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Journal articles on the topic 'Emydura macquarii'

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Published: 4 June 2021

Last updated: 7 February 2022

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1

Scheelings, T. Franciscus, Ruth Tesdorpf, Celia Hooper, and Kathryn Stalder. "Chromobacterium violaceum Isolation from a Macquarie Turtle (Emydura macquarii)." Journal of Herpetological Medicine and Surgery 22, no. 1 (July 1, 2013): 22. http://dx.doi.org/10.5818/1529-9651-22.1-2.22.

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2

Petrov, Kristen, Jessica Lewis, Natasha Malkiewicz, James U. Van Dyke, and Ricky-John Spencer. "Food abundance and diet variation in freshwater turtles from the mid-Murray River, Australia." Australian Journal of Zoology 66, no. 1 (2018): 67. http://dx.doi.org/10.1071/zo17060.

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Consumers usually respond to variations in prey availability by altering their foraging strategies. Generalist consumers forage on a diversity of resources and have greater potential to ‘switch’ their diet in response to fluctuations in prey availability, in comparison to specialist consumers. We aimed to determine how the diets of two specialist species (the eastern long-necked turtle (Chelodina longicollis) and the broad-shelled turtle (Chelodina expansa) and the more generalist Murray River short-necked turtle (Emydura macquarii) respond to variation in habitat and prey availability. We trapped and stomach-flushed turtles, and compared their diets along with environmental variables (turbidity, macrophyte and filamentous green algae cover, and aquatic invertebrate diversity and abundance) at four wetlands in north-central Victoria. Diets of E. macquarii differed from those of both Chelodina species, which overlapped, across all four sites. However, samples sizes for the two Chelodina species were too small to compare among-wetland variation in diet. Dietary composition of E. macquarii was variable but did not differ statistically among sites. Emydura macquarii preferentially selected filamentous green algae at three of the four sites. Where filamentous green algae were rare, total food bolus volume was reduced and E. macquarii only partially replaced it with other food items, including other vegetation, wood, and animal prey. Many turtles at these sites also had empty stomachs. Thus, filamentous green algae may be a limiting food for E. macquarii. Although E. macquarii has previously been described as a generalist, it appears to have limited ability to replace filamentous green algae with other food items when filamentous green algae are rare.

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3

Scheelings, T. Franciscus. "Use of Intravenous and Intramuscular Alfaxalone in Macquarie River Turtles (Emydura macquarii)." Journal of Herpetological Medicine and Surgery 23, no. 3 (September 1, 2013): 91. http://dx.doi.org/10.5818/1529-9651-23.3.91.

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4

Thompson, Michael B. "Nest Temperatures in the Pleurodiran Turtle, Emydura macquarii." Copeia 1988, no. 4 (December 28, 1988): 996. http://dx.doi.org/10.2307/1445723.

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5

Rogers, Kris D., and David T. Booth. "A method of sampling blood from Australian freshwater turtles." Wildlife Research 31, no. 1 (2004): 93. http://dx.doi.org/10.1071/wr02089.

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Blood sampling is an essential technique in many herpetological studies. This paper describes a quick and humane technique to collect blood samples from three species of Australian chelid turtles (Order Pleurodira): Chelodina expansa, Elseya latisternum, and Emydura macquarii signata.

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6

Chessman, BC. "Diet of the Murray Turtle, Emydura-Macquarii (Gray) (Testudines, Chelidae)." Wildlife Research 13, no. 1 (1986): 65. http://dx.doi.org/10.1071/wr9860065.

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Examination of the stomach contents of 122 E. macquarii from the Murray River, Lake Boga and other waters in northern Victoria and southern New South Wales showed that this species is an opportunistic omnivore. In order of decreasing importance the main food types were filamentous algae, vertebrate (mainly fish) carrion, detritus, periphyton (including sponges), mobile aquatic invertebrates, aquatic macrophytes and terrestrial invertebrates. There was a degree of dietary shift with turtle size, small specimens containing more detritus and periphyton and less filamentous algae, macrophytes and carrion than bigger ones. The diets of mature males and females did not differ appreciably. Diel changes in stomach content volumes indicated that E. macquarii feeds mainly during the daytime.

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7

Chessman, Bruce C. "Distribution, abundance and population structure of the threatened western saw-shelled turtle, Myuchelys bellii, in New South Wales, Australia." Australian Journal of Zoology 63, no. 4 (2015): 245. http://dx.doi.org/10.1071/zo15034.

