Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

Santori, Claudia; Spencer, Ricky‐John; Thompson, Michael B.; Whittington, Camilla M.; Burd, Thomas H.; Currie, Samantha B.; Finter, Timothy J.; Dyke, James U. Van

doi:10.1038/s41598-020-71544-3

Cited by 20 publications

(16 citation statements)

References 36 publications

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“…Freshwater turtles are an important part of the trophic structure and biodiversity of rivers (Lovich et al, 2018), are highly dependent on flow and flooding regimes (Chessman, 1988; Howard et al, 2016), and are important regulators of water quality (Santori et al, 2020). Globally, however, our understanding of these relationships is poor relative to many other organisms, and Australian freshwater turtles are no exception.…”

Section: Discussionmentioning

confidence: 99%

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Abundance and nutritional status of freshwater turtles to guide delivery of environmental flows in the Murray‐Darling Basin, south‐eastern Australia

Francis

Brandis

Chessman

2022

Aquatic Conservation

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Almost half of Australian freshwater turtle species are formally listed as threatened, but little is known about the effects of water management and other factors on the abundance and health of freshwater turtles in arid and semi‐arid regions. This study investigated how river flows (including the controlled release of water from an upstream storage facility, or ‘environmental flow’) and water quality might affect the abundance and nutritional status of three freshwater turtle species in three dryland rivers of the Murray–Darling basin in south‐eastern Australia. No response in abundance or nutritional status of the broad‐shelled turtle, Chelodina expansa, the eastern long‐necked turtle, Chelodina longicollis, and the Macquarie turtle, Emydura macquarii, was detected in relation to river flows, possibly because of the small magnitude of the environmental flow. However, for C. expansa, the catch per unit effort (CPUE) was negatively related to increasing macrophyte cover, electrical conductivity (EC, an indicator of salinity), and turbidity. CPUE for C. longicollis was positively related to macrophyte cover and EC, and for E. macquarii it was positively related to macrophyte cover. Haematological measurements suggested that the turtles had healthy nutritional status. Body condition and blood glucose and protein were related significantly to EC, whereas haematological measurements varied significantly among species and between spring and summer. The main conclusion is that water management measures to help the conservation of these turtles should include sufficient environmental flow to produce overbank flooding, thereby creating and maintaining a wide range of habitat suitable for the differing needs of the individual species.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Abundance and nutritional status of freshwater turtles to guide delivery of environmental flows in the Murray‐Darling Basin, south‐eastern Australia

Francis

Brandis

Chessman

2022

Aquatic Conservation

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“…For freshwater turtles in Australia, predicted declines in abundance are now being confirmed quantitatively (Chessman 2011;Van Dyke et al 2019). Declines in ecosystem condition and resilience coupled with increased recognition of the ecosystem services provided by turtles; are driving efforts to improve resource management for this guild of freshwater species (Santori et al 2020;Sinha 1995). Human impacts on freshwater turtles however, affect all life-stages, and complexities within their own life-histories means multiple management strategies are required to meet this challenge (Spencer et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Adaptive Management to Reduce Nest Inundation of a Critically Endangered Freshwater Turtle: Confirming the Win-win

Espinoza

Marshall

Limpus

et al. 2022

Environmental Management

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Inundation of Australian freshwater turtle nests has been identified as a threat to recruitment and long-term viability of species such as the critically endangered white-throated snapping turtle (Elseya albagula). Water level fluctuations within water storage infrastructure can inundate significant proportions of E. albagula nests in any year. Using an ecological risk assessment framework, operating rules for a water storage in the Burnett River (South East Queensland, Australia) were implemented to support nesting of E. albagula. Turtles were encouraged to nest at higher elevations on riverbanks by maintaining higher water levels in the impoundment during the nesting season, followed by lowering of water levels during the incubation period to minimise rates of nest inundation from riverine inflows. To verify the success of the new rules, a three-year confirmation monitoring program of nest heights and water levels was undertaken. Results of confirmation monitoring showed that 3% (2018), 11% (2019) and 0% (2020) of E. albagula nests were inundated under the new operating rules, compared to previously estimated nest inundation rates of >20% in ~24% of years of a 118-year simulation period (1890–2008) under previous storage operating rules. Emergency releases from an upstream storage in 2019 and 2020 for dam safety did not affect the success of the rule, demonstrating its resilience to natural and artificial flow regimes. This study demonstrates the importance of confirmation monitoring in verifying the efficacy of targeted changes to water management, and highlights potential application across other water storage infrastructure with threatened freshwater turtle populations requiring adaptive management.

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“…Multiple factors are driving chelonian population declines including climate change, habitat loss, illegal trade for meat and the pet industry, impacts of invasive species and synergistic interactions among these threats. Turtles are long lived and reach high densities, and their decline and loss can be especially damaging in freshwater ecosystems where they provide ecosystem functions such as nutrient cycling, soil bioturbation and water quality regulation (Lovich et al, 2018; Santori et al, 2020). Invasive species can adversely affect native turtle populations by competition, predation and habitat modification, and by acting as disease vectors (e.g.…”

Section: Introductionmentioning

confidence: 99%

Geospatial assessment of freshwater invasive species to inform turtle conservation and management

Araya‐Donoso

Orton

Ryan

et al. 2022

Aquatic Conservation

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1. Identifying the ecological factors that determine the spread of invasive species is key to adequately managing endangered species in freshwater ecosystems.Invasive species are a main threat to turtles, which are targets of major conservation efforts worldwide.2. In freshwater ecosystems of the south-western USA, invasive bullfrog (Lithobates catesbeianus) and crayfish species (Faxonius virilis and Procambarus clarkii) represent a major risk to the desert mud turtle (Kinosternon sonoriense sonoriense), state-listed as a Species of Greatest Conservation Need in Arizona. As a species in the early stages of population decline, the desert mud turtle is a top candidate for the development of management plans to decrease extinction risk.3. An invasion risk assessment tool was built from available occurrence data for K. s. sonoriense and the invasive bullfrog and crayfish species in Arizona using 5,886 de-duplicated records from public databases and reports from the Arizona Game and Fish Department. The occurrence density of K. s. sonoriense was calculated state-wide to define populations in which the level of invasion by bullfrog and crayfish was assessed. The environmental factors associated with the abundance of invasive species in populations of K. s. sonoriense were then analysed. 4. A higher prevalence of crayfish and bullfrog was detected in turtle populations located in perennial streams. Invasive abundance was significantly higher in turtle populations at higher elevation and closer to the main river trunk for both invasive taxa. Higher bullfrog abundance was detected near human settlements, whereas crayfish were more abundant further from human settlements. 5. These results will inform which populations of K. s. sonoriense require intensive surveying and control of invasive species to maintain the health of native desert mud turtle populations. This study provides valuable information regarding the environmental conditions associated with the abundance of invasive species threatening turtle populations, helping to develop science-based management of freshwater ecosystems.

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Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

Cited by 20 publications

References 36 publications

Abundance and nutritional status of freshwater turtles to guide delivery of environmental flows in the Murray‐Darling Basin, south‐eastern Australia

Abundance and nutritional status of freshwater turtles to guide delivery of environmental flows in the Murray‐Darling Basin, south‐eastern Australia

Adaptive Management to Reduce Nest Inundation of a Critically Endangered Freshwater Turtle: Confirming the Win-win

Geospatial assessment of freshwater invasive species to inform turtle conservation and management

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