Eavesdropping on dolphins: Investigating the habits of bottlenose dolphins (Tursiops truncatus) through fixed acoustic stations.

This study investigates the bottlenose dolphin (Tursiops truncatus, Montagu 1821) habitat use in the Portofino marine protected area (NW Italy) and adjacent waters, a core area for the dolphins and a highly touristic area in the Mediterranean Sea. A permanent automated real-time passive acoustic monitoring system, able to detect and track dolphins continuously, was tested in the area within the activities of the Life+ Nature project ARION. The habits of bottlenose dolphins was investigated considering the resident rate inside the area, which quantifies the amount of time dolphins spent in these waters, by means of random forest regression. The dependency of dolphin resident rate was analyzed in relation to four explanatory variables: sea surface temperature, season, time of day, and proximity to the coast. Dolphins spent more time in the area during spring and when sea surface temperature ranged between 15-16°C. Summer resulted the season with lower dolphin residency with significant difference between working day and weekend, in the last the lowest residency was recorded. Main findings provide important information to properly manage the area in order to protect bottlenose dolphins.

The commercial IT company Softeco Sismat S.r.l. is one of the three associated beneficiaries of the EU LIFE+ project named ARION (grant number: LIFE09 NAT/IT/000190 ARION). The authors Christian Melchiorre (ChM) and Gianni Viano (GV) are employed by the commercial IT company named Softeco Sismat S.r.l. that provided support in the form of salaries for these authors [ChM, GV]. The contribution of the authors employed by this commercial company (ChM, GV) mainly consists on the production of data analysis tools (automated detection alarm generation, creation of the detection database, etc.) and web platforms for data sharing (smartphone app, project web site, etc.). No restrictions are applied by this commercial company on any kind of product regarding this study. This commercial affiliation does not alter our adherence to PLOS ONE policies on sharing data and materials.