Abstract
The installation of floating offshore wind farms in the Mediterranean Sea is attracting interest for their role in the energy transition and environmental implications. Yet limited research exists on the underwater noise of floating systems, especially in this biodiversity hotspot already affected by human pressures. This study evaluates the acoustic impact of the SAIPEM Hexafloat scaled-prototype floating platform, monitored at the MaRELab site in Naples from September to December 2023. An autonomous recorder positioned 30 m from the turbine collected data. Noise levels varied monthly and daily, reflecting the complexity of the site’s soundscape. Multiple sources were present: intense maritime traffic, waves, and biological sounds such as crustacean impulses, fish choruses, and occasional dolphin clicks. To isolate the turbine contribution, analyses accounted for temporal trends and overlapping sources including traffic, waves, and wind. Turbine noise was lower than maritime traffic or wave noise, concentrated at low frequencies up to 1 kHz. For the 1/3 octave bands at 63 and 125 Hz, turbine activity increased levels by about 4 dB when waves were under 1 m. A tonal component around 400 Hz appeared at maximum blade speed, and the anchoring system produced impulses and tones up to 8 kHz. According to Southall et al. (Aquat Mamm 47(5):421–464, 2021), noise levels do not suggest physiological risk for marine organisms, though short-term masking effects on fish communication may occur. Test sites with scaled-down turbines and anchoring systems facilitate the testing of new technological solutions and environmental impact assessments. However, further evaluation is needed to extrapolate these findings to large-scale scenarios involving multiple turbines with their respective anchoring systems.