Biodiversität und DNA-Taxonomie von Algen und Cyanobakterien in kalzifizierenden Biofilmen

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To verify and further elucidate taxon-specific activities of cyanobacteria and microalgae in stromatolite formation is the main goal of this project. In the previous project phase key player cyanobacteria and diatoms from two exemplar tufa creeks were revealed and it is now needed to explore their in situ abundances and distribution patterns in relation to CaCO3 precipitates and CaCO3-free areas. This will be visualized by rRNA-targeted Fluorescence In Situ Hybridization. The calcification potential of the key player cyanobacteria and algae will be tested as well which includes the establishment of new cultures as well. To further investigate the cyanobacterial control of stromatolite formation, cyanobacteria from a water setting significantly different from the tufa creeks need to be investigated and, therefore, the stratified microbial mats in the hypersaline environment at Christmas island (Kiritimati) will be selected. Seasonal changes in the taxonomic composition of the tufa creek biofilms may act as a possible additional driving force of tufa formation which will be assessed using rapid molecular methods. Results from the previous project phase indicate that the diversity of eukaryotic algae other than diatoms in relation to calcification may yet have been underestimated and thus it will be further evaluated here using culture-independent methods.