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Behavioral inference of diving metabolic rate in free-ranging leatherback turtles

Bradshaw, Corey J. A., McMahon, Clive R. and Hays, Graeme C. (2007). Behavioral inference of diving metabolic rate in free-ranging leatherback turtles. Physiological and Biochemical Zoology,80(2):209-219.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 19 times in Scopus Article | Citations

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IRMA ID A00003xPUB49
Title Behavioral inference of diving metabolic rate in free-ranging leatherback turtles
Author Bradshaw, Corey J. A.
McMahon, Clive R.
Hays, Graeme C.
Journal Name Physiological and Biochemical Zoology
Publication Date 2007
Volume Number 80
Issue Number 2
ISSN 1537-5293   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-33847081244
Start Page 209
End Page 219
Total Pages 11
Place of Publication Chicago, IL, United States
Publisher The University of Chicago Press
Field of Research 0602 - Ecology
0608 - Zoology
1116 - Medical Physiology
HERDC Category C1 - Journal Article (DEST)
Abstract Good estimates of metabolic rate in free-ranging animals are essential for understanding behavior, distribution, and abundance. For the critically endangered leatherback turtle (Dermochelys coriacea), one of the world's largest reptiles, there has been a long-standing debate over whether this species demonstrates any metabolic endothermy. In short, do leatherbacks have a purely ectothermic reptilian metabolic rate or one that is elevated as a result of regional endothermy? Recent measurements have provided the first estimates of field metabolic rate (FMR) in leatherback turtles using doubly labeled water; however, the technique is prohibitively expensive and logistically difficult and produces estimates that are highly variable across individuals in this species. We therefore examined dive duration and depth data collected for nine free-swimming leatherback turtles over long periods (up to 431 d) to infer aerobic dive limits (ADLs) based on the asymptotic increase in maximum dive duration with depth. From this index of ADL and the known mass-specific oxygen storage capacity (To(2)) of leatherbacks, we inferred diving metabolic rate (DMR) as. We predicted that if leatherbacks conform to the To(2)/ADL 2 purely ectothermic reptilian model of oxygen consumption, these inferred estimates of DMR should fall between predicted and measured values of reptilian resting and field metabolic rates, as well as being substantially lower than the FMR predicted for an endotherm of equivalent mass. Indeed, our behaviorally derived DMR estimates (mean = 0.73 +/- 0.11 mL O-2 min(-1) kg(-1)) were times the resting metabolic rate 3.00 +/- 0.54 measured in unrestrained leatherbacks and times 0.50 +/- 0.08 the average FMR for a reptile of equivalent mass. These DMRs were also nearly one order of magnitude lower than the FMR predicted for an endotherm of equivalent mass. Thus, our findings lend support to the notion that diving leatherback turtles are indeed ectothermic and do not demonstrate elevated metabolic rates that might be expected due to regional endothermy. Their capacity to have a warm body core even in cold water therefore seems to derive from their large size, heat exchangers, thermal inertia, and insulating fat layers and not from an elevated metabolic rate.
Keywords seal mirounga leonina
aerobic dive limit
dermochels coriacea
heart rate
green turtles
oxygen stores
depth
energetics
thermoregulation
DOI http://dx.doi.org/10.1086/511142   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)


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