Weekly Reports Polarstern
The Expedition PS101 from Tromsø to Bremerhaven
RV Polarstern has departed for the expedition PS101 from Tromsø on Sept. 9th, 2016 and is on the way to the survey area, the Karasik Seamount, at 87°N and 61°E. The expedition is dedicated to a systematic study of this giant seamount at Gakkel Ridge north of Franz-Joseph-Land, and to the exchange of several components of the FRAM Arctic observatory infrastructure. Seamounts are biological and biogeochemical hot spots, which attract abundant life due to their specific morphology, which influences currents and productivity. This seamount rises from more than 5000 m water depth to 500m and stretches out for 60 km perpendicular to the Gakkel Ridge. With spreading rates of less than 13 mm/y, the Gakkel Ridge is considered the slowest spreading mid-ocean ridge on earth. Due to its remoteness and ice-cover it has been poorly explored, and very few direct observations at the potential vent locations have been made. Previous Polarstern missions in 2001, 2011, 2015 have detected sponge gardens, remnants of chemosynthetic fauna and nearby temperature anomalies in the rift valley suggesting active hydrothermalism. A key focus of the expedition is to further investigate the seamount and its associated hydrothermalism, and to record its influence on fauna, biogeochemical processes and the seafloor ecosystem. State-of-the-art underwater technologies including the new WHOI Robot NUI will be used to study this extreme environment. Furthermore, the state of the sea ice and pelagic productivity in the Arctic autumn will be assessed to ground truth observations of the FRAM infrastructure. The expedition PS101 aims at an integrative analysis of the seamount system, to determine its baseline status at a time of rapid sea ice decline and increasing human access to the region.