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Burrunan dolphin

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Burrunan dolphin
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Tursiops
Species:
T. australis
Subspecies:
T. a. 0
Trinomial name
Tursiops australis 0
Charlton-Robb et al. 2011
Synonyms

Tursiops australis

The Burrunan dolphin (Tursiops australis) is a proposed species of bottlenose dolphin found in parts of Victoria, Australia first described in 2011.[1] Its exact taxonomy is debated: numerous studies support it as being a separate species within the genus Tursiops and occupying a basal position within the genus,[2][3][4][5][6][7][8] with limited phylogenetic studies using different methodologies indicate that it is a subspecies of the Indo-Pacific bottlenose dolphin (Tursiops aduncus).[9][2] The Burrunan dolphin is not currently recognized as a species by the Society for Marine Mammalogy or American Society of Mammalogists, which cites problematic methodology in the original study proposing species status and recommends further research.[10][11]

There are only two known resident populations in Victoria, Australia, with an estimated total population size of less than 180 individuals, and the predicted effective populations sizes small; Port Phillip Bay: 81.5, Gippsland Lakes and Tasmania: 65.5.[12]

Prior to proposal of the name T. (aduncus) australis, the term "Tursiops species, southern Australian bottlenose dolphin (SABD)" had been used.[13]

Taxonomy

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The Burrunan dolphin has had a heavily debated taxonomy. It was formally named Tursiops australis by the researcher who described it, Kate Charlton-Robb of Monash University, and colleagues. The dolphin's common name, Burrunan, is an Aboriginal name in the Boonwurrung, Woiwurrung and Taungurung languages, meaning "large sea fish of the porpoise kind".[14][13] The name australis is the Latin adjective "southern", and refers to the Australian range of the dolphin. It was the third time since the late 19th century that a new dolphin species had been recognised.[15]

Some differences had previously been noted prior to its description, but for a long time not enough evidence was available to classify it as its own taxon.[16] An examination of their skulls, external characteristics, and DNA from old and current samples revealed unique characteristics supporting its classification as a separate species. However, later studies either supported or disputed these findings.[11]

In March 2020, the Canadian Journal of Zoology published "Taxonomy and distribution of bottlenose dolphins (genus Tursiops) in Australian waters: an osteological clarification" by Maria Jedensjö et al., which questioned the classification of T. australis as a distinct species. The study conducted a comprehensive osteological survey on the skulls of 264 dolphins using 2D and 3D morphometrics, and found that the Burrunan dolphin fell well within T. truncatus using both techniques.[9] However, a larger body of evidence still exists to validate the Burrunan as a species using mtDNA regions,[2] concatenated mtDNA/nuDNA sequences,[3] the mitogenome,[4][5][6][7] and more recently the time-calibrated molecular phylogeny of Certiodactyla.[8]

In May 2020, a separate phylogenomic analysis that used a double digest RADseq protocol (in contrast to the previous studies, which used whole mitogenomes) found that the South Australian form of the Burrunan dolphin fell within T. aduncus, forming a monophyletic lineage that is sister to an undescribed, wider coastal Australasian subspecies. Samples from the original species description, including the holotype of the species, from Victoria and Tasmania, were not included in this study. The same study also disputed the alleged polyphyly between Tursiops and Stenella found in previous studies, finding this to be a consequence of reticulate evolution in Tursiops (including past introgression from Stenella) and incomplete lineage sorting in the studies.[2] The American Society of Mammalogists has followed the results of this study and now classifies T. australis under T. aduncus, although it also acknowledges the debate over its status.[2][11]

Description

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The Burrunan dolphin is dark bluish-gray at the top near to the dorsal fin extending over the head and sides of the body. Along the midline, it is a lighter gray which extends as a blaze over on the side near the dorsal fin. Ventrally, it is off-white, which reaches over the eye and the flipper in some instances. By size, it is smaller than the common bottlenose dolphin, but larger than the Indo-Pacific bottlenose dolphin, measuring between 2.27 and 2.78 m (7.4 and 9.1 ft) in length.[13]