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The western saw-shelled turtle is listed as threatened globally, nationally, and within the Australian state of New South Wales. Although nearly all of the geographic range of the species lies within New South Wales, little information has been available on the distribution, abundance and structure of New South Wales populations. Through a survey of 60 sites in 2012–15, I established that M. bellii is much more widely distributed in New South Wales than has previously been recognised, comprising four disjunct populations, including two in the New South Wales portion of the Border Rivers basin. It occurs mainly in larger, cooler rivers upstream of barriers to dispersal of the Macquarie turtle, Emydura macquarii macquarii. Although M. bellii is locally abundant, its populations are greatly dominated by large adults and recruitment appears to be low. Eye abnormalities are common in some populations but do not necessarily impair body condition or preclude long-term survival. The species is threatened by competition with E. macquarii, which appears to be expanding its range through translocation by humans, and possibly by predation, disease and drought. Long-term monitoring of M. bellii is needed to assess population trends and responses to threats, and active management to restrict the further spread of E. macquarii is probably required to ensure the persistence of M. bellii throughout its current range.

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8

Chessman, BC. "Seasonal and Diel Activity of Fresh-Water Turtles in the Murray Valley, Victoria and New South-Wales." Wildlife Research 15, no. 3 (1988): 267. http://dx.doi.org/10.1071/wr9880267.

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Activity cycles of Chelodina expansa, C. longicollis and Emydura macquarii were inferred from captures in baited traps set in the Murray River and Lake Boga. C. expansa and E, macquarii were caught only from October to April, while C. longicollis was taken in all months but June and July. Minimum water temperatures at capture were highest for C. expansa and lowest for C. longicollis. Diel cycles of catch rate were often weak, but tended to be bimodal for all species, with peaks near dawn and in the afternoon or evening. Unlike the Chelodina species, E. macquarii was ofen caught near midnight. In the laboratory (at c.24�C with light:dark 12:12 h), the average diel pattern of locomotor activity was weakly bimodal in C. expansa, strongly bimodal in C. longicollis and unimodal in E. macquarii.

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9

Alibardi, Lorenzo, and Michael B. Thompson. "Morphogenesis of shell and scutes in the turtle Emydura macquarii." Australian Journal of Zoology 47, no. 3 (1999): 245. http://dx.doi.org/10.1071/zo99001.

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Formation of the scutes and dermis of the embryonic shell of the turtle Emydura macquarii was studied using light and electron microscopy. Shell morphogenesis begins at embryonic stage 15 and the shape of the shell is mostly completed by embryonic stage 19. The carapace anlagen arises as a thickening of the skin in the dorsal part of the mid-trunk region between the anterior and posterior limbs. This thickening extends ventro-laterally to form ridges at the margins of the carapace. Each ridge forms as a thick epidermal placode over a condensation of mesenchymal cells. The epidermis behind the advancing margins of the carapace is cuboidal or columnar but does not form placodes. The margins of the carapace expand rapidly in all directions. The plastron anlagen is derived from epidermal cells localised in the latero-ventral regions between the fore- and hind-limbs. Plastron placodes are present laterally, while the mid-ventral and central epidermis remains cuboidal or columnar but does not form placodes at embryonic stage 16. The plastron thickening rapidly moves from a latero-ventral position to a flat ventral position between embryonic stages 16 and 19. Dermal–epidermal anchoring complexes occur throughout placodes of both the carapace and plastron, but are rare in non-placode areas. The accumulation of a dense mesenchyme beneath the shell epidermis forms a dermal cushion that surrounds the body cavity. The superficial dermis close to the epidermis is made of mesenchymal fibroblasts at embryonic stage 19, although the inner-most areas contain bipolar fibroblasts and extracellular fibrils. Scutes with serrations at their borders form as invaginations of the epidermis into the dermis in the mid-dorsal areas of the embryo at embryonic stages 18–19. Dermal–epidermal anchoring complexes are located around the infoldings that form the scutes of the hinge region. The epidermis of the shell has 2–3 suprabasal cells at embryonic stages 19–22, and lacks keratinisation before embryonic stage 22 when it has 4–6 suprabasal layers with 2–3 external layers made of flat cells. The dermis thickens and has numerous collagen fibrils after embryonic stage 19. The formation of dermal bones begins at embryonic stage 18–19 in the plastron. Only small areas of the carapace near to the bridge have begun to form dermal bone at embryonic stage 19. Calcification begins at embryonic stage 19, but is still incomplete at embryonic stages 24–25.

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10

Blamires, Sean J., Ricky-John Spencer, Peter King, and Michael B. Thompson. "Population parameters and life-table analysis of two coexisting freshwater turtles: are the Bellinger River turtle populations threatened?" Wildlife Research 32, no. 4 (2005): 339. http://dx.doi.org/10.1071/wr04083.

