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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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2
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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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3
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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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4
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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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5
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Gray H, van Waerebeek K, Owen J, Collins T, Minton G, Ponnampalam L, Willson A, Baldwin R, Hoelzel AR. Evolutionary drivers of morphological differentiation among three bottlenose dolphin lineages, Tursiops spp. (Delphinidae), in the northwest Indian Ocean utilizing linear and geometric morphometric techniques. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Local adaptation and adaptive radiations are typically associated with phenotypic variation suited to alternative environments. In the marine environment, the nature of relevant ecological or environmental transitions is poorly understood, especially for highly mobile species. Here we compare three genetic lineages in the genus Tursiops (bottlenose dolphins), using linear measurements and geometric morphometric techniques, in the context of environmental variation in the northwest Indian Ocean. Cranial morphology was clearly differentiated comparing Tursiops truncatus and Tursiops aduncus, while a recently discovered genetic lineage, found in the Arabian Sea, was morphologically most similar to T. aduncus from the same region, but distinct for various measures, particularly metrics associated with the lateral dimension of the skull. The extent of divergence between T. truncatus and T. aduncus compared to differences between the T. aduncus lineages is consistent with the recent phylogeny for these species. Therefore, with the corroboration of genetic and morphological inference, we propose two conservation units of T. aduncus be recognized in the region at a sub-specific level so that their conservation can be managed effectively. We consider possible evolutionary mechanisms associated with regional habitat characteristics and the exploitation of distinct prey resources.
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Affiliation(s)
- Howard Gray
- Department of Biosciences, University of Durham, South Road, Durham DH1 3LE, UK
| | | | - Joseph Owen
- Department of Archaeology, Simon Fraser University, Education Building 9635, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Tim Collins
- Wildlife Conservation Society Ocean Giants Program, 2300 Southern Boulevard, Bronx, NY 10460-1099, USA
| | - Gianna Minton
- Megaptera Marine Conservation, 2242PT Den Haag, The Netherlands
| | | | - Andrew Willson
- Future Seas Global SPC, PO Box 286, Postal Code 116, Muscat, Sultanate of Oman
| | - Robert Baldwin
- Five Oceans Environmental Services, PO Box 660, PC131, Ruwi, Sultanate of Oman
| | - A Rus Hoelzel
- Department of Biosciences, University of Durham, South Road, Durham DH1 3LE, UK
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6
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Churchill M, Baltz C. Evolution of orbit size in toothed whales (Artiodactyla: Odontoceti). J Anat 2021; 239:1419-1437. [PMID: 34287886 PMCID: PMC8602015 DOI: 10.1111/joa.13522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 07/05/2021] [Accepted: 07/08/2021] [Indexed: 11/30/2022] Open
Abstract
For many marine tetrapods, vision is important for finding food and navigating underwater, and eye size has increased to improve the capture of light in dim ocean depths. Odontocete whales, in contrast, rely instead on echolocation for navigation and prey capture. We tested whether the evolution of echolocation has influenced the orbit size, a proxy for eye size, and examined how orbit size evolved over time. We also assessed variation in orbit size amongst whales and tested how body size, diving ability, sound production, foraging habitat, and prey capture strategy influenced the orbit size using phylogenetic independent contrasts and phylogenetic ANOVAs. Using measurements of orbit length and bizygomatic width, we calculated proportional orbit size for 70 extant and 29 extinct whale taxa, with an emphasis on Odontoceti. We then performed ancestral character state reconstruction on a time-calibrated composite phylogeny. Our analysis revealed that there was no shift in proportional orbit size from archaeocetes through stem odontocetes, indicating that the evolution of echolocation did not influence the orbit size. Proportional orbit size increased in Ziphiidae, Phocoenidae, and Cephalorhynchus. Proportional orbit size decreased in Balaenidae, Physeteridae, Platanistidae, and Lipotidae. Body size, diving ability, foraging environment, and prey capture strategy had a significant influence on orbit size, but only without phylogenetic correction. An increase in orbit size is associated with deep diving behavior in beaked whales, while progenesis and retention of juvenile features into adulthood explain the pattern observed in Phocoenidae and Cephalorhynchus. Decrease in proportional orbit size is associated with adaptation toward murky freshwater environments in odontocetes and skim feeding in balaenids. Our study reveals that the evolution of echolocation had little effect on orbit size, which is variable in whales, and that adaptation for different feeding modes and habitat explains some of this variance.
