Description: The Arctic Ocean is quite vulnerable and sensitive to climatic changes and has received increasing attention in recent years because of the drastic decrease of sea ice cover and change in ice composition. The environmental changes are expected to have severe consequences for the structure of the pelagic system and trophic interactions, for the cycling of organic matter and carbon sequestering and thus will also affect the life at the seafloor. Long – term studies are rare in this region and no reliable baseline information exists from which change can be identified. Our work at HAUSGARTEN, offers the unique opportunity in making an important contribution to establish such a baseline, and to trace possible effects of global warming in this sensitive region of the Ocean. Multidisciplinary research activities at the observatory include yearly sampling and analyses in the water column and at the seafloor, and year round measurements by moored instruments (e.g. sediment traps, current meters, temperature- and oxygen sensors). Some of these instruments are also installed at platforms at the seafloor. Since the beginning of our investigations in 1999 we observed an abyssal warming, significant alterations in the species composition in the pelagic realm, a decrease in the quality of organic matter supply to the deep sea as well as considerable shifts in both, microbial and megafauna community composition at great water depths. In this presentation the mayor findings of our research in the area will be presented.