DARCSEAS - RV Meteor cruise M84/1

La Valetta (Malta) - Istanbul (Turkey),
February 9-22, 2011

Chief scientist: PD Dr. Matthias Zabel

The DARCLIFE project aims to constrain the factors that control the distribution of benthic archaea in marine sedimentary systems and to determine their role within the marine carbon cycle. The DARCSEAS cruise was initiated to meet specific sample needs of the DARCLIFE project.

The cruise allowed us to investigate five sites in the southern Black Sea, Sea of Marmara, and the eastern Mediterranean that provide an ideal set of environmentally diverse settings in close proximity to each other. We selected five locations (GeoB15101-15105) with highly variable hydrological, geochemical, and depositional regimes. These sites allow us to study the distribution and carbon sources of benthic archaea under various environmental conditions and to grow and enrich cren- and euryarachaeota from different habitats. We retrieved fresh material using gravity corer, multicorer, in-situ pumps, and rosette sampler.

Site GeoB15105 is situated in the Black Sea, the largest stratified basin of the modern world. The slightly brackish water column is anoxic below the pycnocline and the hydrologic evolution of the Black Sea since the last glacial maximum (LGM) went along with strongly contrasting environmental conditions and the accumulation of organic carbon rich sapropels. Due to the anoxic conditions, lack of bioturbation and relatively high sedimentation rates (~15 – 20 cm kyr-1), the Black Sea provides excellent conditions for the preservation of molecular biomarkers and DNA.

Site GeoB15104 is located in the Sea of Marmara, which is characterized by high tectonic activity, submarine landslides and tsunamis, active gas seepage along the surface expression of the main active fault system, dense gas hydrate deposits in the first few meters of sediment and considerable oil potential. As a gateway between the Mediterranean and Black seas, the Sea of Marmara has long been recognized for its important role in the evolution of Quaternary paleoceanography. During the late Holocene, geochemical conditions have changed several times and sapropelic layers with high contents of terrestrial organic matter were desposited under suboxic bottom water conditions.

The Urania Basin (Site GeoB15101) and Discovery Basin, (Site GeoB15102), belong to a series of five brine-filled anoxic basins in the eastern Mediterranean. The thickness of the brines may be up to 500 m and a sharp density contrast occurs with the interface to normal sea-water at 3200-3500 m below sea level. The hypersaline brines result from redissolution of late Messinian evaporites and have migrated to form brine pools on the seafloor where some closed depressions exist, probably only some 2000 yrs ago. During this period, unique prokaryotic and eukaryotic microbial communities developed that adapted to these extreme environments.

At Site GeoB15103 in the Eastern Mediterranean south of Cyprus, we expected to find a series of 10 sapropel layers within the upper 7m of the sediment column und thus sharp contrasts in organic matter content: beside the typical high total organic carbon contents for these sapropels (up to 4.5 wt%), the content of organic carbon is very low (0.1-0.3 wt%).

For more detailed information on the sampled sites see DARCSEAS.

Our scientific work during DARCSEAS was accompanied by the artist Andreas Schön, a painter and photographer who joined the expedition in the framework of a cooperation between MARUM, Hanse-Wissenschaftskolleg Delmenhorst (HWK Institute for advanced study) and the journal "mare - Die Zeitschrift der Meere". Together with the chief scientist, Dr. Mathias Zabel, Andreas Schön recorded his impressions in an expedition logbook (in German).

Important dates

December 20, 2010
Declaration of dangerous goods due

January 14, 2011 - 08:00 am
Collection of containers in Bremen

February 9-22, 2011
DARCSEAS: RV Meteor cruise M84/1 (La Valetta - Istanbul)