PS120 - Weekly Report No. 3 | 17 - 23 June 2019

Working in the Ocean

[24. June 2019] 

It is Sunday today on the POLARSTERN. I was delighted with the crispy croissant and apricot jam, which I consumed for breakfast with a delicious cup of creamy coffee, this morning. Our research doesn´t stop on Sundays. Ship time for ocean research is too precious.

We had many highlights this week. We particularly enjoyed answering the questions on Climate we got over Skype from the young people attending the Climate Conference in Leipzig and the joint action we had for Fridays4future in collaboration with the RV Sonne was an uplifting experience.

We now have reached waters (in front of Portugal) which are familiar to us, because we have sampled here at set coordinates before on previous ocean expeditions, e.g. on Transits from Bremerhaven to Capetown. We are now revisiting these sampling sites and will examine how temperature has changed over the past years in the different depths.  We know that the surface of the oceans have warmed by a mean of 0.8 °C, but how exactly this manifests over depth is largely unknown. After all, it is not trivial to take samples of water way out in the ocean, and then even more difficult to take them at depths of many kilometres. This can be done only with specially equipped ships such as the POLARSTERN. Using a so-called „Rosette“ with watersamplers (10 l Nisken bottles) and a monitoring device called a CTD (conductivity, temperature, depth) we sample water at different depths. When we get the water back to the surface, we divide it up fairly between the scientists and analyse/conserve it immediately. One of the interesting topics on which we know very little is  the diversity of microorganisms in the oceans.

We are very lucky to have the microbiologist Dr. Anneke Heins from the Max-Planck-Institut für Mikrobiologie, Bremen, on board with us. She is teaching the scholars and all of us new methods for doing this. She has kindly put together a piece on her work, to share with you all at home.  

“Microbiology aboard the Polarstern

Hunting bacterial communities from South to North and from the surface to the seafloor”

For four weeks now, we have been sampling different water masses across the Atlantic Ocean from the Falkland Islands to Bremerhaven aboard the RV Polarstern. Our international scholars are gaining lab and field work experience by taking samples from the CTD rosette. First, the  sampled water is filtered successively through filters with decreasing pore sizes (10 µm, 3 µm and 0.2 µm filter pore size), then the scholars extract environmental DNA (eDNA) from these size fractions, which is stained and visualized on a gel. For later cultivation purpose, the scholars learn how to dilute samples, inoculate plates and store samples. In the context of climate change, our scholars discuss current publications on the bacterial communities in the Atlantic Ocean and how these might change with increasing water temperatures, acidification and other effects of a changing climate. How bacteria react to these environmental changes remains largely unknown and unmonitored, despite their major role in the carbon and other nutrient cycles. Bringing attention to this topic is of major importance, especially for young scientists, who can implement their knowledge into their field of work. The integration of single topics and breaching of their usual boundaries is one of the great chances that this expedition provides. It teaches the students the connection between the disciplines – from the smallest microbe at the ocean floor to atmospheric phenomena over scales of many kilometers.

Now  it is nearly time for Sunday lunch, which one tries very hard not to miss on POLARSTERN, because it is particularly tasty and caringly prepared. It also always helps to sit down to these Sunday meals, when one is tired from working all night and when the days run into one another and we forget which day of the week it is. We are doing well here, working hard, and with the help of everyone on board, everything has functioned as planned.

Sending our best wishes to you, our families, friends and colleagues.

Karen Wiltshire



Karen Helen Wiltshire

Scientific Coordination

Rainer Knust
Rainer Knust


Sanne Bochert
Sanne Bochert