Sedimentary DNA based reconstruction of cyanobacterial communities from Lake Tiefer See NE Germany for the last 11 000 years Climate change and human driven eutrophication promote the spread of harmful cyanobacteria blooms in lakes worldwide which affects water quality and impairs the aquatic food chain. In recent times sedimentary ancient DNA based (sedaDNA) studies were used to probe how centuries of climate and environmental changes have affected cyanobacterial assemblages in temperate lakes. However there is a lack of information on the consistency between sediment deposited cyanobacteria communities versus those of the water column and on the individual role of natural climatic changes versus human pressure on cyanobacteria community dynamics over multi millennia time scales. Therefore this thesis uses sedimentary ancient DNA of Lake Tiefer See in northeastern Germany to trace the deposition of cyanobacteria along the water column into the sediment and to reconstruct cyanobacteria communities spanning the last 11 000 years using a set of molecular techniques including quantitative PCR biomarkers metabarcoding and metagenome sequence analyses. ...