1
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Abildtrup Nielsen N, Dawson SM, Torres Ortiz S, Wahlberg M, Martin MJ. Hector's dolphins (Cephalorhynchus hectori) produce both narrowband high-frequency and broadband acoustic signals. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:1437-1450. [PMID: 38364047 DOI: 10.1121/10.0024820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/25/2024] [Indexed: 02/18/2024]
Abstract
Odontocetes produce clicks for echolocation and communication. Most odontocetes are thought to produce either broadband (BB) or narrowband high-frequency (NBHF) clicks. Here, we show that the click repertoire of Hector's dolphin (Cephalorhynchus hectori) comprises highly stereotypical NBHF clicks and far more variable broadband clicks, with some that are intermediate between these two categories. Both NBHF and broadband clicks were made in trains, buzzes, and burst-pulses. Most clicks within click trains were typical NBHF clicks, which had a median centroid frequency of 130.3 kHz (median -10 dB bandwidth = 29.8 kHz). Some, however, while having only marginally lower centroid frequency (median = 123.8 kHz), had significant energy below 100 kHz and approximately double the bandwidth (median -10 dB bandwidth = 69.8 kHz); we refer to these as broadband. Broadband clicks in buzzes and burst-pulses had lower median centroid frequencies (120.7 and 121.8 kHz, respectively) compared to NBHF buzzes and burst-pulses (129.5 and 130.3 kHz, respectively). Source levels of NBHF clicks, estimated by using a drone to measure ranges from a single hydrophone and by computing time-of-arrival differences at a vertical hydrophone array, ranged from 116 to 171 dB re 1 μPa at 1 m, whereas source levels of broadband clicks, obtained from array data only, ranged from 138 to 184 dB re 1 μPa at 1 m. Our findings challenge the grouping of toothed whales as either NBHF or broadband species.
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Affiliation(s)
- Nicoline Abildtrup Nielsen
- Marine Biological Research Center, Department of Biology, University of Southern Denmark, 5300 Kerteminde, Denmark
| | - Stephen M Dawson
- Department of Marine Science, University of Otago, Dunedin 9054, New Zealand
| | - Sara Torres Ortiz
- Marine Biological Research Center, Department of Biology, University of Southern Denmark, 5300 Kerteminde, Denmark
| | - Magnus Wahlberg
- Marine Biological Research Center, Department of Biology, University of Southern Denmark, 5300 Kerteminde, Denmark
| | - Morgan J Martin
- Center for Marine Acoustics, Bureau of Ocean Energy Management, Sterling, Virginia 20166, USA
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2
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Georgiev DD. Evolution of Consciousness. Life (Basel) 2023; 14:48. [PMID: 38255663 PMCID: PMC10817314 DOI: 10.3390/life14010048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 12/01/2023] [Accepted: 12/25/2023] [Indexed: 01/24/2024] Open
Abstract
The natural evolution of consciousness in different animal species mandates that conscious experiences are causally potent in order to confer any advantage in the struggle for survival. Any endeavor to construct a physical theory of consciousness based on emergence within the framework of classical physics, however, leads to causally impotent conscious experiences in direct contradiction to evolutionary theory since epiphenomenal consciousness cannot evolve through natural selection. Here, we review recent theoretical advances in describing sentience and free will as fundamental aspects of reality granted by quantum physical laws. Modern quantum information theory considers quantum states as a physical resource that endows quantum systems with the capacity to perform physical tasks that are classically impossible. Reductive identification of conscious experiences with the quantum information comprised in quantum brain states allows for causally potent consciousness that is capable of performing genuine choices for future courses of physical action. The consequent evolution of brain cortical networks contributes to increased computational power, memory capacity, and cognitive intelligence of the living organisms.
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Affiliation(s)
- Danko D Georgiev
- Institute for Advanced Study, 30 Vasilaki Papadopulu Str., 9010 Varna, Bulgaria
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3
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Laeta M, Oliveira JA, Siciliano S, Lambert O, Jensen FH, Galatius A. Cranial asymmetry in odontocetes: a facilitator of sonic exploration? ZOOLOGY 2023; 160:126108. [PMID: 37633185 DOI: 10.1016/j.zool.2023.126108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/31/2023] [Accepted: 08/04/2023] [Indexed: 08/28/2023]
Abstract
Directional cranial asymmetry is an intriguing condition that has evolved in all odontocetes which has mostly been associated with sound production for echolocation. In this study, we investigated how cranial asymmetry varies across odontocete species both in terms of quality (i.e., shape), and quantity (magnitude of deviation from symmetry). We investigated 72 species across all ten families of Odontoceti using two-dimensional geometric morphometrics. The average asymmetric shape was largely consistent across odontocetes - the rostral tip, maxillae, antorbital notches and braincase, as well as the suture crest between the frontal and interparietal bones were displaced to the right, whereas the nasal septum and premaxillae showed leftward shifts, in concert with an enlargement of the right premaxilla and maxilla. A clear phylogenetic signal related to asymmetric shape variation was identified across odontocetes using squared-change parsimony. The magnitude of asymmetry was widely variable across Odontoceti, with greatest asymmetry in Kogiidae, Monodontidae and Globicephalinae, followed by Physeteridae, Platanistidae and Lipotidae, while the asymmetry was lowest in Lissodelphininae, Phocoenidae, Iniidae and Pontoporiidae. Ziphiidae presented a wide spectrum of asymmetry. Generalized linear models explaining magnitude of asymmetry found associations with click source level while accounting for cranial size. Using phylogenetic generalized least squares, we reconfirm that source level and centroid size significantly predict the level of cranial asymmetry, with more asymmetric marine taxa generally consisting of bigger species emitting higher output sonar signal, i.e. louder sounds. Both characteristics theoretically support foraging at depth, the former by allowing extended diving and the latter being adaptive for prey detection at longer distances. Thus, cranial asymmetry seems to be an evolutionary pathway that allows odontocetes to devote more space for sound-generating structures associated with echolocation and thus increases biosonar search range and foraging efficiency beyond simple phylogenetic scaling predictions.
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Affiliation(s)
- Maíra Laeta
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, 20941-160 Rio de Janeiro, RJ, Brazil.
| | - João A Oliveira
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, 20941-160 Rio de Janeiro, RJ, Brazil
| | - Salvatore Siciliano
- Departamento de Ciências Biológicas, Escola Nacional de Saúde Pública Sergio Arouca/Fiocruz, 21040-360 Rio de Janeiro, RJ, Brazil; Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos (GEMM-Lagos), Rua São José, 1.260, Praia Seca, 28970-000 Araruama, RJ, Brazil
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, 1000 Brussels, Belgium
| | - Frants H Jensen
- Section for Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark; Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MA 02543, USA; Biology Department, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Anders Galatius
- Section for Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
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Zhao L, Giorli G, Caruso F, Dong L, Gong Z, Lin M, Li S. Echolocation clicks of free-ranging Indo-Pacific finless porpoises (Neophocaena phocaenoides) in Hainan waters. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 153:1934. [PMID: 37002078 DOI: 10.1121/10.0017655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/06/2023] [Indexed: 05/18/2023]
Abstract
The echolocation clicks of free-ranging Indo-Pacific finless porpoises (IPFPs, Neophocaena phocaenoides) have been rarely studied in the wild. This paper aims at describing the echolocation-click characteristics of IPFPs and examining whether IPFPs adapt their sonar system to the habitats in Hainan waters, China. The echolocation clicks were recorded using a 13 elements star-shaped array of hydrophones. A total of 65 on-axis clicks were identified and analyzed. IPFPs use echolocation clicks with a source level (SL) of 158 ± 9 dB re: 1 μPa peak-peak, mean peak, and centroid frequency of 134 ± 3 kHz, -3 dB bandwidth of 14 ± 2 kHz and produce at inter-click intervals of 104 ± 51 ms. The results relative to other porpoises show that finless porpoises in Hainan waters produce clicks with moderate SLs and high peak frequency. These results could be useful in detecting the presence and estimating the density of IPFPs during passive acoustic monitoring in the study area and serve to shed light on the interpopulation variation of click characteristics of finless porpoises as well.
