Impacts and dynamics of nitrogen supply in lake ecosystems
Anthropogenically enhanced nitrogen supply in lakes often implies changes in the lakes ecosystems and due to the worlds' increasing food demand and the related nitrogen rich fertilizers, nitrogen supply will further increase in the future. This study investigates the influence of enhanced nitrogen load on plankton communities in lakes in Upper Bavaria (Lakes Brunnsee, Klostersee and Thalersee near the Limnological Research Station in Seeon) and determines changes of the nitrogen load in the past. For the evaluation of the recent nitrogen flux from the atmosphere to lake sediments, nitrogen concentrations are measured in precipitation, lake pelagial and lake sediments. Analyses of total nitrogen content and nitrogen stable isotopes in lake sediment cores allow to detect changes in the nitrogen load of the past ~150 years. In mecocosm-experiments on the lakes, the influence of enhanced nitrogen supply on biomass stoichiometry and biodiversity of natural phytoplankton communities and the interaction with zooplankton will be investigated.