I am interested in interactions that aquatic organisms have with each other and to their natural environment. In short that is called Aquatic Ecology. Microorganisms can “eat” many different chemical compounds and they can respire with other chemicals than oxygen. My research focuses on how different members of a microbial community are linked into chemical food webs via what they “eat”: One bacterium will gain energy by oxidizing organic debris with sulfate and it will release hydrogen sulfide as waste. Another bacterium will gain energy by oxidizing that hydrogen sulfide with oxygen and regenerate the sulfate. Anyone can find this system at a muddy shore. If the mud is disturbed it releases the smell of rotten egg. That is the hydrogen sulfide. The reason why it does not smell unless disturbed is that the sulfide-oxidizing bacteria “eat” the hydrogen sulfide.

  The molecules that are waste for one bacteria move by molecular diffusion to those bacteria that see it as food. Sometimes the two partners are linked closely together; sometimes they are separated by many meters. I study the “chemical food web” in marine sediment by measuring the transport of molecules between the bacteria. I get most of my data from the distribution of dissolved chemicals in sediment cores. My work has taken me around the world on many research vessels. It has even taken me to the bottom of the ocean in a submarine. I get invited to sail because I can weld, cook, dive, solder, and operate cranes and fork lifts. Life on a research vessel is a lot more than Aquatic Ecology!

  As an important tool in my work I build computer models of the microbial food web. This helps me to test my ideas and to calculate things that I can not measure. My models are very simple from a mathematical point of view. But the ideas and concepts that I test in them can be on the cutting edge of research. I teach students how to build such models in a “hands on” course in computer modeling of biological processes.

Research areas:

• Biogeochemistry
• Microbial ecology