Wadden Seagrass Restoration
Participating parties
Waddenvereniging (Wadden Sea Society), Natuurmonumenten (Nature Conservation), Rijkswaterstaat Noord-Nederland (Directorate-General for Public Works and Water Management North Netherlands), Deltares
Project description
High sands protect the coast against the sea. Seagrass fields are ‘silt catchers’ and contribute to silt sedimentation, and thus enable high sands to grow with the sea. A potential way of restoring seagrass fields is to collect mature seagrass stalks towards the end of the flowering season and take them to the areas in question, packed in floating bags (nets). There, the seeds will be able to germinate in the shelter of shellfish banks. Experience with this method has been gained already in the United States. To select the most promising location, use can be made of the recently prepared ‘opportunity map’.
This concerns an experimental project of some four hectares that can be executed within one to two years.
Growing sandbanks
The speed with which sandbanks grow in relation to seagrass is expected to be relatively slow, but that also applies to the rising of the sea level. It is clear, however, that more needs to be done. For example, it is accepted that the restoration of old, stable mussel banks would further improve the situation, although not enough is known yet about how they should be restored.
There is every indication that seagrass fields in the Dutch Wadden Sea were affected by a fungal disease in the 1930s and did not recover due to the water’s great turbidity as well as a lack of freshwater and saltwater transitions. These transitions disappeared, among others, as a result of the closure of the Zuiderzee and later the Lauwersmeer. Consideration is currently being given to ways of (partly) restoring these transitions.
Characteristic biotope
Seagrass has virtually disappeared from the Dutch Wadden Sea. Seagrass fields in the area between the Wadden and the edge of the salt marshes contribute to the preservation and formation of the salt marshes. Moreover, seagrass fields are biotopes with characteristic biodiversity.
Seagrass - or seaweed - used to be abundantly present and was employed in a variety of ways. This is a topical issue once again, given the new seagrass fields that have emerged recently.
Feasibility
The project could be financed from the Wadden Sea budget of the EU Water Framework Directive (EWFD). However, funds still have to be raised for monitoring tasks and communication (perhaps also webcams).
Land need not be purchased for this project. The land belongs to Domeinen (Dutch State Property Service, which is part of the Ministry of Finance) and is being administered by Rijkswaterstaat. This means that implementation of the project could start swiftly.
Waddenvereniging and Natuurmonumenten could mobilize volunteers quickly. Support and monitoring could come from research institutes such as Deltares, NIOO and Radboud University.
