Bacterioplankton and its role in the marine carbon cycle in changing coastal seas
Today’s ocean is the largest sink for anthropogenic CO2 in the global carbon cycle, resulting in a considerable slowdown of global warming but also in the rapid acidification of the oceans. The assimilation and mineralization of dissolved organic carbon (DOC) by marine bacterioplankton is a major process in the ocean carbon cycle. About 50 % of the carbon fixed by primary production is re -mineralized by bacteria. The role of bacteria in the marine carbon cycle is more complex, however. They can also influence the export of carbon from the surface ocean to deeper water by exhibiting positive (e.g. by releasing sticky transparent exopolymers) or negative (e.g. by digestion of sticky phytoplankton mucus by bacterial enzymes) effects on the formation of fast sinking aggregates. Little is known, however, how these processes are influenced by environmental factors or which changes are to expect in a high CO2 environment.
My research interests are in the influence of community structure (functional diversity) versus physiological changes of bacteria on the marine carbon cycle in the surface ocean. I am also interested in differences between seasons and the effect of global and regional environmental changes on these processes as well as in possible shifts in food web structures. To investigate this I want to use a set of molecular biological and biogeochemical methods:
- Molecular fingerprinting: e.g. Automated Ribosomal Intergenic Spacer Analysis (ARISA)
- Measurement of bacterial activity: carbon uptake, respiration, excretion of enzymes
- Measurement of labile and exportable carbon fractions
- Measurement of environmental data: temperature, salinity, …
- (In situ -) Mesocosms
For this purpose I am glad to work with two working groups at the Alfred – Wegener – Institute, the Helmholtz University Young Investigators Group “Global Change & the Future Marine Carbon Cycle” (GloCar) of Dr. Anja Engel and the microbial ecology working group of Dr. Gunnar Gerdts and Dr. Antje Wichels.
- POLMAR PhD scholarship recipient
