Abstract
This technical report describes the results of a study conducted in 2022 of the benthos community in Anholt wind farm and a reference area with a similar bottom habitat in nearby Aalborg Bugt. The study followed a BACI-design and assessed temporal infauna changes inside and outside the wind farm before and after its construction. Infauna was sampled from an inside monitoring station in 2022 and compared to historical data from 1989-2010 on the same station before construction. Over 10 years of production, the fauna community had changed significantly, with more pronounced changes at the station inside the park than at the reference station. Significant changes were observed in total abundance, biodiversity, species richness and calculated environmental quality indices, but these were coupled to general changes in the Kattegat area rather than to the establishment of the wind farm. Additionally, to study radiating effects from turbines on the fauna community, carbon sedimentation was analysed along transects radiating from the wind turbines at 30 m, 80 m and 130 m distances. The distance to the nearest wind turbine had a weak significant effect on community composition, but only in the northward direction. Overall, there was no general radiating effect on seabed benthos abundance, diversity and species richness. Only one of the three studied monopiles had scour protection at the base. Video transects on the monopiles documented an atypical hard bottom community that was distinctly different from natural boulder reefs in the Kattegat. The hard bottom fauna plays a much more dominant role than the flora on the monopiles and was dominated by sea anemones. The vegetation did not have a large depth distribution.