Resource requirements of the Pacific leatherback turtle population.

The Pacific population of leatherback sea turtles (Dermochelys coriacea) has drastically declined in the last 25 years. This decline has been linked to incidental capture by fisheries, egg and meat harvesting, and recently, to climate variability and resource limitation. Here we couple growth rates with feeding experiments and food intake functions to estimate daily energy requirements of leatherbacks throughout their development.

The genetic component of the forced diving bradycardia response in mammals.

We contrasted the forced diving bradycardia between two genetically similar (inbred) rat strains (Fischer and Buffalo), compared to that of outbred rats (Wistar). The animals were habituated to forced diving for 4 weeks. Each animal was then tested during one 40 s dive on each of 3 days.

Behaviour and physiology: the thermal strategy of leatherback turtles.

Background: Adult leatherback turtles (Dermochelys coriacea) exhibit thermal gradients between their bodies and the environment of ≥8°C in sub-polar waters and ≤4°C in the tropics. There has been no direct evidence for thermoregulation in leatherbacks although modelling and morphological studies have given an indication of how thermoregulation may be achieved.

Methodology/principal Findings: We show for the first time that leatherbacks are indeed capable of thermoregulation from studies on juvenile leatherbacks of 16 and 37 kg.

Validation of the use of doubly labeled water for estimating metabolic rate in the green turtle (Chelonia mydas L.): a word of caution.

Marine turtles often have extremely high water turnover accompanied by a low field metabolic rate (FMR), a combination that can contraindicate the use of doubly labelled water (DLW). Therefore, we conducted a validation study to assess the suitability of the DLW technique for determining FMR of marine turtles. Six green turtles (22.

Tracheal compression delays alveolar collapse during deep diving in marine mammals.

Marine mammals have very compliant alveoli and stiff upper airways; an adaptation that allows air to move from the alveoli into the upper airways, during breath-hold diving. Alveolar collapse is thought occur between 30 and 100 m and studies that have attempted to estimate gas exchange at depth have used the simplifying assumption that gas exchange ceases abruptly at the alveolar collapse depth. Here we develop a mathematical model that uses compliance values for the alveoli and upper airspaces, estimated from the literature, to predict volumes of the respiratory system at depth.

Exercise warms adult leatherback turtles.

Leatherback sea turtles (Dermochelys coriacea) can maintain body temperature (T(B)) up to 18 degrees C above that of the surrounding sea water (T(W)) which allows leatherbacks to enter cold temperate waters and have the largest global range of any reptile. Using a cylindrical model of a leatherback we investigated the extent to which heat production through variation of swim speed could be used in a leatherback's thermal strategy. Drag force of a full scale cast of a leatherback was measured in a low velocity wind tunnel to obtain an estimate of the metabolic cost needed to offset drag.

Deep diving mammals: Dive behavior and circulatory adjustments contribute to bends avoidance.

A mathematical model was created that predicted blood and tissue N(2) tension (P(N2)) during breath-hold diving. Measured muscle P(N2) from the bottlenose dolphin after diving repeatedly to 100 m (Tursiops truncatus [Ridgway and Howard, 1979, Science, 4423, 1182-1183]) was compared with predictions from the model. Lung collapse was modelled as a 100% pulmonary shunt which yielded tissue P(N2) similar to those reported for the dolphin.