Wadden Sea seagrass restoration gains momentum with new sowing and research efforts
The Dutch government is expanding efforts to restore seagrass in the Wadden Sea, a vital ecosystem for marine life. New sowing and experiments aim to boost biodiversity, though challenges like mussel beds and seed availability persist. Citizens benefit from a healthier coastal environment and potential long-term ecological gains.
| Key Data | Details |
|---|---|
| Project | Seagrass restoration in the Wadden Sea (2022–2026) |
| Lead Agency | Dutch Ministry of Infrastructure and Water Management (Rijkswaterstaat) |
| 2026 Focus | Location research, new sowing sites, and dwarf eelgrass experiments |
| 2025 Results | Mixed: Griend field shrank, Ameland stable (34→36 hectares), more seeds |
| New Locations (2026) | West/East of Ameland, Ballastplaat (near Harlingen) |
| Experiment | 'QR code' pattern to study eelgrass-dwarf eelgrass interaction |
| Research Partners | Witteveen+Bos, University of Groningen, The Fieldwork Company, Altenburg & Wymenga |
| Goal | Permanent reintroduction of seagrass in Wadden Sea and Zeeland Delta |
The Ministry of Infrastructure and Water Management (Rijkswaterstaat) oversees the ecological restoration of the Wadden Sea, a UNESCO World Heritage site. Its role includes funding research, coordinating with scientific partners, and implementing measures to protect and revive marine ecosystems like seagrass fields.
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Dutch Ministry of Infrastructure and Water Management resumes seagrass sowing in the Wadden Sea
Published on: March 31, 2026, 12:32 PM
The Dutch Ministry of Infrastructure and Water Management (Rijkswaterstaat) began a new round of seagrass sowing in the Wadden Sea during the week of March 23–29, 2026. This year, the focus is primarily on location research and further expanding knowledge about both eelgrass and dwarf eelgrass.
Seagrass plays a crucial role in the Wadden Sea: it provides food, shelter, and nursery grounds for numerous animal and fish species. By initiating a new sowing round, we are continuing efforts to restore this valuable ecosystem.
2025 review shows mixed results
The 2025 seagrass season presented a mixed picture. The seagrass field near Griend shrank slightly last year, likely due to the formation of new mussel beds in the northeastern part of the field. These mussel beds occupy space that would otherwise be used by seagrass.
Near Ameland, the seagrass field remained stable, with a slight increase in area from 34 to 36 hectares. While the number of eelgrass plants decreased slightly, plant density actually increased. The causes of these changes are still under investigation and may be related to factors such as the abundance of seaweed, temperature variations, and the presence of lugworms.
Additionally, due to limited seed availability in 2025, less seagrass was sown compared to previous years. Monitoring in the summer revealed that the plants grown from these seeds developed shorter blades but produced significantly more seeds. These seeds are naturally dispersed within the system. With many seeds now present, there is hope that new plants will emerge in multiple locations next year.
Research on dwarf eelgrass is still in an experimental phase. Seed trials yielded very few seedlings, likely due to challenging germination conditions. Experiments with cores also showed varying success: near Ameland, only a few plants survived, while near Griend, nearly all plants remained and even expanded from a diameter of 9 cm to about 70 cm.
These experiments examined plant spacing that provides adequate protection and growth space. The fluctuations fall within natural annual variations. Seagrass fields respond to environmental factors, meaning years of growth and decline can alternate.
Plans to expand to new locations in 2026
Since the current seagrass fields near Griend and Ameland are stable and have reached their maximum size, new areas are being explored.
This year, new sowing and research sites will be established to the west and east of the existing field near Ameland. These locations rank high on the opportunity map, and large eelgrass was observed in previous years. Unlike the single large field near Griend, a network of smaller fields may develop near Ameland.
The Ballastplaat, northwest of Harlingen, will also be further investigated. Seagrass continued to grow here after an earlier trial. The large surface area makes this location promising for potential expansion.
In addition to sowing, smaller experiments will be conducted at all locations to better understand natural variations.
The 'QR code' experiment
Scaling up dwarf eelgrass receives extra attention at Griend. Cores will be placed in different sections: one part will follow an optimal spacing pattern, while another will use a checkerboard pattern with empty squares. This will help determine which method leads to the fastest expansion.
The interaction between eelgrass and dwarf eelgrass is also being studied. Dwarf eelgrass traps sediment and locally raises the seabed, creating sheltered pools. Last year, square patterns of dwarf eelgrass were planted, each with a pool in the center. This year, seeds of eelgrass will be sown in these sheltered spots. The goal is to discover how eelgrass and dwarf eelgrass can protect and support each other. From the air, the pattern resembles a QR code, a nickname the experiment has since acquired.
Five-year restoration project
Since 2022, we have been working on a five-year program to restore seagrass in the Wadden Sea and the Zeeland Delta. Witteveen+Bos, the University of Groningen, The Fieldwork Company, and Altenburg & Wymenga are conducting this research on behalf of Rijkswaterstaat. The aim is to permanently reintroduce seagrass in both areas.