Schmidt Alexander, Alard Frank, Handrich Yves
Institut Pluridisciplinaire Hubert Curien, Unité Mixte de Recherche 7178, Departement d'Ecologie, Physiologie, et Ethologie, Université Henri Poincaré, Strasbourg, France.
Am J Physiol Regul Integr Comp Physiol. 2006 Sep;291(3):R608-18. doi: 10.1152/ajpregu.00826.2005.
To investigate thermoregulatory adjustments at sea, body temperatures (the pectoral muscle and the brood patch) and diving behavior were monitored during a foraging trip of several days at sea in six breeding king penguins Aptenodytes patagonicus. During inactive phases at sea (water temperature: 4-7 degrees C), all tissues measured were maintained at normothermic temperatures. The brood patch temperature was maintained at the same values as those measured when brooding on shore (38 degrees C). This high temperature difference causes a significant loss of heat. We hypothesize that high-energy expenditure associated with elevated peripheral temperature when resting at sea is the thermoregulatory cost that a postabsorptive penguin has to face for the restoration of its subcutaneous body fat. During diving, mean pectoral temperature was 37.6 +/- 1.6 degrees C. While being almost normothermic on average, the temperature of the pectoral muscle was still significantly lower than during inactivity in five out of the six birds and underwent temperature drops of up to 5.5 degrees C. Mean brood patch temperature was 29.6 +/- 2.5 degrees C during diving, and temperature decreases of up to 21.6 degrees C were recorded. Interestingly, we observed episodes of brood patch warming during the descent to depth, suggesting that, in some cases, king penguins may perform active thermolysis using the brood patch. It is hypothesized that functional pectoral temperature may be regulated through peripheral adjustments in blood perfusion. These two paradoxical features, i.e., lower temperature of deep tissues during activity and normothermic peripheral tissues while inactive, may highlight the key to the energetics of this diving endotherm while foraging at sea.
为了研究在海上的体温调节适应情况，在六只繁殖期的王企鹅（阿德利企鹅）在海上为期数天的觅食之旅中，监测了它们的体温（胸肌和育雏斑）以及潜水行为。在海上的非活动阶段（水温：4 - 7摄氏度），所测量的所有组织均维持在正常体温。育雏斑的温度维持在与在岸上育雏时测量的温度相同的值（38摄氏度）。这种高温度差导致了显著的热量损失。我们推测，在海上休息时与外周温度升高相关的高能量消耗是一只吸收后状态的企鹅为恢复其皮下体脂而必须面对的体温调节成本。在潜水过程中，胸肌平均温度为37.6±1.6摄氏度。虽然平均而言几乎是正常体温，但六只鸟中有五只的胸肌温度仍显著低于非活动状态时，并且温度下降高达5.5摄氏度。潜水期间育雏斑平均温度为29.6±2.5摄氏度，记录到温度下降高达21.6摄氏度。有趣的是，我们在下潜到深处的过程中观察到育雏斑升温的情况，这表明在某些情况下，王企鹅可能会利用育雏斑进行主动散热。据推测，功能性胸肌温度可能通过血液灌注的外周调节来控制。这两个看似矛盾的特征，即在活动期间深部组织温度较低而在非活动时外周组织为正常体温，可能突出了这种潜水恒温动物在海上觅食时能量学的关键所在。