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Affiliation(s)
- Likun Zhao
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
| | - Giacomo Giorli
- National Institute of Water and Atmospheric Research, Coasts and Oceans, 301 Evans Bay Parade, Greta Point, Wellington, 6021, New Zealand
| | - Francesco Caruso
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
| | - Lijun Dong
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
| | - Zining Gong
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
| | - Mingli Lin
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
| | - Songhai Li
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, 572000, China
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5
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Shil SK, Zahangir MM, Rahman MM, Kibria MM, Das BC, Yadav SK, Siddiki AMAMZ. Postmortem of a juvenile male Ganges River dolphin (
Platanista gangetica
spp.
gangetica
) in Bangladesh. VETERINARY RECORD CASE REPORTS 2023. [DOI: 10.1002/vrc2.573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Subrata Kumar Shil
- Department of Anatomy and Histology Faculty of Veterinary Medicine Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
| | - Md. Mahiuddin Zahangir
- Department of Fish Biology and Biotechnology Faculty of Fisheries Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
| | - Mohammad Mahbubur Rahman
- Department of Pathology and Parasitology Faculty of Veterinary Medicine Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
| | - Md. Manzoorul Kibria
- Halda River Research Laboratory Department of Zoology Faculty of Biological Sciences University of Chittagong Chattogram Bangladesh
| | - Bhajan Chandra Das
- Department of Medicine and Surgery Faculty of Veterinary Medicine Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
| | - Saroj Kumar Yadav
- Department of Medicine and Surgery Faculty of Veterinary Medicine Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
| | - AMAM Zonaed Siddiki
- Department of Pathology and Parasitology Faculty of Veterinary Medicine Chittagong Veterinary and Animal Sciences University Chattogram Bangladesh
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6
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Kolipakam V, Jacob M, Gayathri A, Deori S, Sarma H, Tasfia ST, Rokade A, Negi R, Wakid A, Qureshi Q. Pingers are effective in reducing net entanglement of river dolphins. Sci Rep 2022; 12:9382. [PMID: 35672330 PMCID: PMC9174236 DOI: 10.1038/s41598-022-12670-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 05/13/2022] [Indexed: 11/17/2022] Open
Abstract
Ganges River dolphins echolocate, but this mechanism is inadequate for poor sonar-echoing objects such as the monofilament gillnets, causing considerable net entanglement related mortalities. Net entanglement related deaths are one of the major causes of cetacean population decline around the world. Experiments were carried out to understand the use of pingers—an acoustic deterrent, in aiding the deterrence of dolphins from fishing nets. Based on the dolphin clicks recorded, in an experimental setup spanning 36 days, a 90% deterrence was found; 22.87 ± 0.71 SE dolphin detection positive minutes per hour near non-pingered nets versus 2.20 ± 0.33 SE per hour near pingered net. Within 30 m radii of nets, visual encounters of non-calf reduced by 52% and calf by 9%, in the presence of pingers. No evidence of habituation to pingers, habitat avoidance in dolphins after pinger removal or a change in fish catch in nets because of pingers was found during the study. While the effectiveness of pingers on calves and fish catch needs further experimentation, the use of pingers to minimize net entanglement mortalities in the Ganges River dolphins seems to be the most promising solution currently available. These results have critical implications for the conservation of other species of river dolphins around the world.
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7
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Branstetter BK, Brietenstein R, Goya G, Tormey M, Wu T, Finneran JJ. Spatial acuity of the bottlenose dolphin (Tursiops truncatus) biosonar system with a bat and human comparison. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:3847. [PMID: 35778192 DOI: 10.1121/10.0011676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Horizontal angular resolution was measured in two bottlenose dolphins using a two-alternative forced-choice, biosonar target discrimination paradigm. The task required a stationary dolphin positioned in a hoop to discriminate two physical targets at a range of 4 m. The angle separating the targets was manipulated to estimate an angular discrimination threshold of 1.5°. In a second experiment, a similar two-target biosonar discrimination task was conducted with one free-swimming dolphin, to test whether its emission beam was a critical factor in discriminating the targets. The spatial separation between two targets was manipulated to measure a discrimination threshold of 6.7 cm. There was a relationship between differences in acoustic signals received at each target and the dolphin's performance. The results of the angular resolution experiment were in good agreement with measures of the minimum audible angle of both dolphins and humans and remarkably similar to measures of angular difference discrimination in echolocating dolphins, bats, and humans. The results suggest that horizontal auditory spatial acuity may be a common feature of the mammalian auditory system rather than a specialized feature exclusive to echolocating auditory predators.
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Affiliation(s)
- Brian K Branstetter
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Rachel Brietenstein
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Gavin Goya
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Megan Tormey
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Teri Wu
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - James J Finneran
- United States Navy Marine Mammal Program, Naval Information Warfare Center Pacific, San Diego, California 92152, USA
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8
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de Sousa AA, Todorov OS, Proulx MJ. A natural history of vertebrate vision loss: Insight from mammalian vision for human visual function. Neurosci Biobehav Rev 2022; 134:104550. [PMID: 35074313 DOI: 10.1016/j.neubiorev.2022.104550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 10/08/2021] [Accepted: 01/20/2022] [Indexed: 11/28/2022]
Abstract
Research on the origin of vision and vision loss in naturally "blind" animal species can reveal the tasks that vision fulfills and the brain's role in visual experience. Models that incorporate evolutionary history, natural variation in visual ability, and experimental manipulations can help disentangle visual ability at a superficial level from behaviors linked to vision but not solely reliant upon it, and could assist the translation of ophthalmological research in animal models to human treatments. To unravel the similarities between blind individuals and blind species, we review concepts of 'blindness' and its behavioral correlates across a range of species. We explore the ancestral emergence of vision in vertebrates, and the loss of vision in blind species with reference to an evolution-based classification scheme. We applied phylogenetic comparative methods to a mammalian tree to explore the evolution of visual acuity using ancestral state estimations. Future research into the natural history of vision loss could help elucidate the function of vision and inspire innovations in how to address vision loss in humans.
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Affiliation(s)
- Alexandra A de Sousa
- Centre for Health and Cognition, Bath Spa University, Bath, United Kingdom; UKRI Centre for Accessible, Responsible & Transparent Artificial Intelligence (ART:AI), University of Bath, United Kingdom.
| | - Orlin S Todorov
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Michael J Proulx
- UKRI Centre for Accessible, Responsible & Transparent Artificial Intelligence (ART:AI), University of Bath, United Kingdom; Department of Psychology, REVEAL Research Centre, University of Bath, Bath, United Kingdom
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9
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Zahn MJ, Laidre KL, Stilz P, Rasmussen MH, Koblitz JC. Vertical sonar beam width and scanning behavior of wild belugas (Delphinapterus leucas) in West Greenland. PLoS One 2021; 16:e0257054. [PMID: 34499678 PMCID: PMC8428689 DOI: 10.1371/journal.pone.0257054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/22/2021] [Indexed: 11/18/2022] Open
Abstract
Echolocation signals of wild beluga whales (Delphinapterus leucas) were recorded in 2013 using a vertical, linear 16-hydrophone array at two locations in the pack ice of Baffin Bay, West Greenland. Individual whales were localized for 4:42 minutes of 1:04 hours of recordings. Clicks centered on the recording equipment (i.e. on-axis clicks) were isolated to calculate sonar parameters. We report the first sonar beam estimate of in situ recordings of wild belugas with an average -3 dB asymmetrical vertical beam width of 5.4°, showing a wider ventral beam. This narrow beam width is consistent with estimates from captive belugas; however, our results indicate that beluga sonar beams may not be symmetrical and may differ in wild and captive contexts. The mean apparent source level for on-axis clicks was 212 dB pp re 1 μPa and whales were shown to vertically scan the array from 120 meters distance. Our findings support the hypothesis that highly directional sonar beams and high source levels are an evolutionary adaptation for Arctic odontocetes to reduce unwanted surface echoes from sea ice (i.e., acoustic clutter) and effectively navigate through leads in the pack ice (e.g., find breathing holes). These results provide the first baseline beluga sonar metrics from free-ranging animals using a hydrophone array and are important for acoustic programs throughout the Arctic, particularly for acoustic classification between belugas and narwhals (Monodon monoceros).
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Affiliation(s)
- Marie J Zahn
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America
| | - Kristin L Laidre
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America.,Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, United States of America
| | - Peter Stilz
- Animal Physiology, Institute for Neurobiology, University of Tübingen, Tübingen, Germany
| | | | - Jens C Koblitz
- Max Planck Institute of Animal Behavior, Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.,Department of Biology, University of Konstanz, Konstanz, Germany
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10
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Martin MJ, Torres Ortiz S, Reyes Reyes MV, Marino A, Iñíguez Bessega M, Wahlberg M. Commerson’s dolphins (Cephalorhynchus commersonii) can relax acoustic crypsis. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03035-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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11
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Melo JF, Amorim TOS, Paschoalini M, Andriolo A. The biosonar of the boto: evidence of differences among species of river dolphins ( Inia spp.) from the Amazon. PeerJ 2021; 9:e11105. [PMID: 33981488 PMCID: PMC8071073 DOI: 10.7717/peerj.11105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/22/2021] [Indexed: 11/20/2022] Open
Abstract
Echolocation clicks can reflect the anatomy of the vocalizing animal, enabling the distinction of species. River dolphins from the family Iniidae are formally represented by one species and two subspecies (Inia geoffrensis geoffrensis and I. g. humboldtiana). Additionally, two other species have been proposed (I. boliviensis and I. araguaiaensis) regarding its level of restricted distribution and morph-genetics differences. For the Committee on Taxonomy of the Society for Marine Mammalogy, the specific status of the proposed species relies on further knowledge on morphology, ecology, and genetics. Given that species-specific status is required for conservation efforts, we described and compared the echolocation clicks of Inia spp., searching for specific differences on their vocalizations. The sounds were captured with a Cetacean Research ™ C54XRS (+3/−20 dB, −185 dB re: 1V/μPa) in Guaviare River (Orinoco basin), Madeira River (Madeira basin), Xingu River (Amazon Basin), and Araguaia River (Tocantins-Araguaia basin). We found significant differences in all analyzed parameters (peak frequency, 3 dB bandwidth, 10 dB bandwidth and inter-click interval) for all species and subspecies. Differences in acoustical parameters of clicks are mainly related to the animal’s internal morphology, thus this study may potentially support with information for the species-level classification mostly of I. araguaiaensis (the Araguaian boto). Classifying the Araguaian boto separately from I. geoffrensis has important implications for the species in terms of conservation status, since it is restricted to a highly impacted river system.
