Sediment transport pathways and organic carbon burial impacted by offshore wind farms in shelf seas

The rapid expansion of offshore wind farms increasingly impacts ocean environments. Little is known concerning synergistic effects of wind farm infrastructure on large-scale sediment transport and seabed ecosystem functioning. Using a 3D hydro-morphodynamic model integrating wake effects in both the atmosphere and ocean compartments, we assessed wind farm impacts on regional-scale sediment transport and organic carbon sedimentation in the North Sea. Results suggest that wind farms can alter net sediment transport fluxes by up to 30% locally, reduce mud accumulation in established depocenters and create new depocenters through long-term accumulative effects. These shifts are linked to changes in stratification and residual currents, driving the remobilization of up to 1.3 Mt of fine sediment and 0.05 Mt of particulate organic carbon annually. Wind farms also retain ~ 1.5% of annual riverine sediment input to the open ocean, affecting connectivity with nearshore systems like the Wadden Sea. These findings underscore the need to consider the system-wide impacts in marine spatial planning, ecosystem management and protection.