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Two species of freshwater turtle coexist in the Bellinger River: Elseya georgesi is common but limited to the Bellinger River, whereas Emydura macquarii is widespread but rare in the Bellinger River. The Bellinger River population of E. macquarii has been proposed as a distinct subspecies, so it may be endangered. Survivorship, fecundity, growth, size and age were determined for El. georgesi and the finite rate of increase (λ) was estimated by a life-table analysis using mark–recapture data from surveys between 1988 and 2004. These parameters were compared with those of well studied populations of E. macquarii to assess whether modelling the demographic parameters of El. georgesi could serve as a surrogate for estimating the influences of these demographic parameters on λ in the Bellinger River population of E. macquarii. We estimated that ~4500 El. georgesi inhabit the study area and, despite a size distribution strongly biased towards large individuals, the population is increasing (λ = 1.15) in the best-case scenario, or slightly decreasing (λ = 0.96) in the worst-case scenario. Comparing El. georgesi with E. macquarii from the Bellinger River and elsewhere suggests that E. macquarii grows faster, attains greater maximum size, has a greater clutch size and a higher fecundity than El. georgesi. Hence, El. georgesi does not serve as a good surrogate to determine demographic influences on λ in E. macquarii.

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11

Chessman, BC. "Habitat Preferences of Fresh-Water Turtles in the Murray Valley, Victoria and New-South-Wales." Wildlife Research 15, no. 5 (1988): 485. http://dx.doi.org/10.1071/wr9880485.

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Preferences of Chelodina expansa, Chelodina longicollis and Emydura macquarii (Testudines : Chelidae) for different types of aquatic habitat on the Murray River flood plain in south-eastern Australia were inferred from catch statistics. E. macquarii was the species most often caught in the river itself and river backwaters, whereas C. longicollis formed the majority of captures from oxbow lakes, anabranches, ponds, rain pools and a swamp. Relative abundance of E. macquarii was significantly positively correlated with water body depth, transparency, persistence during dry conditions and flow speed, and negatively correlated with remoteness from the river. C. longicollis demonstrated the opposite pattern, and the proportional catch of C. expansa was weakly correlated with environmental variables. The capacity of C. longicollis for colonising and surviving in small, remote and ephemeral ponds and pools relates to its ability to aestivate and resist desiccation and its propensity for overland migration.

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12

Clark, Natalie J., Courtenay E. Mills, Nicolette A. Osborne, and Kerry M. Neil. "The influence of a new water infrastructure development on the relative abundance of two Australian freshwater turtle species." Australian Journal of Zoology 66, no. 1 (2018): 57. http://dx.doi.org/10.1071/zo17082.

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Development of water infrastructure benefits water security and agriculture but poses risks to habitat and aquatic fauna. Wyaralong Dam was constructed on Teviot Brook in 2010 to provide future urban water supplies for South East Queensland, Australia. Construction of the dam created a large impoundment area and environmental impact assessment predicted significant impacts upon resident freshwater turtle species and their habitats. Differences in habitat requirements, life-history characteristics and sensitivity to change between the Macquarie River turtle (Emydura macquarii macquarii) and the common saw-shelled turtle (Myuchelys latisternum) were expected to influence the impact of the dam on the spatial and temporal abundance of these species. The relative abundance of each species was monitored at sites located within, upstream and downstream of the impoundment across wet and dry seasons during the dam’s first five years of operation. The results of this monitoring program indicate that spatial and temporal variability in the relative abundance of E. macquarii macquarii and M. latisternum occurred during the study but not all expected impacts were realised. Contrary to expectation, the relative abundance of E. macquarii macquarii did not increase over time within, upstream or downstream of the dam. M. latisternum showed greater temporal variability at some sites; however, no clear relationship between relative abundance and operational years was observed during the monitoring program. Spatial variability in relative abundance between sites was dependent upon season, with trends generally consistent across both turtle species. Where differences between species were observed, these are suspected to have resulted from the influence of environmental conditions on species-specific movement behaviours. The monitoring program confirmed the use of the upper limits of the impoundment and the plunge pool below the dam wall by both turtle species but relative abundance within the main body of the impoundment remained low throughout monitoring. The results of the study allow for consideration of the suitability of predefined management measures and the development of recommendations for future monitoring programs prescribed for water infrastructure developments.

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13

Lee, LingSze, Eugenia E. Montiel, and Nicole Valenzuela. "Discovery of Putative XX/XY Male Heterogamety in Emydura subglobosa Turtles Exposes a Novel Trajectory of Sex Chromosome Evolution in Emydura." Cytogenetic and Genome Research 158, no. 3 (2019): 160–69. http://dx.doi.org/10.1159/000501891.

