Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals

Williams, Terrie M.; Fuiman, Lee A.; Kendall, Traci; Berry, P.; Richter, Beau; Noren, Shawn R.; Thometz, Nicole M.; Shattock, Michael J.; Farrell, Edward M.; Stamper, Andy M.; Davis, Randall W.

doi:10.1038/ncomms7055

Cited by 89 publications

(118 citation statements)

References 39 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…2A). In some cases, ΔS O2 appeared to be affected by stroke rate patterns as would be expected during exercise and consistent with recent suggestions that heart rate (and presumably some muscle blood flow) is modulated by exercise (Davis and Williams, 2012;Williams et al, 2015). During shallow dives, California sea lions exhibit higher heart rates than those seen during deep dives (McDonald and Ponganis, 2014).…”

Section: Discussion Flipper Stroke Patternssupporting

confidence: 71%

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions

Tift

Hückstädt

McDonald

et al. 2017

Journal of Experimental Biology

View full text Add to dashboard Cite

The depletion rate of the blood oxygen store, development of hypoxemia and dive capacity are dependent on the distribution and rate of blood oxygen delivery to tissues while diving. Although blood oxygen extraction by working muscle would increase the blood oxygen depletion rate in a swimming animal, there is little information on the relationship between muscle workload and blood oxygen depletion during dives. Therefore, we examined flipper stroke rate, a proxy of muscle workload, and posterior vena cava oxygen profiles in four adult female California sea lions (Zalophus californianus) during foraging trips at sea. Flipper stroke rate analysis revealed that sea lions minimized muscle metabolism with a stroke-glide strategy when diving, and exhibited prolonged glides during the descent of deeper dives (>100 m). During the descent phase of these deep dives, 55± 21% of descent was spent gliding, with the longest glides lasting over 160 s and covering a vertical distance of 340 m. Animals also consistently glided to the surface from 15 to 25 m depth during these deeper dives. Venous hemoglobin saturation (S O2 ) profiles were highly variable throughout dives, with values occasionally increasing during shallow dives. The relationship between S O2 and flipper stroke rate was weak during deeper dives, while this relationship was stronger during shallow dives. We conclude that (1) the depletion of oxygen in the posterior vena cava in deep-diving sea lions is not dependent on stroke effort, and (2) stroke-glide patterns during dives contribute to a reduction of muscle metabolic rate.

show abstract

Section: Discussion Flipper Stroke Patternssupporting

confidence: 71%

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions

Tift

Hückstädt

McDonald

et al. 2017

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…As reported previously, the heart rate of the diving dolphins declined from approximately 130 beats min -1 pre-dive to 30-60 beats min -1 depending on the level of exercise upon submergence (Williams et al, 2015a); it then ranged from 80 to 132 beats min -1 during recovery (Fig. 3).…”

Section: Energetic Cost Of Force Production In Exercising Dolphinssupporting

confidence: 50%

“…2A). These data were compared with data from performances of similarly sized dolphins freely swimming at 10 m depth in large saltwater pools while wearing a three-axis accelerometer recorder or electrocardiogram (ECG)-accelerometer (ACC) recorder (Williams et al, 2015a …”

Section: Materials and Methods Animals And Experimental Designmentioning

confidence: 99%

“…Individual dives were randomly divided into submerged resting or swimming trials ranging in duration from 1 to 6.5 min with the dolphins selecting preferred speeds for swimming. In a subset of trials the dolphins were trained to wear a submersible three-axis accelerometer recorder (3×2.5×0.5 cm, Hobo Pendant G Waterproof Data Logger, Onset Computer Corporation, Bourne, MA, USA) attached to a neoprene and Velcro strap worn around the peduncle, or a custom-designed heart rate unit (16 cm long×3 cm diameter tube, ECG-ACC depth recorder; UUB/4-EIAP ECG/IBI/Acceleration/Pressure Recording System, UFI, Morro Bay, CA, USA) in a neoprene vest (Williams et al, 2015a). Signals from each transducer were recorded at 50-100 Hz.…”

Section: Energetic Cost Of Force Production In Exercising Dolphinsmentioning

confidence: 99%

“…Signals from each transducer were recorded at 50-100 Hz. Two suction cup electrodes (5 cm diameter with a 2 cm diameter silver plate electrode) were used for ECG monitoring as described in Williams et al (2015a). To avoid potential complications with additional drag owing to the vest, the lowprofile peduncle accelerometer was used during trials when oxygen consumption was measured for assessment of stroking costs.…”

Section: Energetic Cost Of Force Production In Exercising Dolphinsmentioning

confidence: 99%

See 2 more Smart Citations

Swimming and diving energetics in dolphins: a stroke-by-stroke analysis for predicting the cost of flight responses in wild odontocetes

