Drivers of the dive response in trained harbour porpoises(Phocoena phocoena)
Abstract
Pronounced dive responses through peripheral vasoconstriction and bradycardia enables prolonged apnoea in marine mammals. For most vertebrates, the dive response is initiated upon face immersion, but little is known about the physical drivers of diving and surfacing heart rate in cetaceans whose faces are always mostly submerged. Using two trained harbour porpoises instrumented with an ECG-measuring DTAG-3, we investigate the initiation and progression of bradycardia and tachycardia during apnoea and eupnoea for varying levels of immersion. We show that paranasal wetting drives bradycardia initiation and progression, whereas apnoea leads to dive-level bradycardia eventually, but not instantly. At the end of dives, heart rate accelerates independently of lung expansion, perhaps in anticipation of surfacing; however, full tachycardia is only engaged upon inhalation. We conclude that breathing drives surface tachycardia, whereas blowhole wetting is an important driver of bradycardia; although, anticipatory/volitional modulation can overrule such responses to sensory inputs.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 01, 2019
- Source ID
- 10.1242/jeb.208637
Entities
People
- Birgitte I McDonald
- Peter Teglberg Madsen
- Siri L Elmegaard
Organizations
- Aarhus University
- California State University
- National Science Foundation
- Natural Sciences, Danish Council for Independent Research
- Office of Naval Research