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The discovery of sex chromosome systems in non-model organisms has elicited growing recognition that sex chromosomes evolved via diverse paths that are not fully elucidated. Lineages with labile sex determination, such as turtles, hold critical cues, yet data are skewed toward hide-neck turtles (suborder Cryptodira) and scant for side-neck turtles (suborder Pleurodira). Here, we used classic and molecular cytogenetics to investigate Emydura subglobosa (ESU), an unstudied side-neck turtle with genotypic sex determination from the family Chelidae, where extensive morphological divergence exists among XX/XY systems. Our data represent the first cytogenetic description for ESU. Similarities were found between ESU and E. macquarii (EMA), such as identical chromosome number (2n = 50), a single and dimorphic nucleolus organizer region (NOR) localized in a microchromosome pair (ESU14) of both sexes (detected via FISH of 18S rDNA). Only the larger NOR is active (detected by silver staining). As in EMA, comparative genome hybridization revealed putative macro XX/XY chromosomes in ESU (the 4th largest pair). Our comparative analyses and revaluation of previous data strongly support the hypothesis that Emydura's XX/XY system evolved via fusion of an ancestral micro-Y (retained by Chelodina longicollis) onto a macro-autosome. This evolutionary trajectory differs from the purported independent evolution of XX/XY from separate ancestral autosomes in Chelodina and Emydura that was previously reported. Our data permit dating this Y-autosome fusion to at least the split of Emydura around 45 Mya and add critical information about the evolution of the remarkable diversity of sex-determining mechanisms in turtles, reptiles, and vertebrates.

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14

Ferguson, Meryl A., and Lesley R. Smales. "Helminth Assemblages of the Turtle Emydura macquarii (Pleurodira: Chelidae) Queensland, Australia." Journal of Parasitology 92, no. 1 (February 2006): 186–88. http://dx.doi.org/10.1645/ge-552r.1.

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15

Cowan, ML, SR Raidal, and A. Peters. "Herpesvirus in a captive Australian Krefft's river turtle (Emydura macquarii krefftii)." Australian Veterinary Journal 93, no. 1-2 (January 2015): 46–49. http://dx.doi.org/10.1111/avj.12290.

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16

Chessman, Bruce C. "Effects of temperature and exercise on metabolism of three species of Australian freshwater turtles: implications for responses to climate change." Australian Journal of Zoology 66, no. 6 (2018): 317. http://dx.doi.org/10.1071/zo18062.

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Oxygen consumption () of Chelodina expansa, C. longicollis and Emydura macquarii (Pleurodira: Chelidae) was measured at rest and during induced exercise at 8, 13, 18, 22, 26, 30 and 34°C. Resting varied significantly among species, being lowest in C. expansa, which is the most sedentary of the three species in nature, and highest in E. macquarii, which is the most energetic, but active did not differ significantly among the three species overall. For both Chelodina species, resting was appreciably lower than expected from regression of on body mass for non-marine turtles globally, a result that reinforces previous evidence of low resting metabolism in Australian chelid turtles. Active of all three species at higher temperatures was similar to reported for active freshwater cryptodires. Resting of all three species increased similarly with temperature, but active and aerobic scope did not. In C. expansa and E. macquarii, active and aerobic scope increased over the full temperature range assessed but in C. longicollis these variables reached a plateau above 22°C. Projected increases in freshwater temperatures in south-eastern Australia as a result of global warming are likely to enhance activity, feeding and growth of the three species (subject to food availability), especially in cooler seasons for C. longicollis and warmer seasons for C. expansa and E. macquarii. However, other aspects of predicted climate change, especially increased drought, are likely to be detrimental.

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17

Chessman, Bruce C. "Behavioural thermoregulation by Australian freshwater turtles: interspecific differences and implications for responses to climate change." Australian Journal of Zoology 67, no. 2 (2019): 94. http://dx.doi.org/10.1071/zo20004.

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The abilities of freshwater turtles to control their body temperatures by behavioural means have implications for activity, food ingestion and digestion, growth, reproduction and potential responses to climate change. I compared various forms of basking in nature, and responses to aquatic and aerial photothermal gradients in the laboratory, among three species of Australian chelid turtles: Chelodina expansa, C. longicollis and Emydura macquarii. Proclivity for behavioural thermoregulation varied substantially among these species, being highest in C. longicollis and lowest in C. expansa. However, C. expansa had a thermophilic response to feeding. For C. longicollis and E. macquarii, behavioural thermoregulation may enhance colonisation of more southerly latitudes or higher elevations as climatic warming proceeds. However, increasing air temperatures may pose a hazard to turtles dispersing or sheltering terrestrially (for example, when water bodies dry during drought). C. longicollis appears the best placed of the three species to avoid this hazard through its abilities to thermoregulate behaviourally and to aestivate in terrestrial microenvironments that are buffered against temperature extremes.

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18

Spencer, Ricky-John, Michael B. Thompson, and Ian D. Hume. "The diet and digestive energetics of an Australian short-necked turtle, Emydura macquarii." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 121, no. 4 (December 1998): 341–49. http://dx.doi.org/10.1016/s1095-6433(98)10132-0.

