A. Fahlman, M. Brodsky, S. Miedler, S. Dennison, M. Ivancic, G. Levine, J. Rocho-Levine, M. Manley, J. Rocabert, and A. Borque Espinosa

We measured respiratory flow (V), breathing frequency (fR), tidal volume (VT), breath durations, and end-expired O2 content in bottlenose dolphins (Tursiops truncatus) before and after static surface breath-holds ranging from 34 to 292 s. There was considerable variation in the end-expired O2, tidal volume VT, and fR following a breath-hold. The analysis suggests that the dolphins attempt to minimize recovery following a dive by altering VT, and fR to rapidly restore the O2 stores. For the first breath following a surface breath-hold, the end-expired O2 decreased with dive duration, while VT, and fR increased. Throughout the recovery, end-expired O2 increased while the respiratory effort (VT, fR) decreased. We propose that the dolphins alter respiratory effort following a breath-hold according to the reduction in end-expired O2 levels, allowing almost complete recovery after 1.2 min.

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