Posted on January 15, 2024
Ørsted and Van Oord’s initiative Ocean Health will install innovative droppable oyster structures in offshore windfarm Borssele 1&2, to introduce European flat oyster and enhance biodiversity in the windfarm. A new installation method will be applied, enabling affordable and manual deployment of oyster brood stock. These droppable oyster brood stock structures were designed and researched by Van Oord and Delft University of Technology and are suitable for large scale application.
‘We want the transition to renewable energy to be one that creates long-term value for people and nature, with a positive impact on climate and biodiversity. We’re partnering with experts like Van Oord to develop scalable restoration measures that can help us meet our net-positive biodiversity impact ambition’, Ruben Dijkstra – Managing Director Ørsted Benelux.
Karen Vennik, Director Offshore Energy: Van Oord has been actively involved in various pilots investigating the most optimal way of restoring flat oyster reefs in the North Sea as part of our Ocean Health mission. With our extensive inhouse environmental engineering knowledge built to date we are continuously looking at ways to create large scale impact. We are very pleased to join forces with Ørsted to achieve a next step in our joint ambition to enhance biodiversity.
150 years ago, roughly 20% of the bottom of the Dutch North Sea was covered with European flat oysters (Ostrea edulis). Oyster reefs provide a range of valuable ecosystem services, including but not limited to improved water quality due to filtration, increase in biodiversity by providing habitat, food and shelter for numerous fish and shellfish species. In the 20th century, the oyster population declined rapidly, primarily due to large scale fisheries and infection by the parasite Bonamia ostreae. Authorities and nature conservation organisations have identified the European flat oyster as a key species, in order to restore and strengthen the North Sea ecosystem.
Offshore wind farms provide hard substrate and undisturbed seabed, offering suitable locations to restore the flat oyster population in the North Sea. Offshore wind farms are currently located far away from the scare natural oyster reefs, which means there is no connectivity. To kick-start oyster reef development, oysters need to be introduced pro-actively.
Previously, Ørsted and Van Oord have both been engaged in multiple efforts to reintroduce the European flat oyster in the Dutch North Sea, by placing liftable brood stock structures. These are structures that contain adult oysters that can reproduce and function as a local larvae pump, leading to oyster settlement and eventually reef formation in the wind farms.
In our continuous efforts to scale up the effort activity on reintroduction European flat oyster reefs in the North Sea, we are looking for the most cost-effective ways to install and monitor oysters. With the innovative droppable oyster structures only a small vessel, such as a crew transfer vessel is required for the manual deployment of the structures. The installation can simply be incorporated in regular maintenance activities which allows us to accelerate biodiversity restoration activities. The new installation method will be tested and monitored in the Borssele 1&2 site starting 2024.