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19

ALIBARDI, LORENZO, and MICHAEL B. THOMPSON. "Epidermal differentiation during carapace and plastron formation in the embryonic turtle Emydura macquarii." Journal of Anatomy 194, no. 4 (May 1999): 531–45. http://dx.doi.org/10.1046/j.1469-7580.1999.19440531.x.

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20

Spencer, Ricky-John. "Growth patterns of two widely distributed freshwater turtles and a comparison of common methods used to estimate age." Australian Journal of Zoology 50, no. 5 (2002): 477. http://dx.doi.org/10.1071/zo01066.

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Turtles are long lived and demographic models requiring estimates of age, growth, fecundity and survival are central for management. Most studies that estimate age and growth of freshwater turtles use annuli as an index of age without estimating its error and very few studies that use growth models include many juveniles, where growth is often large and variable. In this paper, I compare the reliability of growth annuli and common models in determining age and growth of two widely distributed turtles in Australia. Most turtles are carnivorous during the juvenile stage but many species shift to a lower-quality omnivorous diet prior to maturing. Patterns of growth are often characterised by this dietary shift and I compared the growth of a common omnivorous turtle (Emydura macquarii) and a vulnerable sympatric species that is an obligate carnivore (Chelodina expansa). Mark–recapture programs were established in three lagoons on the Murray River. In total, 1218 hatchling E. macquarii were released into two of the lagoons and growth annuli were found to be unreliable in estimating their age by Year 2. The von Bertalanffy and logistic growth models can reliably estimate age of both male and female E. macquarii and C. expansa respectively. Growth is extremely rapid during the juvenile stage of E. macquarii, but is highly variable in C. expansa, with rapid growth occurring only beyond three years of age. Hence growth models fail to predict age when juveniles are excluded from the analyses. Female E. macquarii delay maturity until 9–12 years of age because clutch size is positively related to body size and they can produce only one large clutch per year. Female C.�expansa mature later (at ~14 years) than female E. macquarii and both species are sexually dimorphic, as males mature earlier at smaller sizes than females. Common growth models describe the growth of two widely distributed freshwater turtles, but different patterns of growth and age at maturity relate to quality of diet and reproduction.

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21

Chessman, Bruce C. "Declines of freshwater turtles associated with climatic drying in Australia." Wildlife Research 38, no. 8 (2011): 664. http://dx.doi.org/10.1071/wr11108.

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Context While much attention has been paid to the effects of global temperature increases on the geographical ranges and phenologies of plants and animals, less is known about the impacts of climatically driven alteration of water regimes. Aims To assess how three species of freshwater turtle in Australia’s Murray–Darling Basin have responded to long-term decline in river flow and floodplain inundation due to climatic drying and water diversions. Methods Turtle populations were sampled in a section of the Murray River and its floodplain in 1976–82 following a wet period and in 2009–11 at the end of the most severe drought on record. Catch per unit effort, proportional abundance in different habitat types and population structure were assessed in both periods. Key results Catch per unit effort in baited hoop nets declined by 91% for the eastern snake-necked turtle (Chelodina longicollis) and 69% for the Murray turtle (Emydura macquarii), but did not change significantly for the broad-shelled turtle (Chelodina expansa). In addition, total catches from a range of sampling methods revealed a significantly reduced proportion of juvenile C. longicollis and E. macquarii in 2009–11, suggesting a fall in recruitment. Key conclusions The decline of C. longicollis was likely due mainly to drought-induced loss of critical floodplain habitat in the form of temporary water bodies, and that of E. macquarii to combined effects of drought and predation on recruitment. C. expansa seems to have fared better than the other two species because it is less vulnerable to nest predation than E. macquarii and better able than C. longicollis to find adequate nutrition in the permanent waters that remain during extended drought. Implications Declining water availability may be a widespread threat to freshwater turtles given predicted global impacts of climate change and water withdrawals on river flows. Understanding how each species uses particular habitats and how climatic and non-climatic threats interact would facilitate identification of vulnerable populations and planning of conservation actions.

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22

McGlashan, Jessica K., Ricky-John Spencer, and Julie M. Old. "Embryonic communication in the nest: metabolic responses of reptilian embryos to developmental rates of siblings." Proceedings of the Royal Society B: Biological Sciences 279, no. 1734 (November 30, 2011): 1709–15. http://dx.doi.org/10.1098/rspb.2011.2074.

