Microbial Communities of the North Atlantic and the 3rd Dimension of the Logatchev Hydrothermal Field - Cruise N0. MSM03 - September 20 - November 30, 2006 Reykjavik (Island) - Fort-de-France (France) (English)

The main goal of Leg 1 of MSM03 was to study the diversity, structure and function of the microbial community including bacterioplankton, phytoplankton and virioplankton in the top 500 m of the North Atlantic Ocean. The scientific party included 22 scientists from Germany, the UK, and the USA and was interested in comparing the microbial communities of the contrasting water bodies of the nutrient-rich, cold East Greenland Current, the warm North Atlantik drift and and the nutrient-depleted North Atlantic Gyre. During Leg 2 a lander-type drilling platform was used to investigate the immediate subsurface of the Logatchev hydrothermal field at the slow-spreading Mid-Atlantic Ridge in order to document the nature of the underlying rocks, the possible depth zonations of the mineralization, and alteration as well as their age relationships. Drilling proved difficult, not only because of the terrain encountered, but also because of the soft nature of the subseafloor rocks (serpentinite). Drilling penetrated up to 15 m into the subseafloor and recovered lithologies that changed our view of the formation and the subseafloor processes at ultramafic-hosted hydrothermal fields. Other goals included pore water and sediment sampling in order to better understand the sulfur cycle, the variability of the subsurface microbiology and their influence on the formation and alteration of hydrothermal mineral precipitates. Scientists from Germany representing the fields of economic geology, petrology, geochemistry and microbiology, technicians and engineers from the UK as well as scientists from Russia, China and Switzerland participated in the cruise.