Figura 1 - uploaded by Clarissa De Vita
Content may be subject to copyright.
Source publication
The common dolphin is a cosmopolitan species that has a high genetic variability. In the Mediterranean, the species differ genetically and acoustically from the Atlantic populations and is thus considered as a subset. However, little is known about the distribution and habits of the common dolphin. The lack of data has prevented a good understandin...
Citations
... Further research is required to improve knowledge on common dolphin clicks and burst pulses, as studies focusing on these signals are still rare and contradictory (Ceraulo et al., 2015;De Vita, 2016;Erbe et al., 2017;Papale et al., 2021). Limited work on the characterization of short-beaked common dolphin whistles has been conducted worldwide, with to date an emphasis on the modulation of the acoustic parameters in connection with behavioural contexts and group size (Ansmann, Goold, Evans, Simmonds, & Keith, 2007;De Vita, 2016;Griffiths, 2009;Petrella et al., 2012;Silvestri, 2017), as well as genetic, morphological, environmental, and cultural differences (Papale et al., 2014). ...
... Further research is required to improve knowledge on common dolphin clicks and burst pulses, as studies focusing on these signals are still rare and contradictory (Ceraulo et al., 2015;De Vita, 2016;Erbe et al., 2017;Papale et al., 2021). Limited work on the characterization of short-beaked common dolphin whistles has been conducted worldwide, with to date an emphasis on the modulation of the acoustic parameters in connection with behavioural contexts and group size (Ansmann, Goold, Evans, Simmonds, & Keith, 2007;De Vita, 2016;Griffiths, 2009;Petrella et al., 2012;Silvestri, 2017), as well as genetic, morphological, environmental, and cultural differences (Papale et al., 2014). ...
... The majority of the available knowledge on the short-beaked common dolphin acoustic signals in the Mediterranean Sea is related to the structural characteristics of whistles (Table 3), their emission pattern associated with various behavioural states, and their geographic variation within the basin (Azzolin, 2008;Azzolin et al., 2014Azzolin et al., , 2021De Vita, 2016;Gannier et al., 2010;Papale et al., 2014;Silvestri, 2017;Venier, 2007 T A B L E 2 Acoustic characteristics and geographic location of short-beaked common dolphin burst-pulses recorded and analysed in the Sicily Strait, Central Mediterranean Sea summer acoustic pollution, distance from mud deposits). Most of these parameters have been and continue to be modelled against common dolphin presence and distribution in Mediterranean research areas, with increasing publications in recent years (Bonizzoni et al., 2019;Cañadas & Hammond, 2008;Cañadas & Vázquez, 2017;Gannier, 2021;Giannoulaki et al., 2017;Giménez et al., 2017;Giménez, Cañadas et al., 2018;Karamitros et al., 2020;Moura et al., 2012). ...
Preservation of endangered species is now recognized as a relevant component of regional and global conservation actions achieved through the maintenance of the remaining populations in a favourable conservation status. The Mediterranean common dolphin (Delphinus delphis) is listed as an Endangered subpopulation in the International Union for Conservation of Nature Red List, with declining numbers in some of the areas where it has been studied for numerous years. Prey
depletion, fisheries bycatch, pollution, health risks, and climate change are among the recognized threats that the species is facing in the region.
The existing national, regional, and international legislation pertinent to Mediterranean countries should aid greater science–policy management integration and support innovative research and monitoring towards effective conservation. The challenges inherent in studying the pelagic D. delphis should not preclude the use of long-term, year-round, multiplatform surveys, side by side with the latest
molecular tools, which aid our understanding of its populations' genetic diversity, resistance to diseases, and resilience in a semi-enclosed fast-changing sea.
Addressing the multiplicity of problems confronting the species requires collaborative effort at all levels to share and merge resources, data, and expertise more efficiently. In this review, we provide an overview of the current knowledge on the Mediterranean common dolphin, the main threats, and knowledge gaps that are priorities for addressing its conservation, while providing clear recommendations for effectively safeguarding the species and its habitat at both local and regional levels.
https://onlinelibrary.wiley.com/doi/10.1002/aqc.3538
... A limited amount of literature is available on short-beaked common dolphin whistle repertoire (Ansmann et al., 2007;Griffith, 2009;Henderson et al., 2011;Petrella et al., 2012;De Vita, 2016;Azzolin et al., submitted) and this study represents one of the few efforts to evaluate species' whistle usage during different behavioural activities. Whistles recorded around Ischia ...
The short-beaked common dolphin (Delphinus delphis) is a cosmopolitan cetacean species and relatively little is known on its behaviour and ecology worldwide. In the Mediterranean Sea, the species is listed as ‘endangered’ in the IUCN Red List of Threatened Animals in 2003, based on criterion A2, which refers to a 50% decline in abundance over the last three generations, where causes "may not be discontinued or may not be understood or may not be reversible".
A limited amount of literature is available on the acoustic behaviour of short-beaked common dolphin, particularly on the whistles’ characteristics and repertoire. Whistles are narrowband tonal sounds, highly modulated in frequency and consisting of a fundamental frequency contour, that typically falls between 5 and 20 kHz, and often several harmonics that are multiples of the fundamental and that decrease in amplitude as the distance increases. The function of these sounds is related to communication and social interactions.
This study represents one of the few efforts to elucidate the whistles’ acoustic features and usage by short-beaked common dolphin during different behavioural activities and in relation to geographical/social variables in the Mediterranean Sea (off Ischia Island, Tyrrhenian Sea, Italy).
Acoustic data were collected during 6 independent encounters and a total of 1382 whistles and 197 contours were identified from 644,55 min of recordings. Vocalizations spanned from 2.7645 kHz to 21.8945 kHz, with most whistles occurring between 7.86±1.63 kHz and 15.26±2.91 kHz and whistle duration ranged from 0.05 to 6.49s (mean ±SD; 1.13± 0.5). The whistles recorded were classified into seven contour categories, of which Sine and Upsweeps resulted the most common. In addition, frequency and modulation parameters, as well as duration, were measured for each whistle type, and relations with the attributes of the encounters (behavioural activities, group size and composition, etc) emerged. Furthermore, of the 197 whistle types here analyzed, 20% have been identified in more than one encounters, suggesting a possible degree of stability in the whistle repertoire of common dolphins inhabiting the Island of Ischia. Finally, whistle repetition rate, diversity and imitation were found to vary significantly between different behavioural activities, appearing effective in the species’ communication schemes understanding.
