Ørsted and Van Oord have installed droppable oyster structures around the Borssele 1&2 offshore wind farm in the southern Dutch North Sea.
These are portable reef structures with adult oysters attached. Larvae produced by the oysters should colonize and ultimately form oyster reefs at the site.
According to Van Oord, this new installation technique is an economic way of introducing oysters at wind farms on a large scale to boost biodiversity.
The company has been working with Ørsted to reintroduce the European flat oyster to the North Sea. Previously, oysters were deposited mainly on large, heavy oyster structures, which Van Oord says is a costly process involving a crane installation.
Droppable oyster structures can be installed by manual placement on the seabed from the deck of a small vessel. Transport and installation can be incorporated into regular maintenance conducted at the wind farm.
An underwater camera will monitor the structures and oysters over time, assessing the impact on the local ecosystem.
In the late 1800s, about 20% of the Dutch North Sea seabed was covered with large-scale oyster reefs, Van Oord said, but these wild oyster reefs have virtually disappeared from the North Sea as a whole.
They provided filtration that improved water quality, along with habitats, food and shelter to various species of fish and shellfish.
North Sea wind farms provide a hard substrate and undisturbed seabed that can support restoration of the flat oyster population in the North Sea.
