ALKOR AL355

From May 29 to June 21, 2010, R/V ALKOR is working in the eastern Gotland Basin (central Baltic Sea.). The cruise led by Dr. Olaf Pfannkuche (IFM-GEOMAR, RD2, Marine Geosystems), is carried out within the framework of the FP-7 project HYPOX (In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and land-locked water bodies, www.hypox.net/). A major focus of this cruise is on in situ measurements of turnover and fluxes of nitrogen compounds, phosphate, iron, manganese and carbon in the benthic boundary layer at variable oxygen concentrations of the bottom water. In parallel to these measurements of the natural environment, the effects of variable oxygen availability (thresholds) in the bottom water on N-speciation and release of nutrients shall be determined by in situ experiments. Further activities of this cruise comprise biological investigations (meiobenthos, epibenthos) and sea floor imaging. A lander observatory will be deployed at 97m for three weeks to measure near bottom currents, the variability of oxygen in the sediment contact water and to take time lapse photos of benthos activity.