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Affiliation(s)
- Jéssica F Melo
- Laboratório de Ecologia Comportamental e Bioacústica - LABEC, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.,Grupo de Pesquisa em Mamíferos Aquáticos Amazônicos, Mamirauá Sustainable Development Institute, Tefé, Amazonas, Brazil
| | - Thiago O S Amorim
- Laboratório de Ecologia Comportamental e Bioacústica - LABEC, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.,Instituto Aqualie, Juiz de Fora, Minas Gerais, Brazil
| | - Mariana Paschoalini
- Laboratório de Ecologia Comportamental e Bioacústica - LABEC, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.,Grupo de Pesquisa em Mamíferos Aquáticos Amazônicos, Mamirauá Sustainable Development Institute, Tefé, Amazonas, Brazil.,Instituto Aqualie, Juiz de Fora, Minas Gerais, Brazil
| | - Artur Andriolo
- Laboratório de Ecologia Comportamental e Bioacústica - LABEC, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.,Instituto Aqualie, Juiz de Fora, Minas Gerais, Brazil
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12
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Malinka CE, Tønnesen P, Dunn CA, Claridge DE, Gridley T, Elwen SH, Teglberg Madsen P. Echolocation click parameters and biosonar behaviour of the dwarf sperm whale ( Kogia sima). J Exp Biol 2021; 224:224/6/jeb240689. [PMID: 33771935 DOI: 10.1242/jeb.240689] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 02/11/2021] [Indexed: 11/20/2022]
Abstract
Dwarf sperm whales (Kogia sima) are small toothed whales that produce narrow-band high-frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, are usually produced by small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range echolocation and fast click rates. Here, we sought to address the problem of how the little-studied and deep-diving Kogia can hunt with NBHF clicks in the deep sea. Specifically, we tested the hypotheses that Kogia produce NBHF clicks with longer inter-click intervals (ICIs), higher directionality and higher source levels (SLs) compared with other NBHF species. We did this by deploying an autonomous deep-water vertical hydrophone array in the Bahamas, where no other NBHF species are present, and by taking opportunistic recordings of a close-range Kogia sima in a South African harbour. Parameters from on-axis clicks (n=46) in the deep revealed very narrow-band clicks (root mean squared bandwidth, BWRMS, of 3±1 kHz), with SLs of up to 197 dB re. 1 µPa peak-to-peak (μPapp) at 1 m, and a half-power beamwidth of 8.8 deg. Their ICIs (mode of 245 ms) were much longer than those of porpoises (<100 ms), suggesting an inspection range that is longer than detection ranges of single prey, perhaps to facilitate auditory streaming of a complex echo scene. On-axis clicks in the shallow harbour (n=870) had ICIs and SLs in keeping with source parameters of other NBHF cetaceans. Thus, in the deep, dwarf sperm whales use a directional, but short-range echolocation system with moderate SLs, suggesting a reliable mesopelagic prey habitat.
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Affiliation(s)
- Chloe E Malinka
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Pernille Tønnesen
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Charlotte A Dunn
- Bahamas Marine Mammal Research Organisation (BMMRO), Sandy Point, Abaco, Bahamas.,Sea Mammal Research Unit, University of St Andrews, St Andrews KY16 8LB, UK
| | - Diane E Claridge
- Bahamas Marine Mammal Research Organisation (BMMRO), Sandy Point, Abaco, Bahamas.,Sea Mammal Research Unit, University of St Andrews, St Andrews KY16 8LB, UK
| | - Tess Gridley
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7605, South Africa.,Sea Search Research and Conservation, Muizenberg, Cape Town 7945, South Africa
| | - Simon H Elwen
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7605, South Africa.,Sea Search Research and Conservation, Muizenberg, Cape Town 7945, South Africa
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13
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Pedersen MB, Tønnesen P, Malinka CE, Ladegaard M, Johnson M, Aguilar de Soto N, Madsen PT. Echolocation click parameters of short-finned pilot whales (Globicephala macrorhynchus) in the wild. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:1923. [PMID: 33765819 DOI: 10.1121/10.0003762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Short-finned pilot whales (Globicephala macrorhynchus) are large, deep-diving predators with diverse foraging strategies, but little is known about their echolocation. To quantify the source properties of short-finned pilot whale clicks, we made 15 deployments off the coast of Tenerife of a deep-water hydrophone array consisting of seven autonomous time-synced hydrophone recorders (SoundTraps), enabling acoustic localization and quantification of click source parameters. Of 8185 recorded pilot whale clicks, 47 were classified as being recorded on-axis, with a mean peak-to-peak source level (SL) of 181 ± 7 dB re 1 μPa, a centroid frequency of 40 ± 4 kHz, and a duration of 57 ± 23 μs. A fit to a piston model yielded an estimated half-power (-3 dB) beam width of 13.7° [95% confidence interval (CI) 13.2°-14.5°] and a mean directivity index (DI) of 22.6 dB (95% CI 22.5-22.9 dB). These measured SLs and DIs are surprisingly low for a deep-diving toothed whale, suggesting we sampled the short-finned pilot whales in a context with little need for operating a long-range biosonar. The substantial spectral overlap with beaked whale clicks emitted in similar deep-water habitats implies that pilot whale clicks may constitute a common source of false detections in beaked whale passive acoustic monitoring efforts.
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Affiliation(s)
- M B Pedersen
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - P Tønnesen
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - C E Malinka
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - M Ladegaard
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - M Johnson
- Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C, Denmark
| | - N Aguilar de Soto
- Biodiversidad, Ecología Marina y Conservación (BIOECOMAC), University of La Laguna, 38206 La Laguna, Tenerife, Canary Islands, Spain
| | - P T Madsen
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
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14
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Georgiev DD. Quantum information theoretic approach to the mind–brain problem. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 158:16-32. [DOI: 10.1016/j.pbiomolbio.2020.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/02/2020] [Accepted: 08/05/2020] [Indexed: 12/25/2022]
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15
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Dähne M, Bär T, Gallus A, Benke H, Herold E, Stilz P. No need to shout? Harbor porpoises (Phocoena phocoena) echolocate quietly in confined murky waters of the Wadden Sea. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:EL382. [PMID: 33138503 DOI: 10.1121/10.0002347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/30/2020] [Indexed: 06/11/2023]
Abstract
Porpoise echolocation parameters may vary depending on their acoustic habitat and predominant behavior. Research was conducted in the Wadden Sea, an acoustically complex, tidally driven habitat with high particle resuspension. Source levels and echolocation parameters of wild harbor porpoises were estimated from time-of-arrival-differences of a six-element hydrophone array. The back-calculated peak-to-peak apparent source level of 169 ± 5 dB re 1 μPa was significantly lower than reported from Inner Danish Waters (-20 dB) and British Columbia (-9 dB) with narrower bandwidth. Porpoises therefore reduce their source level in the Wadden Sea under acoustically complex conditions suggesting an avoidance of cluttering.
