Work

Laying out the foundations: Assessing the spatial extent and drivers of offshore wind turbine artificial reef effects on soft sediments

Year: 2025

Type: article

Abstract: With the rapid expansion of offshore energy, numerous artificial structures are being installed on the seabed, including wind turbine foundations. This study investigates the “artificial reef” (AR) effect of bottom-fixed offshore wind farms (OWFs) on soft sediment benthic communities. While previous studies have focused on distances ≥30 m from turbines, in this study, sediment and macrobenthic samples were collected at shorter distances (1 m, 7 m, 15 m and 25 m) from the scour protection layer (SPL) around a monopile and a gravity-based foundation in two Belgian OWFs, 10–13 years post-installation. Results show a localized AR footprint for both turbine foundations, with enriched benthic communities within 15 m of the SPL. In comparison to communities 25 m distanced away from the SPL, a higher average species richness (+100 %), abundance (+117 %), functional richness (+438 %), and bioturbation potential (+86 %) was prevalent, whereas the magnitude of enriched structural and functional diversity in the footprint varied respectively between 16 and 80 % and 15–110 % depending on the OWF. Beyond the AR footprint, communities resembled those at reference sites (240–570 m), with less surface dwellers, suspension feeders and a prevalence of burrowing biodiffusors that contribute little to bioturbation. While the AR effect's magnitude depends on local conditions and foundation design, our trait-based analysis indicates that sediment fining, biofouling drop-offs and organic enrichment are consistent drivers shaping the AR footprint. • Localized artificial reef footprint on soft-sediments around offshore wind turbines. • Increased macrobenthos abundance, biomass and diversity in the footprint. • Reef effects on structural and functional diversity depend on local conditions. • Similar species trait responses identified within the footprint across turbine types.

Source: Journal of Sea Research

DOI: 10.1016/j.seares.2025.102631