North Sea ReViFES – Empirical Wind Farm Data

Offshore wind farms are increasingly recognised as potential locations for marine nature enhancement. In addition to providing renewable energy, wind farms introduce hard substrates to the seabed through turbine foundations and scour protections, while also excluding bottom-disturbing activities such as bottom trawling. Together, these conditions create opportunities for the development of reef-like communities in areas that are otherwise dominated by sandy seabeds.

 

Although nature-inclusive design has become an important ambition in offshore wind development, much of the expected ecological benefit has historically been based on observations, assumptions, and expert judgement rather than direct empirical evidence. In particular, little was known about how scour protection design influences biodiversity outcomes or whether specific design choices can actively enhance ecological value.

This project investigated how scour protections function as artificial reefs in offshore wind farms and whether modifications to scour protection design can improve biodiversity. The research focused on understanding which species communities develop on existing scour protections and identifying design characteristics that support richer and more diverse benthic communities.

The findings provide valuable insight for offshore wind developers, regulators and restoration practitioners seeking to incorporate nature-inclusive design into future projects. By linking biodiversity outcomes to measurable design features, the project helps translate ecological ambitions into practical engineering solutions.

The objective of this project was to provide empirical evidence on the ecological role of scour protections in offshore wind farms and to identify design principles that can enhance marine biodiversity. Through field studies on existing scour protections and controlled experiments with different rock materials, the project aimed to support evidence-based nature-inclusive offshore wind development.

2020-2025

Project dates

Southern North Sea

Location

North Sea ReViFES consortium: NIOZ Royal Netherlands Institute for Sea Research, Wageningen University & Research (WUR), University of Groningen, Utrecht University, TU Delft, Van Oord and Waardenburg Ecology.

Project lead and partners

Epibenthic communities and benthic fauna

Target species

Methods

This project examined how scour protections in offshore wind farms contribute to marine biodiversity and whether specific design choices can enhance their ecological value. Two complementary field studies were conducted in operational wind farms in the Southern North Sea, using non-destructive monitoring techniques and field-based experiments. The first study investigated the communities that naturally develop on existing scour protections, while the second tested how different scour protection designs influence biodiversity.

Epibenthic communities on existing scour protections
The first study used Remotely Operated Vehicle (ROV) footage collected along radial transects around turbine foundations in four offshore wind farms in the Southern North Sea. Surveys covered three habitat zones associated with scour protections: the hard armour layer, the transition zone between rock and sand, and the surrounding sandy seabed.
Epibenthic species were identified and counted from video footage to assess community composition and biodiversity patterns. The analysis examined how local factors, such as habitat type and substrate characteristics, influenced community structure. In addition, differences between wind farms were compared to investigate the influence of larger-scale factors such as geographic distance and connectivity between sites.
Benthic biodiversity and scour protection rock types
The second study investigated whether scour protection design can actively enhance biodiversity. A field experiment was conducted at Borssele offshore wind farm Lot V in the Dutch North Sea, where three commonly used scour protection materials were tested: granite, rough concrete and marble.
Research cages containing the different rock types were deployed on existing scour protections and left in place for nine months. Following retrieval, the rocks and associated benthic fauna were analysed in the laboratory. Species were identified and counted, and the biodiversity associated with each rock type was compared.
The study also examined how different species used the available habitat, including attached, free-living, tube-dwelling, burrowing and crevice-dwelling organisms. In addition, the surface area of each rock treatment was measured to assess the relationship between available habitat complexity and biodiversity.

Results

Both studies demonstrate that offshore wind farm scour protections can function as artificial reefs that support diverse benthic and epibenthic communities. More importantly, the results show that biodiversity outcomes are not fixed: specific scour protection design choices can significantly influence the ecological value of offshore wind farms.

Epibenthic communities on existing scour protections
A rich epibenthic community was recorded across the four offshore wind farms included in the study. In total, 47 species from seven different phyla were observed, including sponges, anemones, tubeworms, crabs, molluscs, sea stars and fish. The presence of these communities demonstrates that scour protections provide valuable hard-substrate habitat within an otherwise predominantly sandy seabed environment.
Community composition differed strongly between the three habitat zones surrounding turbine foundations. The armour layer supported a distinct and more abundant community than the adjacent sandy seabed, while the transition zone contained a mix of species from both habitats. The large differences observed between zones highlight the importance of scour protections in creating ecological diversity at a local scale.
The results also showed that wind farms located closer to one another tended to support more similar species communities than wind farms further apart. This suggests that geographic location and connectivity influence which species are able to colonise scour protections, alongside local habitat conditions.
Benthic biodiversity and scour protection design
The field experiment demonstrated that scour protection design can directly influence biodiversity outcomes. More than 17,000 individual animals belonging to 131 different taxa were recorded on the experimental rock treatments after nine months. Several ecologically important species were present, including ross worm (Sabellaria spinulosa), sand mason worm (Lanice conchilega), and blue mussel (Mytilus edulis).
Surface area proved to be the strongest predictor of biodiversity. Rock designs with greater surface complexity supported more species and higher numbers of organisms. This provides clear evidence that increasing surface area through variation in rock size, shape and texture can enhance biodiversity within scour protections.
Rock type also influenced the composition and functional diversity of benthic communities. Calcareous rock such as marble supported a broader range of ecological functions, including a higher proportion of attached and crevice-dwelling organisms. The results indicate that mixing different rock materials can create more diverse habitats and support a wider range of species than a single rock type alone.
Implications for nature-inclusive offshore wind farms
A key outcome of this project is that nature-inclusive scour protection design can produce measurable biodiversity benefits within a relatively short period of time. Biodiversity responses to rock type and habitat complexity were clearly visible within nine months, demonstrating that design choices made during wind farm construction can have rapid ecological effects.
The studies provide some of the first empirical evidence that optimised scour protection designs can actively enhance biodiversity in offshore wind farms. By demonstrating the importance of habitat complexity, substrate diversity, and regional connectivity, the project provides practical guidance for future nature-inclusive offshore wind developments and supports the integration of biodiversity objectives into wind farm design.

Tips & Tricks

Scour Protection Design

  • Maximise surface area when designing scour protections. Increased surface area provides more attachment points, shelter, and habitat complexity, leading to higher benthic biodiversity.
  • Consider using a mix of rock types rather than a single material. Different substrates support different ecological functions and can increase the functional diversity of reef communities.
  • Incorporate habitat heterogeneity wherever possible. Variations in rock size, shape, and crevice availability create a wider range of microhabitats for marine species.

Monitoring

  • Use ROV surveys for routine monitoring of scour protections. They provide a non-destructive method for assessing epibenthic communities and tracking biodiversity development over time.
  • Monitor multiple habitat zones, including the armour layer, transition zone, and adjacent seabed. Ecological differences between these zones can be substantial and provide valuable information on reef effects.
  • Include both species diversity and functional diversity in monitoring programmes to better understand how communities use the available habitat.

Site Planning

  • Consider the regional context of a wind farm. Communities on scour protections become less similar as geographic distance increases, meaning local environmental conditions influence biodiversity outcomes.
  • Treat scour protections as ecosystem assets rather than purely engineering structures. Their design can actively contribute to biodiversity enhancement during the operational life of a wind farm.
  • Build nature-inclusive measures into the original design phase where possible, as ecological benefits can be achieved while maintaining the primary engineering function of the scour protection.

Let's talk

Would you like to know more about this project or get involved? Send an email to the project lead.

k.didderen@waardenburg.eco