The second leg of the 25th Polarstern expedition to the Arctic started on 30th June 2010 in Longyearbyen and will end on 29th July 2010 in Reykjavik. The work planned for the HAUSGARTEN area will contribute to the new research programme PACES (Polar Regions and Coasts in the Changing Earth System) of the AWI, which started at the beginning of 2009, as well as to the EU projects ESONET, HERMIONE, and HYPOX. The planned research adds to the time-series studies at HAUSGARTEN, where we investigate the impacts of Climate Change on an Arctic marine deep-sea ecosystem through field studies, observations and models since 1999. Climate-induced variations in plankton communities of Fram Strait will be investigated by the new AWI research group PEBCAO (Phytoplankton Ecology and Biogeochemistry in the Changing Arctic Ocean). Within the framework of the KONGHAU project (Impact of climate change on Arctic marine community structures and food webs) we will retrieve additional sediment samples on the continental shelf off Svalbard and inside Kongsfjorden. KONGHAU combines data collected over the past 12 years from time-series work at Kongsfjorden and HAUSGARTEN. The oceanographic work embedded in the EU project ACOBAR (Acoustic technology for observing the interior of the Arctic Ocean) is dedicated to investigate the water mass and heat exchange between the Arctic and the northern North Atlantic, with special emphasis on the inter-annual and decadal variability of the circulation in Fram Strait. Hydrographic measurements will be taken along 78°50’N, and water samples for tracer determinations will be collected. Oceanographic moorings with current, temperature and salinity meters deployed two years ago will be recovered and re-deployed with new instruments to extend the existing time-series. During the expedition, observations and countings of sea birds and marine mammals from the previous leg will be continued.