Soltwedel, Thomas, Michael Klages, Jens Matthiessen, Eva-Maria Nöthig, Eberhard Sauter and Ingo Schewe

Alfred-Wegener-Institute for Polar and Marine Research, P.O. Box 120 161, 27515 Bremerhaven, Germany, Tel: +49 471 4831 1775, Fax: +49 471 4831 1776, E-mail: tsoltwedel@awi-bremerhaven.de

Multidisciplinary investigations at a deep-sea long-term station in polar regions

In summer 1999, the Alfred-Wegener-Institute for Polar and Marine Research established a deep-sea long-term station (AWI-“Hausgarten”) at 79°N / 4°E in the eastern Fram Strait off Svålbard, to assess temporal variations in biological, geochemical and sedimentological parameters. AWI-“Hausgarten” consists of a central experimental area at about 2500 m water depth as well as of 9 sampling sites along a depth transect between 1000-5500 m, and 7 sites along a latitudinal transect at approx. 2500 m water depth crossing the experimental area. Fluxes of particulate organic matter to the seafloor were characterized and quantified using sediment traps. The exchange of solutes between the sediments and the overlaying waters were studied with a new designed water samplers which is able to sample larger water volumes from different water horizons up to 2 m above the seafloor as well as micro-profiling units and incubation chambers integrated in free-falling devices. Sediment samples were analyzed for various biogenic compounds indicating food availability at the seafloor, benthic activities and the total biomass of benthic micro-organisms. The quantification of benthic organisms from bacteria to megafauna is a major goal in the biological investigations. To identify factors controlling the high biodiversity in the deep sea, we started a number of experiments using a deep-diving ROV system. Long-term investigations at AWI-"Hausgarten" will help to assess seasonal and interannual variabilities at a polar deep-sea site in the light of environmental changes (NAO, Global Change).