Description: Transparent exopolymer particles (TEP) form from dissolved precursors and significantly contribute to the pool of particulate organic carbon in the ocean. In addition, TEP are an important structural component since they provide attachment sites for microbes on a nanometer to micrometer scale. To investigate the effect of ocean acidification on the concentration and dynamics of TEP, we conducted a series of experimental studies in the Baltic Sea in summer 2007 within the frame of the SOPRAN (Surface Ocean PRocesses in the ANthropocene) project. At this time diazotrophs were the main primary producers. Thus, the relation between autotrophic N2-fixation and heterotrophic activity (uptake of radiolabeld Leucine) was determined and compared with TEP concentration measurements to elucidate how production and fate of TEP may be altered due to short term responses to acidification.We observed that the amount of TEP as well as microbiological activities were sensitive to changes in pCO2. Our results indicate a decrease of TEP concentration with increasing pCO2 under net heterotrophic conditions. Furthermore, significant correlations between TEP concentration and bacterial abundance suggest a tight coupling between the dynamics of acidic carbohydrates and bacteria dynamics.Our results imply that ocean acidification could potentially affect microbial carbon turn-over and, hence, organic matter cycling in the ocean.

Description: In July 2007 free floating mesocosm with app. 60m³ of volume were deployed in the southern Baltic Proper for app. two weeks. A gradient of increasing pCO2 concentrations was adjusted starting with the present concentration of 312 µatm up to 1600µatm as highest concentration. The response of the autotrophic plankton community was recorded in terms of nitrogen fixation rates. Heterotrophic activity was calculated based on the uptake of radiolabeled Thymidine. There was no clear increase of nitrogen fixation rates with higher pCO2. It rather seemed that the colonial species 〉10µm suffered under decreasing pH while the size fraction 〈10µm did not show any significant response In contrast to that cell specific bacterial biomass production sharply decreased within the first 24 hours after acidification but showed increasing activity with increasing CO2 concentration for the rest of the experiment. . A daily cycle of N-fix rates was only visible in the mesocosm with no pCO2 changes which also had highest N-fixation rates of up to 1.4nmol N/L/h.Our results indicate decoupling of primary and secondary production under increasing CO2 concentrations.

Description: The separation of Northeast Greenland and Svalbard is the result of large-scale strike slip movements during Cainozoic times. Geological evidence for these movements can be found onshore both on North Greenland and Svalbard. However, the role of the submarine Yermak Plateau in this process is quite speculative. New multi-channel seismic (10 km spacing) and aeromagnetic data (7.5 km spacing) across the north-western part of the plateau show that the acoustic basement strikes in similar direction as the geological units onshore Svalbard do. A prominent fault zone separates these most likely continental structures in the west from a more N-S extended transitional crustal block in the eastern part of the plateau. This north-eastern part of the plateau is characterized by strong magnetic anomalies, which at least indicate highly intruded, and stretched continental or even oceanic crust. Furthermore, the seismic data show, that the plateau-like bathymetry is quite young. During most of its Cainozoic history the Yermak Plateau had a rough topography, similar to the recent topography onshore Spitsbergen. Thus, the paleo-bathymetry might have played already an important role for the water exchange between the Arctic Ocean and the North Atlantic prior to the opening of the Fram Strait, which is today the main path way for the water masses.

Description: Deep seismic refraction data were gathered along the East Greenland rifted margin between the Jan Mayen and Greenland fracture zones (72°N 77°N) in 2003. Investigations of the deep structure of the continental margin provide key constraints on the formation of the margin and its structural evolution during and after Late Cretaceous - Early Tertiary rifting and continental break-up. Regional P-wave velocity models were inferred from forward travel-time modeling of land stations and ocean bottom hydrophone (OBH) recordings along four seismic refraction profiles. For the first time, transects off East Greenland provide a full insight into the crustal architecture of the transition from continental to oceanic crust. An overall view shows significant variations in the crustal structure along the margin. These include a decrease in the thicknesses of the magmatic underplate towards the north, and a widening of the COT in the south. P-wave velocities of the underplated material range between 7.1 and 7.4 km/s. The horizontal extent is widest (~200 km) along the southern profiles north of the Jan Mayen Fracture Zone and decrease further north towards the Greenland Fracture Zone. The maximum thickness of the underplated material is 15 - 16 km. From earlier investigations, a southward decrease in the amount of underplated material is observable and near Scoresby Sund no underplating was identified. Furthermore, the P-wave velocity models reveal a ~120 km wide continent ocean transition zone (COT), based on an interpretation of the extent of continental sediments and the lateral increase of velocities in the crustal layers. Excess magmatism must have been present during a long-term rifting process, accompanying the wide extension of the continental crust and giving rise to the voluminous magmatic underplating. This interpretation and the crustal variations along the margin could be consistent with a model featuring rift propagation from north to south. Additionally a comparison of P-wave velocity models of the East Greenland Margin and Vøring Margin reveals significantly asymmetric crustal architectures. The voluminous magmatic underplating and asymmetrical conjugate margins formations are evidence for complex pre- and syn-rift processes.