Field energetics and lung function in wild bottlenose dolphins, Tursiops truncatus, in Sarasota Bay Florida

Abstract

We measured respiratory flow rates, and expired O ₂ in 32 (2–34 years, body mass [ M _b] range: 73–291 kg) common bottlenose dolphins ( Tursiops truncatus) during voluntary breaths on land or in water (between 2014 and 2017). The data were used to measure the resting O ₂ consumption rate ( $\dot{\text{V}}{\text{O}}_2$ , range: 0.76–9.45 ml O ₂min ⁻¹kg ⁻¹) and tidal volume ( V _T, range: 2.2–10.4 l) during rest. For adult dolphins, the resting V _T, but not $\dot{\text{V}}{\text{O}}_2$ , correlated with body mass ( M _b, range: 141–291 kg) with an allometric mass-exponent of 0.41. These data suggest that the mass-specific V _T of larger dolphins decreases considerably more than that of terrestrial mammals (mass-exponent: 1.03). The average resting $\text{s}\dot{\text{V}}{\text{O}}_2$ was similar to previously published metabolic measurements from the same species. Our data indicate that the resting metabolic rate for a 150 kg dolphin would be 3.9 ml O ₂min ⁻¹ kg ⁻¹, and the metabolic rate for active animals, assuming a multiplier of 3–6, would range from 11.7 to 23.4 ml O ₂min ⁻¹ kg ⁻¹.\absbreak Our measurements provide novel data for resting energy use and respiratory physiology in wild cetaceans, which may have significant value for conservation efforts and for understanding the bioenergetic requirements of this species.