Distribution and habitat

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The recognition of T. australis is particularly significant given the endemism of this new subspecies to a small geographic region of southern and south-eastern Australia.[1] Only two resident populations of the Burrunan dolphin have been identified, one in Port Phillip and the other in the Gippsland Lakes.[12] Their combined population has been estimated as about 100 in Port Phillip and 50 in Gippsland.[14] Additionally, T. australis haplotypes have been documented in dolphins located in waters off eastern Tasmania, and in coastal waters of South Australia in the Spencer Gulf region and west to St Francis Island. The initial report on the Burrunan dolphin suggested that the low number of individuals found might immediately qualify the population for protection under the Environment Protection and Biodiversity Conservation Act.[13] The Burrunan dolphin is yet to be listed, or categorized, under the EPBC Act or IUCN Red List due to data deficiencies; however, it is listed as ‘Critically Endangered’ under the State of Victoria's Flora and Fauna Guarantee Act 1988.[17][18]

Threats

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The species is found in estuaries and sheltered bays of the southern coasts of Australia, often in locations that make them vulnerable to human activities.[19] Anthropogenic disturbances, such as dolphin-swim tour vessels, distract Burrunan dolphins from foraging and resting.[20] The Burrunan is vulnerable to extinction due to several different factors relating to exposure to threats, data deficiency, low genetic diversity and low population sizes, high mercury levels,[21] and increased risk from pathogens and contaminants. Small localised populations may be at high risk of extinction through demographic and genetic stochasticity,[12] particularly if they occur close to urban areas where anthropogenic threats abound. Anthropogenic activities, such as cetacean-based tourism [20] or recreational boating,[22] can impact dolphins through physical presence, non-compliance to regulations and acoustic disturbance. Such disturbances can negatively affect the long-term viability of small resident populations, summarised in Puszka et al. 2021.[22]

As recent case study conducted by the Marine Mammal Foundation and RMIT (Research Lead Dr Kate Robb), provided the first field assessment of vessel compliance with the Wildlife (Marine Mammal) Regulations 2009 in Gippsland Lakes, Australia, and provided the first assessment of the endangered Gippsland Lakes Burrunan dolphin (Tursiops australis) population's behavioural ecology.[22] Dolphin behaviour and vessel regulation compliance data were collected during boat-based surveys of Gippsland Lakes from July 2017 to January 2018, with a total of 22 dolphin group sightings resulting in 477 five-minute point samples. 77% of dolphin sightings involved vessel interactions (within 400 m), and 56 regulation breaches were observed. These breaches were most severe in summer (mean = 4.54 breaches/hour). Vessels were found to alter dolphin behaviour before, during, and after interactions and regulation breaches, including increased mating (mate guarding) and milling behavioural states, and increased ‘fish catch’, ‘high leap’ and ‘tail slap’ behavioural events. These behavioural changes may indicate masking of the dolphins' acoustic communication, disturbance of prey, increased dolphin transition behaviours, and/or induced stress and changes to group structure (including increased mate guarding).[22]

Fresh water skin disease (FWSD) has been described from the population in Gippsland Lakes, when weather conditions caused excessive influx of fresh water into the normally brackish-to-salty lake system. Increased incidence of these weather events could threaten the small population in the lakes.[23][24]

[edit]
  • Burrunan dolphin bow riding in Port Phillip Bay, Victoria, Australia
    Burrunan dolphin bow riding in Port Phillip Bay, Victoria, Australia
  • Burrunan dolphins in Port Phillip Bay, Victoria, Australia
    Burrunan dolphins in Port Phillip Bay, Victoria, Australia
  • Burrunan dolphins jumping
    Burrunan dolphins jumping
  • Burrunan dolphin
    Burrunan dolphin