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Affiliation(s)
- Michael Dähne
- Deutsches Meeresmuseum, Katharinenberg 14-20, 18439 Stralsund, Germany
| | - Tom Bär
- Deutsches Meeresmuseum, Katharinenberg 14-20, 18439 Stralsund, Germany
| | - Anja Gallus
- Deutsches Meeresmuseum, Katharinenberg 14-20, 18439 Stralsund, Germany
| | - Harald Benke
- Deutsches Meeresmuseum, Katharinenberg 14-20, 18439 Stralsund, Germany
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16
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Kuroda M, Miki N, Matsuishi TF. Determinants of echolocation click frequency characteristics in small toothed whales: recent advances from anatomical information. Mamm Rev 2020. [DOI: 10.1111/mam.12212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Mika Kuroda
- Faculty of Fisheries Sciences Hokkaido University 3‐1‐1 Minato‐cho Hakodate Hokkaido041‐8611Japan
| | - Nobuhiro Miki
- Future University Hakodate 116‐2 Kamedanakano‐cho Hakodate Hokkaido041‐8655Japan
| | - Takashi Fritz Matsuishi
- Faculty of Fisheries Sciences Hokkaido University 3‐1‐1 Minato‐cho Hakodate Hokkaido041‐8611Japan
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17
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Branstetter BK, Van Alstyne KR, Strahan MG, Tormey MN, Wu T, Breitenstein RA, Houser DS, Finneran JJ, Xitco MJ. Spectral cues and temporal integration during cylinder echo discrimination by bottlenose dolphins (Tursiops truncatus). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:614. [PMID: 32872984 DOI: 10.1121/10.0001626] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
Three bottlenose dolphins (Tursiops truncatus) participated in simulated cylinder wall thickness discrimination tasks utilizing electronic "phantom" echoes. The first experiment resulted in psychometric functions (percent correct vs wall thickness difference) similar to those produced by a dolphin performing the task with physical cylinders. In the second experiment, a wide range of cylinder echoes was simulated, with the time separation between echo highlights covering a range from <30 to >300 μs. Dolphin performance and a model of the dolphin auditory periphery suggest that the dolphins used high-frequency, spectral-profiles of the echoes for discrimination and that the utility of spectral cues degraded when the time separation between echo highlights approached and exceeded the dolphin's temporal integration time of ∼264 μs.
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Affiliation(s)
- Brian K Branstetter
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Kaitlin R Van Alstyne
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Madelyn G Strahan
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Megan N Tormey
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Teri Wu
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Rachel A Breitenstein
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - Dorian S Houser
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA
| | - James J Finneran
- U.S. Navy Marine Mammal Program, San Diego, California 92152, USA
| | - Mark J Xitco
- U.S. Navy Marine Mammal Program, San Diego, California 92152, USA
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18
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Coombs EJ, Clavel J, Park T, Churchill M, Goswami A. Wonky whales: the evolution of cranial asymmetry in cetaceans. BMC Biol 2020; 18:86. [PMID: 32646447 PMCID: PMC7350770 DOI: 10.1186/s12915-020-00805-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/01/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unlike most mammals, toothed whale (Odontoceti) skulls lack symmetry in the nasal and facial (nasofacial) region. This asymmetry is hypothesised to relate to echolocation, which may have evolved in the earliest diverging odontocetes. Early cetaceans (whales, dolphins, and porpoises) such as archaeocetes, namely the protocetids and basilosaurids, have asymmetric rostra, but it is unclear when nasofacial asymmetry evolved during the transition from archaeocetes to modern whales. We used three-dimensional geometric morphometrics and phylogenetic comparative methods to reconstruct the evolution of asymmetry in the skulls of 162 living and extinct cetaceans over 50 million years. RESULTS In archaeocetes, we found asymmetry is prevalent in the rostrum and also in the squamosal, jugal, and orbit, possibly reflecting preservational deformation. Asymmetry in odontocetes is predominant in the nasofacial region. Mysticetes (baleen whales) show symmetry similar to terrestrial artiodactyls such as bovines. The first significant shift in asymmetry occurred in the stem odontocete family Xenorophidae during the Early Oligocene. Further increases in asymmetry occur in the physeteroids in the Late Oligocene, Squalodelphinidae and Platanistidae in the Late Oligocene/Early Miocene, and in the Monodontidae in the Late Miocene/Early Pliocene. Additional episodes of rapid change in odontocete skull asymmetry were found in the Mid-Late Oligocene, a period of rapid evolution and diversification. No high-probability increases or jumps in asymmetry were found in mysticetes or archaeocetes. Unexpectedly, no increases in asymmetry were recovered within the highly asymmetric ziphiids, which may result from the extreme, asymmetric shape of premaxillary crests in these taxa not being captured by landmarks alone. CONCLUSIONS Early ancestors of living whales had little cranial asymmetry and likely were not able to echolocate. Archaeocetes display high levels of asymmetry in the rostrum, potentially related to directional hearing, which is lost in early neocetes-the taxon including the most recent common ancestor of living cetaceans. Nasofacial asymmetry becomes a significant feature of Odontoceti skulls in the Early Oligocene, reaching its highest levels in extant taxa. Separate evolutionary regimes are reconstructed for odontocetes living in acoustically complex environments, suggesting that these niches impose strong selective pressure on echolocation ability and thus increased cranial asymmetry.
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Affiliation(s)
- Ellen J Coombs
- Genetics, Evolution, and Environment Department, University College London, Gower Street, London, WC1E 6BT, UK.
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK.
| | - Julien Clavel
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Travis Park
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
| | - Morgan Churchill
- Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, WI, 54901, USA
| | - Anjali Goswami
- Genetics, Evolution, and Environment Department, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Life Sciences, Natural History Museum, London, Cromwell Road, London, SW7 5BD, UK
- Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK
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19
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Roy Chowdhury G, Roy K, Goyal N, Warudkar A, Raza RH, Qureshi Q. On the evidence of the Irrawaddy Dolphin Orcaella brevirostris (Owen, 1866) (Mammalia: Cetartiodactyla: Delphinidae) in the Hooghly River, West Bengal, India. JOURNAL OF THREATENED TAXA 2020. [DOI: 10.11609/jott.5171.12.8.15905-15908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
We report the presence and status of the Irrawaddy Dolphin Orcaella brevirostris in the Hooghly River of West Bengal, India. These observations were made while conducting our field work on the Ganges River Dolphin, which involved vessel-based surveys as well as intensive monitoring from an anchored boat.
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20
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Yang L, Sharpe M, Temple AJ, Jiddawi N, Xu X, Berggren P. Description and classification of echolocation clicks of Indian Ocean humpback (Sousa plumbea) and Indo-Pacific bottlenose (Tursiops aduncus) dolphins from Menai Bay, Zanzibar, East Africa. PLoS One 2020; 15:e0230319. [PMID: 32168368 PMCID: PMC7069646 DOI: 10.1371/journal.pone.0230319] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 02/26/2020] [Indexed: 11/18/2022] Open
Abstract
Passive acoustic monitoring (PAM) is a powerful method to study the occurrence, movement and behavior of echolocating odontocetes (toothed whales) in the wild. However, in areas occupied by more than one species, echolocation clicks need to be classified into species. The present study investigated whether the echolocation clicks produced by small, at-risk, resident sympatric populations of Indian Ocean humpback dolphin (Sousa plumbea) and Indo-Pacific bottlenose dolphin (Tursiops aduncus) in Menai Bay, Zanzibar, East Africa, could be classified to allow species specific monitoring. Underwater sounds of S. plumbea and T. aduncus groups were recorded using a SoundTrap 202HF in January and June-August 2015. Eight acoustic parameters, i.e. -10 dB duration, peak, centroid, lower -3 and lower -10 dB frequencies, and -3 dB, -10 dB and root-mean-squared bandwidth, were used to describe and compare the two species’ echolocation clicks. Statistical analyses showed that S. plumbea clicks had significantly higher peak, centroid, lower -3 and lower -10 dB frequencies compared to T. aduncus, whereas duration and bandwidth parameters were similar for the two species. Random Forest (RF) classifiers were applied to determine parameters that could be used to classify the two species from echolocation clicks and achieved 28.6% and 90.2% correct species classification rates for S. plumbea and T. aduncus, respectively. Both species were classified at a higher rate than expected at random, however the identified classifiers would only be useful for T. aduncus monitoring. The frequency and bandwidth parameters provided most power for species classification. Further study is necessary to identify useful classifiers for S. plumbea. This study represents a first step in acoustic description and classification of S. plumbea and T. aduncus in the western Indian Ocean region, with potential application for future acoustic monitoring of species-specific temporal and spatial occurrence in these sympatric species.
