Hotspot microbial ecosystem research in the Eastern Mediterranean: Fluid flow, transport processes and community structure at cold seeps - Cruise No. MSM13/4 - November 21 - December 14, 2009 - Limassol (Cyprus) - Limassol (Cyprus) (English)

Cruise leg MSM 13/4, together with leg MSM 13/3, investigated chemosynthetic ecosystems in the deep Eastern Mediterranean. The microbial life and diverse chemosynthetic communities at three fluid escape structures in water depths of 1000 - 2000 m were studied: The East Delta in the eastern Nile fan province, the Central Area, and the Anaximander area. In the food-poor environment of the East Mediterranean a large contrast in fauna abundance between the rather scarce fauna of the pelagic deep-sea sediments and the highly abundant fauna of many of the cold seeps in this area, including the mud volcano Amsterdam, was observed. Several ROV explorations of the different habitats on this mud volcano allowed us to identify the numerous spots or patches of increased bivalve or polychaete abundance. The presence of species such as the mussel Idas, clam (Vesicomyid) species and tube worms in association with dark grey or black sediments pointed to the presence of reduced habitats thriving on chemical derived energy. Several AUV dives were used to obtain high-resolution bathymetry maps of the mud volcano and seeps sites in the pockmark area. Additionally PARASOUND mapping revealed several gas flares mainly located at the mud volcano rim. In situ biogeochemical measurements showed elevated oxygen consumption in combination with high dissolved methane effluxes. Heat flow transects were used to define the active area of the mud volcano. These combined studies will help to reveal the geological processes, which cause different ecosystem structures and habitat distributions, and to quantify the amount and fate of climate relevant gases that escape with the fluids or are utilized and consumed by the chemosynthetic biota.