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Mohsenian N, Methion S, Moshiri H, Hassan SK, Afkhami S, Tollab MA, Sadeh M, Braulik GT, López BD. Abundance estimation, group dynamics, and residence patterns of Indian Ocean humpback dolphin (Sousa plumbea) in the Dayer-Nakhiloo Marine National Park, Northern Persian Gulf, Iran. EUR J WILDLIFE RES 2022. [DOI: 10.1007/s10344-022-01565-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abstract
Humpback dolphins (Sousa spp.) are obligate shallow-water and resident species, and they typically live in fission-fusion societies composed of small-sized groups with changeable membership. However, we have scant knowledge of their behavioral ecology, starting with potential factors influencing inter-population variability of their group sizes. Here, we compiled a new global dataset of humpback dolphin group sizes based on 150 published records. Our data indicated an inter-specific consistency of group-living strategy among the 4 species in the Sousa genus, as these species preferred living in small-sized groups with a mean size of mostly no more than 10, a minimum size of single individual or small pairs, and a maximum size of several tens or ≈100. In addition, we clearly showed the geographic variations in group sizes of humpback dolphins at a global scale. We found that the geographic variations in humpback dolphin group sizes were primarily associated with the latitude, sea surface temperature, and abundance. To conclude, our findings provide insights into social dynamics and socioecological trade-offs of humpback dolphins, and help better understand how these resident animals adapted to their shallow-water habitats from the perspectives of biogeography and socioecology.
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Affiliation(s)
- Mingming Liu
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,University of Chinese Academy of Sciences, Beijing, China.,School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Mingli Lin
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China
| | - David Lusseau
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK.,National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Songhai Li
- Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.,Tropical Marine Science Institute, National University of Singapore, Singapore
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Laeta M, Ruenes GF, Siciliano S, Oliveira JA, Galatius A. Variation in cranial asymmetry among the Delphinoidea. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa161] [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
The remarkable directional cranial asymmetry of odontocete skulls has been proposed to be related to sound production. We investigated the variation in quality and quantity of cranial asymmetry in the superfamily Delphinoidea using geometric morphometrics and then investigated the relationship between asymmetry and aspects of sound production. In the average asymmetric shape, the dorsal aspect of the skull outline and interparietal suture crest were displaced to the right, while the nasal septum, nasal bones and right premaxilla were displaced to the left. The nasal bone, premaxilla and maxilla were all larger on the right side. Three delphinoid families presented similar expressions of asymmetry; however, the magnitude of the asymmetry varied. The Monodontidae showed the greatest magnitude of asymmetry, whereas the Phocoenidae were much less asymmetric. The most speciose family, the Delphinidae, presented a wide spectrum of asymmetry, with globicephalines and lissodelphinines among the most and least asymmetric species, respectively. Generalized linear models explaining the magnitude of asymmetry with characteristics of echolocation clicks, habitat use and size revealed associations with source level, dive depth and centroid size. This supports a relationship between asymmetry and sound production, with more asymmetric species emitting louder sounds. For example, louder clicks would be beneficial for prey detection at longer ranges in deeper waters.
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Affiliation(s)
- Maíra Laeta
- Programa de Pós-graduação em Biodiversidade e Biologia Evolutiva, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos, Praia Seca, Araruama, RJ, Brazil
| | - Greicy F Ruenes
- Programa de Pós-graduação em Ecologia e Recursos Naturais, Universidade Estadual do Norte Fluminense “Darcy Ribeiro”, Campos dos Goytacazes, RJ, Brazil
- Laboratório de Ecologia de Mamíferos, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, Brazil
| | - Salvatore Siciliano
- Laboratório de Biodiversidade, Instituto Oswaldo Cruz/Fiocruz, Rio de Janeiro, Rio de Janeiro, Brazil
- Grupo de Estudos de Mamíferos Marinhos da Região dos Lagos, Praia Seca, Araruama, RJ, Brazil
| | - João A Oliveira
- Setor de Mastozoologia, Departamento de Vertebrados, Museu Nacional/Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Anders Galatius
- Marine Mammal Research, Department of Bioscience, Aarhus University, Roskilde, Denmark
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Gui D, Yu RQ, Karczmarski L, Ding Y, Zhang H, Sun Y, Zhang M, Wu Y. Spatiotemporal Trends of Heavy Metals in Indo-Pacific Humpback Dolphins (Sousa chinensis) from the Western Pearl River Estuary, China. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:1848-1858. [PMID: 28075564 DOI: 10.1021/acs.est.6b05566] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We assessed the spatiotemporal trends of the concentrations of 11 heavy metals (HMs) in the liver and kidney of Indo-Pacific humpback dolphins (Sousa chinensis) from western Pearl River Estuary (PRE) during 2004-2015. The hepatic levels of Cr, As, and Cu in these dolphins were among the highest reported for cetaceans globally, and the levels of Zn, Cu, and Hg were sufficiently high to cause toxicological effects in some of the animals. Between same age-sex groups, dolphins from Lingdingyang were significantly more contaminated with Hg, Se, and V than those from the West-four region, while the opposite was true for Cd. Generalized additive mixed models showed that most metals had significant but dissimilar temporal trends over a 10-year period. The concentrations of Cu and Zn increased significantly in recent years, corresponding to the high input of these metals in the region. Body-length-adjusted Cd levels peaked in 2012, accompanied by the highest annual number of dolphin stranding events. In contrast to the significant decrease in HM levels in the dolphins in Hong Kong waters (the eastern reaches of the PRE), the elevated metal exposure in the western PRE raises serious concerns.
