Body temperature independence of solar radiation in free-ranging loggerhead turtles, Caretta caretta, during internesting periods

Sato, Katsufumi; Sakamoto, Wataru; Matsuzawa, Yoshimasa; Tanaka, Hideji; Minamikawa, Shingo; Naito, Yoshimasa

doi:10.1007/bf00353611

Cited by 34 publications

(20 citation statements)

References 14 publications

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“…These findings strongly suggest that ESTs serve at least dual functions: (a) to re-oxygenation following lactate accumulation, and (b) to rewarming following dives to cold water. Thus, when loggerhead sea turtles spend prolonged periods at the water surface they do not necessarily bask in the sun to thermoregulate, as confirmed by the lack of a temporal pattern (Sato et al, 1995). Nonetheless, the turtles may sometimes compensate for low body temperatures caused either temporarily by deep diving below the thermocline or more permanently by low winter temperatures, although we postulated that such behaviour may primarily serve digestive requirements.…”

Section: Discussionmentioning

confidence: 91%

When surfacers do not dive: multiple significance of extended surface times in marine turtles

Hochscheid

Bentivegna

Hamza

et al. 2010

Journal of Experimental Biology

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SUMMARYMarine turtles spend more than 90% of their life underwater and have been termed surfacers as opposed to divers. Nonetheless turtles have been reported occasionally to float motionless at the surface but the reasons for this behaviour are not clear. We investigated the location, timing and duration of extended surface times (ESTs) in 10 free-ranging loggerhead turtles (Caretta caretta) and the possible relationship to water temperature and diving activity recorded via satellite relay data loggers for 101-450 days. For one turtle that dived only in offshore areas, ESTs contributed 12% of the time whereas for the other turtles ESTs contributed 0.4-1.8% of the time. ESTs lasted on average 90 min but were mostly infrequent and irregular, excluding the involvement of a fundamental regulatory function. However, 82% of the ESTs occurred during daylight, mostly around noon, suggesting a dependence on solar radiation. For three turtles, there was an appreciable (7°C to 10.5°C) temperature decrease with depth for dives during periods when ESTs occurred frequently, suggesting a re-warming function of EST to compensate for decreased body temperatures, possibly to enhance digestive efficiency. A positive correlation between body mass and EST duration supported this explanation. By contrast, night-active turtles that exceeded their calculated aerobic dive limits in 7.6-16% of the dives engaged in nocturnal ESTs, probably for lactate clearance. This is the first evidence that loggerhead turtles may refrain from diving for at least two reasons, either to absorb solar radiation or to recover from anaerobic activity.

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Section: Discussionmentioning

confidence: 91%

When surfacers do not dive: multiple significance of extended surface times in marine turtles

Hochscheid

Bentivegna

Hamza

et al. 2010

Journal of Experimental Biology

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“…2). This enhanced independence probably stems from active sea turtles being able to maintain a body temperature that exceeds the water temperature due to muscular heating and thermal inertia (Sato et al 1995, Hochscheid et al 2002. Piecewise linear regression analysis revealed that there is a point of inflection in the thermal dependence of the dive duration, leading to a high R 1 Q 10 value of 4.5 at temperatures below 27.8°C, and a lack of significant temperature-dependence above 27.8°C (Fig.…”

Section: Temperature Fluctuations and Dive Durationmentioning

confidence: 97%

Cold-blooded divers: temperature-dependent dive performance in the wild hawksbill turtle Eretmochelys imbricata

Storch

Wilson²,

Hillis-Starr³

et al. 2005

Mar. Ecol. Prog. Ser.

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Sea turtles are diving ectotherms that are influenced by the temperature of the ambient water, although swimming activity can temper this influence via increased body temperatures enhanced by the thermal inertia of these large animals. We successfully equipped 3 nesting hawksbill turtles Eretmochelys imbricata with time-depth recorders (TDRs) to monitor water temperature and dive depth over the duration of the re-migration interval between 2 successive nesting seasons. Data sets for up to 22 mo were obtained, showing fluctuations in water temperature over the seasons. Nocturnal dive behaviour of the turtles at their foraging grounds revealed an increase in dive duration with decreasing water temperatures in winter. A model is provided to estimate dive duration for the range of temperatures experienced by this species in the wild. The data on vertical velocity during ascent and descent phases as a parameter for activity failed to show thermal dependence. It is concluded that changes in water temperature have an effect on the behavioural ecology of hawksbill turtles.

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“…Sato et al 1995) and in the high level of submergence recorded by satellite transmitters (e.g. Renaud & Carpenter 1994, Gitschlag 1996.…”

Section: Direction Of Travelmentioning

confidence: 99%

Changes in behaviour during the inter-nesting period and post-nesting migration for Ascension Island green turtles

Hays¹,

Luschi²,

Papi³

et al. 1999

Mar. Ecol. Prog. Ser.

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Satellite transmitters were attached to green turtles Chelonia mydas while they were nesting on Ascension Island in the South Atlantic (7"57'S, 14"22'W) and individuals were subsequently monitored during the inter-nesting period and the post-nesting migration to Brazil. During the inter-nesting period, data from the transmitters suggested that turtles generally stayed within 5 km of the nesting beach on which they had originally been observed. During both the inter-nesting period and migration, turtles were submerged the vast majority (>95%) of the tune, suggesting that they neither basked at the surface nor drifted passively during migration to any great extent. There was a clear dichotomy in submergence behaviour, with submergences tending to be of short duration during postnesting migration (mean = 7.3 rnin, 3318 h of data from 5 individuals) and of longer duration during the inter-nesting period (mean = 22.1 min, 714 h of data from 5 different in&viduals). As submergence duration is generally linked to activity levels in sea turtles, this pattern suggests that turtles were comparatively inactive during the inter-nesting period and comparatively active dunng migration. During both the inter-nesting period and the post-nesting migration, die1 submergence patterns were detected with dive duration tending to be longer at night. As the turtles migrated WSW from Ascension Island, there was a reduction in their speed of travel. A numerical model of the near-surface currents suggested that this reduction was associated with the weakening of the WSW flow of the prevailing South Atlantic Equatorial Current.

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Body temperature independence of solar radiation in free-ranging loggerhead turtles, Caretta caretta, during internesting periods

Cited by 34 publications

References 14 publications

When surfacers do not dive: multiple significance of extended surface times in marine turtles

When surfacers do not dive: multiple significance of extended surface times in marine turtles

Cold-blooded divers: temperature-dependent dive performance in the wild hawksbill turtle Eretmochelys imbricata

Changes in behaviour during the inter-nesting period and post-nesting migration for Ascension Island green turtles

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