Objectif The proposed project centres on so far neglected animal-microbe interactions in freshwater sediment that are expected to greatly influence denitrification rates and N2O emission to the atmosphere. We hypothesise that the guts of sediment-dwelling detritivores constitute "mobile microsites" in which bacterial denitrification will be induced by anoxia and high concentrations ofdissolved organic carbon. Over time, the inoculation of sediment with actively denitrifying bacteria via egested feces may favour the development of a structurally and functionally distinct denitrifying community.In a fully integrated approach using the contemporary techniques of Microbial Ecology we aim at:(i) characterising the gut microenvironment of the abundant detritivore Chironomus r iparius (Insecta: Diptera) withmicrosensors and HPLC analysis,(ii) quantifying NO3- consumption and N2O production in gut and sediment using the 15N isotope pairing technique and gaschromatography, and(iii) determining community structure and gene expression of denitrifying bacteria in gut and sediment using the genes coding for NO3- reductase (narG) and N2O reductase (nosZ) as well as their mRNA transcripts.We will test the "mobile microsite" hypothesis in laboratory experiments, using freshwater sediment stocked with C. ripariuslarvae. The general applicability of the hypothesis will be evaluated at several NO3- polluted field sites in Denmark using sediment enclosures experimentally enriched in C. riparius larvae. These investigations will be complemented b y screening other benthic detritivores present at the field sites for denitrification and N2O emission. We expect that the results of this study will improve predictive models of eutrophication (e.g. NO3- dynamics) and global climate change (e.g. N2O emission). Champ scientifique natural sciencesbiological sciencesmicrobiologybacteriologynatural sciencesbiological sciencesecologynatural sciencesearth and related environmental sciencesatmospheric sciencesclimatologyclimatic changes Programme(s) FP6-MOBILITY - Human resources and Mobility in the specific programme for research, technological development and demonstration "Structuring the European Research Area" under the Sixth Framework Programme 2002-2006 Thème(s) MOBILITY-2.1 - Marie Curie Intra-European Fellowships (EIF) Appel à propositions FP6-2002-MOBILITY-5 Voir d’autres projets de cet appel Régime de financement EIF - Marie Curie actions-Intra-European Fellowships Coordinateur UNIVERSITY OF AARHUS Contribution de l’UE Aucune donnée Adresse Nordre Ringgade 1 AARHUS C Danemark Voir sur la carte Liens Site web Opens in new window Coût total Aucune donnée