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Incubation temperature affects developmental rates and defines many phenotypes and fitness characteristics of reptilian embryos. In turtles, eggs are deposited in layers within the nest, such that thermal gradients create independent developmental conditions for each egg. Despite differences in developmental rate, several studies have revealed unexpected synchronicity in hatching, however, the mechanisms through which synchrony are achieved may be different between species. Here, we examine the phenomenon of synchronous hatching in turtles by assessing proximate mechanisms in an Australian freshwater turtle ( Emydura macquarii ). We tested whether embryos hatch prematurely or developmentally compensate in response to more advanced embryos in a clutch. We established developmental asynchrony within a clutch of turtle eggs and assessed both metabolic and heart rates throughout incubation in constant and fluctuating temperatures. Turtles appeared to hatch at similar developmental stages, with less-developed embryos in experimental groups responding to the presence of more developed eggs in a clutch by increasing both metabolic and heart rates. Early hatching did not appear to reduce neuromuscular ability at hatching. These results support developmental adjustment mechanisms of the ‘catch-up hypothesis’ for synchronous hatching in E. macquarii and implies some level of embryo–embryo communication. The group environment of a nest strongly supports the development of adaptive communication mechanisms between siblings and the evolution of environmentally cued hatching.

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23

Flint, M., DJ Limpus, CJ Limpus, JC Patterson-Kane, JA Eales, and PC Mills. "Biochemical and hematological reference intervals for Krefft’s turtles Emydura macquarii krefftii from the Burnett River Catchment, Australia." Diseases of Aquatic Organisms 95, no. 1 (May 24, 2011): 43–48. http://dx.doi.org/10.3354/dao02352.

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24

Wirth, Wytamma, Lin Schwarzkopf, Lee F. Skerratt, Anna Tzamouzaki, and Ellen Ariel. "Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)." Journal of General Virology 100, no. 10 (October 1, 2019): 1431–41. http://dx.doi.org/10.1099/jgv.0.001324.

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Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species (Emydura macquarii krefftii) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 102 . 52 (1.98–2.93) and 104.43 (3.81–5.19) TCID50 ml−1, respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16–25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [P<0.01, 95 % confidence interval (CI): 1.81–6.36] and 3.71 (P<0.01, 95 % CI: 1.76–7.80), respectively. Skin lesions, previously only reported in ranaviral infection in lizards, were observed in the majority of intramuscularly inoculated hatchlings that developed ranaviral disease. The histological changes were consistent with those in previous reports for reptiles and consisted of necrosis at or near the site of injection, in the spleen, liver and oral cavity. Systemic inflammation was also observed, predominantly affecting necrotic organs. The estimates reported here can be used to model ranaviral disease and quantify and manage at-risk populations.

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25

Wirth, Wytamma, and Ellen Ariel. "Temperature-dependent infection of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with a ranavirus isolate (Bohle iridovirus, Iridoviridae)." FACETS 5, no. 1 (January 1, 2020): 821–30. http://dx.doi.org/10.1139/facets-2020-0012.

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Fish, amphibians, and reptiles exhibit temperature-dependent ranaviral disease. We performed an experimental infection at four different environmental temperatures (16, 22, 28, and 34 °C) to investigate the effect of temperature on ranaviral infection in Krefft’s turtle ( Emydura macquarii krefftii). Infection rates and viral loads were determined by quantitative polymerase chain reaction to detect ranaviral DNA in liver samples at 21 d postexposure. The rate of infection differed across the temperature treatment groups. Infection rates were 44%, 90%, 60%, and 10% for the 16, 22, 28, and 34 °C temperature groups, respectively. Highest viral load was observed in the 28 °C temperature group, and there was a statistically significant difference in viral load between the 16 and 28 °C temperature groups ( p = 0.027). Based on the results of this study, the temperature of maximal infection rate for ranaviral infection in Krefft’s river turtles is estimated to be 23.2 °C (SD = 4.5). The findings of this study can inform management decisions in terms of disease control and treatment and form a platform for modelling disease outbreaks.

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McGlashan, Jessica K., Michael B. Thompson, James U. Van Dyke, and Ricky-John Spencer. "Thyroid Hormones Reduce Incubation Period without Developmental or Metabolic Costs in Murray River Short-Necked Turtles (Emydura macquarii)." Physiological and Biochemical Zoology 90, no. 1 (January 2017): 34–46. http://dx.doi.org/10.1086/689744.

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Alibardi, Lorenzo. "Cell proliferation, adhesion, and differentiation of keratinocytes in the developing beak and egg-tooth of the turtle Emydura macquarii." Protoplasma 257, no. 5 (June 13, 2020): 1433–45. http://dx.doi.org/10.1007/s00709-020-01518-9.

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Santori, Claudia, Ricky-John Spencer, James U. Van Dyke, and Michael B. Thompson. "Road mortality of the eastern long-necked turtle (Chelodina longicollis) along the Murray River, Australia: an assessment using citizen science." Australian Journal of Zoology 66, no. 1 (2018): 41. http://dx.doi.org/10.1071/zo17065.

