Long-term ecological research of aquatic ecosystems is fundamental to the understanding of ecosystem functioning given the complex nature of the effects of environmental forces. It contributes to the testing and development of ecosystem theory. Our three prime case study sites, with time series spanning several decades, represent common aquatic ecosystem types: Müggelsee- a shallow, polymictic, eutrophic lake; Stechlinsee- a deep, dimictic, oligotrophic lake; and the River Spree - a typical lowland river. The long-term monitoring programme on thermal, chemical and planktological properties, along with four automatic research stations, belong to the prime research infrastructure of the IGB. Several sites serve as ongoing study- and reference sites : the Tagliamento - a large alpine river, wetlands e.g. Demnitzer Mühlenfließ and lakes of different status, like the dimictic eutrophic Arendsee in nearby Brandenburg. Our long-term research attracts interdisciplinary research at the IGB, cooperation in international networks such as GLEON or European projects, and feeds into the internal research foci ‘Biodiversity’ and ‘Boundaries’.

The high temporal, taxonomical, and spatial resolution of the time series enables us to disentangle system complexity in ways to make imprints of extrinsic and intrinsic forces tractable – as such improving basic understanding of ecosystem functioning.

We aim to understand the impact of climatic forcing at different temporal scales on abiotic and biotic system levels in lakes and rivers and (ii) the role of biodiversity with respect to ecosystem functioning, adaptation, trends, threads and novel ecosystems. Studies are set in the context of multiple stressor effects such as changes in the climate, the catchments, eutrophication, changes in land use and the severity and frequency of extreme events.

Our long-term research has been crucial for management, as well as public and political outreach. It contributed substantially to recommendations given in the latest IPCC-report and supports national environmental agencies in their efforts to translate e.g. ‘Lake Indicator’ variables with respect to global warming impacts or recommendations for ecosystem management into political action.

We will proceed with the above mentioned prime research foci. Our long-term research will, however, be strengthened by detailed process studies given the establishment of large scale in-situ enclosure facilities e.g. at Stechlinsee. Studies on carbon dynamics between the aquatic and catchment realms will gain in relevance. We also seek to strengthen theory testing with empirical data–e.g. analyse system conditions prior to thresholds or else driven tipping points.