An integrated comparative physiology and molecular approach pinpoints mediators of breath-hold capacity in dolphins.

Background And Objectives: Ischemic events, such as ischemic heart disease and stroke, are the number one cause of death globally. Ischemia prevents blood, carrying essential nutrients and oxygen, from reaching tissues, leading to cell and tissue death, and eventual organ failure. While humans are relatively intolerant to ischemic events, other species, such as marine mammals, have evolved a unique tolerance to chronic ischemia/reperfusion during apneic diving.

Dynamic body acceleration as a proxy to predict the cost of locomotion in bottlenose dolphins.

Estimates of the energetic costs of locomotion (COL) at different activity levels are necessary to answer fundamental eco-physiological questions and to understand the impacts of anthropogenic disturbance to marine mammals. We combined estimates of energetic costs derived from breath-by-breath respirometry with measurements of overall dynamic body acceleration (ODBA) from biologging tags to validate ODBA as a proxy for COL in trained common bottlenose dolphins (Tursiops truncatus). We measured resting metabolic rate (RMR); mean individual RMR was 0.

Respiratory sinus arrhythmia and submersion bradycardia in bottlenose dolphins ().

Among the many factors that influence the cardiovascular adjustments of marine mammals is the act of respiration at the surface, which facilitates rapid gas exchange and tissue re-perfusion between dives. We measured heart rate () in six adult male bottlenose dolphins () spontaneously breathing at the surface to quantify the relationship between respiration and , and compared this with during submerged breath-holds. We found that dolphins exhibit a pronounced respiratory sinus arrhythmia (RSA) during surface breathing, resulting in a rapid increase in after a breath followed by a gradual decrease over the following 15-20 s to a steady that is maintained until the following breath.