See also

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References

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  1. ^ a b Charlton-Robb, Kate; Gershwin, Lisa-ann; Thompson, Ross; Austin, Jeremy; Owen, Kylie; McKechnie, Stephen (2011-09-14). "A New Dolphin Species, the Burrunan Dolphin Tursiops australis sp. nov., Endemic to Southern Australian Coastal Waters". PLOS ONE. 6 (9): e24047. Bibcode:2011PLoSO...624047C. doi:10.1371/journal.pone.0024047. ISSN 1932-6203. PMC 3173360. PMID 21935372.
  2. ^ a b c d e Oremus, Marc; Garrigue, Claire; Tezanos-Pinto, Gabriela; Scott Baker, C. (2015-04-02). "Phylogenetic identification and population differentiation of bottlenose dolphins (Tursiopsspp.) in Melanesia, as revealed by mitochondrial DNA". Marine Mammal Science. 31 (3): 1035–1056. doi:10.1111/mms.12210. ISSN 0824-0469.
  3. ^ a b Gray, H.W.I.; Nishida, S.; Welch, A.J.; Moura, A.E.; Tanabe, S.; Kiani, M.S.; Culloch, R.; Möller, L.; Natoli, A.; Ponnampalam, L.S.; Minton, G. (May 2018). "Cryptic lineage differentiation among Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the northwest Indian Ocean". Molecular Phylogenetics and Evolution. 122: 1–14. doi:10.1016/j.ympev.2017.12.027. hdl:2328/39105. ISSN 1055-7903. PMID 29294405. S2CID 3689432.
  4. ^ a b Ben Chehida, Yacine; Thumloup, Julie; Schumacher, Cassie; Harkins, Timothy; Aguilar, Alex; Borrell, Asunción; Ferreira, Marisa; Rojas-Bracho, Lorenzo; Robertson, Kelly M.; Taylor, Barbara L.; Víkingsson, Gísli A. (December 2020). "Mitochondrial genomics reveals the evolutionary history of the porpoises (Phocoenidae) across the speciation continuum". Scientific Reports. 10 (1): 15190. doi:10.1038/s41598-020-71603-9. ISSN 2045-2322. PMC 7494866. PMID 32938978.
  5. ^ a b Horreo, Jose L. (May 2019). "New insights into the phylogenetic relationships among the oceanic dolphins (Cetacea: Delphinidae)". Journal of Zoological Systematics and Evolutionary Research. 57 (2): 476–480. doi:10.1111/jzs.12255. ISSN 0947-5745. S2CID 91933816.
  6. ^ a b Moura, Andre E.; Nielsen, Sandra C. A.; Vilstrup, Julia T.; Moreno-Mayar, J. Victor; Gilbert, M. Thomas P.; Gray, Howard W. I.; Natoli, Ada; Möller, Luciana; Hoelzel, A. Rus (2013-11-01). "Recent Diversification of a Marine Genus (Tursiops spp.) Tracks Habitat Preference and Environmental Change". Systematic Biology. 62 (6): 865–877. doi:10.1093/sysbio/syt051. ISSN 1063-5157. PMID 23929779.
  7. ^ a b Lee, Kyunglee; Lee, JunMo; Cho, Yuna; Kim, Hyun Woo; Park, Kyum Joon; Sohn, Hawsun; Choi, Young-Min; Kim, Hye Kwon; Jeong, Dae Gwin; Kim, Ji Hyung (2018-01-09). "First report of the complete mitochondrial genome and phylogenetic analysis of Fraser's dolphin Lagenodelphis hosei (Cetacea: Delphinidae)". Conservation Genetics Resources. 11 (1): 47–50. doi:10.1007/s12686-017-0964-1. ISSN 1877-7252. S2CID 20551792.
  8. ^ a b Zurano, Juan P.; Magalhães, Felipe M.; Asato, Ana E.; Silva, Gabriel; Bidau, Claudio J.; Mesquita, Daniel O.; Costa, Gabriel C. (April 2019). "Cetartiodactyla: Updating a time-calibrated molecular phylogeny". Molecular Phylogenetics and Evolution. 133: 256–262. doi:10.1016/j.ympev.2018.12.015. ISSN 1055-7903. PMID 30562611.
  9. ^ a b Jedensjö, M.; Kemper, C.M.; Milella, M.; Willems, E.P.; Krützen, M. (July 2020). "Taxonomy and distribution of bottlenose dolphins (genus Tursiops ) in Australian waters: an osteological clarification". Canadian Journal of Zoology. 98 (7): 461–479. doi:10.1139/cjz-2018-0270. ISSN 0008-4301. S2CID 216179066.
