Physiological changes in post-hatchling green turtles (Chelonia mydas) following short-term fasting: implications for release protocols

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March, DT, Ariel, E, Munns, S, Rudd, D, Blyde, D, Christidis, L & Kelaher, BP 2019, 'Physiological changes in post-hatchling green turtles (Chelonia mydas) following short-term fasting: implications for release protocols', Conservation Physiology, vol. 7, no. 1.

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Relocation of sea turtle nests and the retention of post-hatchlings for head-starting programs are both commonly used to improve conservation outcomes and facilitate eco-tourism ventures. Currently, there is little literature surrounding the husbandry protocols required during these programs to optimize post-release outcomes. To assess the impact of varied feeding regimes on exercise performance, (which will hereafter be referred to as ‘fitness’), 40 10-month-old captive post-hatchling green turtles (Chelonia mydas) were divided into four groups of 10 and fasted for either 3, 9, 10 or 15 h. The animals were then subjected to a fitness test via repetitive use of the ‘righting reflex’ on land. Health assessments were conducted prior to the fitness test, including; heart rate, haematocrit (Hct), heterophil to lymphocyte ratio and the measurement of 11 biochemical analytes, including pH, partial pressures of carbon dioxide (PvCO2) and oxygen (PvO2), lactate, bicarbonate (HCO3), sodium (Na+), potassium (K+), chloride (Cl), ionized calcium (iCa2+), glucose and urea. Results were corrected for multiple comparisons and significant differences among groups were demonstrated for temperature, pH, HCO3, iCa2+, urea and lactate. To investigate physiological relationships between analytes, correlation coefficients were calculated between fitness and glucose, fitness and lactate, glucose and lactate, pH and iCa2+, pH and K+, pH and PvCO2, pH and HCO3 and Hct and K+. Following correction for multiple comparisons, significant relationships were seen between pH and iCa2+ and pH and HCO3. Post-hatchling turtles appear to enter a catabolic state when exposed to short-term fasting. While this did not have a direct impact on fitness, the production of an intense energetic output from a catabolic state may induce a physiological debt. This study suggests that handling that induces a physical response should be minimized and animals should be fed within 10 h of release.

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