Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals. Academic Article uri icon


  • Unlike their terrestrial ancestors, marine mammals routinely confront extreme physiological and physical challenges while breath-holding and pursuing prey at depth. To determine how cetaceans and pinnipeds accomplish deep-sea chases, we deployed animal-borne instruments that recorded high-resolution electrocardiograms, behaviour and flipper accelerations of bottlenose dolphins (Tursiops truncatus) and Weddell seals (Leptonychotes weddellii) diving from the surface to >200m. Here we report that both exercise and depth alter the bradycardia associated with the dive response, with the greatest impacts at depths inducing lung collapse. Unexpectedly, cardiac arrhythmias occurred in >73% of deep, aerobic dives, which we attribute to the interplay between sympathetic and parasympathetic drivers for exercise and diving, respectively. Such marked cardiac variability alters the common view of a stereotypic 'dive reflex' in diving mammals. It also suggests the persistence of ancestral terrestrial traits in cardiac function that may help explain the unique sensitivity of some deep-diving marine mammals to anthropogenic disturbances.

published proceedings

  • Nat Commun

altmetric score

  • 160.25

author list (cited authors)

  • Williams, T. M., Fuiman, L. A., Kendall, T., Berry, P., Richter, B., Noren, S. R., ... Davis, R. W.

citation count

  • 74

complete list of authors

  • Williams, Terrie M||Fuiman, Lee A||Kendall, Traci||Berry, Patrick||Richter, Beau||Noren, Shawn R||Thometz, Nicole||Shattock, Michael J||Farrell, Edward||Stamper, Andy M||Davis, Randall W

publication date

  • January 2015