Impact of climate variability on the bentho-pelagic coupling in a large river

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Benthic consumers can play an important role in controlling plankton in river systems. The degree of the loss to the benthos is strongly dependent on climate related factors, i.e. temperature and rain fall (water level). Mismatches in the balance between the growth of planktonic organisms and their loss induced by the benthos might strongly influence the ecosystem function. Here we aim to provide a data to explain and predict the benthic impact on the development of different plankton groups in response to changing climate conditions using River Rhine as a model system. Under normal conditions the trophic interactions between benthic and pelagic communities in rivers are much closer than in standing waters. Different approaches including field studies as well as experiments on the bentho-pelagic coupling will be applied. The experiments will be conducted in different flow channels including river bypass systems in order to estimate the impact of benthic key species and benthic communities on the different plankton groups under changing temperature condition. The spatial and temporal dynamics of potential benthic consumers (especially among the biofilm-associated fauna) will be investigated in the field. In addition, based on a long term sampling campaign, the analysis of the dynamics of significant plankton groups will be continued with focus on the impact of climate variations on the plankton composition. If there are significant changes in the matches/mismatches of bentho-pelagic interactions this would have tremendous influences on the functioning of river systems (degradation of organic compounds, etc.). The major aim of our study will be the analysis of conditions for possible mismatches. River systems are generally expected to face the greatest environmental changes with global climatic changes compared to lake or marine systems.