The past decades have seen remarkable changes in key arctic variables, including a decrease in sea-ice extent and sea-ice thickness, changes in temperature and salinity of arctic waters, and associated shifts in nutrient distributions. To detect and track the impact of large-scale environmental changes in the transition zone between the northern North Atlantic and the central Arctic Ocean, the Alfred Wegener Institute for Polar and Marine Research (AWI) established in 1999 about 150 km west of Svalbard the deep-sea long-term observatory HAUSGARTEN, which constitutes the first, and until now only open-ocean long-term station in a polar region. 21 permanent sampling sites along a depth transect between 1000 – 5500 m, and along a latitudinal transect following the 2500 m water depth isobath are revisited yearly. The central HAUSGARTEN station serves as an experimental area for biological short- and long-term experiments at the deep seafloor, simulating various scenarios in changing environmental settings. Multidisciplinary research activities at HAUSGARTEN comprise biochemical analyses to estimate the input of organic matter from phytodetritus sedimentation and activities and biomasses of the small sediment-inhabiting biota as well as assessments of distribution patterns of benthic organisms (covering size classes from bacteria to meiofauna as well as megafauna).