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Affiliation(s)
- Morgan Churchill
- Department of BiologyUniversity of Wisconsin OshkoshOshkoshWIUSA
| | - Colin Baltz
- Department of BiologyUniversity of Wisconsin OshkoshOshkoshWIUSA
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7
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Goerger A, Darmaillacq AS, Shashar N, Dickel L. Early Exposure to Water Turbidity Affects Visual Capacities in Cuttlefish ( Sepia officinalis). Front Physiol 2021; 12:622126. [PMID: 33643067 PMCID: PMC7902506 DOI: 10.3389/fphys.2021.622126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 01/18/2021] [Indexed: 12/02/2022] Open
Abstract
In La Manche (English Channel) the level of turbidity changes, not only seasonally and daily in seawater but also along the coast. As a consequence, vision in marine species is limited when based only on contrast-intensity. It is hypothesized that polarization sensitivity (PS) may help individuals detect preys and predators in turbid environments. In the cuttlefish, Sepia officinalis, to date, all behavioral studies have been conducted on animals reared in clear water. But the cuttlefish sensory system is adapted to a range of turbid environments. Our hypothesis was that rearing cuttlefish in clear water may affect the development of their visual system, and potentially affect their visually guided behaviors. To test this, newly-hatched cuttlefish, from eggs laid by females brought in from the wild, were reared for 1 month under three different conditions: clear water (C group), low turbidity (0.1 g / l of clay, 50–80 NTU, LT group) and high turbidity (0.5 g / l of clay, 300–400 NTU, HT group). The visual capacities of cuttlefish were tested with an optomotor apparatus at 7 days and at 1 month post-hatching. Optomotor responses of juveniles were measured by using three screen patterns (black and white stripes, linearly polarized stripes set at different orientations, and a uniform gray screen). Optomotor responses of juveniles suggest that exposure to turbid water improves the development of their PS when tested in clear water (especially in LT group) but not when tested in turbid water. We suggest that the use of slightly turbid water in rearing systems may improve the development of vision in young cuttlefish with no detrimental effect to their survival rate. Future research will consider water turbidity as a possible factor for the improvement of cuttlefish well-being in artificial rearing systems.
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Affiliation(s)
- Alice Goerger
- Normandie Univ., UNICAEN, Ethos (Ethologie Animale et Humaine) UMR 6552, Caen, France
| | | | - Nadav Shashar
- Department of Life Sciences, Ben Gurion University of the Negev, Eilat, Israel
| | - Ludovic Dickel
- Normandie Univ., UNICAEN, Ethos (Ethologie Animale et Humaine) UMR 6552, Caen, France
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8
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Bianucci G, de Muizon C, Urbina M, Lambert O. Extensive Diversity and Disparity of the Early Miocene Platanistoids (Cetacea, Odontoceti) in the Southeastern Pacific (Chilcatay Formation, Peru). Life (Basel) 2020; 10:life10030027. [PMID: 32197480 PMCID: PMC7151620 DOI: 10.3390/life10030027] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/14/2020] [Accepted: 03/16/2020] [Indexed: 11/27/2022] Open
Abstract
Several aspects of the fascinating evolutionary history of toothed and baleen whales (Cetacea) are still to be clarified due to the fragmentation and discontinuity (in space and time) of the fossil record. Here we open a window on the past, describing a part of the extraordinary cetacean fossil assemblage deposited in a restricted interval of time (19–18 Ma) in the Chilcatay Formation (Peru). All the fossils here examined belong to the Platanistoidea clade as here redefined, a toothed whale group nowadays represented only by the Asian river dolphin Platanista gangetica. Two new genera and species, the hyper-longirostrine Ensidelphis riveroi and the squalodelphinid Furcacetus flexirostrum, are described together with new material referred to the squalodelphinid Notocetus vanbenedeni and fragmentary remains showing affinities with the platanistid Araeodelphis. Our cladistic analysis defines the new clade Platanidelphidi, sister-group to Allodelphinidae and including E. riveroi and the clade Squalodelphinidae + Platanistidae. The fossils here examined further confirm the high diversity and disparity of platanistoids during the early Miocene. Finally, morphofunctional considerations on the entire platanistoid assemblage of the Chilcatay Formation suggest a high trophic partitioning of this peculiar cetacean paleocommunity.
