The Danube Delta Biosphere Reserve is a sensitive ecosystem crossing the Romanian and Ukrainian borders. Many studies have been performed separately, in the Romanian or the Ukrainian part of the delta, without a common coordination. This integrated project reunites two teams of hydrobiologists from both countries in a joint effort to assess the impactof environmental change upon different types of aquatic ecosystems.Theproject will assess the ecological impact of environmental changes regarding water quantity and quality of the Danube River upon aquatic communities of plankton, benthic organisms and macrophytes. Comparing regulated and natural channels as well as lakes with larger and smaller nutrient load is a key topic of the study. For the first time such a comparison will be possible between the Romanian and Ukrainian parts of the delta.