As a child I used to play “Schiffe versenken”. I think in English it’s called “play battleships”. This was all just on a piece of paper. It was also just on a piece of paper when Jan introduced an idea to me which he and Lennart had come up with: Sink our mesocosms. What a crazy concept! The mesocosms were made to float. Sinking them sounded like committing a massacre. But on second thought the idea become somewhat less crazy. We are in need of protecting our floating giant test tubes from damage by drifting ice floes. Not an easy task given the strong surface currents we are experiencing in the Gullmar Fjord. Once the ice starts drifting, it develops incredible forces. Wouldn’t our giant babies be much safer under the ice?

Anchor weights ready for deployment

Well then, why not sink the mesocosms. The drawing Jan had prepared to explain how to sink them looked daring. When he started explaining it, it only got worse. It took us two days of discussions and weighing the pros and cons before most of us felt comfortable that it was doable. The next step was going shopping: Jan toured the hardware stores and mountaineer shops in the area to get hundreds of meters of extra ropes, shekels, and some high-tech clamps. Matias contacted the Swedish railway company to inquire about railway wheels for sale. Andrea phoned various shipyards and junk dealers in search for disused anchors or scrap metal – we needed seven anchor weights of at least 300 kg each. At the end we decided to use some railway wheels stored at GEOMAR’s logistics centre in Kiel, which Mario delivered in Kristineberg the next day.

What followed were three days of frantic preparations to get ready for “sinking the mesocosms”. The railway wheels were transported out to the mesocosms on the side of Wassermann and lowered to their position at the sea floor very carefully. Pulley tackles were connected. Buoys were taken out and anchoring ropes shortened. Lots of hard work for everyone involved, in particular Jan, the man in charge, and his team of divers, Michael, Matthias and Matze. At the end of all this, from a bird’s view our mesocosm set-up doesn’t look much different. But underneath the surface is a system that will make them dive under if needed.

WASSERMANN breaking the ice

Now we are anxiously watching the weather forecast. Freezing temperatures for at least another week. Right now the north-easterly winds are strong enough to prevent new ice formation. It’s predicted to stay like this for at least another few days. Let’s hope we don’t need to play “Schiffe versenken” after all.

By Ulf Riebesell