25th of June – 1st of July 2007 (Week 26)

Over the last week we have established a certain routine: early in the morning we deploy the ‘elevator’, a big container for samples and instruments followed by the remotely operated vehicle (ROV) QUEST (owned by the Centre of Marine Environmental Science MARUM, University of Bremen). The dives last between 10 and 14 hours. After recovery of the ROV, winch-operated gear is deployed at the sea floor at a water depth of some 1250m.

Since Monday, we have recovered several sediment cores under ambient pressure with a dynamic autoclave piston corer, developed at the University of Bremen. This technology enables us to collect gas hydrate, a substance similar to ice, formed in the sediments with a minimal loss of volatile gases. Gas hydrates only remain stable under specific pressure and temperature regimes and contain high concentrations of methane. The first deployment was already a great success as we recorded extremely high quantities of methane from gas hydrates during the controlled depressurisation of the sediment core. Furthermore, gas samples were collected for further analysis at the home laboratories.

The routine described above was only interrupted once for two days when the forecast of the board meteorologist went: “A low pressure system of 990 hPa from Finland moves westerly and will reach the Lofoten area tomorrow. It will merge with another low pressure system of 985 hPa from Denmark to form an extensive low pressure system which will become stationary over Scandinavia. Forecast: Wind from north-easterly directions with speeds around 7 Beaufort, good visibility, sometimes hazy. Sea state: Wave heights of 4m.”  This meant a pause of all ROV activities a safe deployment and recovery of the ROV is impossible at such wave heights (it seemed to some of us as if the waves even exceeded the forecast).

Therefore, we started with sampling programmes which were originally scheduled for later during the cruise: i.e. gravity corer, dynamic autoclave piston corer, multiple corer, giant box corer, temperature loggers and a free-falling lander system. With the samples on board the scientists disappeared quickly into their laboratories. Most of the cruise participants have worked on RV Polarstern or other research vessels before. Therefore, an efficient routine could be established swiftly. This would have been impossible to achieve, however, was it not for the unfaltered assistance of the crew.

On Wednesday and Thursday, the chief scientist, the co-chief scientists and the leader of the ROV team stood on the main working deck in the early hours of the morning to assess the up- and downwards movement of the ship where the ROV was going to be deployed.

Together with the captain it was decided that the sea state would not allow for a deployment and recovery that was safe for both humans and equipment. By Friday morning, the weather had calmed down sufficiently for the ROV to proceed to dive and we followed our old routine. Until Sunday, we have conducted five successful ROV dives and were able to carry out promising experiments.

With best regards from the ship on behalf of all cruise participants,

Michael Klages