An overview of research efforts to understand the effects of underwater sound on cetaceans

Guan, Shane; Brookens, Tiffini

doi:10.1016/j.watbs.2023.100141

Cited by 6 publications

(4 citation statements)

References 151 publications

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“…We found four solutions (76.91, 314.64, 55.704, and 227.88 Hz). The first and the third solutions are in good agreement with the sensitivity data for low‐frequency hearing cetaceans as reported by Guan and Brookens (2023), who showed that at c . 60 dB the minimal heard frequency in a functional group including low‐frequency hearing cetaceans is around 60 Hz.…”

Section: Resultssupporting

confidence: 89%

The tympanoperiotic complex of the blue whale, Balaenoptera musculus

Bisconti,

Bosselaers,

Locatelli

et al. 2024

The Anatomical Record

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The tympanoperiotic complex of a blue whale Balaenoptera musculus is described and compared to the homologous structures in the other extant and fossil baleen whale species. The periotic and the tympanic bulla represent informative anatomical regions in both functional and phylogenetic studies and for this reason a micro‐CT scan of the bones was performed in order to better characterize their external aspect and to reconstruct the inner structures. In particular, the cochlea, the semicircular canals and associated portions of the periotic are reconstructed so that these structures may be used in phylogenetic analyses. We observed that the blue whale periotic is characterized by the presence of a strong dorsal protrusion which is posteriorly bordered by a previously undescribed morphological character that we name the posterotransverse fossa. The peculiar shape of the anterior process and the en echelon organization of the posterior foramina of the pars cochlearis are also described and compared. From a phylogenetic perspective, the blue whale is confirmed to be closely related to the fin whale, Balaenoptera physalus, but it is suggested, based on ear bone characters only, that it diverged before the other balaenopterid species in the phylogeny of Balaenopteridae. This placement supports a series of morphological observations suggesting that the extant blue whale was an early‐diverging member of Balaenoptera. Our results help to decipher the evolutionary origin of the blue whale, the largest living animal, by allowing new and more detailed morphological analyses of the balaenopterid fossil record.

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Section: Resultssupporting

confidence: 89%

The tympanoperiotic complex of the blue whale, Balaenoptera musculus

Bisconti,

Bosselaers,

Locatelli

et al. 2024

The Anatomical Record

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“…The auditory system of cetaceans is poorly understood, although it has been the subject of moderate attention up to this day. Due to the nature of these exceptional mammals, functional studies have been made to grade their hearing capacities (Mooney et al, 2012;Southall et al, 2019;Guan and Brookens, 2023). Pioneering studies used a direct mapping technique to precisely delineate the auditory area in the cortex of the bottlenose dolphin Tursiops truncatus (Bullock et al, 1968;Ladygina and Supin, 1970;Sokolov et al, 1972;Bullock and Gurevich, 1979;Popov et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Age-related changes in the primary auditory cortex of newborn, adults and aging bottlenose dolphins (Tursiops truncatus) are located in the upper cortical layers

Graïc,

Corain,

Finos

et al. 2024

Front. Neuroanat.

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IntroductionThe auditory system of dolphins and whales allows them to dive in dark waters, hunt for prey well below the limit of solar light absorption, and to communicate with their conspecific. These complex behaviors require specific and sufficient functional circuitry in the neocortex, and vicarious learning capacities. Dolphins are also precocious animals that can hold their breath and swim within minutes after birth. However, diving and hunting behaviors are likely not innate and need to be learned. Our hypothesis is that the organization of the auditory cortex of dolphins grows and mature not only in the early phases of life, but also in adults and aging individuals. These changes may be subtle and involve sub-populations of cells specificall linked to some circuits.MethodsIn the primary auditory cortex of 11 bottlenose dolphins belonging to three age groups (calves, adults, and old animals), neuronal cell shapes were analyzed separately and by cortical layer using custom computer vision and multivariate statistical analysis, to determine potential minute morphological differences across these age groups.ResultsThe results show definite changes in interneurons, characterized by round and ellipsoid shapes predominantly located in upper cortical layers. Notably, neonates interneurons exhibited a pattern of being closer together and smaller, developing into a more dispersed and diverse set of shapes in adulthood.DiscussionThis trend persisted in older animals, suggesting a continuous development of connections throughout the life of these marine animals. Our findings further support the proposition that thalamic input reach upper layers in cetaceans, at least within a cortical area critical for their survival. Moreover, our results indicate the likelihood of changes in cell populations occurring in adult animals, prompting the need for characterization.

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“…adapted call use or masking) or physical damage (e.g. temporary or permanent hearing loss) could lead to reduced fitness and survival [ 3 ]. However, the acoustic communication systems of cetaceans, e.g.…”

Section: Introductionmentioning

confidence: 99%

Context-driven communication during deep-sea foraging in a social toothed whale

Hessing,

Risser,

Pichot

et al. 2024

R. Soc. Open Sci.

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Social deep-diving odontocetes face the challenge of balancing near-surface proximity to oxygen and group members with foraging in the deep sea. Individuals rely on conspecifics for critical life functions, such as predator defence, but disperse during foraging to feed individually. To understand the role of social acoustic mediation during foraging in deep-diving toothed whales, we investigated the context of social burst-pulse call production in Risso’s dolphin ( Grampus griseus ) using biologgers. Dolphins produced context-specific burst pulses predominantly during daytime foraging, preceding or following foraging dives and in the early descent of daytime deep dives. Individuals applied differential short and long burst-pulse calls intended for either near-surface receivers (horizontal transmission) or deep-foraging receivers (vertical transmission). Our results show that deep-diving toothed whales are reliant on acoustic communication during certain foraging contexts, to relay information including foraging conditions or an individual’s location. Moreover, they accentuate the importance of maintaining acoustic contact with conspecifics, specifically when dispersed during deeper foraging. It also signifies that our oceanic top predators may be specifically vulnerable to the current strong increase in anthropogenic noise. Potential masking of the signals from group members communicating at a distance could undermine their social cohesion, and hence their capacity to maintain vital life functions.

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An overview of research efforts to understand the effects of underwater sound on cetaceans

Cited by 6 publications

References 151 publications

The tympanoperiotic complex of the blue whale, Balaenoptera musculus

The tympanoperiotic complex of the blue whale, Balaenoptera musculus

Age-related changes in the primary auditory cortex of newborn, adults and aging bottlenose dolphins (Tursiops truncatus) are located in the upper cortical layers

Context-driven communication during deep-sea foraging in a social toothed whale

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