Characterizing respiratory capacity in belugas (Delphinapterus leucas)

Area of Science:

• Marine Mammal Physiology
• Respiratory Physiology
• Beluga Whale Biology

Background:

• Understanding beluga whale (Delphinapterus leucas) respiratory physiology is crucial for assessing their health in managed care and the wild.
• Limited data exists on beluga respiratory mechanics, particularly tidal volume, lung capacity, and flow rates during spontaneous and trained breathing.

Purpose of the Study:

• To measure and characterize respiratory parameters in beluga whales, including tidal volume, breath duration, and flow rates.
• To compare measured respiratory values with predictions from terrestrial mammal scaling equations and cetacean lung capacity estimates.

Main Methods:

• Respiratory flow and breath duration were measured in nine beluga whales during spontaneous and trained maximal breaths (chuffs).
• Tidal volume (V_T) was calculated, and expiratory (V˙_exp) and inspiratory (V˙_insp) flow rates were determined.
• Measurements were compared to estimated total lung capacity (TLC_est) and vital capacities (V_C).

Main Results:

• Mean inspiratory tidal volume (16.7 ± 4.7 L) was larger than predicted for terrestrial mammals and represented a significant portion of estimated lung capacity.
• Expiratory flow rates were significantly higher than inspiratory flow rates during both spontaneous and trained breaths.
• Breath duration was shorter for forced breaths (chuffs) compared to spontaneous breaths.

Conclusions:

• Beluga whales exhibit distinct respiratory mechanics, with larger-than-predicted tidal volumes and high expiratory flow rates.
• These findings provide essential baseline data for beluga whale respiratory capacity, informing conservation and veterinary care.
• The study highlights the need for species-specific respiratory models for marine mammals.