Deutsches Ozeanographisches
Datenzentrum Inventur der Poseidon-Reise POS450 (DOD-Ref-No.20130082)
Inventory of Poseidon Cruise POS450 (DOD-Ref-No.20130082)

Working area
Poseidon POS450 02.04.2013 - 13.04.2013   Mediterranean Sea, Western Basin  

Chief Scientist
Port of departure
Port of return
Station map
Heuer Verena Universitat Bremen, Zentrum fur Marine Umweltwissenschaften Barcelona Malaga   

Ziel der Reise / Objectives of Cruise:

RV POSEIDON cruise POS450 "DARCSEAS II" (April 02-13, 2013) was conducted to investigate how marine microbial communities respond to the riverine input of terrestrial organic matter. The expedition targeted two large rivers in the Western Mediterranean with contrasting climatic and hydrological regime of their hinterland: the River Rhone off France and the River Moulouya off Morocco. In both cases, samples for geochemical and microbiological investigations were taken from the water column and from sediments on the seafloor along a series of sites following the trajectory of terrestrial organic matter input. Four different sampling devices were deployed: gravity corer, multicorer, CTD-rosette, and in-situ pumps. The highest priority of our work program was the preparation and storage of subsamples for complex geochemical and microbiological experiments and analysis in the home laboratories. Due to time constraints, shipboard analyses were limited to sedimentological core descriptions and gas analysis. Within less than 11 days, the cruise covered 1118 nm, operated 106 hours on site, established 15 new GeoB sites (GeoB 17301 – GeoB 17315), and yielded >4000 discrete samples for post-cruise research. Site information has been uploaded to the World Data Base Pangaea, metadata of samples have been recorded in the data base ExpeditionDis, and samples for post-cruise research are stored together with archive halves of the retrieved gravity cores at the MARUM GeoB Core Repository. The recovered number of high quality samples constitutes an excellent basis for scientific studies in the framework of the project 'Deep subsurface archaea: carbon cycle, life strategies, and role in sedimentary ecosystems' (DARCLIFE), in which the cruise participants collaborate at the University of Bremen. DARCLIFE is funded through an Advanced Grant of the European Research Council to Kai-Uwe Hinrichs, Professor of Organic Geochemistry at MARUM & Department of Geosciences, University of Bremen. Archaea constitute a poorly understood domain of life. They have long been considered exotics that only occur in extreme environments like hot springs and salt lakes, but are nowadays increasingly recognized as globally abundant organisms that mediate processes which are important for the emission of greenhouse gases and cycling of nutrients. In sediments below the seafloor, the so-called benthic archaea have a cosmopolitan distribution, make up a significant - if not dominant - portion of life, and consist of numerous novel phylogenetic lineages that are at present uncultured. The survival of archaea in deeply buried, old sediments might be related to their ability to cope with extreme energy starvation and their presumed ability to degrade complex recalcitrant organic residues. DARCSEAS II was tailored to study the relationship between benthic archaea and the quality and quantity of the small fraction of organic matter that is transferred into the deep subseafloor. As riverine organic matter is highly degraded and nitrogen-poor, it might be expected to suffer minimal respiration in the ocean. However, the opposite is true: only a small fraction of the preserved organic matter in sediments is land derived, suggesting that terrestrial organic matter is extensively remineralized at sea. With DARCSEAS II we aim to explore the role of benthic archaea in this process.

Messungen / Measurements

Typ der Messungen
Type of measurements
Daten im DOD
Data in DOD
MARUM Heuer Verena 2 cores G04
Core-soft bottom (no. of cores)
mini corer. no
MARUM Heuer Verena 12 cores G04
Core-soft bottom (no. of cores)
gravity corer. no
MARUM Heuer Verena 19 cores G04
Core-soft bottom (no. of cores)
multi corer. no
MARUM Heuer Verena 12 meas. G71
In-situ sea floor measurements
in situ pump. no
MARUM Heuer Verena 13 stations H09
Water bottle stations
CTD Rosette. no