Ørsted, The Rich North Sea, Wageningen Marine Research and the Win-Wind consortium have recently launched a study on the behaviour of cod and lobster in Ørsted’s wind farm Borssele 1&2. Ørsted has installed four artificial reefs in the windmill park in the fourth quarter of 2020, in line with its ambition to design nature-inclusive offshore wind farms. Researchers use transponders to study these species that have a marked preference for hard substrate, such as artificial reefs, in their direct living environment. Moreover, eDNA samples will be taken from the water to provide insight into the development of biodiversity on the artificial reefs. The offshore wind farm has been fully operational since the last quarter of 2020. The official opening will take place on September 6th 2021.

Research on underwater life in wind farms
Research¹ shows that biodiversity in offshore wind farms increases around the bases of the turbines. Ørsted, Wageningen Marine Research, the Win-Wind consortium and The Rich North Sea are investigating additional strategies to stimulate marine life in wind parks. In this collaborative study, the researchers assess the impacts of four artificial reefs on marine nature. The study of these artificial reefs in Borssele 1&2 consists of three parts. First, the movements of individual Atlantic cod are monitored over a period of over two years to study their behaviour around each artificial reef. Secondly, a similar study of the movements of European lobsters is conducted. And finally, the biodiversity is mapped through a variety of monitoring methods.

Tracking cod
In the first part of the project, researchers from Wageningen Marine Research study the behaviour of individual Atlantic cod (Gadus morhua) around the installed reefs. The cod was selected because it is seen as a key species, making it important in the functioning of the local ecosystem. The survival and behaviour of the Atlantic cod provide the first clues about the suitability of the artificial reef as a habitat. During this stage of the study, 45 cod were fitted with acoustic transponders. The fish were caught on-site, equipped with a transponder and released back into the water. The transponders provide real-time information on the animals’ movements and activities. These data allow the behaviour of each individual fish to be studied so that the artificial reef’s functioning to improve nature can be evaluated.

Lobster behaviour
The European lobster’s (Homarus gammarus) behaviour is studied by researchers from Wageningen Marine Research, the Win-Wind consortium and The Rich North Sea. The researchers equipped twelve lobsters with acoustic transponders. Insight into the movements, distribution and activities of the lobsters can be linked to the predation pressure of lobsters on the reef community. This, in turn, provides insight into the expected biological development of the artificial reefs. The knowledge acquired through this part of the project will help fill a gap in scientific literature. Knowledge about the mobility of lobsters is also useful for the possible development of a sustainable lobster harvest.

Biodiversity around the reefs
The third part of the project, which is led by The Rich North Sea, monitors the biodiversity around the recently placed reefs. This is done through eDNA analysis. This method is used to establish the number of species present in the water. Researchers take water samples, which are analysed in a laboratory. The analysis shows what animal species and organisms are present in the area. This study is repeated annually so that the development of biodiversity through time is followed.

Towards a toolbox
Over the next three years, the researchers aim to discover more about how nature develops on and around the artificial reefs. How do the tagged cod and lobsters behave in the wind farm, and do they use the artificial reefs as shelter and foraging area? How does biodiversity develop? The results of this study are to be published and added to The Rich North Sea’s open access toolbox. This toolbox contains a combination of scientific knowledge and operational experience, which provides insight into the opportunities and possibilities of combining offshore wind farming and artificial reefs with biodiversity improvements.

¹ Coolen, J.W.P, Van Der, Babeth Weide, Cuperus Joël, Maxime Blomberg, Van, Godfried W.N.M Moorsel, Marco A Faasse, Oscar G Bos, Steven Degraer, and Han J Lindeboom. 2020. “Benthic Biodiversity on Old Platforms, Young Wind Farms, and Rocky Reefs. Ices Journal of Marine Science 77 (3): 1250–65.