Effect of particles from wind turbine blades erosion on blue mussels Mytilus edulis

Offshore wind farms (OWFs) pose new anthropogenic pressures on the marine environment as the erosion of turbine blades release organic and inorganic substances with potential consequences for marine life. In the present study, possible effects of the released particles and their chemical constituents on the metabolic profile of the blue mussel, Mytilus edulis, were investigated, utilizing ¹H NMR spectroscopy. In the lab, mussels were exposed for 7 and 14 days to different concentrations (10 and 40 mg L^-1) of microplastic (MP) particles which were derived from cryo-milled rotor blade coatings and core materials (glass fiber polymer, GFP). Raman imaging techniques revealed that 30-40 % of the coating and GFP particles had MP sizes below 5 μm, with the majority (∼98 %) being ≤50 μm. Despite the identified enrichment factors (EF) for metals and metalloids from the rotor blade materials, especially Ba, Cu, Cd, Cr and Ni with EFs between 0.93 and 6.1, untargeted metabolic profiling of the entire soft body tissues of M. edulis showed no significant metabolic disruption, regardless of the particle concentration. Observed trends in elevated concentrations of metabolites may indicate a possible short-term effect on mussels' neuroendocrine system and a possible long-term effect on energy metabolism. Experimental worst-case scenario of massive abrasion and the minimal response observed in M. edulis under the conditions tested suggest that erosion caused by wind turbine blades may pose little to no risk to bivalves at this stage. However, it is important to note that this study is only a preliminary step and further studies are needed to obtain a comprehensive overview of the issue before reaching a definite firm conclusion regarding the potential threat of OWFs abrasion to the marine environment, particularly considering the planned future extension of windpark construction in connection with the ongoing EU-wide energy transition.