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Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Granskog, M.A.; Kivi, K. |
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Title |
Biomass, composition and activity of organism assemblages along a salinity gradient in sea ice subjected to river discharge in the Baltic Sea |
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Journal Article |
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Year |
2006 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
30 |
Issue |
2 |
Pages |
183-197 |
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Abstract |
A study was undertaken to examine the activity and composition of the seasonal Baltic Sea land-fast sea-ice biota along a salinity gradient in March 2003 in a coastal location in the SW coast of Finland. Using a multi-variable data set, the less well-known algal and protozoan communities, and algal and bacterial production in relation to the physical and chemical environment were investigated. Also, the first coincident measurements of bacterial production and dissolved organic matter (DOM) in a sea-ice system are reported. Communities in sea ice were clearly autotrophy-dominated with algal biomass representing 79% of the total biomass. Protozoa and rotifers made up 18% of biomass in the ice and bacteria only 3%. Highest biomasses were found in mid-transect bottom ice. Water column assemblages were clearly more heterotrophic: 39% algae, 12% bacteria and 49% for rotifers and protozoa. Few significant correlations existed between DOM and bacterial variables, reflecting the complex origin of ice DOM. Dynamics of dissolved organic carbon, nitrogen and phosphorus (DOC, DON and DOP) were also uncoupled. A functional microbial loop is likely to be present in the studied ice. Existence of an under-ice freshwater plume affects the ecosystem functioning: Under-ice water communities are influenced directly by river-water mixing, whereas the ice system seems to be more independent–the interaction mainly taking place through the formation of active bottom communities. |
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Springer-Verlag |
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Heidelberg |
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0722-4060 |
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Sampling: Nine stations along a 40km salinity gradient from inner Pojo Bay through the Archipelago to the edge of the open sea |
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Call Number |
refbase @ admin @ Kaartokallio++2006 |
Serial |
744 |
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Author |
Thomas, D.N. |
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Title |
Photosynthetic microbes in freezing deserts |
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Journal Article |
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Year |
2005 |
Publication |
Trends in Microbiology |
Abbreviated Journal |
Trends Microbiol |
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Volume |
13 |
Issue |
3 |
Pages |
87-88 |
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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. |
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Elsevier Science B.V. |
Place of Publication |
Amsterdam |
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English |
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English |
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0966-842X |
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Call Number |
refbase @ admin @ Thomas2005 |
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755 |
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Lakaniemi, A.-M.; Hulatt, C.J.; Thomas, D.N.; Tuovinen, O.H.; Puhakka, J.A. |
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Title |
Biogenic hydrogen and methane production from Chlorella vulgaris and Dunaliella tertiolecta biomass |
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Journal Article |
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Year |
2011 |
Publication |
Biotechnology for Biofuels |
Abbreviated Journal |
Biotechnol Biofuels |
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4 |
Issue |
1 |
Pages |
34 |
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BACKGROUND: Microalgae are a promising feedstock for biofuel and bioenergy production due to their high photosynthetic efficiencies, high growth rates and no need for external organic carbon supply. In this study, utilization of Chlorella vulgaris (a fresh water microalga) and Dunaliella tertiolecta (a marine microalga) biomass was tested as a feedstock for anaerobic H2 and CH4 production. RESULTS: Anaerobic serum bottle assays were conducted at 37 degrees C with enrichment cultures derived from municipal anaerobic digester sludge. Low levels of H2 were produced by anaerobic enrichment cultures, but H2 was subsequently consumed even in the presence of 2-bromoethanesulfonic acid, an inhibitor of methanogens. Without inoculation, algal biomass still produced H2 due to the activities of satellite bacteria associated with algal cultures. CH4 was produced from both types of biomass with anaerobic enrichments. Polymerase chain reaction-denaturing gradient gel electrophoresis profiling indicated the presence of H2-producing and H2-consuming bacteria in the anaerobic enrichment cultures and the presence of H2-producing bacteria among the satellite bacteria in both sources of algal biomass. CONCLUSIONS: H2 production by the satellite bacteria was comparable from D. tertiolecta (12.6 ml H2/g volatile solids (VS)) and from C. vulgaris (10.8 ml H2/g VS), whereas CH4 production was significantly higher from C. vulgaris (286 ml/g VS) than from D. tertiolecta (24 ml/g VS). The high salinity of the D. tertiolecta slurry, prohibitive to methanogens, was the probable reason for lower CH4 production. |
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Department of Chemistry and Bioengineering, Tampere University of Technology, PO Box 541, FI-33101 Tampere, Finland. aino-maija.lakaniemi@tut.fi |
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English |
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ISSN |
1754-6834 |
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PMID:21943287; PMCID:PMC3193024 |
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Call Number |
refbase @ user @ |
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12985 |
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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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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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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 |
Thomas, D.N.; Mock, T. |
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Title |
Life in frozen veins – coping with the cold |
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Journal Article |
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Year |
2005 |
Publication |
The Biochemist |
Abbreviated Journal |
Biochemist |
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Volume |
27 |
Issue |
1 |
Pages |
12-16 |
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Keywords |
adaptation; Antarctic; Arctic; low temperature; micro-organism; sea ice |
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Abstract |
Every autumn a fundamental transition occurs in the surface waters of Polar Oceans. The surface waters of millions of square kilometres freeze to form an ice layer that varies from a few centimetres through to several metres thick, and which effectively separates the ocean from the atmosphere above. Ice made from seawater is a porous, semi-solid matrix permeated by a labyrinth of brine channels and pores, and within these a diverse microbial assemblage, including viruses, archaea, bacteria, flagellates and unicellular algae can thrive. These assemblages can reach such high abundances that the ice becomes a rich coffee colour. The microbial assemblages are in turn a rich food source for grazing proto- and zooplankton, especially in winter when food in the water column is scarce. |
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Biochemical Society |
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London |
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refbase @ admin @ Thomas+Mock2005 |
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765 |
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