Importance of Empirical Particle Motion Measurements for Monitoring Underwater Noise from Wave Energy Converters

Underwater noise from Marine Energy Con- verters (MECs), including Wave Energy Converters (WECs), is a recognized stressor for marine organisms. Current monitoring guidelines focus on scalar pressure, but particle motion is equally important, especially in complex shallow- water environments where WEC systems can affect the soundscape. Many marine species detect sound primarily through particle motion, highlighting the need to include it in monitoring frameworks. This work underscores the importance and role of sound in marine habitats. Us- ing a 3D accelerometer and hydrophone, we collected acoustic data near an Inertial Sea Wave Energy Converter (ISWEC) off Pantelleria, Sicily. Our initial measurements showed discrepancies between pressure and particle mo- tion and higher variability along the vertical axis. These results stress the necessity of incorporating particle motion alongside pressure in underwater noise assessments, with potential implications for benthic and demersal species. They also highlight the need for deeper investigation into particle motion dynamics, particularly in the context of marine energy converter operations in shallow-water environments.