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Affiliation(s)
- Liangliang Yang
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, England, United Kingdom
- Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Matt Sharpe
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, England, United Kingdom
| | - Andrew J. Temple
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, England, United Kingdom
| | - Narriman Jiddawi
- Institute of Fisheries Research Zanzibar, Ministry of Agriculture, Natural Resources, Livestock and Fisheries, Zanzibar, Tanzania
| | - Xiaomei Xu
- Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
- * E-mail: (XX); (PB)
| | - Per Berggren
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, England, United Kingdom
- * E-mail: (XX); (PB)
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21
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Jensen FH, Keller OA, Tyack PL, Visser F. Dynamic biosonar adjustment strategies in deep-diving Risso's dolphins driven partly by prey evasion. ACTA ACUST UNITED AC 2020; 223:jeb.216283. [PMID: 31822550 DOI: 10.1242/jeb.216283] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/02/2019] [Indexed: 11/20/2022]
Abstract
Toothed whales have evolved flexible biosonar systems to find, track and capture prey in diverse habitats. Delphinids, phocoenids and iniids adjust inter-click intervals and source levels gradually while approaching prey. In contrast, deep-diving beaked and sperm whales maintain relatively constant inter-click intervals and apparent output levels during the approach followed by a rapid transition into the foraging buzz, presumably to maintain a long-range acoustic scene in a multi-target environment. However, it remains unknown whether this rapid biosonar adjustment strategy is shared by delphinids foraging in deep waters. To test this, we investigated biosonar adjustments of a deep-diving delphinid, the Risso's dolphin (Grampus griseus). We analyzed inter-click interval and apparent output level adjustments recorded from sound recording tags to quantify in situ sensory adjustment during prey capture attempts. Risso's dolphins did not follow typical (20logR) biosonar adjustment patterns seen in shallow-water species, but instead maintained stable repetition rates and output levels up to the foraging buzz. Our results suggest that maintaining a long-range acoustic scene to exploit complex, multi-target prey layers is a common strategy amongst deep-diving toothed whales. Risso's dolphins transitioned rapidly into the foraging buzz just like beaked whales during most foraging attempts, but employed a more gradual biosonar adjustment in a subset (19%) of prey approaches. These were characterized by higher speeds and minimum specific acceleration, indicating higher prey capture efforts associated with evasive prey. Thus, tracking and capturing evasive prey using biosonar may require a more gradual switch between multi-target echolocation and single-target tracking.
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Affiliation(s)
- Frants H Jensen
- Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C, Denmark .,Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Onno A Keller
- Department of Coastal Systems, Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg Texel, The Netherlands.,Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands.,Department of Animal Ecology, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Peter L Tyack
- Scottish Oceans Institute, School of Biology, University of St Andrews, East Sands, St Andrews KY16 8LB, UK
| | - Fleur Visser
- Department of Coastal Systems, Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg Texel, The Netherlands.,Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GE Amsterdam, The Netherlands.,Kelp Marine Research, 1624CJ Hoorn, The Netherlands
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22
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Interacting effects of vessel noise and shallow river depth elevate metabolic stress in Ganges river dolphins. Sci Rep 2019; 9:15426. [PMID: 31659202 PMCID: PMC6817857 DOI: 10.1038/s41598-019-51664-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/03/2019] [Indexed: 11/13/2022] Open
Abstract
In riverine ‘soundscapes’, complex interactions between sound, substrate type, and depth create difficulties in assessing impacts of anthropogenic noise pollution on freshwater fauna. Underwater noise from vessels can negatively affect endangered Ganges river dolphins (Platanista gangetica), which are ‘almost blind’ and rely entirely on high-frequency echolocation clicks to sense their environment. We conducted field-based acoustic recordings and modelling to assess acoustic responses of Platanista to underwater noise exposure from vessels in the Ganga River (India), which is now being transformed into a major waterway. Dolphins showed enhanced activity during acute noise exposure and suppressed activity during chronic exposure. Increase in ambient noise levels altered dolphin acoustic responses, strongly masked echolocation clicks, and more than doubled metabolic stress. Noise impacts were further aggravated during dry-season river depth reduction. Maintaining ecological flows, downscaling of vessel traffic, and propeller modifications to reduce cavitation noise, could help mitigate noise impacts on Ganges river dolphins.
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23
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Gong Z, Dong L, Caruso F, Lin M, Liu M, Dong J, Li S. Echolocation signals of free-ranging pantropical spotted dolphins (Stenella attenuata) in the South China Sea. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 145:3480. [PMID: 31255156 DOI: 10.1121/1.5111742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 05/28/2019] [Indexed: 06/09/2023]
Abstract
Echolocation signals of free-ranging pantropical spotted dolphins (Stenella attenuata) in the western Pacific Ocean have not been studied much. This paper aims to describe the characteristics of echolocation signals of S. attenuata in the northern South China Sea. A six-arm star array with 13 hydrophones was used and a total of 131 on-axis clicks were identified to analyze the acoustic features of the echolocation signals of dolphins. The mean center frequency was 89 ± 13 kHz, with mean peak-to-peak sound source levels of 190 ± 6 dB re: 1 μPa @ 1 m. The mean -3 dB bandwidth and root-mean-square bandwidth were 62 ± 15 kHz and 26 ± 3 kHz, respectively, with mean -10 dB duration of 18 ± 4 μs and root-mean-square duration of 6 ± 2 μs. The results showed that click parameters of S. attenuata in the northern South China Sea are different from those of clicks of the species in Hawaii waters. The differences in click parameters may be due to both behavioral context and/or environmental adaptation of S. attenuata in different habitats.
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Affiliation(s)
- Zining Gong
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Lijun Dong
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Francesco Caruso
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Mingli Lin
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Mingming Liu
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Jianchen Dong
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
| | - Songhai Li
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China
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24
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Smith AB, Pacini AF, Nachtigall PE, Laule GE, Aragones LV, Magno C, Suarez LJA. Transmission beam pattern and dynamics of a spinner dolphin (Stenella longirostris). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 145:3595. [PMID: 31255135 DOI: 10.1121/1.5111347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/24/2019] [Indexed: 06/09/2023]
Abstract
Toothed whales possess a sophisticated biosonar system by which ultrasonic clicks are projected in a highly directional transmission beam. Beam directivity is an important biosonar characteristic that reduces acoustic clutter and increases the acoustic detection range. This study measured click characteristics and the transmission beam pattern from a small odontocete, the spinner dolphin (Stenella longirostis). A formerly stranded individual was rehabilitated and trained to station underwater in front of a 16-element hydrophone array. On-axis clicks showed a mean duration of 20.1 μs, with mean peak and centroid frequencies of 58 and 64 kHz [standard deviation (s.d.) ±30 and ±12 kHz], respectively. Clicks were projected in an oval, vertically compressed beam, with mean vertical and horizontal beamwidths of 14.5° (s.d. ± 3.9) and 16.3° (s.d. ± 4.6), respectively. Directivity indices ranged from 14.9 to 27.4 dB, with a mean of 21.7 dB, although this likely represents a broader beam than what is normally produced by wild individuals. A click subset with characteristics more similar to those described for wild individuals exhibited a mean directivity index of 23.3 dB. Although one of the broadest transmission beams described for a dolphin, it is similar to other small bodied odontocetes.
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Affiliation(s)
- Adam B Smith
- Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, Hawaii 96744, USA
| | - Aude F Pacini
- Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, Hawaii 96744, USA
| | - Paul E Nachtigall
- Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, Hawaii 96744, USA
| | - Gail E Laule
- Ocean Adventure, Camayan Wharf, West Ilanin Forest, Subic Bay Freeport Zone, Philippines
| | - Lemnuel V Aragones
- Institute of Environmental Science and Meteorology, University of the Philippines, Diliman, Quezon City, Philippines
| | - Carlo Magno
- Ocean Adventure, Camayan Wharf, West Ilanin Forest, Subic Bay Freeport Zone, Philippines
| | - Leo J A Suarez
- Ocean Adventure, Camayan Wharf, West Ilanin Forest, Subic Bay Freeport Zone, Philippines
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25
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Niu FQ, Yang YM, Zhou ZM, Wang XY, Monanunsap S, Junchompoo C. Echolocation clicks of free-ranging Irrawaddy dolphins (Orcaella brevirostris) in Trat Bay, the eastern Gulf of Thailand. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 145:3031. [PMID: 31153324 DOI: 10.1121/1.5100619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Little is known about the vocalizations of Irrawaddy dolphins (Orcaella brevirostris) in the Gulf of Thailand. The present study first described the echolocation clicks of Irrawaddy dolphins in Trat Bay, in the eastern Gulf of Thailand, using a broadband hydrophone system. Over 2 h of acoustic recordings were collected during 14-day study periods in December 2017 and December 2018. Several criteria were used to judge if a click was on axis or as close to the acoustic axis as possible. To calculate the distance of dolphins, a low-budget localization method based on arrival time differences between the direct and indirect signals was used in the present study. The clicks had a mean peak-to-peak source level of 192 ± 3 dB re 1 μPa, an energy flux density source level of 131 ± 3 dB re 1 μPa2s, a mean centroid frequency of 98 ± 10 kHz, a mean duration of 16 ± 2 μs, and a -3 dB bandwidth of 79 ± 13 kHz. The click parameters of the Irrawaddy dolphins in Trat Bay were slightly different from the clicks recorded from the dolphins in Sundarbans, Bangladesh. The present study provided a basic description of the click characteristics of Irrawaddy dolphins in Trat Bay, which could contribute to the management and conservation strategies for local Irrawaddy dolphins, and a basic reference for the proper input parameters in passive acoustic monitoring and detection.
