Blood O2 affinity of a large polar elasmobranch, the Greenland shark Somniosus microcephalus

Herbert, Neill A.; Skov, Peter Vilhelm; Tirsgaard, Bjørn; Bushnell, Peter G.; Brill, Richard W.; Clark, Caira; Steffensen, John F.

doi:10.1007/s00300-017-2142-z

Cited by 27 publications

(3 citation statements)

References 33 publications

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“…In addition, some residents of OMZs possess adaptations to increase gill diffusion capacities in order to facilitate oxygen uptake in low oxygen conditions including large gill surface areas and thin blood-to-water diffusion distances [17,18,72,79]. Identifying the oxygen partial pressures (pO 2 ) at which blood is 50% saturated (P 50 ) (e.g., [80]) and the pO 2 at which sixgill sharks can no longer maintain aerobic metabolism at a level independent of ambient pO 2 (P crit ) [18] will better define the oxygen tolerance of sixgill sharks, though the latter is technically challenging for large-bodied species, particularly in the deep-sea.…”

Section: Discussionmentioning

confidence: 99%

Diel patterns in swimming behavior of a vertically migrating deepwater shark, the bluntnose sixgill (Hexanchus griseus)

et al. 2020

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Diel vertical migration is a widespread behavioral phenomenon where organisms migrate through the water column and may modify behavior relative to changing environmental conditions based on physiological tolerances. Here, we combined a novel suite of biologging technologies to examine the thermal physiology (intramuscular temperature), fine-scale swimming behavior and activity (overall dynamic body acceleration as a proxy for energy expenditure) of bluntnose sixgill sharks (Hexanchus griseus) in response to environmental changes (depth, water temperature, dissolved oxygen) experienced during diel vertical migrations. In the subtropical waters off Hawai'i, sixgill sharks undertook pronounced diel vertical migrations and spent considerable amounts of time in cold (5-7˚C), low oxygen conditions (10-25% saturation) during their deeper daytime distribution. Further, sixgill sharks spent the majority of their deeper daytime distribution with intramuscular temperatures warmer than ambient water temperatures, thereby providing them with a significant thermal advantage over non-vertically migrating and smaller-sized prey. Sixgill sharks exhibited relatively high rates of activity during both shallow (night) and deep (day) phases and contrary to our predictions, did not reduce activity levels during their deeper daytime distribution while experiencing low temperature and dissolved oxygen levels. This demonstrates an ability to tolerate the low oxygen conditions occurring within the local oxygen minimum zone. The novel combination of biologging technologies used here enabled innovative in situ deep-sea natural experiments and provided significant insight into the behavioral and physiological ecology of an ecologically important deepwater species.

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Section: Discussionmentioning

confidence: 99%

Diel patterns in swimming behavior of a vertically migrating deepwater shark, the bluntnose sixgill (Hexanchus griseus)

et al. 2020

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“…Blood pH was unchanged during the relatively short (1 hr) period of hyperoxia exposure in this study. Thus in the absence of a Bohr shift, a characteristic feature of elasmobranchs (Herbert et al., 2017), it is likely Hb‐O 2 saturation in arterial blood was unchanged or increased relative to normoxia. In the wels catfish ( S. glanis ), due to stable PaO 2 , PvO 2, and blood pH, the arterio‐venous O 2 content difference was unchanged after 24 hr exposure to moderate hyperoxia (186% air sat.)…”

Section: The Effects Of Hyperoxia On the Oxygen Transport Cascadementioning

confidence: 99%

Fish and hyperoxia—From cardiorespiratory and biochemical adjustments to aquaculture and ecophysiology implications

2020

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Hyperoxia occurs when water oxygen (O2) levels exceed normal atmospheric pressure (i.e., >100% air saturation). Fish can experience hyperoxia in shallow environments due to photosynthesis or in aquaculture through O2 supplementation. This review provides a comprehensive synthesis of the effects of hyperoxia on fish, spanning influences on cardiorespiratory function, acid‐base balance, oxidative stress and whole animal performance (e.g., thermal tolerance and growth). Fish hypoventilate in hyperoxia, but arterial and venous blood oxygenation increases in spite of reduced convection. Persistently high levels of blood oxygenation in hyperoxia do not commonly result in reduced blood O2 carrying capacity, but assessments in undisturbed fish are required to clarify this. Hypoventilation also causes the retention of carbon dioxide, hence respiratory acidosis. Another consequence of hyperoxia is increased levels of oxidative stress and concomitant changes to antioxidant defence systems. Despite these changes, however, the bulk of evidence shows no effect of hyperoxia on growth. Hyperoxia does impact the aerobic metabolic rate of fish with either no effect or elevated resting metabolic rate and substantial increases in maximum metabolic rate. There is also evidence that hyperoxia increases aerobic capacity improves cardiac performance and mitigates anaerobic stress during acute warming. Along with improved upper thermal tolerance in some species, these findings collectively suggest that hyperoxia might provide fish a metabolic refuge during acute warming. Since hyperoxia occurs in shallow aquatic habitats, further research establishing the ecophysiological implications of concomitant heat stress and hyperoxia is pertinent, particularly with a changing climate.

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“…Greenland sharks (Somniosus microcephalus) live in deep, cold water in high northern latitudes, grow to a large size (>5 m), have a lifespan of hundreds of years (Hansen, 1963;Nielsen et al, 2016) and appear to be very sluggish with little capacity for sustained high-speed swimming (Compagno et al, 2005;Watanabe et al, 2012;Nielsen et al, 2016). Although one of the largest extant marine fish, knowledge of their life history, ecology and physiology is very limited (MacNeil et al, 2012;Herbert et al, 2017;Costantini et al, 2017). There are virtually no in vivo measurements of physiological parameters from this species, because of the difficulty of obtaining and handling specimens.…”

Section: Introductionmentioning

confidence: 99%

Blood pressure in the Greenland shark as estimated from ventral aortic elasticity

Shadwick

Bernal

Bushnell

et al. 2018

Journal of Experimental Biology

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We conducted inflations of freshly excised ventral aortas of the Greenland shark,, and used pressure-diameter data to estimate the point of transition from high to low compliance, which has been shown to occur at the mean blood pressure in other vertebrates including fishes. We also determined the pressure at which the modulus of elasticity of the aorta reached 0.4 MPa, as occurs at the compliance transition in other species. From these analyses, we predict the average ventral aortic blood pressure in to be about 2.3-2.8 kPa, much lower than reported for other sharks. Our results support the idea that this species is slow moving and has a relatively low aerobic metabolism. Histological investigation of the ventral aorta shows that elastic fibres are present in relatively low abundance and loosely connected, consistent with this aorta having high compliance at a relatively low blood pressure.

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Blood O2 affinity of a large polar elasmobranch, the Greenland shark Somniosus microcephalus

Cited by 27 publications

References 33 publications

Diel patterns in swimming behavior of a vertically migrating deepwater shark, the bluntnose sixgill (Hexanchus griseus)

Diel patterns in swimming behavior of a vertically migrating deepwater shark, the bluntnose sixgill (Hexanchus griseus)

Fish and hyperoxia—From cardiorespiratory and biochemical adjustments to aquaculture and ecophysiology implications

Blood pressure in the Greenland shark as estimated from ventral aortic elasticity

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