% CO(2), 10 Wm(-3)). These systems may be a sustainable method of biomass production, but their effectiveness is sensitive to operational parameters. |
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Address |
School of Ocean Sciences, College of Natural Sciences, Bangor University, Askew Street, Menai Bridge, Isle of Anglesey LL59 5AB, UK. osp418@bangor.ac.uk |
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English |
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0960-8524 |
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PMID:21376576 |
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Call Number |
refbase @ user @ |
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12983 |
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Author |
Mock, T.; Thomas, D.N. |
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Title |
Recent advances in sea-ice microbiology |
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Journal Article |
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Year |
2005 |
Publication |
Environmental Microbiology |
Abbreviated Journal |
Environ Microbiol |
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Volume |
7 |
Issue |
5 |
Pages |
605-619 |
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Abstract |
Over the past 50 years there has been much effort invested in the investigation of the ecology of sea ice. Sea ice is an ephemeral feature of the Arctic and Southern Oceans and smaller water bodies such as the Baltic and Caspian Seas. The semisolid ice matrix provides a range of habitats in which a diverse range of microbial organisms thrive. In the past 5 years there has been considerable steps forward in sea-ice research, in particular regarding the analysis of sea-ice microstructure and the investigation of the diversity and adaptation of microbial communities. These studies include: (i) controlled simulated and in situ studies on a micrometer scale to unravel the dynamic of the microhabitat with consequences for the organisms; (ii) the introduction of molecular approaches to uncover the diversity of uncultured still unknown microorganisms; and (iii) studies into the molecular adaptation of selected model organisms to the extreme environment. This minireview presents some of the most recent findings from sea-ice studies within the framework of these aims. |
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Blackwell Publishing, Inc. |
Place of Publication |
Oxford |
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ISSN |
1462-2912 |
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Notes |
Minireview |
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no |
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Call Number |
refbase @ admin @ Mock+Thomas2005 |
Serial |
750 |
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Author |
Granskog, M.A.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Ehn, J.; Sonninen, E. |
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Title |
Scales of horizontal patchiness in chlorophyll a, chemical and physical properties of landfast sea ice in the Gulf of Finland (Baltic Sea) |
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Journal Article |
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Year |
2005 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
28 |
Issue |
4 |
Pages |
276-283 |
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Horizontal variation of first-year landfast sea ice properties was studied in the Gulf of Finland, the Baltic Sea. Several scales of variation were considered; a number of arrays with core spacings of 0.2, 2 and 20 m were sampled at different stages of the ice season for small-scale patchiness. Spacing between these arrays was from hundreds of meters to kilometers to study mesoscale variability, and once an onshore–offshore 40-km transect was sampled to study regional scale variability. Measured variables included salinity, stable oxygen isotopes (δ18O), chlorophyll a (chl-a), nutrients and dissolved organic carbon. On a large scale, a combination of variations in the under-ice water salinity (ice porosity), nutrient supply and the stage of ice development control the build-up of ice algal biomass. At scales of hundreds of meters to kilometers, there was significant variability in several parameters (salinity, chl-a, snow depth and ice thickness). Analyses of the data from the arrays did not show evidence of significant patchiness at scales <20 m for algal biomass. The results imply that the sampling effort in Baltic Sea ice studies should be concentrated on scales of hundreds of meters to kilometers. Using the variations observed in the study area, the estimate for depth-integrated algal biomass in landfast sea ice in the Gulf of Finland (March 2003) is 5.5±4.4 mg chl-a m-2. |
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Address |
Granskog: Arctic Centre, University of Lapland, P.O. Box 122, 96101 Rovaniemi, Finland |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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English |
Summary Language |
English |
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0722-4060 |
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Baltic Sea; Gulf of Finland |
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no |
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Call Number |
refbase @ admin @ Granskog++2005 |
Serial |
739 |
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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 |
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Book Whole |
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Year |
2003 |
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402 pp |
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Keywords |
Sea Ice |
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Abstract |
Sea ice, which covers up to 7% of the planet's surface, is a major component of the world's oceans, partly driving ocean circulation and global climate patterns. It provides a habitat for a rich diversity of marine organisms, and is a valuable source of information in studies of global climate change and the evolution of present day life forms. Increasingly, sea ice is being used as a proxy for extraterrestrial ice covered systems.
Sea Ice provides a comprehensive review of our current available knowledge of polar pack ice, the study of which is severely constrained by the logistic difficulties of working in such harsh and remote regions of the earth. The book's editors, Drs Thomas and Dieckmann have drawn together an impressive group of international contributing authors, providing a well-edited and integrated volume, which will stand for many years as the standard work on the subject. Contents of the book include details of the growth, microstructure and properties of sea ice, large-scale variations in thickness and characteristics, its primary production, micro-and macrobiology, sea ice as a habitat for birds and mammals, sea ice biogeochemistry, particulate flux, and the distribution and significance of palaeo sea ice. |
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Address |
Thomas: School of Ocean Sciences, University of Wales, Bangor, UK; Dieckmann: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany |
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Blackwell Science Ltd |
Place of Publication |
Oxford |
Editor |
Thomas, D.N.; Dieckmann, G.S. |
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Language |
English |
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ISBN |
0-632-05808-0 |
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Notes |
40 Illustrations |
Approved |
yes |
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Call Number |
refbase @ user @ library-34/436/1 |
Serial |
7 |
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