Burrunan dolphin

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Burrunan dolphin
Burrunan Dolphin (Tursiops australis)-B.png
Scientific classification OOjs UI icon edit-ltr.svg
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]

Contents

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

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. [17]

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

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

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. [18] [19]

Threats

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. [20] Anthropogenic disturbances, such as dolphin-swim tour vessels, distract Burrunan dolphins from foraging and resting. [21] 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, [22] 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 [21] or recreational boating, [23] 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. [23]

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. [23] 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). [23]

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. [24] [25]

See also

Related Research Articles

<span class="mw-page-title-main">Dolphin</span> Marine mammals, closely related to whales and porpoises

A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and possibly extinct Lipotidae. There are 40 extant species named as dolphins.

<span class="mw-page-title-main">Bottlenose dolphin</span> Genus of dolphin

Bottlenose dolphins are aquatic mammals in the genus Tursiops. They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus definitively contains three species: the common bottlenose dolphin, the Indo-Pacific bottlenose dolphin, and Tamanend's bottlenose dolphin. Others, like the Burrunan dolphin, may be alternately considered their own species or be subspecies of T. aduncus. Bottlenose dolphins inhabit warm and temperate seas worldwide, being found everywhere except for the Arctic and Antarctic Circle regions. Their name derives from the Latin tursio (dolphin) and truncatus for their characteristic truncated teeth.

<span class="mw-page-title-main">Oceanic dolphin</span> Family of marine mammals

Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the Globicephalinae. Delphinidae is a family within the superfamily Delphinoidea, which also includes the porpoises (Phocoenidae) and the Monodontidae. River dolphins are relatives of the Delphinoidea.

<span class="mw-page-title-main">Toothed whale</span> Parvorder of cetaceans

The toothed whales are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. 73 species of toothed whales are described. They are one of two living groups of cetaceans, the other being the baleen whales (Mysticeti), which have baleen instead of teeth. The two groups are thought to have diverged around 34 million years ago (mya).

<span class="mw-page-title-main">Common dolphin</span> Species of mammal

The common dolphin is the most abundant cetacean in the world, with a global population of about six million. Despite this fact and its vernacular name, the common dolphin is not thought of as the archetypal dolphin, with that distinction belonging to the bottlenose dolphin due to its popular appearances in aquaria and the media. However, the common dolphin is often depicted in Ancient Greek and Roman art and culture, most notably in a mural painted by the Greek Minoan civilization.

<span class="mw-page-title-main">False killer whale</span> Species of oceanic dolphin in the genus Pseudorca

The false killer whale is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found in oceans worldwide but mainly in tropical regions. It was first described in 1846 as a species of porpoise based on a skull, which was revised when the first carcasses were observed in 1861. The name "false killer whale" comes from having a skull similar to the orca, or killer whale.

<span class="mw-page-title-main">Indo-Pacific bottlenose dolphin</span> Species of mammal

The Indo-Pacific bottlenose dolphin is a species of bottlenose dolphin. This dolphin grows to 2.6 m (8.5 ft) long, and weighs up to 230 kg (510 lb). It lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its belly is lighter grey or nearly white with grey spots.

<i>Lagenorhynchus</i> Genus of mammals

Lagenorhynchus is a genus of oceanic dolphins in the infraorder Cetacea, presently containing six extant species. However, there is consistent molecular evidence that the genus is polyphyletic and several of the species are likely to be moved to other genera. In addition, the extinct species Lagenorhynchus harmatuki is also classified in this genus.

<span class="mw-page-title-main">Atlantic spotted dolphin</span> Species of mammal

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<span class="mw-page-title-main">Common bottlenose dolphin</span> Species of bottlenose dolphin

The common bottlenose dolphin or Atlantic bottlenose dolphin is a wide-ranging marine mammal of the family Delphinidae. In the order Cetacea, the common bottlenose is most similar to whales, porpoises, and other dolphins, and they are found in the waters around the globe. The common bottlenose dolphin is a very familiar dolphin due to the wide exposure it gets in captivity in marine parks and dolphinariums, and in movies and television programs. It inhabits temperate and tropical oceans throughout the world, and is absent only from polar waters. While formerly known simply as the bottlenose dolphin, this term is now applied to the genus Tursiops as a whole. As considerable genetic variation has been described within this species, even between neighboring populations, many experts think additional species may be recognized.

<span class="mw-page-title-main">Cetacean surfacing behaviour</span> Cetacean movement types

Cetacean surfacing behaviour is a grouping of movement types that cetaceans make at the water's surface in addition to breathing. Cetaceans have developed and use surface behaviours for many functions such as display, feeding and communication. All regularly observed members of the order Cetacea, including whales, dolphins and porpoises, show a range of surfacing behaviours.

<span class="mw-page-title-main">Gippsland Lakes</span> Lake network in Victoria, Australia

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<span class="mw-page-title-main">Tethys Research Institute</span>

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<span class="mw-page-title-main">Kate Robb</span> Australian marine mammalogist

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Fresh water skin disease (FWSD) is a disease of marine cetaceans in coastal and estuarine environments, caused when they are exposed for extended periods to water with lower than normal levels of salt (hypo-saline). It has been observed in dolphins that were displaced into freshwater lakes, and in normally-salty lakes and estuaries where salinity has dropped suddenly due to flooding or storm runoff.

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References

  1. 1 2 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. 1 2 3 4 5 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. 1 2 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.
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  7. 1 2 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. 1 2 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. 1 2 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. 1 2 "Explore the Database". www.mammaldiversity.org. Retrieved 2021-09-05.
  12. 1 2 3 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. 1 2 3 4 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. 1 2 "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. ↑ "Explore the Database". www.mammaldiversity.org. Retrieved 2021-09-05.
  18. ↑ 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)
  19. ↑ 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.
  20. ↑ Menkhorst, P.W.; Knight, F. (2011). A field guide to the mammals of Australia (3rd ed.). Melbourne: Oxford University Press. p. 236. ISBN   9780195573954.
  21. 1 2 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.
  22. ↑ 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.
  23. 1 2 3 4 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.
  24. ↑ 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.
  25. ↑ 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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