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Samples from the bottom of the ocean: “Octopus Prime” in action

Proben vom Meeresboden in 4200 Metern Wassertiefe. Erster Tiefsee-Einsatz des MUCs namens

We eagerly awaited these samples, the first from the very bottom of the ocean to reach the deck. These samples were especially exciting because the bottom of the ocean at this station is at 4200 m water depth; moreover, it was our very first use of this sampler in the deep sea, which the ICBM just recently acquired.

It was a memorable moment as our shiny new multicorer (nicknamed “MUC” or “Octopus Prime”; the manufacturer of this instrument is a company called

Oktopus) vanished into the deep blue of the Pacific. It took 4 hours for the sampler to reach the bottom and then return to the deck of the Sonne.

At the bottom of the ocean, the MUC’s 8 sampling tubes penetrate up to 30 cm deep into the sediments. A trigger then releases, shutting the tops and the bottoms of the tubes, and the valuable sediment cores are then transported back to the surface. Theoretically this is all very straightforward, but nevertheless it was very nerve-wracking: did the sampler work in the deep? Would we have sufficient sediment for all of our experiments?

As the MUC came back on board, we were very relieved: it worked! We extruded the sediment (removed it from the tubes, like pushing it out of a toothpaste-tube), collecting subsamples at specific depths with sterile syringes. The samples are either analyzed directly on board, or they are carefully packed, in order to analyze them later in our lab at the ICBM.

We are particularly interested in finding out how many bacteria live in the sediments at this great depth of the ocean, and who is a member of these microbial communities. We are very eager to find out which organisms are found in different sections of the sediments at different locations; we hope that sampling at the next stations goes just as well as at the first one!