Murray River Turtle

''Emydura macquarii'', also known as the Murray River turtle, Macquarie River turtle, eastern short-necked turtle, eastern short-neck turtle, and southern river turtle, is a species of freshwater turtle in the family Chelidae. Named after the Macquarie River of New South Wales, the turtle is a wide-ranging species that occurs throughout many of the rivers of the eastern half of Australia.

Etymology and taxonomy

The generic name, ''Emydura'', is derived from the Greek ''emys'' (freshwater turtle) and the Greek ''oura'' (tail), Latinized to ''ura''. Its grammatical gender is feminine. The specific epithet, ''macquarii'', refers to the turtle's type locality: the Macquarie River. It would seem that the species was not named after Governor Lachlan Macquarie, for whom the river is named.

The species' common names include Murray River turtle,Species "''Emydura macquarii'' " at The Reptile Database
/ref> Macquarie River turtle, eastern short-necked turtle, eastern short-neck turtle, and southern river turtle.

The subspecific name, ''emmotti'', is in honour of Australian farmer and naturalist Angus Emmott (born 1962).

The subspecific name, ''krefftii'', is in honour of German-born Australian naturalist Gerard Krefft. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Emydura macquarii'', p. 165; ''E. m. emmotti'', p. 83; ''E. m. krefftii'', p. 146).

A species formerly thought to be a separate species, the Bellinger River Emydura is now considered synonymous with the Macquarie River turtle.

The species ''Emydura macquarii'' is in the family Chelidae.

Collection history and discovery

This species, ''Emydura macquarii'', has a long and complicated nomenclatural history, including even its original description. The holotype was originally collected by René Primevère Lesson (1794–1849) and Prosper Garnot (1794–1838) in 1824. During an expedition on the '' La Coquille'', captained by Louis Isidore Duperrey, which visited Sydney, Australia, from 17 January to 25 March 1824, they visited Bathurst, and collected the holotype from the Macquarie River.Cann J (1998). ''Australian Freshwater Turtles''. Singapore: Beumont Publishing. p. 101. .

The first description of the species, as ''Emys macquaria'', was offered by Baron Georges Cuvier in 1829, Cuvier GLCFD (1829). ''Le Regne Animal. Vol. 2 XV.'' Paris: Deterville, p. 406 (ii). but this description is nowadays seen as a ''nomen nudum''. Hence, the description, as ''Chelys (Hydraspis) macquarii'', by John Edward Gray in 1830, is considered the valid description.

Geographic range

''Emydura macquarii'' is found across several states:
* in the coastal Queensland rivers and the Cooper Creek ecosystem, along with Fraser Island and Brisbane
* in the Macquarie River basin and all its major tributaries, along with a number of coastal rivers up the New South Wales coast
* in northern Victoria
* in South Australia, in the billabongs and channels of Cooper Creek, and also along the Murray River; also, introduced populations in the Adelaide city area

Description and habitat

''Emydura macquarii'' holotype: MNHN 9409, dorsal view, left
''Emydura macquarii'' holotype: MNHN 9409, ventral view, left
The Macquarie River turtle is almost entirely aquatic. Its intergular plate reaches the front edge of the shell, while its plastrons are "cut away", allowing their legs to move freely and thus swim powerfully.

Feeding

The Macquarie River turtle is omnivorous. Its diet includes small crustaceans, aquatic insects, filamentous algae, and possibly aquatic weeds.

Life cycle and sex determination

The Macquarie River turtle nests from October to early January, and multiple clutches of eggs may be laid, in nests excavated in the riverbanks.

''Emydura macquarii'' uses the XY sex-determination system, making it one of the few turtle species that has a genetic sex-determination mechanism. The X and Y chromosomes are macrochromosomes, unlike most genetically sex-determined turtles including its close relative '' Chelodina longicollis'', which has microchromosomes. It is also hypothesised that this turtle's sex chromosomes were formed from the translocation of an ancestral Y microchromosome onto an autosome. It can often be difficult to determine the gender of a turtle when it is young, but it becomes more apparent when it grows.

Importance

Turtles are an important element of the river ecosystem owing to their feeding on dead fish after a fish kill event, returning ammonia and dissolved oxygen to the river much faster than by natural decomposition (3–6 days vs 25–27 days).

Conservation status and efforts

Threats to the turtles' habitat include water pollution and increased sediment loads from nearby agriculture and forestry activities, construction of bridges and fords, extraction of river sand and gravel, clearing and degradation of riparian vegetation, water diversion, and changes to river flows. Foxes (an introduced species in Australia) and goannas may eat the eggs, and foxes may eat the turtles as well. In South Australia, river system regulation and roadkill are also considered threats to the species.

Efforts to protect the species include the use of professional shooters to kill foxes; working with local councils to build nesting islands, and improving monitoring of species.

''Emydura macquarii'' is listed as "vulnerable" in the state of South Australia under relevant state legislation. After it was found that freshwater turtle numbers had declined by up to 91 per cent some sections of the Murray, conservation efforts increased, with the Government of South Australia allocating $450,000 to help establish the state's first turtle management plan, dubbed the "Together Understanding and Restoring Turtles in our Landscapes and Ecosystems" (TURTLE) project. A management strategy is being developed in collaboration with First Nations people, for whom the turtles have great cultural significance, along with environmental experts.

Parasites

''Emydura macquarii'' is often infected with the flatworm ''Choanocotyle elegans''. Sue, Lindsay Jue (1998). "Description and life-cycle of two new species of ''Choanocotyle'' n. g. (Trematoda: Plagiorchiida), parasites of Australian freshwater turtles, and the erection of the family Choanocotylidae". ''Systematic Parasitology'' 41 (1): 47–61.

References

Further reading

* xxx + 1,033 pp.
* 688 pp. (''Emydura macquarii'', pp. 50–51).

{{Taxonbar , from=Q1063950

macquarii
Murray River
Reptiles of Queensland
Reptiles described in 1830
Taxa named by John Edward Gray
Reptiles of New South Wales
Reptiles of Victoria (state)
Turtles of Australia