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Affiliation(s)
- Duan Gui
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
| | - Ri-Qing Yu
- Department of Biology, University of Texas at Tyler , Tyler, Texas 75799, United States
| | - Leszek Karczmarski
- The Swire Institute of Marine Sciences, School of Biological Sciences, The University of Hong Kong , Cape d'Aguilar, Shek O, Hong Kong
| | - Yulong Ding
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
| | - Haifei Zhang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
| | - Yong Sun
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
| | - Mei Zhang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
| | - Yuping Wu
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou, 510275, China
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Jefferson TA, Curry BE. Humpback Dolphins: A Brief Introduction to the Genus Sousa. ADVANCES IN MARINE BIOLOGY 2015; 72:1-16. [PMID: 26555620 DOI: 10.1016/bs.amb.2015.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The delphinid genus Sousa has recently undergone a major revision, and currently contains four species, the Atlantic humpback (Sousa teuszii), Indian Ocean humpback (Sousa plumbea), Indo-Pacific humpback (Sousa chinensis), and Australian humpback (Sousa sahulensis) dolphins. Recent molecular evidence suggests that humpback dolphins in the Bay of Bengal may comprise a fifth species. These moderate-sized dolphin species are found in shallow (<30m), coastal waters of the eastern Atlantic, Indian, and western Pacific oceans. Abundance and trends have only been studied in a few areas, mostly in eastern Africa, China, and northern Australia. No global, empirically derived abundance estimates exist for any of the four species, but none appear to number more than about 20,000 individuals. Humpback dolphins feed mostly on small fishes, and sometimes shrimps; occur for the most part in small groups (mostly 12 or less); have limited nearshore movements; and in most parts of their range exhibit a fission/fusion type of social organization. Major threats that affect all the species are entanglement in fishing gear, and habitat degradation/destruction from various forms of coastal development. Impacts from vessel traffic (including behavioural disturbance and displacement, as well as mortality and morbidity from collisions with vessels) appear to be significant in most areas. Several other threats are apparently significant only in particular parts of the range of some species (e.g. high levels of organochlorine contaminants affecting Indo-Pacific humpback dolphins in Hong Kong). Direct hunting only occurs in limited areas and primarily on a small scale. Conservation actions so far have been limited, with most populations receiving little study and almost no management attention. Much more work is needed on humpback dolphin population status, threats, and how the major threats can be reduced or eliminated. Extinction risks for the four species and some populations are preliminarily re-assessed using the IUCN Red List criteria in the current volume. The results suggest that all four species in the genus are threatened at some level (suggested Red List status ranges from Vulnerable for S. chinensis and S. sahulensis to Critically Endangered for S. teuszii).
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Affiliation(s)
| | - Barbara E Curry
- Physiological Ecology and Bioenergetics Laboratory, University of Central Florida, Orlando, Florida, USA
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Braulik GT, Findlay K, Cerchio S, Baldwin R. Assessment of the Conservation Status of the Indian Ocean Humpback Dolphin (Sousa plumbea) Using the IUCN Red List Criteria. ADVANCES IN MARINE BIOLOGY 2015; 72:119-141. [PMID: 26555624 DOI: 10.1016/bs.amb.2015.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Indian Ocean humpback dolphins (Sousa plumbea) are obligate shallow-water dolphins that occur exclusively in the near-shore waters of the Indian Ocean, from South Africa to the Bay of Bengal. They have a narrow habitat preference, restricted distribution and do not appear very abundant across any part of their range. There is no estimate of total species abundance; all populations that have been quantitatively evaluated have been small in size, usually fewer than 200 individuals. Fishing, dredging, land reclamation, construction blasting, port and harbour construction, pollution, boat traffic and other coastal development activities all occur, or are concentrated within, humpback dolphin habitat and threaten their survival. Although data are far from sufficient to make a rigorous quantitative assessment of population trends for this species, the scale of threats is large enough over a significant enough portion of the range to suspect or infer a decline of at least 50% over three generations, which qualifies it for listing on the IUCN Red List as Endangered. The issue primarily responsible is incidental mortality in fisheries, but the loss and degradation of habitat is likely a contributing factor. None of the threats have been adequately addressed in any part of the species' range, even though threat levels are increasing virtually everywhere.
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Affiliation(s)
- Gill T Braulik
- Wildlife Conservation Society-Tanzania Program, Zanzibar, Tanzania.
| | - Ken Findlay
- Mammal Research Institute Whale Unit, University of Pretoria, Pretoria, South Africa
| | | | - Robert Baldwin
- Five Oceans Environmental Services LLC, Sultanate of Oman
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