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Turtles face a variety of threats (e.g. habitat destruction, introduced predators) that are pushing many species towards extinction. Vehicle collisions are one of the main causes of mortality of adult freshwater turtles. To conceptualise the level of threat that roads pose to Australians turtles, we analysed data gathered through the citizen science project TurtleSAT along the Murray River. We recorded 124 occurrences of turtle road mortality, which included all three local species (Chelodina expansa, Chelodina longicollis, and Emydura macquarii). Chelodina longicollis was the most commonly reported species killed on roads. We found that rain and time of year affect the likelihood of C. longicollis being killed on roads: increased turtle mortality is associated with rain events and is highest during the month of November, which coincides with their nesting season. Chelodina longicollis was most likely to be killed on the Hume Highway and roads around major urban centres; therefore, we recommend that governing bodies focus management practices and increase awareness at these locations. The degree of road mortality that we detected in this study requires mitigation, as it may contribute to the decline of C. longicollis along the Murray River.

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Platt, Thomas R., and Sylvie Pichelin. "Uterotrema australispinosa n. gen., n. sp. (Digenea: Spirorchidae), a Parasite of a Freshwater Turtle Emydura macquarii from Southern Queensland, Australia." Journal of Parasitology 80, no. 6 (December 1994): 1008. http://dx.doi.org/10.2307/3283450.

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Priest, Toni E., and Craig E. Franklin. "Effect of Water Temperature and Oxygen Levels on the Diving Behavior of Two Freshwater Turtles: Rheodytes leukops and Emydura macquarii." Journal of Herpetology 36, no. 4 (December 2002): 555–61. http://dx.doi.org/10.1670/0022-1511(2002)036[0555:eowtao]2.0.co;2.

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Ferguson, M. A., T. H. Cribb, and L. R. Smales. "Life-cycle and biology of Sychnocotyle kholo n. g., n. sp. (Trematoda: Aspidogastrea) in Emydura macquarii (Pleurodira: Chelidae) from southern Queensland, Australia." Systematic Parasitology 43, no. 1 (May 1999): 41–48. http://dx.doi.org/10.1023/a:1006179916764.

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Todd, Erica V., David Blair, and Dean R. Jerry. "Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle, Emydura macquarii krefftii , from Australia." Ecology and Evolution 4, no. 5 (February 11, 2014): 606–22. http://dx.doi.org/10.1002/ece3.968.

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Bower, Deborah S., Clare E. Death, and Arthur Georges. "Ecological and physiological impacts of salinisation on freshwater turtles of the lower Murray River." Wildlife Research 39, no. 8 (2012): 705. http://dx.doi.org/10.1071/wr11214.

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Context The increasing intensity and extent of anthropogenically mediated salinisation in freshwater systems has the potential to affect freshwater species through physiological and ecological processes. Determining responses to salinisation is critical to predicting impacts on fauna. Aims We aimed to quantify the response of wild-caught turtles from freshwater lakes that had become saline in the lower Murray River catchment. Methods Plasma electrolytes of all three species of freshwater turtle from South Australia were compared among two freshwater sites (Horseshoe Lagoon and Swan Reach), a brackish lake (Lake Bonney) and a saline lake (Lake Alexandrina). Key results Chelodina longicollis, C. expansa and Emydura macquarii from a brackish lake had higher concentrations of plasma sodium and chloride than those from freshwater habitats. However, osmolytes known to increase under severe osmotic stress (urea and uric acid) were not elevated in brackish sites. Turtles from the highly saline lake were colonised by an invasive marine worm which encased the carapace and inhibited limb movement. Conclusions Freshwater turtles in brackish backwaters had little response to salinity, whereas the C. longicollis in a saline lake had a significant physiological response caused by salt and further impacts from colonisation of marine worms. Implications Short periods of high salinity are unlikely to adversely affect freshwater turtles. However, secondary ecological processes, such as immobilisation from a marine worm may cause unexpected impacts on freshwater fauna.

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McKnight, Donald T., Kyall R. Zenger, Ross A. Alford, and Roger Huerlimann. "Microbiome diversity and composition varies across body areas in a freshwater turtle." Microbiology 166, no. 5 (May 1, 2020): 440–52. http://dx.doi.org/10.1099/mic.0.000904.

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There is increasing recognition that microbiomes are important for host health and ecology, and understanding host microbiomes is important for planning appropriate conservation strategies. However, microbiome data are lacking for many taxa, including turtles. To further our understanding of the interactions between aquatic microbiomes and their hosts, we used next generation sequencing technology to examine the microbiomes of the Krefft’s river turtle (Emydura macquarii krefftii). We examined the microbiomes of the buccal (oral) cavity, skin on the head, parts of the shell with macroalgae and parts of the shell without macroalgae. Bacteria in the phyla Proteobacteria and Bacteroidetes were the most common in most samples (particularly buccal samples), but Cyanobacteria , Deinococcus-thermus and Chloroflexi were also common (particularly in external microbiomes). We found significant differences in community composition among each body area, as well as significant differences among individuals. The buccal cavity had lower bacterial richness and evenness than any of the external microbiomes, and it had many amplicon sequence variants (ASVs) with a low relative abundance compared to other body areas. Nevertheless, the buccal cavity also had the most unique ASVs. Parts of the shell with and without algae also had different microbiomes, with particularly obvious differences in the relative abundances of the families Methylomonaceae, Saprospiraceae and Nostocaceae . This study provides novel, baseline information about the external microbiomes of turtles and is a first step in understanding their ecological roles.

