Offshore wind energy: Opportunities for nature restoration and biodiversity
In the past, oyster beds and other solid structures on the North Sea floor provided shelter and habitat for specific marine species. Due to overfishing, disease and climate change, the beds, and with them the species, have disappeared. Wind farms offer a new opportunity for shellfish and benthic animals. Oyster beds can be reestablished between the wind turbines, and smart ecological design can create new habitats on the stones surrounding the base of wind turbines (which are placed there to prevent them from being damaged by sea currents).
Flat oyster reefs on 3D printed structures
The European flat oyster (Ostrea edulis) has been selected for restoration projects to enhance species and habitat conservation. Flat oyster beds not only belong in the North Sea, but they also provide a habitat for other benthic flora and fauna, food and shelter for crab, lobster and shrimp, and a place for fish to spawn. Predatory fish, seabirds and marine mammals find food on the reefs. Oyster beds also have a beneficial effect on the water quality.
In the Borkum Reef Grounds, above Schiermonnikoog, the first oysters were released on (among other things) 3D printed reef structures in May 2018. Also, over 80,000 oysters were sown and 4 monitoring cages were placed on the seabed. This project is being carried out together with Bureau Waardenburg, commissioned by WWF.
Can relocated oysters reproduce?
The first results are encouraging: the released oysters survive well and reproduce. Other pilot projects together with Bureau Waardenburg have meanwhile started in the Gemini Wind Farm and Eneco Wind Farm Luchterduinen. Wageningen Marine Research has been commissioned by the wind energy sector and nature conservation organisations to study the survival, growth and reproduction of oysters in cages.
In order to assess the suitability of wind farms for oyster reefs, Wageningen Marine Research has developed a research framework that has been applied to each potential/planned location. Based on this, Zee-Energie, Buitengaats, Borssele and Luchterduinen have been identified as likely locations for more extensive research before large-scale oyster restoration projects can start. For this we work together with Bureau Waardenburg and SAS Consultancy from the Flat Oyster Consortium.
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Biodiversity on hard substrate
Wageningen Marine Research provides advice to wind farm operators, the government and nature conservation organisations. For example, on identifying species with potential for nature restoration or proposing technical modifications to wind farms. Our research provides clarity on the most suitable research methods and the best opportunities for nature-inclusive construction.
Which species thrive on and around underwater structures?
From October 2015 to September 2017, experts from Wageningen Marine Research took part in the RECON project, in which the impact of wind turbines and oil platforms in the North Sea on the ecosystem was investigated in detail. The project examined the composition of species on offshore structures, the factors that influence it and how the various communities interact.
On the foundations of the wind turbines and platforms and on stones around the foundations, 193 different species were found. Among them are mussels, cold water corals, crabs, lobsters, tube worms and anemones. Man-made reefs and artificial substrates such as steel appear to differ little from natural reef structures in terms of biodiversity in deep water. Artificial reefs can also form stepping stones for further colonisation of the North Sea by species that are usually only found near coastal areas.