Communicating the Issue of Underwater Noise Pollution: The Deaf as a Fish Project.

Aquatic noise pollution is largely ignored by the lay public. How experts communicate this issue is critical to move public opinion. In 2010, the Cassa di Risparmio di Gorizia (CaRiGO) bank sponsored the Deaf as a Fish project that included local underwater noise monitoring, a boat census, a pamphlet for nonexperts, and some seminars and public meetings. This project allowed us to raise interest in this issue. Using accurate and understandable language in a light-humored setting goes far toward cultivating trust from a public audience that can be intimidated or suspicious of complicated scientific messaging.

Are the 1/3-Octave Band 63- and 125-Hz Noise Levels Predictive of Vessel Activity? The Case in the Cres-Losinj Archipelago (Northern Adriatic Sea, Croatia).

A 3-years sea ambient-noise (SAN) monitoring was carried out in the Cres-Losinj Archipelago (Croatia), where a bottlenose dolphin population is threatened by unregulated nautical tourism. A total of 540 5-min SAN samples were collected and analyzed in an Indicator 11.2.1 (Marine Strategy Framework Directive) perspective. The 1/3-octave band center frequencies of 63 and 125 Hz (re 1 µPa.rms) proved to be predictive of local predominant ship type over time. However, the noisiest band level was centered on 200 Hz. We therefore suggest measuring a wider frequency band than those requested in Indicator 11.2.1.

Brown meagre vocalization rate increases during repetitive boat noise exposures: a possible case of vocal compensation.

This study investigated whether or not boat noise causes variations in brown meagre (Sciaena umbra) vocalizations recorded in a nearshore Mediterranean marine reserve. Six nocturnal experimental sessions were carried out from June to September 2009. In each of them, a recreational boat passed over vocalizing fish 6 times with 1 boat passage every 10 min. For this purpose three different boats were used in random order: an 8.5-m cabin-cruiser (CC), a 5-m fiberglass boat (FB), and a 7-m inflatable boat (INF). In situ continuous acoustic recordings were collected using a self-standing sonobuoy. Because boat noise levels largely exceeded both background noise and S. umbra vocalizations in the species' hearing frequency range, masking of acoustic communication was assumed. Although no immediate effect was observed during a single boat passage, the S. umbra mean pulse rate increased over multiple boat passages in the experimental condition but not in the control condition, excluding that the observed effect was due to a natural rise in fish vocalizations. The observed vocal enhancement may result either from an increased density of callers or from an increased number of pulses/sounds produced by already acoustically active individuals, as a form of vocal compensation. These two explanations are discussed.

Dual-route imitation in preschool children.

Imitation can be realized via two different routes: a direct route that translates visual input into motor output when gestures are meaningless or unknown, and a semantic route for known/meaningful gestures. Young infants show imitative behaviours compatible with the direct route, but little is known about the development of the semantic route, studied here for the first time. The present study examined preschool children (3-5years of age) imitating gestures that could be transitive or intransitive, and meaningful or meaningless. Both routes for imitation were already present by three years of age, and children were more accurate at imitating meaningful-intransitive gestures than meaningless-intransitive ones; the reverse pattern was found for transitive gestures. Children preferred to use their dominant hand even if they had to anatomically imitate the model to do this, showing that a preference for specular imitation is not exclusive at these ages.

Leisure boating noise as a trigger for the displacement of the bottlenose dolphins of the Cres-Losinj archipelago (northern Adriatic Sea, Croatia).

The waters of the Cres-Losinj archipelago are subject to intense boat traffic related to the high number of leisure boats frequenting this area during the summer tourist season. Boat noise dominates the acoustic environment of the local bottlenose dolphin (Tursiops truncatus) population. This study investigates the spatial and temporal change in the underwater noise levels due to intense boating, and its effect on the distribution of the bottlenose dolphins. In the period 2007-2009 sea ambient noise (SAN) was sampled across ten acoustic stations. During data collection the presence of leisure boats was recorded if they were within 2 km of the sampling station. Bottlenose dolphin spatial distribution was monitored in the same period. Results showed a strong positive correlation between high SAN levels and boat presence, particularly in the tourist season. Dolphin distribution indicated significant seasonal displacements from noisy areas characterized by the intense leisure boating.