Bacteria are immensely diverse and drive many ecosystem processes. Bacterial biogeography as well as the coupling between bacterial community composition and functioning is affecting entire ecosystems but the mechanisms behind these processes are still unclear. We analyzed the composition of active and present bacterial communities of seven natural freshwater ecosystems with low, medium and high connectivity between local communities by high-throughput sequencing of 16S rRNA and the 16S rRNA gene. We also assessed functioning of the bacterial community as bulk bacterial production and carbon substrate use. <p> Environmental freshwater bacteria from water column and sediments.