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Affiliation(s)
- Fu Qiang Niu
- Third Institute of Oceanography, Ministry of Natural Resources, 361005, Xiamen, China
| | - Yan Ming Yang
- Third Institute of Oceanography, Ministry of Natural Resources, 361005, Xiamen, China
| | - Zai Ming Zhou
- Third Institute of Oceanography, Ministry of Natural Resources, 361005, Xiamen, China
| | - Xian Yan Wang
- Third Institute of Oceanography, Ministry of Natural Resources, 361005, Xiamen, China
| | - Somchai Monanunsap
- Marine and Coastal Resources Research and Development Center, the Eastern Gulf of Thailand, 21170, Rayong, Thailand
| | - Chalatip Junchompoo
- Marine and Coastal Resources Research and Development Center, the Eastern Gulf of Thailand, 21170, Rayong, Thailand
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Melo-Santos G, Figueiredo Rodrigues AL, Tardin RH, de Sá Maciel I, Marmontel M, Da Silva ML, May-Collado LJ. The newly described Araguaian river dolphins, Inia araguaiaensis (Cetartiodactyla, Iniidae), produce a diverse repertoire of acoustic signals. PeerJ 2019; 7:e6670. [PMID: 31041149 PMCID: PMC6476290 DOI: 10.7717/peerj.6670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 02/22/2019] [Indexed: 11/20/2022] Open
Abstract
The recent discovery of the Araguaian river dolphin (Inia araguaiaensis) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour. We analysed frequency contours of 727 signals (sampled at 10 ms temporal resolution). These contours were analyzed using an adaptive resonance theory neural network combined with dynamic time-warping (ARTwarp). Using a critical similarity value of 96%, frequency contours were categorized into 237 sound-types. The most common types were emitted when calves were present suggesting a key role in mother-calf communication. Our findings show that the acoustic repertoire of river dolphins is far from simple. Furthermore, the calls described here are similar in acoustic structure to those produced by social delphinids, such as orcas and pilot whales. Uncovering the context in which these signals are produced may help understand the social structure of this species and contribute to our understanding of the evolution of acoustic communication in whales.
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Affiliation(s)
- Gabriel Melo-Santos
- Sea Mammal Research Unit/Scottish Oceans Institute, University of St Andrews, St Andrews, Scotland, United Kingdom
- BioMA—Biology and Conservation of Amazonian Aquatic Mammals, Belém, Pará, Brazil
- Graduate program in Theory and Research of Behavior, Universidade Federal do Pará, Belém, Pará, Brazil
- Research Group on Amazonian Aquatic Mammals, Mamirauá Institute for Sustainable Development, Tefé, Amazonas, Brazil
- Laboratory of Ornithology and Bioacoustics, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Angélica Lúcia Figueiredo Rodrigues
- BioMA—Biology and Conservation of Amazonian Aquatic Mammals, Belém, Pará, Brazil
- Graduate program in Theory and Research of Behavior, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Rodrigo Hipólito Tardin
- Department of Ecology, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratory of Bioacoustics and Cetacean Ecology, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Israel de Sá Maciel
- Laboratory of Bioacoustics and Cetacean Ecology, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil
- Graduate Program in Animal Biology, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Miriam Marmontel
- Research Group on Amazonian Aquatic Mammals, Mamirauá Institute for Sustainable Development, Tefé, Amazonas, Brazil
| | - Maria Luisa Da Silva
- Graduate program in Theory and Research of Behavior, Universidade Federal do Pará, Belém, Pará, Brazil
- Laboratory of Ornithology and Bioacoustics, Universidade Federal do Pará, Belém, Pará, Brazil
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Jensen FH, Johnson M, Ladegaard M, Wisniewska DM, Madsen PT. Narrow Acoustic Field of View Drives Frequency Scaling in Toothed Whale Biosonar. Curr Biol 2018; 28:3878-3885.e3. [DOI: 10.1016/j.cub.2018.10.037] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/12/2018] [Accepted: 10/12/2018] [Indexed: 11/27/2022]
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Frainer G, Plön S, Serpa NB, Moreno IB, Huggenberger S. Sound Generating Structures of the Humpback DolphinSousa plumbea(Cuvier, 1829) and the Directionality in Dolphin Sounds. Anat Rec (Hoboken) 2018; 302:849-860. [DOI: 10.1002/ar.23981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/01/2018] [Accepted: 07/14/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Guilherme Frainer
- Programa de Pós‐Graduação em Biologia Animal, Departamento de ZoologiaUniversidade Federal do Rio Grande do Sul 91540‐000 Porto Alegre Brazil
- Centro de Estudos CosteirosLimnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul 95625‐000 Imbé Brazil
- Department II of AnatomyUniversity of Cologne 50924 Cologne Germany
| | - Stephanie Plön
- African Earth Observation Network (AEON) ‐Earth Stewardship Science Research Institute (ESSRI)Nelson Mandela University 6031 Port Elizabeth South Africa
| | - Nathalia B. Serpa
- Programa de Pós‐Graduação em Biologia Animal, Departamento de ZoologiaUniversidade Federal do Rio Grande do Sul 91540‐000 Porto Alegre Brazil
- Centro de Estudos CosteirosLimnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul 95625‐000 Imbé Brazil
| | - Ignacio B. Moreno
- Programa de Pós‐Graduação em Biologia Animal, Departamento de ZoologiaUniversidade Federal do Rio Grande do Sul 91540‐000 Porto Alegre Brazil
- Centro de Estudos CosteirosLimnológicos e Marinhos (CECLIMAR/UFRGS), Campus Litoral Norte, Universidade Federal do Rio Grande do Sul 95625‐000 Imbé Brazil
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Martin MJ, Gridley T, Elwen SH, Jensen FH. Heaviside's dolphins ( Cephalorhynchus heavisidii) relax acoustic crypsis to increase communication range. Proc Biol Sci 2018; 285:rspb.2018.1178. [PMID: 30051842 DOI: 10.1098/rspb.2018.1178] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 06/26/2018] [Indexed: 11/12/2022] Open
Abstract
The costs of predation may exert significant pressure on the mode of communication used by an animal, and many species balance the benefits of communication (e.g. mate attraction) against the potential risk of predation. Four groups of toothed whales have independently evolved narrowband high-frequency (NBHF) echolocation signals. These signals help NBHF species avoid predation through acoustic crypsis by echolocating and communicating at frequencies inaudible to predators such as mammal-eating killer whales. Heaviside's dolphins (Cephalorhynchus heavisidii) are thought to exclusively produce NBHF echolocation clicks with a centroid frequency around 125 kHz and little to no energy below 100 kHz. To test this, we recorded wild Heaviside's dolphins in a sheltered bay in Namibia. We demonstrate that Heaviside's dolphins produce a second type of click with lower frequency and broader bandwidth in a frequency range that is audible to killer whales. These clicks are used in burst-pulses and occasional click series but not foraging buzzes. We evaluate three different hypotheses and conclude that the most likely benefit of these clicks is to decrease transmission directivity and increase conspecific communication range. The expected increase in active space depends on background noise but ranges from 2.5 (Wenz Sea State 6) to 5 times (Wenz Sea State 1) the active space of NBHF signals. This dual click strategy therefore allows these social dolphins to maintain acoustic crypsis during navigation and foraging, and to selectively relax their crypsis to facilitate communication with conspecifics.
