Diving behaviour, aquatic respiration and blood respiratory properties: a comparison of hatchling and juvenile Australian turtles

Clark, Natalie J.; Gordos, Matthew A.; Franklin, Craig E.

doi:10.1111/j.1469-7998.2008.00454.x

Cited by 19 publications

(15 citation statements)

References 32 publications

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“…At 24°C the c warm-acclimated snakes also had a longer modal dive duration and were again capable of dives 15 min longer than the d cool-acclimated snakes In comparison to terrestrial snakes and some sea snakes, Acrochordids have very low SMR (Heatwole and Seymour 1975;Glass and Johansen 1976;Seymour 1982) and the metabolic rates of A. arafurae in the present study were consistent with those published for other Acrochordid species (Heatwole and Seymour 1975;Glass and Johansen 1976). Like most ectotherms (Buikema and Armitage 1969;Tocher and Davison 1996;Tullis and Baillie 2005;Clark et al 2008a), the standard metabolic rate of A. arafurae in this study was acutely thermally sensitive: metabolic rates were higher at 32°C than at 24°C regardless of acclimation group. However, the Q 10 for metabolic rate was higher in cool-acclimated snakes (2.9) than in warmacclimated snakes (2.2), suggesting that acclimation to high temperatures reduced the thermal sensitivity of metabolic rate in A. arafurae.…”

Section: Number Of Divessupporting

confidence: 93%

“…Since the rate of oxygen consumption (metabolic rate) in ectotherms is temperature dependent (Ege and Krogh 1914;Pörtner et al 2006), exposure to high temperatures results in an increase in metabolic rate, which for air-breathing aquatic vertebrates translates into a reduction in dive duration. This inverse relationship between water temperature and dive duration has been demonstrated for a number of diving ectotherms (Heatwole 1975(Heatwole , 1977Priest and Franklin 2002;Clark et al 2008a). Higher temperatures are also expected to increase the risk of predation as animals must surface more frequently to sustain a higher aerobic metabolic rate .…”

Section: Introductionmentioning

confidence: 86%

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Benefits of thermal acclimation in a tropical aquatic ectotherm, the Arafura filesnake, Acrochordus arafurae

2012

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The presumption that organisms benefit from thermal acclimation has been widely debated in the literature. The ability to thermally acclimate to offset temperature effects on physiological function is prevalent in ectotherms that are unable to thermoregulate year-round to maintain performance. In this study we examined the physiological and behavioural consequences of long-term exposure to different water temperatures in the aquatic snake Acrochordus arafurae. We hypothesised that long dives would benefit this species by reducing the likelihood of avian predation. To achieve longer dives at high temperatures, we predicted that thermal acclimation of A. arafurae would reduce metabolic rate and increase use of aquatic respiration. Acrochordus arafurae were held at 24 or 32°C for 3 months before dive duration and physiological factors were assessed (at both 24 and 32°C). Although filesnakes demonstrated thermal acclimation of metabolic rate, use of aquatic respiration was thermally independent and did not acclimate. Mean dive duration did not differ between the acclimation groups at either temperature; however, warm-acclimated animals increased maximum and modal dive duration, demonstrating a longer dive duration capacity. Our study established that A. arafurae is capable of thermal acclimation and this confers a benefit to the diving abilities of this snake.

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Section: Number Of Divessupporting

confidence: 93%

Section: Introductionmentioning

confidence: 86%

Benefits of thermal acclimation in a tropical aquatic ectotherm, the Arafura filesnake, Acrochordus arafurae

2012

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“…This percentage is much lower than that reported in previous studies of Elu. macrurus where aquatic respiration supported ∼25% of the total oxygen consumption (Clark et al , 2008). At 30 mmHg, respiratory partitioning shifted and aquatic respiration decreased significantly to the point where the turtles were actually losing oxygen to the surrounding water.…”

Section: Discussionmentioning

confidence: 99%

“…At the beginning of the experimental trial, the air stones were switched off and the respirometers were then sealed and initial samples of water (5 mL) and air (20 mL) were taken from the sampling ports via a syringe to establish baseline levels of O 2 . After an experimental period of 2 h, the final aquatic and aerial gas samples were taken and analysed for oxygen content (see Clark, Gordos & Franklin, 2008 for a complete description of the methods). To account for the allometric scaling of metabolic rate both aerial VO 2 and aquatic VO 2 were scaled to 0.75 and standardized to an average sized turtle (12 g).…”

