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Carbon isotope fractionation in developing natural phototrophic biofilms
1Department of Marine Microbiology, Netherlands Institute of Ecology – KNAW, P.O. Box 140, 4400 AC Yerseke, The Netherlands
2Marine Biological Laboratory, Institute of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
3Department of Environmental Biotechnology, TU Delft, Julianalaan 67, 2628 BC Delft, The Netherlands
*now at: Department of Environmental Biotechnology, TU Delft, Julianalaan 67, 2628 BC Delft, The Netherlands
Abstract. Natural phototrophic biofilms are influenced by a broad array of abiotic and biotic factors and vary over temporal and spatial scales. Different developmental stages can be distinguished and growth rates will vary due to the thickening of the biofilm, which are expected to lead to a limitation of light or mass transport. In this study it is shown that a variation of the availability of CO2 leads to a shift in fractionation, thereby affecting δ13C signatures during the successive developmental stages. For phototrophic freshwater biofilms it was found that the δ13C value became less negative with the thickening of the biofilm, while the opposite trend in δ13C values was found in marine biofilms. Modeling and pH profiling indicated that the change in the freshwater system was caused by an increase in CO2 limitation resulting in an increase of HCO3− as C-source. The opposite trend in the marine system could be explained by a higher heterotrophic biomass and activity causing a higher carbon recycling and thereby lower δ13C values. We conclude that δ13C was more related to the net areal photosynthesis rate and carbon recycling, rather than to the growth rate of the biofilms.
Discussion Paper (PDF, 603 KB) Interactive Discussion (Closed, 3 Comments) Final Revised Paper (BG)
Citation: Staal, M., Thar, R., Kühl, M., van Loosdrecht, M. C. M., Wolf, G., de Brouwer, J. F. C., and Rijstenbil, J. W.: Carbon isotope fractionation in developing natural phototrophic biofilms, Biogeosciences Discuss., 4, 69-98, 2007. Bibtex EndNote Reference Manager