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Affiliation(s)
- Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, 56126 Pisa, Italy
- Correspondence:
| | - Christian de Muizon
- CR2P (CNRS, MNHN, SU), Muséum National d’Histoire Naturelle, Département Origines et Évolution, 75005 Paris, France;
| | - Mario Urbina
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima 15072, Peru;
| | - Olivier Lambert
- Institut Royal des Sciences Naturelles de Belgique, D.O. Terre et Histoire de la Vie, 1000 Brussels, Belgium
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9
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Kaplan JD, Goodrich SY, Melillo-Sweeting K, Reiss D. Behavioural laterality in foraging bottlenose dolphins ( Tursiops truncatus). ROYAL SOCIETY OPEN SCIENCE 2019; 6:190929. [PMID: 31827837 PMCID: PMC6894562 DOI: 10.1098/rsos.190929] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
Lateralized behaviour is found in humans and a wide variety of other species. At a population level, lateralization of behaviour suggests hemispheric specialization may underlie this behaviour. As in other cetaceans, dolphins exhibit a strong right-side bias in foraging behaviour. Common bottlenose dolphins in The Bahamas use a foraging technique termed 'crater feeding', in which they swim slowly along the ocean floor, scanning the substrate using echolocation, and then bury their rostrums into the sand to obtain prey. The bottlenose dolphins off Bimini, The Bahamas, frequently execute a sharp turn before burying their rostrums in the sand. Based on data collected from 2012 to 2018, we report a significant right-side (left turn) bias in these dolphins. Out of 709 turns recorded from at least 27 different individuals, 99.44% (n = 705) were to the left (right side and right eye down) [z = 3.275, p = 0.001]. Only one individual turned right (left side and left eye down, 4/4 turns). We hypothesize that this right-side bias may be due in part to the possible laterization of echolocation production mechanisms, the dolphins' use of the right set of phonic lips to produce echolocation clicks, and a right eye (left hemisphere) advantage in visual discrimination and visuospatial processing.
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Affiliation(s)
| | - Samantha Y. Goodrich
- Department of Psychology, St Mary's College of Maryland, St Mary's City, MD, USA
| | | | - Diana Reiss
- Department of Psychology, Hunter College, CUNY, New York, NY, 10065, USA
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10
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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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11
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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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12
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Affiliation(s)
- Fredric L Frye
- La Primavera Farm, 33422 Highway 128, Cloverdale, CA 95425-9428, USA
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13
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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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14
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Wohlert D, Kröger J, Witt M, Schmitt O, Wree A, Czech-Damal N, Siebert U, Folkow L, Hanke FD. A Comparative Morphometric Analysis of Three Cranial Nerves in Two Phocids: The Hooded Seal (Cystophora cristata) and the Harbor Seal (Phoca vitulina). Anat Rec (Hoboken) 2015; 299:370-8. [PMID: 26643122 DOI: 10.1002/ar.23298] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/30/2015] [Indexed: 11/07/2022]
Abstract
While our knowledge about the senses of pinnipeds has increased over the last decades almost nothing is known about the organization of the neuroanatomical pathways. In a first approach to this field of research, we assessed the total number of myelinated axons of three cranial nerves (CNs) in the harbor (Phoca vitulina, Pv) and hooded seal (Cystophora cristata, Cc). Axons were counted in semithin sections of the nerves embedded in Epon and stained with toluidine blue. In both species, the highest axon number was found within the optic nerve (Pv 187,000 ± 8,000 axons, Cc 481,600 ± 1,300 axons). Generally, considering absolute axon numbers, far more axons were counted within the optic and trigmenial nerve (Pv 136,700 ± 2,500 axons, Cc 179,300 ± 6,900 axons) in hooded in comparison to harbor seals. The axon counts of the vestibulocochlear nerve are nearly identical for both species (Pv 87,100 ± 8,100 axons, Cc 86,600 ± 2,700 axons). However, when comparing cell density, the cell density is almost equal for all nerves for both species except for the optic nerve in which cell density was particularly higher than in the other nerves and higher in hooded in comparison to harbor seals. We here present the first comparative analysis of three CNs in two phocid seals. While the CNs of these closely related species share some general characteristics, pronounced differences in axon numbers/densities are apparent. These differences seem to reflect differences in e.g. size, habitat, and/or functional significance of the innervated sensory systems.
