Reassessment of the cardio-respiratory stress response, using the king penguin as a model

International audienceResearch in to short-term cardio-respiratory changes in animais in reaction to a psychologicalstressor typically describes increases in rate of oxygen consumption (Vo,) and heart rate.Consequently, the broad consensus is that they represent a fundamental stressor responsegeneralizable across adult species. However, movement levels can also change in the presenceof a stressor, yet studies have not accounted for this possible confound on heart rate. Thus thedirect effects of psychological stressors on the cardio-respiratory system are not resolved. Weused an innovative experimental design employing accelerometers attached to king penguins(Aptenodytes patagonicus) to measure and thus account for mavement levels in a sedentary yetfree-ta-mave animal model during a repeated measures stress experiment. As with previousstudies on other species, incubating king penguins (N = 6) exhibited significant increases inboth Va, and heart rate when exposed ta the stressor. Hawever, mavement levels, while stilllaw, also increased in respanse ta the stressar. Once this was accaunted for by camparingperiads oftime during the control and stress conditions when movement levels were similar asrecorded by the accelerometers, only Va, significantly increased; there was no change in heartrate. These findings offer evidence that changing movement levels have an important effect onthe measured stress response and that the cardia-respiratary respanse per se ta a psycholog icalstressor (Le. the respanse as a result of physialagical changes directly attributable to thestressar) is an increase in Vo, withaut an increase in heart rate