The scope of this project is to assess microbial diversity from an ecologically relevant perspective, to relate this diversity to environmental factors (e.g. physico-chemical conditions, environmental changes, climate) and to analyse the contribution of microbes or microbial diversity to the overall biodiversity in lakes, taking into account endogenous ecosystem properties and responses to environmental stresses. It is intended to demonstrate that molecular markers, such as pigments and especially lipids, can be used for this purpose.
Fairly stable lipids (hopanoids, sterols, gamma ceranes, etc.) will be analyzed in the water column and in the sediments of lakes. A total of 24 lake sites will be selected along the major climatic zones of Europe and with respect to trophic status of the lakes.
It is assumed that stable lipids and pigments, ubiquitously distributed in the organic matter of lake sediments, can be used as markers of the diversity of living communities. To validate the results obtained on changes in lipid and pigment contents in relation to environmental changes, they will be compared to other approaches, in particular palaeoecological methods, primarily fossil remain studies (e.g. Diatoms, Ostracods, Cladocera).
Further microbiological, biochemical and chemical laboratory experiments will be performed to validate the significance of lipids as markers. Finally multivariate statistical analyses will be employed to investigate the importance of environmental variables in explaining any differences in microbial diversity observed along the investigated time scales and environmental gradients.
Finally, a model will be generated allowing a prognosis of changes in microorganism diversity in relation to environmental changes of global relevance.