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Affiliation(s)
- Dennis Wohlert
- Sensory and Cognitive Ecology, University of Rostock, Institute for Biosciences, Rostock, 18059, Germany.,Department of Anatomy, Rostock University Medical Center, Rostock, 18057, Germany
| | - Jürgen Kröger
- Sensory and Cognitive Ecology, University of Rostock, Institute for Biosciences, Rostock, 18059, Germany
| | - Martin Witt
- Department of Anatomy, Rostock University Medical Center, Rostock, 18057, Germany
| | - Oliver Schmitt
- Department of Anatomy, Rostock University Medical Center, Rostock, 18057, Germany
| | - Andreas Wree
- Department of Anatomy, Rostock University Medical Center, Rostock, 18057, Germany
| | - Nicole Czech-Damal
- University of Hamburg, Biocenter Grindel, Institute of Zoology and Zoological Museum, Hamburg, 20146, Germany
| | - Ursula Siebert
- University of Veterinary Medicine Hannover, Institute for Terrestrial and Aquatic Wildlife Research, Büsum, 25761, Germany
| | - Lars Folkow
- Department of Arctic and Marine Biology, University of Tromsø-the Arctic University of Norway, Tromsø, 9037, Norway
| | - Frederike D Hanke
- Sensory and Cognitive Ecology, University of Rostock, Institute for Biosciences, Rostock, 18059, Germany
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15
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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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Jensen FH, Rocco A, Mansur RM, Smith BD, Janik VM, Madsen PT. Clicking in shallow rivers: short-range echolocation of Irrawaddy and Ganges River dolphins in a shallow, acoustically complex habitat. PLoS One 2013; 8:e59284. [PMID: 23573197 PMCID: PMC3616034 DOI: 10.1371/journal.pone.0059284] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/13/2013] [Indexed: 11/26/2022] Open
Abstract
Toothed whales (Cetacea, odontoceti) use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica) and Irrawaddy dolphins (Orcaella brevirostris) within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB) re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191) re 1 µPapp. These source levels are 1–2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.
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Affiliation(s)
- Frants H Jensen
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
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Bashir T, Khan A, Behera SK, Gautam P. Time Dependent Activity Pattern of Ganges River DolphinPlatanista gangetica gangeticaand its Response to Human Presence in Upper Ganges River, India. MAMMAL STUDY 2013. [DOI: 10.3106/041.038.0110] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Akamatsu T, Wang D, Wang K, Li S, Dong S. Scanning sonar of rolling porpoises during prey capture dives. J Exp Biol 2010; 213:146-52. [PMID: 20008371 DOI: 10.1242/jeb.037655] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Dolphins and porpoises have excellent biosonar ability, which they use for navigation, ranging and foraging. However, the role of biosonar in free-ranging small cetaceans has not been fully investigated. The biosonar behaviour and body movements of 15 free-ranging finless porpoises (Neophocaena phocaenoides) were observed using electronic tags attached to the animals. The porpoises often rotated their bodies more than 60 deg., on average, around the body axis in a dive bout. This behaviour occupied 31% of the dive duration during 186 h of effective observation time. Rolling dives were associated with extensive searching effort, and 23% of the rolling dive time was phonated, almost twice the phonation ratio of upright dives. Porpoises used short inter-click interval sonar 4.3 times more frequently during rolling dives than during upright dives. Sudden speed drops, which indicated that an individual turned around, occurred 4.5 times more frequently during rolling dives than during upright dives. Together, these data suggest that the porpoises searched extensively for targets and rolled their bodies to enlarge the search area by changing the narrow beam axis of the biosonar. Once a possible target was detected, porpoises frequently produced short-range sonar sounds. Continuous searching for prey and frequent capture trials appeared to occur during rolling dives of finless porpoises. In contrast, head movements ranging ±2 cm, which can also change the beam axis, were regularly observed during both dives. Head movements might assist in instant assessment of the arbitrary direction by changing the beam axis rather than prey searching and pursuit.
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Affiliation(s)
- T. Akamatsu
- National Research Institute of Fisheries Engineering, Fisheries Research Agency, Kamisu, Hasaki, Kashima, Ibaraki 314-0408, Japan
| | - D. Wang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - K. Wang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - S. Li
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - S. Dong
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
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Abstract
Background Free-ranging narwhals (Monodon monoceros) were instrumented in Admiralty Inlet, Canada with both satellite tags to study migration and stock separation and short-term, high-resolution digital archival tags to explore diving and feeding behaviour. Three narwhals were equipped with an underwater camera pod (Crittercam), another individual was equipped with a digital archival tag (DTAG), and a fifth with both units during August 2003 and 2004. Results Crittercam footage indicated that of the combined 286 minutes of recordings, 12% of the time was spent along the bottom. When the bottom was visible in the camera footage, the narwhals were oriented upside-down 80% of the time (range: 61
100%). The DTAG data (14.6 hours of recordings) revealed that during time spent below the surface, the two tagged narwhals were supine an average of 13% (range: 9–18%) of the time. Roughly 70% of this time spent in a supine posture occurred during the descent. Conclusion Possible reasons for this upside-down swimming behaviour are discussed. No preference for a clockwise or counter-clockwise direction of roll was observed, discounting the possibility that rolling movements contribute to the asymmetric left-handed helical turns of the tusk.
