Ventilation and gas exchange before and after voluntary static surface breath-holds in clinically healthy bottlenose dolphins, Tursiops truncatus.

We measured respiratory flow (V̇), breathing frequency (f_R), tidal volume (V_T), breath duration 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, V_T and f_R following a breath-hold. The analysis suggests that the dolphins attempt to minimize recovery following a dive by altering V_T and f_R to rapidly replenish the O₂ stores. For the first breath following a surface breath-hold, the end-expired O₂ decreased with dive duration, while V_T and f_R increased. Throughout the recovery period, end-expired O₂ increased while the respiratory effort (V_T, f_R) 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.

Duke Scholars

Author Andreas Fahlman Marine Science and Conservation