Vocal universals and geographic variations in the acoustic repertoire of the common bottlenose dolphin

Acoustical geographic variation is common in widely distributed species and it is already described for several taxa, at various scales. In cetaceans, intraspecific variation in acoustic repertoires has been linked to ecological factors, geographical barriers, and social processes. For the common bottlenose dolphin (Tursiops truncatus), studies on acoustic variability are scarce, focus on a single signal type-whistles and on the influence of environmental variables. Here, we analyze the acoustic emissions of nine bottlenose dolphin populations across the Atlantic Ocean and the Mediterranean Sea, and identify common signal types and acoustic variants to assess repertoires' (dis)similarity. Overall, these dolphins present a rich acoustic repertoire, with 24 distinct signal sub-types including: whistles, burst-pulsed sounds, brays and bangs. Acoustic divergence was observed only in social signals, suggesting the relevance of cultural transmission in geographic variation. The repertoire dissimilarity values were remarkably low (from 0.08 to 0.4) and do not reflect the geographic distances among populations. Our findings suggest that acoustic ecology may play an important role in the occurrence of intraspecific variability, as proposed by the 'environmental adaptation hypothesis'. Further work may clarify the boundaries between neighboring populations, and shed light into vocal learning and cultural transmission in bottlenose dolphin societies.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Sustainable dolphin watching tours as a tool to increase public awareness of marine conservation. A comparative analysis between two Mediterranean destinations and implications for management.

Dolphin watching is growing fast along the Mediterranean coasts, without an equivalent effort for its management. Whale and dolphin watching has been promoted as ecotourism with conservation benefits. However, only a few studies have investigated the potential of these tours to change the awareness of the participants and improve their pro-conservation sentiments. In the present study, the motivation, interest, knowledge, expectations and satisfaction of the dolphin watchers were evaluated in two sites (Sardinia and Lošinj). The aim was to better address management strategies of dolphin watching in the Mediterranean Sea. Based on the questionnaires filled by the participants, the dolphin watchers in both destinations showed a generally high environmental awareness and sense of responsibility towards marine conservation. Moreover, awareness and responsibility increased after the experience. The results reveal that a carefully planned education would maximise the pro- environmental effects of the tours and minimise the impact on the target species

Data Descriptor: Underwater recordings of the whistles of bottlenose dolphins in Fremantle Inner Harbour, Western Australia

© The Author(s) 2017. Dolphins use frequency-modulated whistles for a variety of social functions. Whistles vary in their characteristics according to context, such as activity state, group size, group composition, geographic location, and ambient noise levels. Therefore, comparison of whistle characteristics can be used to address numerous research questions regarding dolphin populations and behaviour. However, logistical and economic constraints on dolphin research have resulted in data collection biases, inconsistent analytical approaches, and knowledge gaps. This Data Descriptor presents an acoustic dataset of bottlenose dolphin (Tursiops aduncus) whistles recorded in the Fremantle Inner Harbour, Western Australia. Data were collected using an autonomous recorder and analysed using a range of acoustic measurements. Acoustic data review identified 336 whistles, which were subsequently measured for six key characteristics using Raven Pro software. Of these, 164 'high-quality' whistles were manually measured to provide an additional five acoustic characteristics. Digital files of individual whistles and corresponding measurements make this dataset available to researchers to address future questions regarding variations within and between dolphin communities

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

The study of marine soundscapes is a growing field of research. Recording hardware is becoming more accessible; there are a number of off-the-shelf autonomous recorders that can be deployed for months at a time; software analysis tools exist as shareware; rawor preprocessed recordings are freely and publicly available. However, what is missing are catalogues of commonly recorded sounds. Sounds related to geophysical events (e.g. earthquakes) and weather (e.g. wind and precipitation), to human activities (e.g. ships) and to marine animals (e.g. crustaceans, fish and marine mammals) commonly occur. Marine mammals are distributed throughout Australia's oceans and significantly contribute to the underwater soundscape. However, due to a lack of concurrent visual and passive acoustic observations, it is often not known which species produces which sounds. To aid in the analysis of Australian and Antarctic marine soundscape recordings, a literature review of the sounds made by marine mammals was undertaken. Frequency, duration and source level measurements are summarised and tabulated. In addition to the literature review, new marine mammal data are presented and include recordings from Australia of Omura's whales (Balaenoptera omurai), dwarf sperm whales (Kogia sima), common dolphins (Delphinus delphis), short-finned pilot whales (Globicephala macrorhynchus), long-finned pilot whales (G. melas), Fraser's dolphins (Lagenodelphis hosei), false killer whales (Pseudorca crassidens), striped dolphins (Stenella coeruleoalba) and spinner dolphins (S. longirostris), as well as the whistles and burst-pulse sounds of Australian pygmy killer whales (Feresa attenuata). To date, this is the most comprehensive acoustic summary for marine mammal species in Australian waters