From Green Energy to Marine Food Webs: Tracking Critical Raw Materials and Mercury in Offshore Wind Farm Ecosystems of the North Sea

The rapid expansion of offshore wind farms (OWFs) in the North Sea is a cornerstone of
Europe’s transition toward renewable energy. While OWFs can provide ecological benefits by providing artificial habitats, they may also profoundly alter the marine environment through introducing environmental contaminants. Critical Raw Materials (CRMs) including Rare Earth Elements (REEs), which are essential components of wind turbine infrastructure, may enter marine ecosystems through corrosion, weathering or sediment interactions, potentially accumulating within marine food webs.
Framed within the Biodiversa+ funded MARE-WIND project, this PhD research investigates the occurrence, bioaccumulation, and trophic transfer of these technology-critical elements alongside legacy contaminants in North Sea OWF ecosystems. A recent sampling campaign in a Belgian offshore wind farm, allowed the collection of diverse organisms associated with turbine foundations and surrounding habitats, including invertebrates, crustaceans, echinoderms, cephalopods, and fish. Currently, laboratory analyses are being carried out on the samples to quantify contaminants across multiple trophic levels. Biological samples are being analysed for a suite of trace elements using inductively coupled plasma mass spectrometry, focusing on CRMs and technology-critical metals (Nb,
Sb, Ta, In, Pt) as well as REEs (La, Ce, Nd, Dy). In parallel, total Hg and MeHg concentrations are being quantified using direct mercury analyser and gas chromatography-atomic fluorescence spectrometry. To characterize trophic structure and identify contaminant transfer pathways, stable isotope ratios (δ¹³C, δ¹⁵N and δ³⁴S) are being measured across all sampled taxa. Furthermore, these target CRMs and REEs are being investigated in stranded harbour seals, grey seals, and harbour porpoises from Belgian and German coasts to evaluate potential accumulation in top predators. This project will provide one of the first integrated assessments of emerging and legacy contaminants associated with OWF infrastructures, contributing vital insights for the biodiversity-conscious management of future marine energy developments.