Direct and indirect calorimetry measurements during the annual growth cycle of juvenile frogs Rana ridibunda P

A thermodynamic study of the energetic metabolism in juvenile amphibians was conducted over an annual cycle of growth. The total energy flux (delta H = enthalpy variation) was measured with direct microcalorimetry and accounted for the sum of all metabolic pathways. Indirect calorimetry, oxygen consumption measurements (VO2), provides the values for the oxidative metabolism-dependent energy. A comparison between the results of both techniques simultaneously performed, provides for the calculation of the energetic efficiency, which indicates the respective importance of aerobic and anaerobic metabolisms during the annual biological cycle. It is clear that oxidative metabolism does not represent all, nor even a constant percentage of the total energy production of the frog, Rana ridibunda. The ration (Formula: see text) varied between 0.72 and 1.00, according to the season and the feeding or fasting periods. These results are discussed with special reference to the ecophysiology and behaviour of this species.