[MARMAM] New publication: Thermoregulation in leatherback turtles

James Casey jamespatrickcasey at gmail.com
Thu Jul 3 06:42:16 PDT 2014


Dear Marman list members,

Please find attached to this e-mail a recent publication in *The Journal of
Experimental Biology* on thermoregulation in leatherback turtles (*Dermochelys
coriacea*). The study presents the first body temperature recordings of
freely swimming adult leatherbacks at high latitude foraging grounds off
Nova Scotia, Canada. The results provide additional support for endothermy
in leatherbacks by highlighting the role of heat produced via visceral
organs (i.e. specific dynamic action) for maintenance of a large (>10C)
thermal gradient in cold water. The study also found that behavior (i.e.
use of warm surface waters) had a significant effect on their body
temperatures, while exploiting a seasonally high abundance of prey at high
latitudes.


*Behavioral and metabolic contributions to thermoregulation in freely
swimming leatherback turtles at high latitudes*

By James P. Casey, Michael C. James, and Amanda S. Williard

 Leatherback turtles in the Northwest Atlantic Ocean have a broad
geographic range that extends from nesting beaches near the equator to
seasonal foraging grounds as far north as Canada. The ability of
leatherbacks to maintain core body temperature (Tb) higher than that of the
surrounding water is thought to be a key element of their biology that
permits them to exploit productive waters at high latitudes. We provide the
first recordings of Tb from freely swimming leatherbacks at a northern
foraging ground, and use these data to assess the importance of behavioral
adjustments and metabolic sources of heat for maintenance of the thermal
gradient (Tg). The mean Tb for individual leatherbacks ranged from 25.4±1.7
to 27.3±0.3°C, and Tg ranged from 10.7±2.4 to 12.1±1.7°C. Variation in mean
Tb was best explained by the amount of time that turtles spent in the
relatively warm surface waters. A diel trend in Tb was apparent, with
daytime cooling suggestive of prey ingestion and night-time warming
attributable to endogenous heat production. We estimate that metabolic
rates necessary to support the observed Tg are ~3 times higher than resting
metabolic rate, and that specific dynamic action is an important source of
heat for foraging leatherbacks.



*The Journal of Experimental Biology* (2014) 217, 2331-2337
doi:10.1242/jeb.100347


Sincerely,

James Casey
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