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Affiliation(s)
- Morgan J Martin
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, c/o Sea Search Research and Conservation NPC, 4 Bath Rd, Cape Town 7945, South Africa
| | - Tess Gridley
- Centre for Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, c/o Sea Search Research and Conservation NPC, 4 Bath Rd, Cape Town 7945, South Africa
| | - Simon H Elwen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, c/o Sea Search Research and Conservation NPC, 4 Bath Rd, Cape Town 7945, South Africa
| | - Frants H Jensen
- Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C, Denmark.,Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Woods Hole, MA 02543, USA
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Kelkar N, Dey S, Deshpande K, Choudhary SK, Dey S, Morisaka T. Foraging and feeding ecology ofPlatanista: an integrative review. Mamm Rev 2018. [DOI: 10.1111/mam.12124] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Nachiket Kelkar
- Ashoka Trust for Research in Ecology and the Environment (ATREE); Royal Enclave, Srirampura, Jakkur PO Bangalore 560064 Karnataka India
| | - Subhasis Dey
- Vikramshila Biodiversity Research & Education Centre; T.M. Bhagalpur University; Bhagalpur 812007 Bihar India
| | - Kadambari Deshpande
- Ashoka Trust for Research in Ecology and the Environment (ATREE); Royal Enclave, Srirampura, Jakkur PO Bangalore 560064 Karnataka India
| | - Sunil Kumar Choudhary
- Vikramshila Biodiversity Research & Education Centre; T.M. Bhagalpur University; Bhagalpur 812007 Bihar India
| | - Sushant Dey
- Vikramshila Biodiversity Research & Education Centre; T.M. Bhagalpur University; Bhagalpur 812007 Bihar India
| | - Tadamichi Morisaka
- Graduate School of Bioresources; Mie University; 1577 Kurimamachiya-cho Tsu City Mie Prefecture 514-8507 Japan
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de Freitas M, Smith JN, Jensen FH, Beedholm K, Madsen PT. Echolocation click source parameters of Australian snubfin dolphins (Orcaella heinsohni). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:2564. [PMID: 29716291 DOI: 10.1121/1.5034174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The Australian snubfin dolphin (Orcaella heinsohni) is endemic to Australian waters, yet little is known about its abundance and habitat use. To investigate the feasibility of Passive Acoustic Monitoring for snubfin dolphins, biosonar clicks were recorded in Cygnet Bay, Australia, using a four-element hydrophone array. Clicks had a mean source level of 200 ± 5 dB re 1 μPa pp, transmission directivity index of 24 dB, mean centroid frequency of 98 ± 9 kHz, and a root-mean-square bandwidth of 31 ± 3 kHz. Such properties lend themselves to passive acoustic monitoring, but are comparable to similarly-sized delphinids, thus requiring additional cues to discriminate between snubfins and sympatric species.
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Affiliation(s)
- Mafalda de Freitas
- Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark
| | - Joshua N Smith
- Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia, 6150, Australia
| | - Frants H Jensen
- Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, 8000 Aarhus C, Denmark
| | - Kristian Beedholm
- Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark
| | - Peter T Madsen
- Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark
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32
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Fang L, Wu Y, Wang K, Pine MK, Wang D, Li S. The echolocation transmission beam of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:771. [PMID: 28863578 PMCID: PMC5552390 DOI: 10.1121/1.4996499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 07/02/2017] [Accepted: 07/14/2017] [Indexed: 06/07/2023]
Abstract
While the transmission beam of odontocetes has been described in a number of studies, the majority of them that have measured the transmission beam in two dimensions were focused on captive animals. Within the current study, a dedicated cross hydrophone array with nine elements was used to investigate the echolocation transmission beam of free-ranging Indo-Pacific humpback dolphins. A total of 265 on-axis clicks were analyzed, from which the apparent peak to peak source levels ranged between 168 to 207 dB (mean 184.5 dB ± 6.6 dB). The 3-dB beam width along the horizontal and vertical plane was 9.6° and 7.4°, respectively. Measured separately, the directivity index of the horizontal and vertical plane was 12.6 and 13.5 dB, respectively, and the overall directivity index (both planes combined) was 29.5 dB. The beam shape was slightly asymmetrical along the horizontal and vertical axis. Compared to other species, the characteristics of the transmitting beam of Indo-Pacific humpback dolphins were relatively close to the bottlenose dolphin (Tursiops truncatus), likely due to the similarity in the peak frequency and waveform of echolocation clicks and comparable body sizes of the two species.
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Affiliation(s)
- Liang Fang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Lab of Marine Bioresource and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, Guangdong 510275, People's Republic of China
| | - Yuping Wu
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Lab of Marine Bioresource and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, Guangdong 510275, People's Republic of China
| | - Kexiong Wang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Matthew K Pine
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Ding Wang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Songhai Li
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China
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Ladegaard M, Jensen FH, Beedholm K, da Silva VMF, Madsen PT. Amazon river dolphins (Inia geoffrensis) modify biosonar output level and directivity during prey interception in the wild. J Exp Biol 2017; 220:2654-2665. [DOI: 10.1242/jeb.159913] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/08/2017] [Indexed: 11/20/2022]
Abstract
Toothed whales have evolved to live in extremely different habitats and yet they all rely strongly on echolocation for finding and catching prey. Such biosonar based foraging involves distinct phases of searching for, approaching, and capturing prey, where echolocating animals gradually adjust sonar output to actively shape the flow of sensory information. Measuring those outputs in absolute levels requires hydrophone arrays centred on the biosonar beam axis, but this has never been done for wild toothed whales approaching and capturing prey. Rather, field studies make the assumption that toothed whales will adjust their biosonar in the same manner to arrays as they will when approaching prey. To test this assumption, we recorded wild botos (Inia geoffrensis) as they approached and captured dead fish tethered to a hydrophone in front of a star-shaped seven-hydrophone array. We demonstrate that botos gradually decrease interclick intervals and output levels during prey approaches, using stronger adjustment magnitudes than extrapolated from previous boto array data. Prey interceptions are characterised by high click rates, but although botos buzz during prey capture, they do so at lower click rates than marine toothed whales, resulting in a much more gradual transition from approach phase to buzzing. We also demonstrate for the first time that wild toothed whales broaden biosonar beamwidth when closing in on prey, as it is also seen in captive toothed whales and in bats, thus resulting in a larger ensonified volume around the prey, likely aiding prey tracking by decreasing the risk of prey evading ensonification.
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Affiliation(s)
- Michael Ladegaard
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
| | | | - Kristian Beedholm
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
| | | | - Peter Teglberg Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
- Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
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Koblitz JC, Stilz P, Rasmussen MH, Laidre KL. Highly Directional Sonar Beam of Narwhals (Monodon monoceros) Measured with a Vertical 16 Hydrophone Array. PLoS One 2016; 11:e0162069. [PMID: 27828956 PMCID: PMC5102362 DOI: 10.1371/journal.pone.0162069] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/17/2016] [Indexed: 11/19/2022] Open
Abstract
Recordings of narwhal (Monodon monoceros) echolocation signals were made using a linear 16 hydrophone array in the pack ice of Baffin Bay, West Greenland in 2013 at eleven sites. An average -3 dB beam width of 5.0° makes the narwhal click the most directional biosonar signal reported for any species to date. The beam shows a dorsal-ventral asymmetry with a narrower beam above the beam axis. This may be an evolutionary advantage for toothed whales to reduce echoes from the water surface or sea ice surface. Source level measurements show narwhal click intensities of up to 222 dB pp re 1 μPa, with a mean apparent source level of 215 dB pp re 1 μPa. During ascents and descents the narwhals perform scanning in the vertical plane with their sonar beam. This study provides valuable information for reference sonar parameters of narwhals and for the use of acoustic monitoring in the Arctic.
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Affiliation(s)
| | | | | | - Kristin L. Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, United States of America
- * E-mail: (JCK); (KLL)
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35
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Ladegaard M, Jensen FH, de Freitas M, Ferreira da Silva VM, Madsen PT. Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar. ACTA ACUST UNITED AC 2016; 218:3091-101. [PMID: 26447198 DOI: 10.1242/jeb.120501] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SLpp of 190.3 ± 6.1 dB re. 1 µPa, mean SLEFD of 132.1 ± 6.0 dB re. 1 µPa(2)s, mean Fc of 101.2 ± 10.5 kHz, mean BWRMS of 29.3 ± 4.3 kHz and mean ICI of 35.1 ± 17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6-10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9-25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars.
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Affiliation(s)
- Michael Ladegaard
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus 8000, Denmark
| | - Frants Havmand Jensen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Mafalda de Freitas
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus 8000, Denmark
| | | | - Peter Teglberg Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus 8000, Denmark Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
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Knopf JP, Hof PR, Oelschläger HHA. The Neocortex of Indian River Dolphins (Genus Platanista): Comparative, Qualitative and Quantitative Analysis. BRAIN, BEHAVIOR AND EVOLUTION 2016; 88:93-110. [PMID: 27732977 DOI: 10.1159/000448274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/06/2016] [Indexed: 11/19/2022]
Abstract
We investigated the morphology of four primary neocortical projection areas (somatomotor, somatosensory, auditory, visual) qualitatively and quantitatively in the Indian river dolphins (Platanista gangetica gangetica, P. gangetica minor) with histological and stereological methods. For comparison, we included brains of other toothed whale species. Design-based stereology was applied to the primary neocortical areas (M1, S1, A1, V1) of the Indian river dolphins and compared to those of the bottlenose dolphin with respect to layers III and V. These neocortical fields were identified using existing electrophysiological and morphological data from marine dolphins as to their topography and histological structure, including the characteristics of the neuron populations concerned. In contrast to other toothed whales, the visual area (V1) of the 'blind' river dolphins seems to be rather small. M1 is displaced laterally and the auditory area (A1) is larger than in marine species with respect to total brain size. The layering is similar in the cortices of all the toothed whale brains investigated; a layer IV could not be identified. Cell density in layer III is always higher than in layer V. The maximal neuron density in P. gangetica gangetica is found in layer III of A1, followed by layers III in V1, S1, and M1. The cell density in layer V is at a similar level in all primary areas. There are, however, some differences in neuron density between the two subspecies of Indian river dolphins. Taken as a whole, it appears that the neocortex of platanistids exhibits a considerable expansion of the auditory field. Even more than other toothed whales, they seem to depend on their biosonar abilities for navigation, hunting, and communication in their riverine habitat.
