Resting metabolic rate and lung function in fasted and fed rough‐toothed dolphins, Steno bredanensis

Abstract

AbstractWe measured resting metabolic rate (RMR), tidal volume (VT), breathing frequency (fR), respiratory flow, and end‐expired gases in rough‐toothed dolphins (Steno bredanensis) housed in managed care after an overnight fast and 1–2 hr following a meal. The measured average (± standard deviation) VT (4.0 ± 1.3 L) and fR (1.9 ± 1.0 breaths/min) were higher and lower, respectively, as compared with estimated values from both terrestrial and aquatic mammals, and the average VT was 43% of the estimated total lung capacity. The end‐expired gas levels suggested that this species keep alveolar O2 (10.6% or 80 mmHg) and CO2 (7.6% or 57 mmHg), and likely arterial gas tensions, low and high, respectively, to maximize efficiency of gas exchange. We show that following an overnight fast, the RMR (566 ± 158 ml O2/min) was 1.8 times the estimated value predicted by Kleiber for terrestrial mammals of the same size. We also show that between 1 and 2 hr after ingestion of a meal, the metabolic rate increases an average of 29% (709 ± 126 ml O2/min). Both body mass (Mb) and fR significantly altered the measured RMR and we propose that both these variables should be measured when estimating energy use in cetaceans.