Emissions of methane gas from cold seeps on the seafloor have a strong impact on a number of biogeochemical processes. These processes include the development of deep-sea benthic ecosystems via the process of anaerobic oxidation of methane <Boetius et al., 2000> or the precipitation of carbonates <Ritger et al., 1987>. The fluxes of other chemical species associated with methane emissions may even influence the chemical composition of seawater <Aloisi et al., 2004>. Such gas emissions may have been much more intensive in the past with a strong impact onglobal climate <Dickens, 1999>, as suggested bycarbon isotope data. Many international and national research projects, such as the METRO collaborative project (Methane and Methane Hydrates Within the Black Seac Structural Analyses, Quantification and Impact of a Dynamic Methane Reservoir), part of the German research and development program Geotechnologien, focus on these cold seep sites and stimulate interdisciplinary work between a variety of scientific groups.