Title Temperature effects on carbon and nitrogen metabolism in some maritime Antarctic freshwater phototrophic communities
Author Velázquez, D.; Rochera, C.; Camacho, A.; Quesada, A.
Author Affil Velázquez, D., Universidad Autonoma de Madrid, Departamento de Biologia, Madrid, Spain. Other: Universitat de Valencia, Spain
Source Polar Biology, 34(7), p.1045-1055. Publisher: Springer-Verlag, Berlin, Germany. ISSN: 0722-4060
Publication Date July 2011
Notes In English. 48 refs. GeoRef Acc. No: 309873. CRREL Acc. No: 65006930
Index Terms bacteria; ecology; photosynthesis; salinity; temperature; Antarctica--Livingston Island; Antarctica; biochemistry; biofilms; Byers Peninsula; carbon; cyanobacteria; fresh- water environment; Livingston Island; metabolism; microorganisms; nitrogen; photochemistry; phototrophic taxa; Scotia Sea Islands; South Shetland Islands
Abstract Biofilms growing on ice and benthic mats are among the most conspicuous biological communities in Antarctic landscapes and harbour a high diversity of organisms. These communities are consortia that make important contributions to carbon and nitrogen input in non-marine Antarctic ecosystems. Here, we study the effect of increasing temperatures on the carbon and nitrogen metabolism of two benthic communities on Byers Peninsula (Livingston Island, Maritime Antarctica): a biofilm dominated by green algae growing on seasonal ice, and a land-based microbial mat composed mainly of cyanobacteria. Inorganic carbon photoassimilation, urea and nitrate uptake and N2-fixation (acetylene reduction activity) rates were determined in situ in parallel at five different temperatures (0, 5, 10, 15, 25°C) using thermostatic baths. The results for the cyanobacterial mat showed that photosynthesis and N2-fixation responded positively to increased temperatures, but urea and NO3-uptake rates did not show a significant variation related to temperature. This microbial mat exhibits relatively low activity at 0°C whereas at higher temperatures (up to 15°C), N2-fixation rate increased significantly. Similarly, the maximum photosynthetic activity increased in parallel with temperature and showed no saturation up to 25°C. In contrast, the ice biofilm displayed higher photosynthetic activity at 0°C than at the other temperatures assayed, and it showed elevated photoinhibition at warmer temperatures.
URL http://hdl.handle.net/10.1007/s00300-011-0964-7
Publication Type journal article
Record ID 91548