While the Polarstern did her utmost best to break through the pack ice towards the shelf, most scientists finished their practical station work and had the first look at the preliminary results. As member of the benthology team I work on the smallest, though surprisingly amazing members of the multicellular benthos, the Nematoda. These wormlike creatures are so numerously present and show such a great variability that they simply have to fulfil an important role down there. Because they are so small you need a microscope with high magnification to be able to identify them. Therefore and also because I plan to do some biochemical analyses on the nematodes found in the deep-sea sediments, my preliminary results on board would be limited to mentioning that the sampling we did by means of the multiple corer was successful so far.

But besides looking at which species the communities are composed of, I want to find out what they feed on and if different genera or species have preference for certain food sources on their menu. With these concrete questions in mind I set up an experiment in a cold container on board. I incubated 20 cores, taken with the multiple corer at Maud Rise, in a dark room at the temperature found at the bottom (0.5°C) and oxygenated the water. The only thing I couldn’t simulate to make them feel at home was pressure. I took quite a risk by taking the samples from 2150m depth.

To keep bacteria and nematodes alive for several days I learned from predecessor to take samples from a depth down to 1800m to be on the safe side. But no risk, no fun, right? So, I injected these cores with different chemical substrates which enhance the growth of certain bacteria and labeled them with a marker (13C). If my nematodes feed on them I can trace this marker in their body tissues. I ran this experiment for 12 days. It was a great pleasure that Oliver Sachs and Eberhard Sauter joined me in this experiment and proposed to measure oxygen profiles in the sediment. And Henri Robert taught me how to extract bacterial DNA and lent me some material to do so. These analyses could add some really nice data to the final result and I’m very excited about it.

Yesterday I ended the experiment by fixing the last samples. I also had a look in the control sample to check if my nematodes were still alive (and thus feeding). I was so thrilled to see two crawling worms that I felt like announcing it through the intercom! However, I guess people would not have rushed down the stairs to share my enthusiasm as they did with the orcas. But that’s ok, because I’m already glad you read through this little note about my work and came to the conclusion that nematodes are quit tough, little beings.

Katja Guilini, University of Ghent



Photos: K. Guilini and G. Veit-Köhler, Senckenberg

Image 20080117_incubation_core_KGuilini.jpg
sediment from the multicorer is incubated for nematode feeding experiments
Location: 64°28.84' S, 2°52.49' E

Image 20080117_slicing_sediment_GVeitKoehler.jpg
sediment from the multicorer is sliced for further analysis
Location: 64°28.84' S, 2°52.49' E