Williams

Kendall

Richter

et al. 2017

Journal of Experimental Biology

Self Cite

View full text Add to dashboard Cite

Exponential increases in hydrodynamic drag and physical exertion occur when swimmers move quickly through water, and underlie the preference for relatively slow routine speeds by marine mammals regardless of body size. Because of this and the need to balance limited oxygen stores when submerged, flight (escape) responses may be especially challenging for this group. To examine this, we used open-flow respirometry to measure the energetic cost of producing a swimming stroke during different levels of exercise in bottlenose dolphins (Tursiops truncatus). These data were then used to model the energetic cost of high-speed escape responses by other odontocetes ranging in mass from 42 to 2738 kg. The total cost per stroke during routine swimming by dolphins, 3.31± 0.20 J kg ), representing the cost of moving the flukes, revealed that LC during routine swimming increased with body mass (M ) for odontocetes according to LC=1.46±0.0005M; a separate relationship described LC during high-speed stroking. Using these relationships, we found that continuous stroking coupled with reduced glide time in response to oceanic noise resulted in a 30.5% increase in metabolic rate in the beaked whale, a deep-diving odontocete considered especially sensitive to disturbance. By integrating energetics with swimming behavior and dive characteristics, this study demonstrates the physiological consequences of oceanic noise on diving mammals, and provides a powerful tool for predicting the biological significance of escape responses by cetaceans facing anthropogenic disturbances.

show abstract

Vertebrate Respiration and Circulation in Extreme Conditions

Lillywhite¹

2021

Encyclopedia of Life Sciences

View full text Add to dashboard Cite

The, acquisition and internal transport of respiratory gases and metabolic fuels depend on linked processes, with design and function related to energetic demands and attributes of the environment. Environmental challenges to these processes reflect variation in the density of gases, temperature and the pressures that prevail in the environmental medium. The limits of vertebrate survival and performance are tested in environments of low oxygen such as soil, mud or water in which animals overwinter sometimes at freezing temperatures; high altitude where the atmospheric density of oxygen is low; and the deeper reaches of ocean where pressure and distance challenge the physiology of air‐breathing vertebrates. Cardiorespiratory functions are also limited by the metabolic demands of animals related to body size, temperature, activity and gravity, which also impacts features of morphology and behaviour. Responses of vertebrates to physical environmental challenges are related to phylogenetic evolutionary changes and include both plasticity of adjustments and genetic/genomic changes influencing form and function, including molecular underpinnings. Key Concepts Aerobic cellular respiration requires internal transport of fuels, oxygen and carbon dioxide, which are exchanged with the external environment and at greater rates during exercise or activity involving muscles. The rate of energy expenditure, or metabolism, per unit of body mass decreases with increasing body size, while increasing with temperature and level of activity. The functional capacities of each step in oxygen transport are matched to each other, and the upper limits to aerobic capacity depend on the integrated function of the linked steps in oxygen transport, rather than any single factor. Saving of energy is related to lowering of body temperature, suppression of metabolism, behavioural reduction of activity and molecular adjustments in fuel usage, among other factors. Countermeasures to gravity's ‘pull’ on blood circulation include tight tissues, relatively nondistending blood vessels, effective neurogenic control of heart and blood vessels and anatomical or behavioural reduction in the vertical length of blood vessels. Increasing altitude reduces the density of oxygen, reduces temperature, increases the diffusion of gases and increases evaporative water loss. The pressure in a fluid column increases with depth as a result of gravity, and increasing pressures in deep water columns compress air spaces, alter the structure of proteins and function of enzymes and decrease the fluidity of membranes. Atmospheric hypoxia limits the distributional range and performance of vertebrates at higher altitudes. Responses to hypoxia may increase the cardiac output and blood flow to tissues, increase the growth of blood vessels, increase blood oxygen capacity and circulating blood volume and adjust metabolic pathways to favour increased efficiency of ATP production. Compared with mammals, birds have superior ability to acquire O 2 and to maintain blood flow to the brain during hypoxia when levels of CO 2 in the blood are reduced. The survival of overwintering ectothermic vertebrates at subzero temperatures is aided by behavioural, physiological and biochemical adaptations that enable animals either to avoid freezing or to tolerate some portion of their body fluids being converted to ice, which is managed by cryoprotectants and antifreeze proteins. Routine dives of diving vertebrates are aerobic, but glycolysis supplements the energy requirements during prolonged submergence or repetitive dives of some species, as well as the low metabolic needs of turtles and frogs hibernating at low temperatures. Vertebrate adaptations for diving deeply include enhanced oxygen reserves primarily in blood, circulation of blood principally to brain and heart, smaller volumes and collapse of the lung to minimize problems associated with buoyancy and the entry into blood of pressurized pulmonary nitrogen, which leads to embolism and the debilitating condition known as the bends. In sea snakes, cardiovascular shunts ‘meter’ the lung oxygen store, lower the partial pressure of oxygen in blood and enable the loss of nitrogen while minimizing the loss of oxygen across the skin.

show abstract

Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals

Cited by 89 publications

References 39 publications

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions

Swimming and diving energetics in dolphins: a stroke-by-stroke analysis for predicting the cost of flight responses in wild odontocetes

Vertebrate Respiration and Circulation in Extreme Conditions

Contact Info

Product

Resources

About