POSEIDON POS412

The 412th expedition of the German research vessel POSEIDON (19 April - 7 May 2011) takes place in the Tyrrhenian Sea north of Sicily. There are some fascinating geological formations like the Palinuro seamount, the Panarea hydrothermal vent field and the Marsili Seamount with presumably unique and so far unknown ecological communities. The major purpose of the research cruise is a geological, chemical and biological characterization of these highly interesting ecosystems. A detailed geological mapping of the research area will provide the basis for sampling. Unusually high concentrations of heavy metals in the sediments are thought to cause a specifically adapted, possibly unique microbial community. Their diversity and ecological function in the sediments, but as well in
Fe/Mn oxide chimneys, bacterial mats and fluids are in focus of the microbiological research. On previous cruises, so-far unidentified tubeworms and decapode species have been recovered. The community structure and function of the microbiota associated with these macroorganisms is of major interest especially concerning sulphur and CO2 metabolism. Furthermore, the light-exposed hydrothermal vent field Panarea is supposed to harbour a specifically adapted phototrophic bacterial community, which is going to be characterized on the proposed cruise. Chemical analyses of fluids and sediments (pore water) will provide the basis for interpretation of the microbiological data. Sampling for microbiological analysis is performed by a ROV of the Mohawk-type by the scottish Oceaneering Inc. Chief Scientist of the cruise is Dr Sven Petersen of the Leibniz Institute of Marine Sciences IFM-GEOMAR.