title: Behavioral and metabolic contributions to thermoregulation in freely swimming leatherback turtles at high latitudes.
abstract: 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.
authors.affiliation: Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA Department of Biology, Barnard College, New York, NY 10027, USA jcasey@barnard.edu williarda@uncw.edu.
authors.forename: James P
authors.initials: JP
authors.lastname: Casey
authors.affiliation: Fisheries and Oceans Canada, Population Ecology Division, Bedford Institute of Oceanography, Dartmouth, NS, Canada, B2Y 4A2.
authors.forename: Michael C
authors.initials: MC
authors.lastname: James
authors.affiliation: Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA jcasey@barnard.edu williarda@uncw.edu.
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Williard
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D001833:Body Temperature Regulation; D002170:Canada; D002940:Circadian Rhythm; D004242:Diving; D016014:Linear Models; D013550:Swimming; D013686:Telemetry; D013696:Temperature; D014426:Turtles / Q000502:physiology*
keywords: Dermochelys coriacea; Diving; Endothermy; Jellyfish; Reptile; Specific dynamic action