In wind farm Luchterduinen an oyster trial took place in recent months: oyster banks and reef balls have been placed on the seabed. With these 'artificial reefs' we want to gain knowledge about the development of oyster banks within wind farms. The first results show that the design of the cages needs to be adapted.
The North Sea Foundation (Stichting de Noordzee) and Natuur & Milieu are conducting research into underwater nature in wind farms. The first research location is the Luchterduinen wind farm. This autumn a number of oyster cages and reef balls have been placed there. A monitoring expedition took place for the first time in the past few days. The first results show that nature development within wind farms is promising, but that the design of the current artificial reefs does not fit the conditions in the wind farm. The organisations have therefore decided to adapt the design of the cages first and then continue the research at sea.
In the 'The Rich North Sea' project, the nature organisations are working with Eneco Luchterduinen, Van Oord and ASN Bank. The nature development in the park is scientifically researched by Wageningen Marine Research, Bureau Waardenburg and Sas consultancy. Together, they are working on a blueprint for nature development within wind farms. These organisations are global pioneers in this field.
When collecting the oyster cages, it turned out that most of the oysters did not survive the winter. Part of the cages sunk into the ground, burying the oysters under a layer of and. However, in the cages where this was not the case, the survival rate of the animals was 80%. A hopeful result: when conditions are good, oysters can thrive in a wind farm on the North Sea. So, it seems that mortality is affected by the design of the cages. This design turned out not to be suitable for the conditions in this wind farm. However, the growth of the oysters shows that there is potential. In both live and dead oysters, the researchers found so-called growth rings. In the coming weeks more research will be done in the laboratory. The design of the cages will then go back to the drawing board.
Plenty of life
Underwater footage was also taken during monitoring. These images show that there is an abundance of life around the cages. The researchers found species such as crabs, mussels, anemones, starfish, pouting and squid eggs. To the delight of the scientists: the development of oyster beds also has potential for other species.
Thanks to a contribution from the Nationale Postcode Lottery's Droomfonds, the research and construction of underwater nature will be extended to other wind farms from 2020. In addition to oysters, the organisations there will also conduct research into living reefs with other shellfish. This is the first time that large-scale research can be carried out into the development of underwater nature in wind farms. The lessons learned from the oyster trial in Luchterduinen will be taken into account. Step by step, the nature organisations will find the most thorough and proven approach for the return of oyster reefs in the North Sea.