With this talk, I will firstly show how the characteristic dendritic network structure of rivers, and spatial dynamics in general, are affecting biodiversity patterns and ecosystem functioning, and how a combination of mathematical models, laboratory-based experiments and large-scale empirical data can help to understand riverine meta-ecosystems. Secondly, I will address how environmental DNA (eDNA) and remote sensing integrate biodiversity information across catchments and can be used to assess the structure of whole ecological communities at unprecedented scales. Together, this provides novel understanding and perspectives on how riverine ecosystems can be managed and preserved.