Electricity on the seafloor

Imagine that there has been a nuclear war and we all live in some kind of fallout zone. Stockholm is full of food, but there is no oxygen. In Uppsala, on the other hand, there is plenty of oxygen but no food. So, what to do? As with so many other things in life the answer to this question is cooperation. Let’s say that people decide to create a chain between the two cities, passing food from Stockholm to Uppsala at the same time as balloons with oxygenated air are sent in the other direction. In this way everybody gets what they need – food and oxygen.

This is the reply I got when I asked Sebastiaan to describe cable bacteria.

Sebastiaan is one half of the cable bacteria team, which also is comprised by Ugo. Ugo and Sebastiaan are the Chip ’n’ Dale on this ship (I have not yet figured out who’s who). One minute they nag at each other like an old married couple, then suddenly they are best friends and try to decide how to easiest lock me up in the cool container. They also happen to be awesome scientists.


Back to the cable bacteria. These fellows can create chains in the sediment, with the top in the oxygenated part and the bottom in the sulfidic part. At each end a half-cell reaction takes place. In the bottom, hydrogen sulphide is oxidized to sulphate ions, releasing electrons that are shuttled through the chain to the top, where the electrons are used to reduce oxygen to water. The bacteria actually create an electric current. They are like a tiiiiiiiny cables. So, Ugo’s and Sebastiaans job during this cruise is to see if there are any cable bacteria in the newly oxygenated sediments of the Baltic Sea. They have been my sediment-digging buddies, collecting sediment cores that they investigate with microsensors to look at oxygen-, hydrogen sulphicde- and pH- profiles. Then they slice the cores for later FISH analysis (technique to detect DNA sequences) and extract the pore water to look at … everything (at least that’s what it seems like to me).



Last Wednesday we had a day off, an extremely rare event during cruises. I joined the guys for a walk to explore Gotland and enjoy the sunny afternoon. Or so I thought. The walk turned out to be a chase after possible cable bacteria sites – every ditch was investigated, every pond looked into. Ugo complained about not having brought tubes to collect sediment cores in. Scientists…

Best wishes from Herrvik,