Respiratory physiology of belugas (Delphinapterus leucas)

Though cetaceans withstand long periods of apnea and exhibit short respiratory exchange periods, many of the fundamental physiological mechanisms underlying cetacean respiration are unknown. This study examined respiratory durations, volumes and flow rates in nine belugas (Delphinapterus leucas) housed in managed care facilities using custom designed pulmonary function equipment.

Large differences were observed among the animals, including vastly different tidal volumes (7.5 20.7 L) and vital capacities (29.8 93.0 L). Measurements of vital capacity may have been affected by behavioral compliance with requested maximal effort cues, but may also have allowed for measurement of larger ranges past those obtainable without training.

Animals exhibited high flow rates with a maximal recorded flow rate of 371 L∙sec–1; slower and less variable inspiratory flows indicate a potential physiological flow limitation not exhibited during expiration.

Tidal volumes were much larger than those predicted based on respiratory scaling equations and were 43 % of the vital capacity. Though previous research suggests that cetaceans may be capable of exchanging 80-90 % of their total lung capacity, these animals were not regularly doing so.

These findings expand upon data previously collected in other species by establishing novel data on respiratory variables in belugas. Development of a healthy baseline could allow for non-invasive investigation into beluga respiratory health.