Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store.

Cassondra L Williams, Max F Czapanskiy, Jason S John, Judy St Leger, Miriam Scadeng, Paul J Ponganis

The Journal of experimental biology 2021 Jan 11

filter terms:

Some marine birds and mammals can perform dives of extraordinary duration and depth. Such dive performance is dependent on many factors, including total body oxygen (O2) stores. For diving penguins, the respiratory system (air sacs and lungs) constitutes 30-50% of the total body O2 store. To better understand the role and mechanism of parabronchial ventilation and O2 utilization in penguins both on the surface and during the dive, we examined air sac partial pressures of O2 (PO2 ) in emperor penguins (Aptenodytes forsteri) equipped with backpack PO2 recorders. Cervical air sac PO2 values at rest were lower than in other birds, while the cervical air sac to posterior thoracic air sac PO2 difference was larger. Pre-dive cervical air sac PO2 values were often greater than those at rest, but had a wide range and were not significantly different from those at rest. The maximum respiratory O2 store and total body O2 stores calculated with representative anterior and posterior air sac PO2 data did not differ from prior estimates. The mean calculated anterior air sac O2 depletion rate for dives up to 11 min was approximately one-tenth that of the posterior air sacs. Low cervical air sac PO2 values at rest may be secondary to a low ratio of parabronchial ventilation to parabronchial blood O2 extraction. During dives, overlap of simultaneously recorded cervical and posterior thoracic air sac PO2 profiles supported the concept of maintenance of parabronchial ventilation during a dive by air movement through the lungs. © 2021. Published by The Company of Biologists Ltd.

Citation

Cassondra L Williams, Max F Czapanskiy, Jason S John, Judy St Leger, Miriam Scadeng, Paul J Ponganis. Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store. The Journal of experimental biology. 2021 Jan 11;224(Pt 1)