Resting metabolic rate and lung function in fasted and fed rough‐toothed dolphins, <i>Steno bredanensis</i>
Andreas Fahlman, Kaylee Rhieu, Brie Alessi, Shelly Marquardt, Michelle B. Schisa, Guillermo J. Sánchez Contreras, Josefin Larsson
Abstract
Abstract We measured resting metabolic rate (RMR), tidal volume ( V T ), breathing frequency ( f R ), 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) V T (4.0 ± 1.3 L) and f R (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 V T was 43% of the estimated total lung capacity. The end‐expired gas levels suggested that this species keep alveolar O 2 (10.6% or 80 mmHg) and CO 2 (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 O 2 /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 O 2 /min). Both body mass ( M b ) and f R significantly altered the measured RMR and we propose that both these variables should be measured when estimating energy use in cetaceans.