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Limnology

LimnologieLimnology is the science of inland waters. Thus it is the branch of ecology which considers lakes, running waters and groundwater. The research in our working group is focussed on the role of microorganisms in the flow of matter and energy in streams and rivers, but we are working also on groundwater environments. Bacteria and other microorganisms in these environments are regarded not only as the main mineralisers of organic matter but also as important food resource for higher trophic levels.
 
 


Main research
  • Structure of microbial communities. The development of molecular biology methods meanwhile allows their application for determining the composition of microbial communities in natural environments. Mainly we are using the techniques of fluorescence-in-situ-hybridisation (FISH/CARD-FISH), temperature as well as denaturing gradient gel electrophoresis (TGGE/DGGE) and sequence analysis.
  • Function of microbial communities. Besides quantifying bacterial biomass production via uptake of labelled (14C/3H) leucine, research is directed especially to the degradation of macromolecular organic substances by use of fluorigenic model substrates. In aquatic environments by far the largest proportion of organic matter consists of high molecular weight compounds, which cannot be incorporated into microbial cells. Thus the macromolecules need to be cleaved into smaller units by extracellular enzymes, which are produced mainly by microorganisms, before they can be utilized.


Most actual topics
  • Desiccating streams. Increasing desiccation of headwater streambeds as a result of climate change and water withdrawal is observed also on Central Europe. The consequences especially for microbial communities and for running water ecosystems in general are in the focus of the group’s research for several years.
  • Groundwater ecosystems exhibit a special food chain because of their dependence on organic matter inputs from the earth’s surface. This results in the dominance of heterotrophic microorganisms. Despite their great importance as drinking water resource, groundwater ecosystems are considerably understudied. But they are studied in the group for a long time.
  • Eichhornia. The activity of mineralising microbial communities associated to the roots of Eichhornia seems to be necessary to enable the high productivity of these important floating plants in the nutrient poor inland waters of Colombia. These processes are investigated in co-operation with the Universidad de Antioquia in Medellín (Colombia).