  10. ^ "List of Marine Mammal Species and Subspecies", Society for Marine Mammalogy, June 2021, retrieved 11 July 2021
  11. ^ a b c "Explore the Database". www.mammaldiversity.org. Retrieved 2021-09-05.
  12. ^ a b c Charlton-Robb, K.; Taylor, A. C.; McKechnie, S. W. (2015-02-01). "Population genetic structure of the Burrunan dolphin (Tursiops australis) in coastal waters of south-eastern Australia: conservation implications". Conservation Genetics. 16 (1): 195–207. doi:10.1007/s10592-014-0652-6. ISSN 1572-9737. S2CID 16178397.
  13. ^ a b c d Charlton-Robb, K.; Gershwin, L.; Thompson, R.; Austin, J.; Owen, K.; McKechnie, Stephen (2011). Fleischer, Robert C. (ed.). "A New Dolphin Species, the Burrunan Dolphin Tursiops australis sp. nov., Endemic to Southern Australian Coastal Waters". PLoS ONE. 6 (9): e24047. Bibcode:2011PLoSO...624047C. doi:10.1371/journal.pone.0024047. PMC 3173360. PMID 21935372.
  14. ^ a b "Researcher discovers new dolphin species in Victoria". Monash University. 15 September 2011. Retrieved 16 September 2011.
  15. ^ Ritchie, Kerrie (15 September 2011). "New dolphin species discovered in Victoria". ABC News. Retrieved 16 September 2011.
  16. ^ "New species of dolphin discovered". BBC News. 15 September 2011. Retrieved 15 September 2011.
  17. ^ State of Victoria Department of Environment, Land, Water and Planning 2021 (1 September 2021). "Flora and Fauna Guarantee Act 1988 - Threatened List. September 2022" (PDF).{{cite web}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  18. ^ Department of Sustainability and Environment. Advisory List of Threatened Vertebrate Fauna in Victoria. In: Department of Sustainability and Environment, editor. Melbourne East, Australia: State Government of Victoria; 2013.
  19. ^ Menkhorst, P.W.; Knight, F. (2011). A field guide to the mammals of Australia (3rd ed.). Melbourne: Oxford University Press. p. 236. ISBN 9780195573954.
  20. ^ a b Filby, Nicole E.; Stockin, Karen A.; Scarpaci, Carol (2014-12-01). "Long-term responses of Burrunan dolphins (Tursiops australis) to swim-with dolphin tourism in Port Phillip Bay, Victoria, Australia: A population at risk". Global Ecology and Conservation. 2: 62–71. doi:10.1016/j.gecco.2014.08.006. ISSN 2351-9894.
  21. ^ Monk, Alissa; Charlton-Robb, Kate; Buddhadasa, Saman; Thompson, Ross M. (2014-08-19). "Comparison of Mercury Contamination in Live and Dead Dolphins from a Newly Described Species, Tursiops australis". PLOS ONE. 9 (8): e104887. Bibcode:2014PLoSO...9j4887M. doi:10.1371/journal.pone.0104887. ISSN 1932-6203. PMC 4138083. PMID 25137255.
  22. ^ a b c d Puszka, Helena; Shimeta, Jeff; Robb, Kate (2021-01-19). "Assessment on the effectiveness of vessel-approach regulations to protect cetaceans in Australia: A review on behavioral impacts with case study on the threatened Burrunan dolphin (Tursiops australis)". PLOS ONE. 16 (1): e0243353. Bibcode:2021PLoSO..1643353P. doi:10.1371/journal.pone.0243353. ISSN 1932-6203. PMC 7815133. PMID 33465088.
  23. ^ Duignan, Pádraig J.; Stephens, Nahiid S.; Robb, Kate (15 December 2020). "Fresh water skin disease in dolphins: a case definition based on pathology and environmental factors in Australia". Scientific Reports. 10 (1): 21979. Bibcode:2020NatSR..1021979D. doi:10.1038/s41598-020-78858-2. ISSN 2045-2322. PMC 7738556. PMID 33319842.
  24. ^ Costa, Jedda (22 December 2020). "Like 'third-degree burns': Cause found for 'horrific' skin lesions on endangered dolphins". ABC News. Australian Broadcasting Corporation.
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