Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata

Chelidae)

Deborah S. Bower, David M. Scheltinga, Simon Clulow, John Clulow, Craig E. Franklin, Arthur Georges

    Research output: Contribution to journalArticle

    11 Citations (Scopus)

    Abstract

    Freshwater biota experience physiological challenges in regions affected by salinization, but often the effects on particular species are poorly understood. Freshwater turtles are of particular concern as they appear to have limited ability to cope with environmental conditions that are hyperosmotic to their body fluids. Here, we determined the physiological responses of two Australian freshwater chelid turtles, Emydura macquarii and Chelodina expansa, exposed to freshwater (0%) and brackish water (15%, representing a hyperosmotic environment). Brackish water is common in the Murray-Darling River Basin within the natural range of these species in Australia during periods of drought, yet it is unknown how well these species tolerate saline conditions. We hypothesized that these turtles would be unable to maintain homeostasis in the 15% water treatment and would suffer osmotic loss of water, increased ionic concentrations and a decrease in body mass. Results revealed that these turtles had elevated plasma concentrations of sodium, chloride, urea and uric acid in the plasma. Plasma ionic concentrations increased proportionally more in E. macquarii than in C. expansa. Individuals of both species reduced feeding in 15% water, indicating that behaviour may provide an additional means for freshwater turtles to limit ion/solute influx when in hyperosmotic environments. This osmoregulatory behaviour may allow for persistence of turtles in regions affected by salinization; however, growth rates and body condition may be affected in the long term. Although we demonstrate that these turtles have mechanisms to survive temporarily in saline waters, it is likely that sustained salinization of waterways will exceed their short- to medium-term capacity to survive increased salt levels, making salinization a potentially key threatening process for these freshwater reptiles.

    Original languageEnglish
    Article numbercow042
    JournalConservation Physiology
    Volume4
    Issue number1
    DOIs
    Publication statusPublished - 2016

    Fingerprint

    salinity tolerance
    Turtles
    Salinity
    Fresh Water
    turtle
    salinization
    brackish water
    plasma
    body fluid
    Biota
    Aptitude
    Reptiles
    Water
    Water Purification
    Droughts
    homeostasis
    Body Fluids
    body condition
    physiological response
    sodium chloride

    Cite this

    Bower, Deborah S. ; Scheltinga, David M. ; Clulow, Simon ; Clulow, John ; Franklin, Craig E. ; Georges, Arthur. / Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata : Chelidae). In: Conservation Physiology. 2016 ; Vol. 4, No. 1.
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    title = "Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata: Chelidae)",
    abstract = "Freshwater biota experience physiological challenges in regions affected by salinization, but often the effects on particular species are poorly understood. Freshwater turtles are of particular concern as they appear to have limited ability to cope with environmental conditions that are hyperosmotic to their body fluids. Here, we determined the physiological responses of two Australian freshwater chelid turtles, Emydura macquarii and Chelodina expansa, exposed to freshwater (0{\%}) and brackish water (15{\%}, representing a hyperosmotic environment). Brackish water is common in the Murray-Darling River Basin within the natural range of these species in Australia during periods of drought, yet it is unknown how well these species tolerate saline conditions. We hypothesized that these turtles would be unable to maintain homeostasis in the 15{\%} water treatment and would suffer osmotic loss of water, increased ionic concentrations and a decrease in body mass. Results revealed that these turtles had elevated plasma concentrations of sodium, chloride, urea and uric acid in the plasma. Plasma ionic concentrations increased proportionally more in E. macquarii than in C. expansa. Individuals of both species reduced feeding in 15{\%} water, indicating that behaviour may provide an additional means for freshwater turtles to limit ion/solute influx when in hyperosmotic environments. This osmoregulatory behaviour may allow for persistence of turtles in regions affected by salinization; however, growth rates and body condition may be affected in the long term. Although we demonstrate that these turtles have mechanisms to survive temporarily in saline waters, it is likely that sustained salinization of waterways will exceed their short- to medium-term capacity to survive increased salt levels, making salinization a potentially key threatening process for these freshwater reptiles.",
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    Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata : Chelidae). / Bower, Deborah S.; Scheltinga, David M.; Clulow, Simon; Clulow, John; Franklin, Craig E.; Georges, Arthur.

    In: Conservation Physiology, Vol. 4, No. 1, cow042, 2016.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata

    T2 - Chelidae)

    AU - Bower, Deborah S.

    AU - Scheltinga, David M.

    AU - Clulow, Simon

    AU - Clulow, John

    AU - Franklin, Craig E.

    AU - Georges, Arthur

    PY - 2016

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    AB - Freshwater biota experience physiological challenges in regions affected by salinization, but often the effects on particular species are poorly understood. Freshwater turtles are of particular concern as they appear to have limited ability to cope with environmental conditions that are hyperosmotic to their body fluids. Here, we determined the physiological responses of two Australian freshwater chelid turtles, Emydura macquarii and Chelodina expansa, exposed to freshwater (0%) and brackish water (15%, representing a hyperosmotic environment). Brackish water is common in the Murray-Darling River Basin within the natural range of these species in Australia during periods of drought, yet it is unknown how well these species tolerate saline conditions. We hypothesized that these turtles would be unable to maintain homeostasis in the 15% water treatment and would suffer osmotic loss of water, increased ionic concentrations and a decrease in body mass. Results revealed that these turtles had elevated plasma concentrations of sodium, chloride, urea and uric acid in the plasma. Plasma ionic concentrations increased proportionally more in E. macquarii than in C. expansa. Individuals of both species reduced feeding in 15% water, indicating that behaviour may provide an additional means for freshwater turtles to limit ion/solute influx when in hyperosmotic environments. This osmoregulatory behaviour may allow for persistence of turtles in regions affected by salinization; however, growth rates and body condition may be affected in the long term. Although we demonstrate that these turtles have mechanisms to survive temporarily in saline waters, it is likely that sustained salinization of waterways will exceed their short- to medium-term capacity to survive increased salt levels, making salinization a potentially key threatening process for these freshwater reptiles.

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    KW - Salt

    KW - Sodium

    KW - Tortoise

    KW - Urea

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