This is what I always thought the Antarctic summer should be like: the sun is shining out of a blue sky, the unfathomable water has a beautiful blue colour, and we are surrounded by icebergs displaying a high variety of shapes.
So I am standing on the work deck at 7 o’clock in the morning, waiting for my turn. The CTD with 24 water bottles, each closed at a different depth all the way down to the seafloor which here lies more than 5,000 m below the surface, is a sampling device in high demand among oceanographers and biologists.
I personally take samples from different depths to determine on board the chlorophyll concentrations down to 200 m. Additionally I take samples for the measurement of particulate organic carbon (POC) down to the seabed, to be made later on land at the AWI. These data provide important reference information needed by every biologist dealing with the life of animals in the water column.
Before me, however, the chemists can take their samples. They measure oxygen and carbon dioxide content of the water. To avoid contamination of their samples with intruding air, they have absolute priority.
Once I filled all my water bottles, I can go to my lab where two filtration apparatuses are waiting for me. I turn on the vacuum pumps to make the water run faster through the very fine filtration platelets, and I wait for the required volume of water to pass through. Sometimes one gets to watch something special during this rather meditative occupation. A blue flash of light emerges from the filter when I fold it to place it in a tube for further processing.
This light, which is called bioluminescence, comes from a copepod, a tiny crustacean. When they are stressed, they emit light. I did indeed stress the tiny creature. May Neptune forgive me.
Sarah Herrmann, Alfred Wegener Institute
Photos: B. Ebbe, Senckenberg