Das Projekt "Ecosystem Engineering: Sediment entrainment and flocculation mediated by microbial produced extracellular polymeric substances (EPS)" wird vom Umweltbundesamt gefördert und von Universität Stuttgart, Institut für Wasser- und Umweltsystemmodellierung durchgeführt. Sediment erosion and transport is critical to the ecological and commercial health of aquatic habitats from watershed to sea. There is now a consensus that microorganisms inhabiting the system mediate the erosive response of natural sediments ('ecosystem engineers') along with physicochemical properties. The biological mechanism is through secretion of a microbial organic glue (EPS: extracellular polymeric substances) that enhances binding forces between sediment grains to impact sediment stability and post-entrainment flocculation. The proposed work will elucidate the functional capability of heterotrophic bacteria, cyanobacteria and eukaryotic microalgae for mediating freshwater sediments to influence sediment erosion and transport. The potential and relevance of natural biofilms to provide this important 'ecosystem service' will be investigated for different niches in a freshwater habitat. Thereby, variations of the EPS 'quality' and 'quantity' to influence cohesion within sediments and flocs will be related to shifts in biofilm composition, sediment characteristics (e.g. organic background) and varying abiotic conditions (e.g. light, hydrodynamic regime) in the water body. Thus, the proposed interdisciplinary work will contribute to a conceptual understanding of microbial sediment engineering that represents an important ecosystem function in freshwater habitats. The research has wide implications for the water framework directive and sediment management strategies.
Das Projekt "Mikroorganismen in der Phyllosphäre von Waldökosystemen gemäßigter Klimazonen unter sich verändernden Umweltbedingungen" wird vom Umweltbundesamt gefördert und von Leibniz-Zentrum für Agrarlandschaftsforschung e.V., Institut für Landschaftsstoffdynamik durchgeführt. Zielsetzung: Aufklärung der Dynamik mikrobieller Epiphytenpopulationen in der Phyllosphäre von Waldbäumen bei erhöhten Luftschadstoffkonzentrationen (N, S, CO2) und bei Befall durch blattsaugende Insekten unter besonderer Berücksichtigung ihrer Enzymaktivitäten im C- und N-Kreislauf und ihrer Biodiversität.
Das Projekt "Geobiologische Interaktionen zwischen Hydrothermalfluiden und symbiotischen Primärproduzenten an Spreizungsachsen" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für marine Mikrobiologie durchgeführt. In den letzten 2 Jahren des SPP 1144 werden wir unsere Untersuchungen an endosymbiontischen Bakterien in Evertebraten, einer der wichtigsten Gruppen von Primärproduzenten an Hydrothermalquellen des Mittelatlantischen Rückens (MAR), abschließen. In enger Zusammenarbeit mit Geologen und Geochemikern soll der Einfluss von unterschiedlichen geologischen Strukturen und Gradienten in Ventfluiden auf symbiontische Diversität, Biomasse und Aktivität aufgeklärt werden. Diese Forschung wird zu einer der Kernfragen des SPP 1144 beitragen: Welche Wechselwirkungen bestehen zwischen hydrothermalen und biologischen Prozessen? Eine weitere Kernfrage des SPP 1144 ist: Wie beeinflussen Achsenmorphologie und Meeresströmungen die Verbreitung von Ventorganismen entlang der Rückenachse? Biogeographische Analysen der Symbionten von Muscheln und Garnelen sollen zeigen, ob geologische und hydrologische Barrieren zwischen den nördlichen und südlichen Hydrothermalquellen zu einer räumlichen Isolierung von symbiotischen Bakterien führen. Die Ergebnisse dieser Forschung liefern einen wichtigen Beitrag zum Verständnis der Kopplung geologischer und biologischer Prozesse an gemäßigt spreizenden Rückenachsen.
Das Projekt "Why are climbing plants so invasive? - an experimental and biomechanical approach to study enhanced growth and competitiveness of climbing plants in the context of CO2 enrichment." wird vom Umweltbundesamt gefördert und von Universität Zürich, Institut für Pflanzenbiologie durchgeführt. Our current understanding of the ecology of lianas and their role in natural ecosystems falls well behind that of most of other plant groups. This gap in current knowledge has potentially serious consequences because (1) climbing plants are known to show significantly enhanced growth under CO2 enrichment (2) many climbing plant species are serious invasive elements in both tropical and temperate ecosystems and cultivated areas and (3) recent censuses of tropical lianas suggest that recent changes in climbing plant growth dynamics might be actually changing vegetation communities in the tropics. These issues therefore beg for detailed studies on the effects of CO2 enrichment on invasive climbing plants. The main aim of this study was to analyse the effects of elevated CO2 concentration on the development, biomass and mechanical properties of two selected invasive climbing species (Ipomoea triloba, Momordica charantia) and an agricultural C4 host plant (Sorghum bicolor) with a new approach on the interface of biophysics and ecophysiology. We investigated a) the effect of elevated CO2 on sorghum without climbers, b) the effect of elevated CO2 on developmental traits of the two invasive species and c) the effect of elevated CO2 on the interaction and crop/climbing plant competition with the effects on growth and yield. Sorghum bicolor plants were grown with two invasive climbing species under ambient (380 ppm) and elevated CO2 (750 ppm) in glasshouse conditions. The results are summarized in three main articles in preparation: First, Sorghum grown alone showed significant differences in biomass allocation between ambinet and elevated CO2, particularly between vegetative and reproductive components and a significant decrease in yield under elevated CO2. In terms of mechanical architecture sorghum plants grown without climbers showed no change in the stiffness of the leaf sheath at elevated CO2 despite increases in vegetative biomass. Second, both liana species showed changes in mechanical, morphological and photosynthetic traits under elevated CO2 resulting in enhanced growth (length + branching). Third, the results from the crop/climbing plant competition experiment demonstrated that the sorghum host plants are more affected under elevated CO2 than ambient CO2 leading to a weakened mechanical architecture and a decrease in panicle biomass and stem carbohydrate production. The results of this study provide fundamental knowledge for the effects of climate change on weed/crop competition and liana growth. Elevated CO2 can potentially increase the invasive climber threat for crops in future which should be taken in account for agricultural management.