R&D highlights edition 2019

Ecosystems and environmental quality 27 T he Markermeer is a large man-made shallow freshwater lake in the centre of the Netherlands where siltation has an adverse effect on water quality and biodiversity. To improve the ecological status and species development, the Marker Wadden - a wetland of five islands - is being built using sand, clay and mud from the Markermeer lake. The Marker Wadden will also reduce the re-suspension of silt in the lake, creating transparency gradients. In addition, more leisure facilities will be created because one island is open to the public. The Marker Wadden is a unique nature restoration project: a new wetland of this size has never been created before with local materials, shaping opportunities for new life above and below the water and generating more leisure opportunities in the area. Moreover, the approach to building the Marker Wadden is new: a nature NGO (Natuurmonumenten) has a proeminent role and Rijkswaterstaat is actively engaging with private companies. This unique collaboration is an excellent opportunity to develop knowledge. Building started in 2016 and it is nearly finished. Research and monitoring on and around the islands began in the summer of 2017 and monitoring under the Knowledge and Innovation Programme Marker Wadden (KIMA) will continue until 2021. The initial results indicate the establishment of the food web: large amounts of zooplankton and small fish were observed (sixteen species were seen around the islands), as well as large amounts of both aquatic and terrestrial insects (including some rare species), which provide enough food for birds to stay and for some species like the Common Tern and Avocet to breed very successfully. Some less common and vulnerable bird species like the Little Tern are also breeding in relatively high numbers. The waters surrounding the Marker Wadden were seen to be remarkably transparent. Marsh vegetation is growingwell on the soil types used to build the islands, although the development of reedbeds and the diversity of the marsh vegetation is limited by bird grazing. The initial results look promising for the ecology. However, trends need to be monitored over a longer period to evaluate the success of this novel ecosystem and to apply this knowledge in other areas with similar problems. The Marker Wadden is open as a Living Lab for other researchers facilitated by KIMA. KIMA welcomed the first external researchers to the Living Lab this summer, such as a PhD student from Delft University of Technology who is studying the behaviour of sandy foreshores in lake systems. Another PhD student from Wageningen University has installed a measuring station on the Marker Wadden to quantify evaporation on large open waters. Deltares is one of the founders of the KIMA, which is operating in parallel and in close cooperation with the building of the Marker Wadden. Together with Rijkswaterstaat, EcoShape and Natuurmonumenten, Deltares is investigating the development of the Marker Wadden ecosystem. KIMA aims to generate and present knowledge about building with sediment, creating ecology with value, and governance. Deltares has been appointed the KIMA knowledge manager and, in this role, it will work on maintaining connections between academic, applied research and the ongoing research and monitoring efforts under the KIMA umbrella. Deltares is also providing specialist knowledge on the three KIMA themes. Contact: Sacha de Rijk, Sacha.deRijk@deltares.nl, t +31 (0)6 5150 4392 Further reading : https://kennismarkerwadden.nl/ MARKER WADDEN: NOVEL ECOSYSTEM AND LIVING LAB Aerial image of Marker Wadden in April 2018 (photo: John Gundlach - Flying Holland) Monitoring of fish on the shores of the Marker Wadden by Sportvisserij Nederland (photo: Gerard de Laak ) A novel ecosystem – the Marker Wadden – has been created to boost productivity and biodiversity in the Markermeer.