![]() Studies in both cetaceans ( Ridgway, 1986 Ridgway et al., 1969) and pinnipeds ( Boutilier et al., 2001 Fahlman et al., 2008) suggest that the available O 2 is seldom the limiting factor for the length of a single dive and that CO 2 may be dictating the surface interval between dives. A central concept in breath-hold diving research has been that the available O 2 and its utilization rate during diving determine the length of a single dive. Time underwater needs to be maximized to enhance foraging efficiency however, animals must ultimately return to the surface to exchange metabolic gases. Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.īreath-hold diving mammals live a life of dual constraints. ![]() In addition, our custom-made system allows us to approximate end tidal gas composition. ![]() The average estimated V̇ O 2 and V̇ CO 2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O 2 min −1 and 0.589 to 0.851 l CO 2 min −1, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. The average s C L of dolphins was 0.31☐.04 cmH 2O −1, which is considerably higher than that of humans (0.08 cmH 2O −1) and that previously measured in a pilot whale (0.13 cmH 2O −1). The esophageal pressures indicated that expiration is passive during voluntary breaths, but active during maximal efforts, whereas inspiration is active for all breaths. Our results indicate that bottlenose dolphins have the capacity to generate respiratory flow rates that exceed 130 l s −1 and 30 l s −1 during expiration and inspiration, respectively. The data were used to estimate the dynamic specific lung compliance (s C L), the O 2 consumption rate ( V̇ O 2) and CO 2 production rates ( V̇ CO 2) during rest. We measured esophageal pressures, respiratory flow rates, and expired O 2 and CO 2 in six adult bottlenose dolphins ( Tursiops truncatus) during voluntary breaths and maximal (chuff) respiratory efforts. ![]()
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