Current conservation status of Australian freshwater turtles

Dyke, James U. Van; Ferronato, Bruno de Oliveira; Spencer, Ricky John

doi:10.1071/zov66n1_in

Cited by 33 publications

(26 citation statements)

References 19 publications

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“…Our results have implications for turtle and freshwater conservation. Emydura macquarii and C. longicollis are in decline across their range, while C. expansa is listed as endangered [9,46,47]. Much of the Murray-Darling river system is degraded [35], and many wetlands have been lost due to flow regulation by dams [21], or drought [24].…”

Section: Discussionmentioning

confidence: 99%

Prey-switching does not protect a generalist turtle from bioenergetic consequences when its preferred food is scarce

et al. 2020

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Background: Optimal foraging theory explains how animals make foraging decisions based on the availability, nutritional content, and handling times of different food types. Generalists solve this problem by consuming a variety of food types, and alter their diets with relative ease. Specialists eat few food types, and may starve if those food types are not available. We integrated stable isotope analyses with previously-published stomach contents and environmental data to investigate how the foraging ecologies of three sympatric freshwater turtle species vary across four wetlands that differ in turbidity and primary producer abundance. Results:We found that the generalist Emydura macquarii consumes a varied diet (but mostly filamentous green algae) when primary producers are available and water is clear, but switches to a more carnivorous diet when the water is turbid and primary producers are scarce, following the predictions of optimal foraging theory. In contrast, two more-specialized carnivorous species, Chelodina expansa and Chelodina longicollis, do not differ in diet across wetlands, and interspecific competition may increase where E. macquarii is carnivorous. When forced to be more carnivorous, E. macquarii exhibits higher rates of empty stomachs, and female turtles have reduced body condition, but neither Chelodina species are affected. Conclusions:Our results provide support for optimal foraging theory, but also show that the ability to change diet does not protect the generalist from experiencing lower foraging success when its preferred food is rare, with direct consequences for their energy budgets. Our results have conservation implications because wetlands in the Murray-Darling river system are increasingly turbid and have low macrophyte abundance, and all three species are declining.

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Section: Discussionmentioning

confidence: 99%

Prey-switching does not protect a generalist turtle from bioenergetic consequences when its preferred food is scarce

et al. 2020

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“…In Australia, and particularly in its largest river system, the Murray–Darling Basin, freshwater turtles have greatly declined (Chessman, 2011; Van Dyke et al., 2018, 2019). TurtleSAT (http://www.turtlesat.org.au) is a citizen science project based on a smartphone and web‐based app.…”

Section: Methodsmentioning

confidence: 99%

Changes in participant behaviour and attitudes are associated with knowledge and skills gained by using a turtle conservation citizen science app

et al. 2021

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Citizen science has become a popular way to collect biodiversity data and engage the wider public in scientific research. It has the potential to improve the knowledge and skills of participants, and positively change their behaviour and attitude towards the environment. Citizen science outcomes are particularly valuable for wildlife conservation, as they could help alleviate human impacts on the environment. We used an online questionnaire to investigate the consequences of participating in an Australian turtle mapping app, TurtleSAT, on skills and knowledge gain, and test for any association between these gains and behavioural or attitudinal changes reported by the participants. One hundred and forty‐eight citizen scientists completed our questionnaire, mostly from the states of New South Wales and Victoria. TurtleSAT was the third most common source of correct answers about turtle ecology and conservation, after a talk about turtles and personal observations/research. Citizen scientists who participated more often were more knowledgeable about turtles than infrequent users. Self‐reported gains in knowledge and skills were positively linked to attitudinal and behavioural changes, such as being more aware of turtles on roads. However, behaviour and attitude changes were not related to participation rate. Respondents also reported that after learning about the current decline in turtle populations, they adopted several turtle‐friendly practices, such as habitat restoration or moving turtles out of harm's way, underlining the importance of increasing people's awareness on species declines. The reported changes in attitudes and behaviours are likely to positively impact the conservation of Australian freshwater turtles. Engagement with citizen science projects like TurtleSAT may result in participants being more interested in the natural world, by learning more about it and being more exposed to it, and therefore contributing more actively to its protection. A free Plain Language Summary can be found within the Supporting Information of this article.

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“…Its introduction beyond its native range may pose a particular hazard to Australian native turtles of the genus Myuchelys, variously known as helmeted, saw-shelled, and snapping turtles. Three of the four recognized species of Myuchelys are either confined or nearly confined to the southern state of New South Wales (NSW), where they occupy highly restricted and disjunct geographical ranges and are officially listed as either Endangered or Critically Endangered (Van Dyke, Ferronato & Spencer, 2018). The western saw-shelled turtle, Myuchelys bellii, comprises a small, isolated population on a headwater stream just north of the NSW border in Queensland (Fielder, Limpus & Limpus, 2014) and four separate populations in inland headwater river systems of northern NSW (Chessman, 2015).…”

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A creeping threat? Introduced Macquarie turtles and the future of endangered helmeted turtles in southern Australia

Chessman

2021

Aquatic Conservation

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1. The introduction of freshwater turtle species outside their natural ranges may threaten native turtles through competition for resources such as food or basking sites, hybridization, and transmission of diseases or parasites.2. The three southern species of Australian helmeted turtles (Myuchelys bellii, Myuchelys georgesi, and Myuchelys purvisi) had no or minimal distributional overlap with the widespread Australian Macquarie turtle, Emydura macquarii, until about 30 years ago. Since that time, E. macquarii has been introduced within the ranges of all three Myuchelys spp., possibly through the release or escape of pet turtles.3. The occurrence, catch per unit effort, and population structure of E. macquarii were compared among four introduced populations within the ranges of southern Myuchelys spp. and four native populations. The aim was to provide insight into the status of the introduced populations, their likely current impact on Myuchelys spp., and their potential for future increase.4. Data analysis suggested that the introduced populations of E. macquarii are at varying stages of the invasion process and not yet severe threats to Myuchelys spp. However, continuing proliferation of introduced E. macquarii is likely, potentially placing intensifying pressure on Myuchelys populations in the long term.5. Research is needed on interactions of E. macquarii and Myuchelys spp. and their comparative competitive abilities in order to inform the difficult policy decision of whether invasive E. macquarii should be removed or controlled.

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Current conservation status of Australian freshwater turtles

Cited by 33 publications

References 19 publications

Prey-switching does not protect a generalist turtle from bioenergetic consequences when its preferred food is scarce

Prey-switching does not protect a generalist turtle from bioenergetic consequences when its preferred food is scarce

Changes in participant behaviour and attitudes are associated with knowledge and skills gained by using a turtle conservation citizen science app

A creeping threat? Introduced Macquarie turtles and the future of endangered helmeted turtles in southern Australia

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