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Georges, Arthur, Fiorenzo Guarino, and Melissa White. "Sex-ratio bias across populations of a freshwater turtle (Testudines : Chelidae) with genotypic sex determination." Wildlife Research 33, no. 6 (2006): 475. http://dx.doi.org/10.1071/wr06047.

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Adult sex ratios vary considerably among populations of single species and across years, but the best evidence is drawn from species with temperature-dependent sex determination. It is difficult to disentangle the effects of bias in the production of the sexes and the effects of a range of other factors contributing to biased adult sex ratios. In this paper, we survey sex ratios across populations of a species constrained to produce 1 : 1 offspring sex ratios by genotypic sex determination and show considerable variation in adult sex ratios. Raw adult sex ratios of Emydura macquarii emmottii were significantly biased in nine of the 11 populations examined. In all but one case, the bias was strongly in favour of males. Part of the bias in sex ratio was attributed to the differing ages of maturity of males and females – males mature younger than females – which leads to more male cohorts being included in the calculations of sex ratio than female cohorts. However, correcting for this effect brought the sex ratios of the populations closer to parity, as expected, and accounted for an overall 62% of the male surplus evident in the adult sex ratio. Even so, it was insufficient to explain the strong male bias (1.2–2.9) in five of the nine populations initially showing such bias. This provides support to those who advise caution in interpreting adult sex ratio data for freshwater turtles in the context of demography, sex allocation or evaluating the impact of climate change.

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Todd, Erica, David Blair, Mark Hamann, and Dean Jerry. "Twenty-nine microsatellite markers for two Australian freshwater turtles, Elseya albagula and Emydura macquarii krefftii: development from 454-sequence data and utility in related taxa." Conservation Genetics Resources 3, no. 3 (January 5, 2011): 449–56. http://dx.doi.org/10.1007/s12686-010-9377-0.

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Thompson, Michael B., Brian K. Speake, Kylie J. Russell, Ruth J. McCartney, and Peter F. Surai. "Changes in fatty acid profiles and in protein, ion and energy contents of eggs of the Murray short-necked turtle, Emydura macquarii (Chelonia, Pleurodira) during development." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 122, no. 1 (January 1999): 75–84. http://dx.doi.org/10.1016/s1095-6433(98)10150-2.

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Martinez, Pedro Alonzo, Tariq Ezaz, Nicole Valenzuela, Arthur Georges, and Jennifer A. Marshall Graves. "An XX/XY heteromorphic sex chromosome system in the Australian chelid turtle Emydura macquarii: A new piece in the puzzle of sex chromosome evolution in turtles." Chromosome Research 16, no. 6 (August 9, 2008): 815–25. http://dx.doi.org/10.1007/s10577-008-1228-4.

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Platt, Thomas R., and Daniel R. Brooks. "Description of Buckarootrema goodmani n. g., n. sp. (Digenea: Pronocephalidae), a Parasite of the Freshwater Turtle Emydura macquarii (Gray, 1830) (Pleurodira: Chelidae) from Queensland, Australia, and a Phylogenetic Analysis of the Genera of the Pronocephalidae Looss, 1902." Journal of Parasitology 87, no. 5 (October 2001): 1115. http://dx.doi.org/10.2307/3285243.

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Santori, Claudia, Ricky-John Spencer, Michael B. Thompson, Camilla M. Whittington, and James U. Van Dyke. "Hatchling short-necked turtles (Emydura macquarii) select aquatic vegetation habitats, but not after one month in captivity." Aquatic Ecology, January 2, 2021. http://dx.doi.org/10.1007/s10452-020-09813-6.

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Wirth, Wytamma, Elizabeth Elliott, Donna Rudd, Linda Hayes, Alicia Maclaine, Narges Mashkour, Shamim Ahasan, Jakob Gorm Dahl, Kezia Drane, and Ellen Ariel. "Cutaneous Lesions in Freshwater Turtles (Emydura macquarii krefftii and Myuchelys latisternum) in a Rainforest Creek in North Queensland, Australia." Frontiers in Veterinary Science 7 (January 31, 2020). http://dx.doi.org/10.3389/fvets.2020.00033.

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