Interreg

Harmonisation of phytoplankton assessment in the German-Dutch Wadden Sea

Undesirable nutrient accumulation (eutrophication) remains a problematic issue in many European coastal waters, although the measures taken in recent decades have already led to a decrease in riverine loads and nutrient concentrations along coasts, thus reducing the impact on coastal ecosystems such as the UNESCO World Heritage Wadden Sea.

At present, the biomass of phytoplankton serves as a key indicator of the extent of eutrophication. As the current assessment of phytoplankton in the German-Dutch coastal waters in the course of the Water Framework Directive (WFD) does not yet provide satisfactory results, a transboundary research project is intended to develop further knowledge that will lead to a more comprehensive understanding of the Wadden Sea system and a harmonised assessment of phytoplankton.

This project follows an innovative approach by choosing a multi-causal research approach and by considering different parameters concerning phytoplankton and eutrophication in a cross-national ecosystem modelling. For this, the latest scientific findings and existing long-term monitoring data have already been included and analyzed in order to achieve the most realistic possible representation of the Wadden Sea system in the various ecosystem models. Based on this, reference conditions for the Wadden Sea and threshold values for the assessment of phytoplankton will be derived in the next steps. In order to complement the existing assessment of phytoplankton using the biomass indicator chlorophyll, an additional assessment approach is being developed that includes various biodiversity indices.

In addition, the project aims to strengthen cooperation between German and Dutch authorities and research institutions and to promote a common understanding of the cross-border issue, thus contributing to a sustainable management of nutrient inputs into the coastal waters of the Dutch-German Wadden Sea. Beyond the activities of the project period, the results of this project can contribute important findings to current developments and discussions in the context of the WFD, MSFD and OSPAR and provide important foundations for a scientifically based system understanding of the Wadden Sea in the long term.