The dive response redefined: underwater behavior influences cardiac variability in freely diving dolphins

SUMMARY A hallmark of the dive response, bradycardia, promotes the conservation of onboard oxygen stores and enables marine mammals to submerge for prolonged periods. A paradox exists when marine mammals are foraging underwater because activity should promote an elevation in heart rate (fH) to support increased metabolic demands. To assess the effect of the interaction between the diving response and underwater activity on fH, we integrated...