CHANGES IN HEART RATE VARIABILITY DURING DIVING IN YOUNG HARBOR SEALS, <i>PHOCA VITULINA</i>

Abstract

A bstract We studied changes in the patterns of heart rate variability (HRV) that coincide with the development of diving skills in harbor seal pups, Phoca vitulina . Heart rate measurements were collected remotely. Spectral analysis of HRV revealed power within a mid‐frequency band (0.1–0.3 Hz) which was prominent, especially in pups less than 10 d of age. In these younger pups, the heart rate switched cyclically between a low and a high diving heart rate every 3–10 sec. Older pups exhibited a highly controlled diving bradycardia with a lower median and a lower variance when compared to younger individuals. These results provide new insight into the maturation of the bradycardia component of the dive response in harbor seal pups.