Stone Rae

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Stone
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Rae
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  • Article
    Resting metabolic rate and lung function in wild offshore common bottlenose dolphins, Tursiops truncatus, near Bermuda
    (Frontiers Media, 2018-07-17) Fahlman, Andreas ; McHugh, Katherine ; Allen, Jason ; Barleycorn, Aaron ; Allen, Austin ; Sweeney, Jay C. ; Stone, Rae ; Faulkner Trainor, Robyn ; Bedford, Guy ; Moore, Michael J. ; Jensen, Frants H. ; Wells, Randall S.
    Diving mammals have evolved a suite of physiological adaptations to manage respiratory gases during extended breath-hold dives. To test the hypothesis that offshore bottlenose dolphins have evolved physiological adaptations to improve their ability for extended deep dives and as protection for lung barotrauma, we investigated the lung function and respiratory physiology of four wild common bottlenose dolphins (Tursiops truncatus) near the island of Bermuda. We measured blood hematocrit (Hct, %), resting metabolic rate (RMR, l O2 ⋅ min-1), tidal volume (VT, l), respiratory frequency (fR, breaths ⋅ min-1), respiratory flow (l ⋅ min-1), and dynamic lung compliance (CL, l ⋅ cmH2O-1) in air and in water, and compared measurements with published results from coastal, shallow-diving dolphins. We found that offshore dolphins had greater Hct (56 ± 2%) compared to shallow-diving bottlenose dolphins (range: 30–49%), thus resulting in a greater O2 storage capacity and longer aerobic diving duration. Contrary to our hypothesis, the specific CL (sCL, 0.30 ± 0.12 cmH2O-1) was not different between populations. Neither the mass-specific RMR (3.0 ± 1.7 ml O2 ⋅ min-1 ⋅ kg-1) nor VT (23.0 ± 3.7 ml ⋅ kg-1) were different from coastal ecotype bottlenose dolphins, both in the wild and under managed care, suggesting that deep-diving dolphins do not have metabolic or respiratory adaptations that differ from the shallow-diving ecotypes. The lack of respiratory adaptations for deep diving further support the recently developed hypothesis that gas management in cetaceans is not entirely passive but governed by alteration in the ventilation-perfusion matching, which allows for selective gas exchange to protect against diving related problems such as decompression sickness.
  • Article
    Surface and diving metabolic rates, and dynamic aerobic dive limits (dADL) in near‐ and off‐shore bottlenose dolphins, Tursiops spp., indicate that deep diving is energetically cheap
    (Wiley, 2023-04-05) Fahlman, Andreas ; Allen, Austin S. ; Blawas, Ashley ; Sweeney, Jay ; Stone, Rae ; Trainor, Robyn Faulkner ; Jensen, Frants H. ; McHugh, Katherine ; Allen, Jason B. ; Barleycorn, Aaron A. ; Wells, Randall S.
    High‐resolution dive depth and acceleration recordings from nearshore (Sarasota Bay, dive depth < 30 m), and offshore (Bermuda) bottlenose dolphins (Tursiops spp.) were used to estimate the diving metabolic rate (DMR) and the locomotor metabolic rate (LMR, L O2/min) during three phases of diving (descent, bottom, and ascent). For shallow dives (depth ≤ 30 m), we found no differences between the two ecotypes in the LMR during diving, nor during the postdive shallow interval between dives. For intermediate (30 m < depth ≤ 100 m) and deep dives (depth > 100 m), the LMR was significantly higher during ascent than during descent and the bottom phase by 59% and 9%, respectively. In addition, the rate of change in depth during descent and ascent (meters/second) increased with maximal dive depth. The dynamic aerobic dive limit (dADL) was calculated from the estimated DMR and the estimated predive O2 stores. For the Bermuda dolphins, the dADL decreased with dive depth, and was 18.7, 15.4, and 11.1 min for shallow, intermediate, and deep dives, respectively. These results provide a useful approach to understand the complex nature of physiological interactions between aerobic metabolism, energy use, and diving capacity.