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Morisaka T, Connor RC. Predation by killer whales (Orcinus orca) and the evolution of whistle loss and narrow-band high frequency clicks in odontocetes. J Evol Biol 2007; 20:1439-58. [PMID: 17584238 DOI: 10.1111/j.1420-9101.2007.01336.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A disparate selection of toothed whales (Odontoceti) share striking features of their acoustic repertoires including the absence of whistles and high frequency but weak (low peak-to-peak source level) clicks that have a relatively long duration and a narrow bandwidth. The non-whistling, high frequency click species include members of the family Phocoenidae, members of one genus of delphinids, Cephalorhynchus, the pygmy sperm whale, Kogia breviceps, and apparently the sole member of the family Pontoporiidae. Our review supports the 'acoustic crypsis' hypothesis that killer whale predation risk was the primary selective factor favouring an echolocation and communication system in cephalorhynchids, phocoenids and possibly Pontoporiidae and Kogiidae restricted to sounds that killer whales hear poorly or not at all (< 2 and > 100 kHz).
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Affiliation(s)
- T Morisaka
- Laboratory of Animal Ecology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan.
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Abstract
Observations suggest that dolphin sonars function well in the very shallow, reverberant, near-shore region of the ocean, and significantly out-perform man-made systems under such conditions. The echolocation characteristics of many small cetaceans have been measured directly and the high performance of biosonar systems is not in question, but explanations for their resolution, target detection, localization and tracking abilities are inadequate and deserve further investigation. The dolphin's lower jaw has been identified as part of an echo-receptor, and several hypotheses have been proposed to explain this. In one of these, the regularity of dolphin teeth was considered as a sonar array. This paper explores the physics of such systems with models based on established radar and sonar principles, and using data from various dolphin species. The insights gained from this modelling then lead to speculative proposals for new sonar receiver concepts that may have advantages over more conventional designs in shallow water operation.
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Affiliation(s)
- Peter Dobbins
- Systems Engineering & Assessment Ltd., SEA House, Bristol Business Park, Bristol, UK.
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Levenson DH, Dizon A. Genetic evidence for the ancestral loss of short-wavelength-sensitive cone pigments in mysticete and odontocete cetaceans. Proc Biol Sci 2003; 270:673-9. [PMID: 12713740 PMCID: PMC1691291 DOI: 10.1098/rspb.2002.2278] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
All mammals ancestrally possessed two types of cone pigments, an arrangement that persists in nearly all contemporary species. However, the absence of one of these cone types, the short-wavelength-sensitive (SWS) cone, has recently been established in several delphinoid cetacean species, indicating that the loss of this pigment type may be widespread among cetaceans. To evaluate the functional condition of SWS cones in cetaceans, partial SWS cone-opsin gene sequences were obtained from nuclear DNA for 16 species representing 12 out of the 14 extant mysticete (baleen) and odontocete (toothed) families. For all these species one or more mutations were identified that indicate that their SWS cone-opsin genes are pseudogenes and thus do not code for functional visual pigment proteins. Parsimonious interpretation of the distribution of some of these mis-sense mutations indicates that the conversion of cetacean SWS coneopsin genes to pseudogenes probably occurred before the divergences of the mysticete and odontocete suborders. Thus, in the absence of dramatic homoplasy, all modern cetaceans lack functional SWS cone visual pigments and, by extension, the visual capacities that such pigments typically support.
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Affiliation(s)
- D H Levenson
- Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0204, USA.
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Blomberg J. Functional aspects of odontocete head oil lipids with special reference to pilot whale head oil. PROGRESS IN THE CHEMISTRY OF FATS AND OTHER LIPIDS 1978; 16:257-78. [PMID: 358267 DOI: 10.1016/0079-6832(78)90047-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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25
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Brown AM, Pye JD. Auditory sensitivity at high frequencies in mammals. ADVANCES IN COMPARATIVE PHYSIOLOGY AND BIOCHEMISTRY 1975; 6:1-73. [PMID: 1092142 DOI: 10.1016/b978-0-12-011506-8.50007-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Wedmid Y, Litchfield C, Ackman RG, Sipos JC, Eaton CA, Mitchell ED. Heterogeneity of lipid composition within the cephalic melon tissue of the pilot whale (Globicephala melaena). BIOCHIMICA ET BIOPHYSICA ACTA 1973; 326:439-47. [PMID: 4776442 DOI: 10.1016/0005-2760(73)90144-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Schevill WE, Watkins WA. Directionality of the sound beam in Leptonychotes weddelli (Mammalia: Pinnipedia). ACTA ACUST UNITED AC 1971. [DOI: 10.1029/ar018p0163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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