Taking the Research Icebreaker to the "Hausgarten"

On June 16, 2004, the German research icebreaker "Polarstern" is scheduled to leave Bremerhaven for her 20th arctic expedition. During the first leg of the expedition, the main emphasis is on measurements of selected pollutants of air, water and snow, as well as on the hydrographic conditions in the Greenland Sea. In addition, any changes in the so-called "AWI-Hausgarten” (“Back Yard"), a long-term monitoring station in the arctic deep sea, will also be of great interest.

The deep sea is the largest, yet least known, habitat on earth. To date, many deep-sea processes and their effects on global climate- and ecosystems remain insufficiently understood, partly because snapshot-style investigations, standard until a few years ago, provide limited tools to answer such questions One-off sampling regimes and measurements cannot give estimates of temporal variability. However, long-term studies at selected locations allow to determine the environmental conditions which influence the development, structure and complexity of deep-sea species' communities. There is a great need for such baseline data in order to be able to estimate the effects of anthropogenic influences on the ecosystem of the deep sea. Only the ability to document temporal variability over extended periods of time enables us to distinguish inter-annual or inter-seasonal fluctuation from long-term (natural) trends.

Research in the "Hausgarten” (“Back-Yard")
In summer 1999, scientists of the 'Alfred Wegener Institute for Polar and Marine Research' established in Fram Strait, west of Spitsbergen (79°N, 4°E.) the first long-term monitoring area of any deep-sea polar region. Apart from a main experimental area in 2500 m water depth (the so-called "AWI Hausgarten"), a total of nine stations between 1000 and 5500 m depth were identified. Over the next years, repeated biological, geochemical and sedimentological investigations will be carried out at these locations. For the current expedition, the main research interests are the quantification of bottom-dwelling organisms and the oxygen consumption on the sea floor, particle transfer into the deep sea, and sedimentation at the edge of the continental shelf west of Spitsbergen. In addition, studies of bacterial deep-sea communities, small sediment-dwelling organisms and deep-sea fishes will also be part of the research programme. Investigations into the effect of methane on benthic foraminifera, which are highly sensitive indicators of environmental conditions, will complement the research activities.

Research facility on the right track
During “Polarstern’s” voyage to the ‘AWI-Hausgarten’, scientists of the “GKSS Forschungszentrum” (‘GKSS Research Centre’) – like the AWI, an institute of the “Helmholtz-Gemeinschaft” – will be able to use the vessel’s research facilities for a variety of air chemistry investigations. The scientists’ primary goal is analysis of the distribution of mercury and persistent organic pollutants. “Polarstern’s” route from Bremerhaven to the waters of the Arctic provides them with the rare opportunity to make serial measurements, which, in a spatial sequence, cover both the source regions of the pollutants as well as remote, comparatively pristine, arctic regions. One phenomenon specific to polar areas is the ‘atmospheric mercury decline’, during which mercury concentrations temporarily drop to background levels. In this context, the scientists intend to investigate to what extent the earth’s polar regions can be expected to act as terminal deposition areas.

Subsequently, “Polarstern” will collect hydrographic data between Greenland and Spitsbergen along latitude 75o degrees north. This exercise is part of a repeated measurements programme, ongoing for the past several years, because “only extensive time series with high quality data allow for the correct detection and explanation of complex changes in arctic waters”, according to expedition leader Gereon Budeus. Deep sea convection plays an especially significant role. Recently, small scale eddies have been discovered, in which convection extends 1000 m deeper down than in the surrounding water. In order to estimate the significance of such eddies, researchers will attempt to follow the development of a comparatively stationary eddy over several years.

Following the completion of studies in the ‘AWI Back Yard’, “Polarstern” is scheduled to anchor in Lonyearbyen, Spitsbergen on July 16, 2004. From there, further legs of the expedition will take the vessel to Fram Strait and the Yermak Plateau. At that time, the research programme will include extensive studies addressing geological, oceanographic, biological and atmospheric chemistry questions.
On October 3rd, “Polarstern” is expected to return to Bremerhaven from its 20th expedition with a rich scientific harvest.

Bremerhaven, June 16, 2004