"One key question in ecological research is which factors regulate community composition and diversity at various temporal and spatial scales. Since bacteria are key drivers of ecosystem function, it is of particular importance to focus on mechanisms regulating their community structure to be able to make predictions about the effects of environmental changes on biogeochemical cycling. In the proposed project I will implement a number of field surveys as well as laboratory and field experiments using bacterial communities in rock pools as model systems. The project investigates the importance of local and regional factors for bacterial community composition and assembly, the character and extent of ecological differentiation within bacterial communities, and the effect of disturbance intensity and frequency on bacterial community composition. This project will therefore significantly advance our knowledge about bacterial biogeography, regulating factors of microbial diversity, and microbial metacommunity ecology. It will also help us to understand to which degree bacterial community composition is predictable from the environmental conditions and provide insights into the resistance and resilience of bacterial communities after a disturbance event. This information will help us to validate whether predictable changes in microbial communities and associated ecosystem processes may occur as a result of climate or environmental change."