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Affiliation(s)
- Julian P Knopf
- Institute of Anatomy III (Dr. Senckenbergische Anatomie), Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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Hoffman JM, Ponnampalam LS, Araújo-Wang C, Kuit SH, Hung SK, Wang JY. Description of whistles of Irrawaddy dolphins (Orcaella brevirostris) from the waters of Matang, Peninsular Malaysia. BIOACOUSTICS 2016. [DOI: 10.1080/09524622.2016.1169558] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Jordan M. Hoffman
- Environmental and Life Sciences, Trent University, Peterborough, Ontario, Canada
| | | | | | - Sui Hyang Kuit
- Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Samuel K. Hung
- Hong Kong Cetacean Research Project, Lam Tin, Kowloon, Hong Kong
| | - John Y. Wang
- CetAsia Research Group, Thornhill, Ontario, Canada
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Au WWL, Martin SW, Moore PW, Branstetter B, Copeland AM. Dynamics of biosonar signals in free-swimming and stationary dolphins: The role of source levels on the characteristics of the signals. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 139:1381-1389. [PMID: 27036275 DOI: 10.1121/1.4944636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The biosonar signals of two free-swimming Atlantic bottlenose dolphins performing a complex sonar search for a bottom target in San Diego Bay were compared with the biosonar signals of a dolphin performing a target discrimination task in a net pen in the same bay. A bite-plate device carried by the free-swimming dolphins supported a hydrophone that extended directly in front of the dolphin. A biosonar measuring tool attached to the bite plate measured the outgoing biosonar signals while the dolphins conducted sonar searches. Each of the free-swimming dolphins used different biosonar search strategy in solving the problem and the dolphins' biosonar signals reflect the difference in strategy. The dolphin in the pen stationed in a hoop while echolocating on a target 6 m away and reported if the indentation on a spherical target was directed toward it. The signals were parameterized by determining the peak-to-peak source levels, source energy flux density, peak frequency, center frequency, root-mean-square (rms) bandwidth, rms duration, and the Q of the signals. Some parameters were similar for the free-swimming and stationary dolphins while some were significantly different, suggesting biosonar signals used by free-swimming animals may be different than signals used by dolphins in a pen.
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Affiliation(s)
- Whitlow W L Au
- Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1346, Kaneohe, Hawaii 96744, USA
| | - Stephen W Martin
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA
| | - Patrick W Moore
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA
| | - Brian Branstetter
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA
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Fang L, Li S, Wang K, Wang Z, Shi W, Wang D. Echolocation signals of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:1346-1352. [PMID: 26428773 DOI: 10.1121/1.4929492] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
While the low-frequency communication sounds of Indo-Pacific humpback dolphins (Sousa chinensis) have been reported in a number of papers, the high-frequency echolocation signals of Sousa chinensis, especially those living in the wild, have been less studied. In the current study, echolocation signals of humpback dolphins were recorded in Sanniang Bay, Guangxi Province, China, using a cross-type hydrophone array with five elements. In total, 77 candidate on-axis clicks from 77 scans were selected for analysis. The results showed that the varied peak-to-peak source levels ranged from 177.1 to 207.3 dB, with an average of 187.7 dB re: 1 μPa. The mean peak frequency was 109.0 kHz with a -3-dB bandwidth of 50.3 kHz and 95% energy duration of 22 μs. The -3-dB bandwidth was much broader than the root mean square bandwidth and exhibited a bimodal distribution. The center frequency exhibited a positive relationship with the peak-to-peak source level. The clicks of the wild Indo-Pacific humpback dolphins were short-duration, broadband, ultrasonic pulses, similar to those produced by other whistling dolphins of similar body size. However, the click source levels of the Indo-Pacific humpback dolphin appear to be lower than those of other whistling dolphins.
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Affiliation(s)
- Liang Fang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Songhai Li
- Sanya Key Laboratory of Marine Mammal and Marine Bioacoustics, Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China
| | - Kexiong Wang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Zhitao Wang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Wenjing Shi
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Ding Wang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
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de Freitas M, Jensen FH, Tyne J, Bejder L, Madsen PT. Echolocation parameters of Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the wild. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 137:3033-41. [PMID: 26093395 DOI: 10.1121/1.4921277] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Echolocation is a key sensory modality for toothed whale orientation, navigation, and foraging. However, a more comparative understanding of the biosonar properties of toothed whales is necessary to understand behavioral and evolutionary adaptions. To address this, two free-ranging sympatric delphinid species, Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus), were studied. Biosonar clicks from both species were recorded within the same stretch of coastal habitat in Exmouth Gulf, Western Australia, using a vertical seven element hydrophone array. S. sahulensis used biosonar clicks with a mean source level of 199 ± 3 dB re 1 μPa peak-peak (pp), mean centroid frequency of 106 ± 11 kHz, and emitted at interclick intervals (ICIs) of 79 ± 33 ms. These parameters were similar to click parameters of sympatric T. aduncus, characterized by mean source levels of 204 ± 4 dB re 1 μPa pp, centroid frequency of 112 ± 9 kHz, and ICIs of 73 ± 29 ms. These properties are comparable to those of other similar sized delphinids and suggest that biosonar parameters are independent of sympatric delphinids and possibly driven by body size. The dynamic biosonar behavior of these delphinids may have, consequently, allowed for adaptations to local environments through high levels of control over sonar beam properties.
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Affiliation(s)
- Mafalda de Freitas
- Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark
| | - Frants H Jensen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Julian Tyne
- Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
| | - Lars Bejder
- Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
| | - Peter T Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark
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Jensen FH, Wahlberg M, Beedholm K, Johnson M, Soto NA, Madsen PT. Single-click beam patterns suggest dynamic changes to the field of view of echolocating Atlantic spotted dolphins (Stenella frontalis) in the wild. J Exp Biol 2015; 218:1314-24. [DOI: 10.1242/jeb.116285] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 02/23/2015] [Indexed: 11/20/2022]
Abstract
Echolocating animals exercise an extensive control over the spectral and temporal properties of their biosonar signals to facilitate perception of their actively generated auditory scene when homing in on prey. The intensity and directionality of the biosonar beam defines the field of view of echolocating animals by affecting the acoustic detection range and angular coverage. However, the spatial relationship between an echolocating predator and its prey changes rapidly, resulting in different biosonar requirements throughout prey pursuit and capture. Here we measured single click beam patterns using a parametric fit procedure to test whether free-ranging Atlantic spotted dolphins (Stenella frontalis) modify their biosonar beamwidth. We recorded echolocation clicks using a linear array of receivers and estimated the beamwidth of individual clicks using a parametric spectral fit, cross-validated with well-established composite beam pattern estimates. The dolphins apparently increased the biosonar beamwidth, to a large degree without changing the signal frequency, when they approached the recording array. This is comparable to bats that also expand their field of view during prey capture, but achieve this by decreasing biosonar frequency. This behaviour may serve to decrease the risk that rapid escape movements of prey take them outside the biosonar beam of the predator. It is likely that shared sensory requirements have resulted in bats and toothed whales expanding their acoustic field of view at close range to increase the likelihood of successfully acquiring prey using echolocation, representing a case of convergent evolution of echolocation behaviour between these two taxa.
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Affiliation(s)
- Frants H. Jensen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08540, USA
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Magnus Wahlberg
- Fjord&Bælt, Margrethes Plads 1, 5300 Kerteminde, Denmark
- Marine Biological Research Center, University of Southern Denmark, Hindsholmsvej 11, 5300 Kerteminde, Denmark
| | - Kristian Beedholm
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
| | - Mark Johnson
- Scottish Oceans Institute, University of St. Andrews, Fife, KY16 8LB, United Kingdom
| | - Natacha Aguilar Soto
- Scottish Oceans Institute, University of St. Andrews, Fife, KY16 8LB, United Kingdom
- BIOECOMAC, Dept. Animal Biology, International Campus of Excellence, La Laguna University, La Laguna 38206, Tenerife, Spain
| | - Peter T. Madsen
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
- Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
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To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey. PLoS One 2014; 9:e96811. [PMID: 24805782 PMCID: PMC4013050 DOI: 10.1371/journal.pone.0096811] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/10/2014] [Indexed: 11/19/2022] Open
Abstract
Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.
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Fenton B, Jensen FH, Kalko EKV, Tyack PL. Sonar Signals of Bats and Toothed Whales. BIOSONAR 2014. [DOI: 10.1007/978-1-4614-9146-0_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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