Abstract
Introduction: With the rapid expansion of offshore wind power, the potential impact of underwater noise from operational wind farms on marine organisms has attracted increasing concern.
Methods: To investigate the acoustic characteristics of underwater noise from wind farms, this study measured underwater noise data from an operational wind farm in the Nanpeng Island area of Yangjiang, Guangdong, and analyzed its time frequency and spectral characteristics.
Results: The results indicate that the acoustic energy in the study area was primarily concentrated at low frequencies below 1000Hz. Distinct wind turbine noise characteristics were observable at both 2m and 5m water depths, and noise levels exhibited a decreasing trend with increasing distance from the wind farm. The wind turbine noise exhibited discrete spectral features, with peak center frequencies mainly distributed at 31.5Hz, 63Hz, 160Hz, and 630Hz. Outside the wind farm, only the 31.5Hz and 63Hz peak bands were prominent. However, within the farm, owing to the proximity of a greater number of operating turbines, all peak frequency bands were more pronounced, and an additional peak emerged around the 250Hz band. Furthermore, by comparing the underwater noise spectra with fish auditory sensitivity curves, a preliminary assessment was conducted to determine the species-specific spatial extent of potential noise perception: the auditory threshold of the large yellow croaker was exceeded only within the wind farm at frequencies around 380Hz; the threshold for the green grouper was exceeded at a distance of 500m from the wind farm; the threshold for the pearl gentian grouper was exceeded at 5.5km; and the Japanese seabass, having the lowest auditory threshold, had its threshold exceeded at all monitoring stations.
Discussion: The findings of this study provide a data reference for assessing the acoustic environmental impact of offshore wind farms and for planning integrated "wind-fishery" development.