Dolphins in a Scaled-Down Mediterranean

Bearzi, Giovanni; Bonizzoni, Silvia; Santostasi, Nina Luisa; Furey, Nathan B.; Eddy, Lavinia; Valavanis, Vasilis D.; Giménez, Olivier

doi:10.1016/bs.amb.2016.07.003

Cited by 22 publications

(35 citation statements)

References 91 publications

(125 reference statements)

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“…Anthropogenic activities such as aquaculture and vessel traffic are known to affect dolphin distribution patterns (e.g., 4 – 6 ). Dolphins’ response to aquaculture activities is variable and complex.…”

Section: Discussionmentioning

confidence: 99%

“…The presence and distribution of marine top predators, such as dolphins, has been linked to a variety of abiotic and biotic factors, which are usually linked to the distribution of their prey, predators and conspecifics 3 . Human activities such as boating, fishing activities and aquaculture can affect dolphin behaviour and ultimately also influence their distribution patterns 4 – 6 . Species distribution models (SDM) provide a useful analytical framework to investigate the environmental and anthropogenic factors affecting species distribution 1 , 2 , 7 .…”

Section: Introductionmentioning

confidence: 99%

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Modelling Dolphin Distribution to Inform Future Spatial Conservation Decisions in a Marine Protected Area

Passadore

Möller

Diaz‐Aguirre

et al. 2018

Sci Rep

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As marine predators experience increasing anthropogenic pressures, there is an urgent need to understand their distribution and their drivers to inform spatial conservation planning. We used an ensemble modelling approach to investigate the spatio-temporal distribution of southern Australian bottlenose dolphins (Tursiops cf. australis) in relation to a variety of ecogeographical and anthropogenic variables in Coffin Bay, Thorny Passage Marine Park, South Australia. Further, we evaluated the overlap between current spatial management measures and important dolphin habitat. Dolphins showed no distinct seasonal shifts in distribution patterns. Models of the entire study area indicate that zones of high probability of dolphin occurrence were located mainly within the inner area of Coffin Bay. In the inner area, zones with high probability of dolphin occurrence were associated with shallow waters (2–4 m and 7–10 m) and located within 1,000 m from land and 2,500 m from oyster farms. The multi-modal response curve of depth in the models likely shows how the different dolphin communities in Coffin Bay occupy different embayments characterized by distinct depth patterns. The majority of areas of high (>0.6) probability of dolphin occurrence are outside sanctuary zones where multiple human activities are allowed. The inner area of Coffin Bay is an important area of year-round habitat suitability for dolphins. Our results can inform future spatial conservation decisions and improve protection of important dolphin habitat.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling Dolphin Distribution to Inform Future Spatial Conservation Decisions in a Marine Protected Area

Passadore

Möller

Diaz‐Aguirre

et al. 2018

Sci Rep

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“…Here, a population of 38 individuals (95% CI = 32-46) was estimated 46 . Most individuals show high resighting frequency, but some dolphins are known to move in and out from the Gulf 47,48 . The mean group size is 8, with a range between 1 and 28 48 (Table 5).…”

Section: Lampedusa Island (La)mentioning

confidence: 99%

Determinants of variability in signature whistles of the Mediterranean common bottlenose dolphin

Manna

Rako‐Gospić²,

Pace

et al. 2022

Sci Rep

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One of the most studied aspects of animal communication is the acoustic repertoire difference between populations of the same species. While numerous studies have investigated the variability of bottlenose dolphin whistles between populations, very few studies have focused on the signature whistles alone and the factors underlying differentiation of signature whistles are still poorly understood. Here we describe the signature whistles produced by six distinct geographical units of the common bottlenose dolphin (Tursiops truncatus) in the Mediterranean Sea and identify the main determinants of their variability. Particularly, the influence of the region (proxy of genetic distance), the geographic site, and the environmental (sea bottom-related) and demographical (population-related) conditions on the acoustic structure of signature whistles was evaluated. The study provides the first evidence that the genetic structure, which distinguishes the eastern and western Mediterranean bottlenose dolphin populations has no strong influence on the acoustic structure of their signature whistles, and that the geographical isolation between populations only partially affected whistle variability. The environmental conditions of the areas where the whistles developed and the demographic characteristics of the belonging populations strongly influenced signature whistles, in accordance with the “acoustic adaptation hypothesis” and the theory of signature whistle determination mediated by learning.

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“…The majority of the effort in the Adriatic and Ionian Sea focuses on behavioural activity, individual identification, threat assessment and movement patterns (Bearzi et al, 1997;Fortuna et al, 2011;Bas ȩt al., 2017a;Bas ̧et al, 2017b;Awbery et al, 2019;Akkaya et al, 2021). Based on previous knowledge, bottlenose dolphins are generally known as a resident species with limited movement (Genov et al, 2009;Bearzi et al, 2016). Contrarily, a recent study documented an adult male bottlenose dolphin travelling between the Northern Adriatic Sea, passing through the Ionian and Tyrrhenian Sea, and finally reaching the Ligurian Sea with an estimated minimum distance of 1251 km across all three seas (Genov et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Akkaya¹,

Awbery

Medcalf³

et al. 2023

Front. Mar. Sci.

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Bottlenose dolphins have a complex vocal repertoire that varies depending on behavioral context, social structure, group composition, and anthropogenic pressures. This current study describes the whistle characteristics of bottlenose dolphins for the first time in the South Adriatic Sea while assessing the potential differences between whistle characteristics of geographically separated dolphins within neighbouring waters of the North Ionian Sea. The results show that whistle characteristics were similar between Taranto Gulf (Italy) and Boka Bay (Montenegro), despite their spatial differences. The mean peak frequency was 10kHz for each study location while the mean minimum and maximum frequency ranged from 7 to 14kHz. The average duration of whistles was 500 milliseconds. These results share similarities with previous literature, although several studies reported slightly different mean peak frequencies, ranging up to 15kHz in the neighbouring waters of Croatia and Italy. Further, harmonics were produced and formed in 40% of the whistles in Taranto Gulf and 30% of the whistles in Boka Bay. A high incidence of harmonics has previously been associated with behavioral states (i.e., travelling) and with certain types of marine traffic (i.e., fishing vessels). Therefore, it is important to collect simultaneous data on the visual behavior of the focal group as well as document the type and density of marine traffic within the proximity of the dolphins to have an in-depth understanding of vocal behavior. Despite the similarities of whistle characteristics of Taranto and Boka Bay, the whistle contours showed notable variations. Upsweep whistles were the most regularly produced whistle type in each location, which coincides with previous studies in the Mediterranean Sea. However, the least produced whistle had a concave contour in Taranto and was flat in Boka Bay. Previous studies have confirmed that flat whistles account for the least produced whistle contour in the Mediterranean Basin. Examining the whistle characteristics and the variation in whistle contours provides an in-depth understanding of the behavioral complexity as well as its plasticity in the presence of pressure. Therefore, future studies need to include behavior, group composition, noise levels, and human presence to enable an effective understanding of variation in whistle characteristics of bottlenose dolphins.

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Dolphins in a Scaled-Down Mediterranean

Cited by 22 publications

References 91 publications

Modelling Dolphin Distribution to Inform Future Spatial Conservation Decisions in a Marine Protected Area

Modelling Dolphin Distribution to Inform Future Spatial Conservation Decisions in a Marine Protected Area

Determinants of variability in signature whistles of the Mediterranean common bottlenose dolphin

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

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