Ju­dith van der Gies­sen

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Department of Biogeochemistry

MPI for Marine Microbiology
Celsiusstr. 1
D-28359 Bremen
Germany

Raum: 

3129

Telefon: 

+49 421 2028-6361

Judith van der Giessen
 

Re­se­arch In­te­rests

I stu­dy the role of mi­cro­or­ga­nisms in methane cycling in freshwater lakes and coastal systems. My re­se­arch sites in­clu­de stratified lakes in Switzerland and seagrass meadows in the Mediterranean Sea:

  • In large lakes, the majority of the produced methane by oxygen sensitive methanogens in sediments is depleted before it reaches the surface waters. Nonetheless, methane super-saturation has been reported to occur in oxic surface waters of freshwater lakes. I study which microbial processes contribute to this so called ‘methane paradox’ in lakes.
  • Seagrass ecosystems store carbon in the form of peat deposits. However, due to the high organic matter content and anoxic conditions in the underlying sediment, they are also systems in which methane production by methanogens readily occurs. I am interested how microorganisms associated with the seagrasses as well as the overlaying water column affect the methane cycling in seagrass meadows.

In my doc­to­ral stu­dy, I per­form stable isotope incubation experiments fol­lo­wed by isotope-ratio mass spectrometry analyses. The­se will be com­bi­ned with biogeochemical in situ profiles (e.g. nut­ri­ents and ga­ses) and molecular methods (e.g. DNA/​RNA se­quen­cing and cell vi­sua­liza­t­i­on).

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