Four so-called oyster tables are located in the Luchterduinen wind farm. An oyster table is a structure of concrete and other material on which live oysters are attached. With the installation of the oyster tables, De Rijke Noordzee, Eneco and Van Oord are working on the restoration of oyster reefs in the North Sea. The oyster tables have an innovative design, which was preceded by four years of research. This design has never been used before. This makes the wind farm a worldwide number one.
Oyster beds disappeared
Until about 200 years ago, large-scale oyster reefs were found on 20% of the Dutch North Sea. Now there are almost no wild oyster beds to be found in the North Sea. This is concerning because oyster beds are important to underwater ecosystems.
Erwin Coolen, program director De Rijke Noordzee: ‘A healthy North Sea is the key to achieving the climate goals. Nature development must therefore be an integral part of the construction of any park. Thousands of turbines will be added in the coming decades, so it is very important that we develop knowledge as quickly as possible about how this can best be done.’
New design oyster tables
The new design of the oyster tables is specially made for conditions such as those found in the Luchterduinen wind farm, where there are high flow speeds and a lot of sand. The new tables, which weigh more than three thousand kilos, are extra stable due to the weight at the bottom. The oyster tables are also located on the rock deposit around the windmill. This prevents the tables from sinking into the sandy seabed. The live oysters are for the first time glued to vertical poles in the new design, instead of being placed in baskets. This gives them enough fresh water and oxygen to survive and reproduce.
Remment ter Hofstede, Van Oord: ‘The knowledge we have gained about the function of oyster tables in previous projects has now been combined in this design for the Luchterduinen. It maximizes the chances of survival for the oyster, and we expect to be able to observe the development of real oyster reefs in this wind farm within a few years.’
Help restore oyster reefs
The oysters placed on the oyster tables may release larvae next year that can settle on a hard surface, for example on the rock deposits around the wind turbines. By giving the oyster a hand around the wind turbines in wind farms, there is a chance for oyster reefs to develop. Future monitoring missions will therefore focus on oyster growth, survival and reproduction.
Marin van Regteren, Eneco: ‘Living within the natural limits of the planet is what Eneco believes in and strives for. It is important that we develop offshore wind farms within the ecological space and contribute positively to nature in the North Sea in the future. With this project, we are taking an important step in promoting the underwater ecosystem.’
Luchterduinen wind farm
The first pilot of De Rijke Noordzee started in 2018 at the Luchterduinen wind farm, 23 kilometers off the coast at Noordwijk aan Zee. In the park, which has been in use since 2015, oyster cages and reef balls were exhibited for this purpose. Now, four years later, the researchers are installing new oyster tables, which have been developed on the basis of experience from previous projects within the wind farm.
The rich North Sea
De Rijke Noordzee researches natural development in offshore wind farms. De Rijke Noordzee was founded four years ago by the environmental organization Natuur & Milieu and Stichting De Noordzee. Because bottom fishing is not allowed in the parks, nature is given the opportunity to recover and flourish again. Thanks to a contribution from the Dream Foundation in the National Postcode Lottery, the rich West Sea can realize this ambition.