Understanding how complex aquatic ecosystems function is vital for the conservation and management of species and natural resources. This project tackles the issue by developing mechanistic tools using which ecosystem functioning can be predicted under alternative scenarios regarding eg human use, climate change, fishing, and environmental alterations. The project objectives are two fold: the development of methodology and theory and their application to three aquatic study systems. Within the methodology development part, we have recently developed a modelling tool using which contemporary species evolution can be studied in an ecosystem context. This allows us to understand evolutionary consequences of external drivers and how selection arises from species interactions.Our tools will provides ways to improve conservation and management of aquatic systems and their healthy structure and functioning.