Section: Methodsmentioning

confidence: 99%

“…The needle tip and plunger of the syringe were dusted with sodium heparin to prevent coagulation. The blood sample was then transferred into a 0.5 mL Eppendorf (North Ryde, Australia) tube and samples collected for analysis of haemoglobin concentration (Hb), haematocrit (Hct) and the determination of P 50 , which was defined as the PO 2 at which 50% of the haemoglobin was saturated (see Clark et al , 2008 for a complete description of the methods).…”

Section: Methodsmentioning

confidence: 99%

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Implications of river damming: the influence of aquatic hypoxia on the diving physiology and behaviour of the endangered Mary River turtle

Clark

Gordos

Franklin

2009

Animal Conservation

Self Cite

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River impoundments are characterized by low oxygen levels as a result of reduced water velocity and increased water depth. Bimodally respiring turtle species are likely to be highly sensitive to changes in aquatic PO 2 with decreases in oxygen levels impacting upon their diving ability. The acute and long-term effects of aquatic hypoxia on dive duration, oxygen consumption and blood respiratory properties were examined in hatchlings of the endangered Mary River turtle Elusor macrurus. It was hypothesized that acute exposure to aquatic hypoxia would cause a decrease in dive duration as a consequence of a decrease in reliance on aquatic respiration. With long-term exposure to hypoxia, we predicted that Elu. macrurus would have the capacity to compensate for the acute effect of hypoxia and that dive duration would increase due to an increase in aquatic respiration, haemoglobin concentration and oxygen affinity (P 50 ). When exposed to hypoxic conditions, aquatic respiration in Elu. macrurus was substantially reduced resulting in a 51% decrease in dive duration. Contrary to our predictions, Elu. macrurus hatchlings did not acclimate, and long-term exposure to hypoxic conditions caused Elu. macrurus to lose significantly more oxygen to the hypoxic water than the normoxic acclimated turtles. The exacerbation of long-term hypoxia on the respiratory physiology and diving ecology of Elu. macrurus raises concerns about the impacts of long-term environmental change as a result of habitat alteration on the survival of freshwater turtle populations.

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The Fish in the Turtle: On the Functionality of the Oropharynx in the Common Musk Turtle Sternotherus odoratus (Chelonia, Kinosternidae) Concerning Feeding and Underwater Respiration

Heiss

Natchev

Beisser

et al. 2010

The Anatomical Record

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In tetrapods, the oropharyngeal cavity and its anatomical structures are mainly, but not exclusively, responsible for the uptake and intraoral transport of food. In this study, we provide structural evidence for a second function of the oropharynx in the North American common musk turtle, Sternotherus odoratus, Kinosternidae: aquatic gas exchange. Using high-speed video, we demonstrate that S. odoratus can grasp food on land by its jaws, but is afterward incapable of lingual based intraoral transport; food is always lost during such an attempt. Scanning electron microscopy and light microscopy reveal that the reason for this is a poorly developed tongue. Although small, the tongue bears a variety of lobe-like papillae, which might be misinterpreted as an adaptation for terrestrial food uptake. Similar papillae also cover most of the oropharynx. They are highly vascularized as shown by light microscopy and may play an important role in aquatic gas exchange. The vascularization of the oropharyngeal papillae in S. odoratus is then compared with that in Emys orbicularis, an aquatic emydid with similar ecology but lacking the ability of underwater respiration. Oropharyngeal papillae responsible for aquatic respiration are also found in soft-shelled turtles (Trionychidae), the putative sister group of the kinosternids. This trait could therefore represent a shared, ancestral character of both groups involving advantages in the aquatic environment they inhabit.

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Diving behaviour, aquatic respiration and blood respiratory properties: a comparison of hatchling and juvenile Australian turtles

Cited by 19 publications

References 32 publications

Benefits of thermal acclimation in a tropical aquatic ectotherm, the Arafura filesnake, Acrochordus arafurae

Benefits of thermal acclimation in a tropical aquatic ectotherm, the Arafura filesnake, Acrochordus arafurae

Implications of river damming: the influence of aquatic hypoxia on the diving physiology and behaviour of the endangered Mary River turtle

The Fish in the Turtle: On the Functionality of the Oropharynx in the Common Musk Turtle Sternotherus odoratus (Chelonia, Kinosternidae) Concerning Feeding and Underwater Respiration

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