Dr. Jari SyvärantaSection of Limnology and Hydrobiology Department of Biological and Environmental Science University of Jyväskylä, Finlandand EcoLab, UMR 5245 (CNRS-UPS-INPT) Université Paul Sabatier Toulouse France |
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Methane in lake food webs ? A need to reconsider traditional views of lake energetics? |
| Recent research in lake ecosystems has clearly identified the contribution of methane-derived carbon to consumers at lower trophic levels. However, there is little more than circumstantial evidence to suggest that organisms from higher trophic levels, such as fish, might be supported by this alternative carbon source. Here I will present results from previous studies illustrating how stable isotope analysis (SIA) has been employed to identify this unique energy source to lower trophic levels (mainly chironomids and cladoceran zooplankton), and that this alternative energy source makes a widespread contribution to lake systems. Also, I will present results from a recent study specifically aimed to follow this isotopically distinct methane-carbon further up the food chain to evaluate its potential contribution to fish energetics. By collecting samples of ruffe (Gymnocephalus cernuus) from varying depths and oxygen conditions within a single lake system, we estimated that up to 37% of the carbon in ruffe from greater depths actually originated from biogenic methane. These results are novel evidence that lake food webs and energetics are even more varied than has hitherto been recognized. |
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Ort |
| 25.05.2009 15:00 Uhr Großer Hörsaal |
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