The researchers call the initial results “promising”. Wind farm developer Ørsted and partner De Rijke Noordzee are also pleased with the new nature development. Ørsted has installed four artificial reefs in the Borssele I & II wind farm as part of its ambition to design wind farms in a nature-inclusive way. Ruben Dijkstra, Managing Director Ørsted Benelux: “It is important that offshore wind energy and ecology go hand in hand. Ørsted sets up innovative biodiversity projects worldwide to test, gain experience and learn. This contributes to realizing our ambition to build offshore wind farms that have a net positive impact on biodiversity. It is great to see that the results of our biodiversity project in the Borssele I & II wind farm are promising. These results are public and we are sharing them with the scientific community.”
Through transmitter research, WMR researchers are studying the behavior of codfish and lobster underwater. Both species prefer hard substrate such as artificial reefs in their immediate habitat. “We want to know what role these artificial reefs play for our target species of cod and European lobster. That way, we can eventually advise on how to optimize these impulses for local biodiversity,” said Benoît Bergès and Marcel Rozemeijer of Wageningen Marine Research.
Codfish as key species
The behavior of Atlantic codfish (Gadus morhua) was chosen to be studied because it is a key species: an important species in the functioning of the local ecosystem. If codfish are doing well, it is an indication that the reefs are also suitable habitat for other species of fish, marine and benthic life.
In July 2021, 45 Atlantic codfish were fitted with acoustic transmitters (“tags”) to track their movements. In May 2022, the acoustic transmitters were retrieved and the data collected, after which the transmitters were redeployed. The data collected provides GPS coordinates through time. This revealed the effect of the four artificial reefs: Atlantic cod are attracted to the reef and like to stay in its vicinity.
Lobster sets high standards
Commissioned by The Rich North Sea, twelve European lobsters (Homarus gammarus) were also fitted with a transmitter and then released. Most lobsters had already left within a day. A few used a reef and its immediate surroundings for a few days, but then migrated on. Researcher Marcel Rozemeijer explains why: “Lobsters make high demands on their environment. They have a strong preference for good burrows to hide in. In addition, they need a lot of food, which also makes demands on the environment.” It was noteworthy, however, that the lobsters walked noticeably slower on and around the reefs. “They were possibly foraging. When they move on over the open sand again, they walk much faster,” said researcher Marcel Rozemeijer.
Follow-up research
The batteries of the transmitters are dead after a year and, in addition, lobsters molt regularly. Therefore, another 19 locally caught cod were tagged in May 2022, and 12 new lobsters were tagged and released. These new data were read in early 2023 and are currently being analyzed. The study will continue until the end of 2023.