Type of infrastructure:
Location:
Country:
Netherlands
Targeted species or habitat:
Implementation period:
2020 - 2028
Implemented by:
The Rich North Sea, Blauwwind consortium, Van Oord, Bluestream offshore, and Eurofins AquaSense
TRL:
6
Funding:
The Rich North Sea and Blauwwind consortium

Knowledge sharing

More detailed information about the project is available at the Rich North Sea’s Toolbox. The project partners aim to share lessons learned with scientists, wind developers and government officials in the Netherlands as well as internationally.

Database Project

Oyster Broodstock Structures at the Blauwwind (Borssele III & IV) Offshore Wind Farm

Objectives

To study flat oyster broodstock placement and rock reef development within offshore wind farms, with a particular focus on assessing the potential reproduction of the European flat oyster, as well as the establishment of young spat.


Short description

In 2020, researchers installed four oyster broodstock structures near the monopile foundations at the Blauwwind offshore wind farm in Borssele III & IVBlauwwind offshore wind farm (Borssele III & IV) is located about 25 kilometres outside the coastline of Zeeland, in the Netherlands. The turbines will supply a renewable energy equivalent to the consumption of 825,000 Dutch households.  , Netherlands. The broodstock structures housed 2,400 live flat oysters enclosed within caged cabin. Additionally, rocks and layers of oyster shell were placed around wind turbine bases at eight different monopiles. This layer of stones, used as scour protection to prevent erosion, may also provide a suitable substrate for oyster settlement.

The pilot project aims to leverage the existing infrastructure of the wind farm to determine whether these oysters could successfully reproduce and if the young oysters, known as spat, could attach to the various substrates placed at the scour protection area, such as stones, gravel, or shell layers.

Innovative ecological monitoring techniques, such as eDNA analysis and remotely operated vehicles equipped with underwater cameras, have been used to assess biodiversity onsite. Four monitoring trips were scheduled between October 2020 and July 2028. The initial trip coincided with the installation of the oyster cages in 2020, while the final trip in 2028 will focus on decommissioning. Monitoring campaigns in 2021 and 2023 found a high survival rate of the adult oysters in the baskets (70% average from 2020 to 2023), with individual oysters showing gonadal development. Young oysters were observed both inside and outside the baskets, and some oyster larvae were found in the surrounding water. The broodstock structures have proven to be stable and an effective method for oyster outplacement.