Interrelation between pesticide inputs, hydromorphology and source populations influencing the recolonization of benthic invertebrate communities

• Applicant: Professor Dr. Werner Brack
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 109219305

The restoration of natural hydromorphological conditions of stream sections aims to improve the riverine fauna. Yet, several of these restoration measures failed to rehabilitate the expected near-natural communities. At the same time, several pesticides are frequently detected in German surface waters that may limit the recolonisation of sensitive, habitat-demanding benthic invertebrate species. This proposal aims to develop two stressor-specific indicators to distinguish between the impacts of pesticide inputs and morphological degradation on macroinvertebrate communities. For this purpose, pesticide concentrations from an ongoing monitoring program will be converted to a measure of toxic stress and used together with effective hydromorphological parameters to derive a 'stressor profile' of sites. Concurrently we will consider the recovery potential of the landscape, taking source populations into account. To transfer the results to sites where no pesticide measurements are available, a GIS-based surface runoff model will be applied to estimate the magnitude of pesticide inputs. Finally, a spatially-explicit 'recolonization potential' model, which will be validated by field investigations, will allow to identify the driving forces affecting the current distribution and potential recolonisation of benthic invertebrate species.

• DFG Programme: Research Grants