Field and modelling study reveals distinct cave-like epifaunal communities inside offshore wind monopiles, suggesting replenishment hole design can support nature-inclusive engineering.
Key Points
To evaluate whether water replenishment holes in offshore wind monopiles alter internal environmental conditions and create distinct semi-enclosed epifaunal habitats compared to exterior surfaces.
Conducted vertical video transects along depth gradients to quantify epifaunal cover on the interior and exterior walls of four monopiles in the southern North Sea.
Applied a coupled hydrodynamic-water quality model over a one-year period to simulate vertical profiles of dissolved oxygen and particulate organic carbon inside monopiles.
Monopile interiors exhibited reduced overall epifaunal cover and less dominance of typical North Sea hard-substrate species, displaying higher heterogeneity enriched with sponges, calcareous tube worms, and brittle stars resembling marine cave communities.
Simulations and observations identified dark, low-flow conditions with vertical gradients in dissolved oxygen and particulate organic carbon, coinciding with organic matter accumulation and signs of microbial mats on the interior seabed.