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Description
The underwater soundscape off the west coast of Ireland is a dynamic acoustic environment shaped by a complex interplay of natural sounds and anthropogenic noises. This region, exposed directly to the north Atlantic, experiences pronounced seasonal and inter-annual fluctuations driven by meteorological forces, oceanographic processes, and biological rhythms.This study investigated the impact of environmental conditions on the underwater soundscape of Galway Bay using passive acoustic monitoring data collected from SmartBay, an integrated marine observatory located off the coast of Spiddal, Co. Galway. The platform collects simultaneous hydrophone and environmental data, facilitating direct comparison between acoustic and environmental records. Data were gathered at one-minute intervals over a week for each season from February 2023 to December 2024, with supplementary recordings obtained for notable weather events. Acoustic indices (acoustic complexity index, normalized difference soundscape index, acoustic diversity index, and acoustic evenness index) were used to characterise the underwater soundscape, and were compared against environmental factors including tidal state, current speed, and calendar season.The soundscape was dominated by geophony year-round, with this dominance being noticeably more intense during the winter months. Sea temperature and wave height emerged as the proximal (environmental) drivers across seasons, with tidal phase having a statistically significant influence on key indices (Kruskal-Wallis, p<0.001). Ebb tide was consistently associated with elevated acoustic complexity, while diel patterns in biological activity indices were most pronounced during calmer seasonal periods.