Characterizing the coastal soundscape of Mount Conero (Adriatic Sea) through passive acoustic monitoring

Passive acoustic monitoring is a non-invasive tool widely used to assess marine biodiversity and ecosystem dynamics. This study characterizes the soundscape of a sandy-bottom habitat in a shallow coastal area along the Conero Regional Park coastline in the Adriatic Sea. Sound contributors were specifically monitored in summer and winter of 2020. In both seasons, geophony, mostly caused by wave action, wind, and precipitation, represented the primary driver of soundscape variability and elevated sound levels. Nevertheless, the area hosts a diverse assemblage of soniferous or potentially soniferous marine species. Most biological frequency signals included low-frequency vocalizations from the cusk-eel (Ophidion rochei) and the shi drum (Umbrina cirrosa), and high-frequency sounds from bottlenose dolphins (Tursiops truncatus) and invertebrates, along with occasional calls from other fish species. Both the cusk-eel and shi drum exhibited strong seasonal and diel patterns, with peak acoustic activity during summer nights, in line with their reproductive periods, though cusk-eel calls were also spotted during winter. Both dolphins and invertebrates occurred on both seasons. Anthropogenic noise was limited to vessel activity, which occurred in both seasons and primarily associated with daytime working hours. Overall, this study provides a detailed characterization of an Adriatic coastal soundscape and highlights the key role of environmental drivers in shaping acoustic conditions. These findings contribute to improving baseline knowledge of Adriatic coastal soundscapes, supporting future studies and assessments.