(with Michael Böttcher, Volker Brüchert, Tim Ferdelman, Niko Finke, Hans Røy, Peter Berg, Kirsten Imhoff and others)
Sites: Namibian shelf and slope, Black Sea
Regulation of anaerobic mineralization, oxygen uptake of the sea bed

Anaerobic oxidation of methane

(with Antje Boetius, Tina Treude, Nina Knab, Christian Borowski, Heiko Löbner and others)
Sites: Black Sea, Kattegat and Skagerrak
See: EU project METROL, DFG project MUMM
Cold seeps, gas bubbles in sediments, methane fluxes and their regulation

Psychrophilic bacteria and the biogeochemistry of Arctic sediments

(with Veronica Vandieken, Maren Nickel, Niko Finke, Volker Brüchert, Marc Mussmann, Carol Arnosti, Christian Knoblauch, and Paul Wassmann)
Sites: Fjords of Svalbard, Berings Sea
Psychrophilic sulfate reducing bacteria and iron reducers
Temperature regulation of microbial processes at low temperature

Nitrate accumulating sulfur bacteria

(with André Preisler, Gaute Lavik, Elze Wieringa, Dirk de Beer, and Heide Schulz)
Communities of Beggiatoa, Thioploca and Thiomargarita
Coupling of nitrate reduction and sulfide oxidation

Deep biosphere

(with Tim Ferdelman, Jens Kallmeyer and others)
Sites: Eastern tropical Pacific Ocean (ODP Leg 201)
See: EU project Deep-BUG (coordinator John Parkes)
Sulfate reduction in marine subsurface sediments
Effects of temperature, pressure and energy sources