Developmental changes in cardiorespiratory patterns associated with terrestrial apnoeas in harbour seal pups

• Published in: Journal of Experimental Biology
• Main Authors: Lapierre, Jennifer L., Schreer, Jason F., Burns, Jennifer M., Hammill, Michael O.
• Format: Text
• Language: English
• Published: Company of Biologists 2004
• Subjects: Research Article; Weddell; harbour seal; Phoca vitulina; Weddell Seals
• Online Access: http://jeb.biologists.org/cgi/content/short/207/22/3891; https://doi.org/10.1242/jeb.01222

During the nursing period seals undergo several physiological and behavioural changes. A key component of development is increased cardiorespiratory control, fundamental for breath-holding and thus diving. This study focused on the ontogenetic changes in cardiac responses to respiration in quietly resting, pre-weaned harbour seal pups ( Phoca vitulina ). During periods of quiet rest, breathing became episodic, eupnoea interspersed with periods of apnoea. Little change was observed in respiration (∼35 breaths min–1) and eupnoeic heart rate (∼160 beats min–1) throughout the nursing period. However, apnoea duration increased (from ∼20 to 40 s), while apnoeic heart rate decreased with age (from ∼150 to 90 beats min–1). The observed decline in apnoeic heart rate resulted from an increase in cardiorespiratory control as pups approached weaning, evident by the ability to maintain a lower heart rate more consistently. Similar changes in cardiorespiratory patterns have been reported for elephant and Weddell seals. Due to the early onset of independent foraging, however, the rate of cardiorespiratory control development was more rapid in harbour seals. Our findings suggest that by 1 month of age, harbour seal pups possess the cardiorespiratory control necessary to sustain long-duration apnoeas, fundamental for proficient diving and successful foraging upon weaning.