Faculty Opinions recommendation of Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

2012 ◽  
Author(s):  
Charles Hawkins
Keyword(s):  
Partial Pressure ◽  
Oxygen Supply

scholarly journals Oxygen supply capacity breathes new life into critical oxygen partial pressure (Pcrit)

2021 ◽  
Vol 224 (8) ◽  
Author(s):  
Brad A. Seibel ◽  
Alyssa Andres ◽  
Matthew A. Birk ◽  
Alexandra L. Burns ◽  
C. Tracy Shaw ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Supply ◽  
Accurate Determination ◽  
Maximum Energy ◽  
Hypoxia Tolerance ◽  
Energy Demands ◽  
Critical Oxygen ◽  
Supply Capacity

ABSTRACT The critical oxygen partial pressure (Pcrit), typically defined as the PO2 below which an animal's metabolic rate (MR) is unsustainable, is widely interpreted as a measure of hypoxia tolerance. Here, Pcrit is defined as the PO2 at which physiological oxygen supply (α0) reaches its maximum capacity (α; µmol O2 g−1 h−1 kPa−1). α is a species- and temperature-specific constant describing the oxygen dependency of the maximum metabolic rate (MMR=PO2×α) or, equivalently, the MR dependence of Pcrit (Pcrit=MR/α). We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The MR need not be constant (regulated), standardized or exhibit a clear breakpoint at Pcrit for accurate determination of α. The α-method has several advantages over Pcrit determination and non-linear analyses, including: (1) less ambiguity and greater accuracy, (2) fewer constraints in respirometry methodology and analysis, and (3) greater predictive power and ecological and physiological insight. Across the species evaluated here, α values are correlated with MR, but not Pcrit. Rather than an index of hypoxia tolerance, Pcrit is a reflection of α, which evolves to support maximum energy demands and aerobic scope at the prevailing temperature and oxygen level.

scholarly journals Oxygen supply capacity in animals evolves to meet maximum demand at the current oxygen partial pressure regardless of size or temperature

2019 ◽  
Author(s):  
Brad A. Seibel ◽  
Curtis Deutsch
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Thermal Tolerance ◽  
Oxygen Supply ◽  
Cardiovascular Health ◽  
Hypoxia Tolerance ◽  
Aerobic Scope ◽  
Supply Capacity

AbstractPhysiological oxygen supply capacity is associated with athletic performance and cardiovascular health and is thought to cause hypometabolic scaling in diverse species. Environmental oxygen is widely believed to be limiting of metabolic rate and aerobic scope, setting thermal tolerance and body size limits with implications for species diversity and biogeography. Here we derive a quantifiable linkage between maximum and basal metabolic rate and their temperature, size and oxygen dependencies. We show that, regardless of size or temperature, the capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure which, for most species assessed, is the current atmospheric pressure. Any reduction in oxygen partial pressure from current values will result in a decrement in maximum metabolic performance. However, oxygen supply capacity does not constrain thermal tolerance and does not cause hypometabolic scaling. The critical oxygen pressure, typically viewed as an indicator of hypoxia tolerance, instead reflects adaptations for aerobic scope. This simple new relationship redefines many important physiological concepts and alters their ecological interpretation.One sentence summary: Metabolism is not oxygen limited

scholarly journals Oxygen supply in aquatic ectotherms: Partial pressure and solubility together explain biodiversity and size patterns

Ecology ◽  
2011 ◽  
Vol 92 (8) ◽  
pp. 1565-1572 ◽  
Author(s):  
Wilco C. E. P. Verberk ◽  
David T. Bilton ◽  
Piero Calosi ◽  
John I. Spicer
Keyword(s):  
Partial Pressure ◽  
Oxygen Supply

scholarly journals Breathing new life into the critical oxygen partial pressure (Pcrit): a new definition, interpretation and method of determination

2020 ◽  
Author(s):  
B. A. Seibel ◽  
A. Andres ◽  
M. A. Birk ◽  
A. L. Burns ◽  
C. T. Shaw ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Supply ◽  
Break Point ◽  
Standard Metabolic Rate ◽  
Hypoxia Tolerance ◽  
Additional Species ◽  
Critical Oxygen ◽  
Mechanistic Basis

AbstractThe critical oxygen partial pressure (Pcrit) is most commonly defined as the oxygen partial pressure below which an animal’s standard metabolic rate can no longer be maintained. It is widely interpreted as measure of hypoxia tolerance, which influences a species’ aerobic scope and, thus, constrains biogeography. However, both the physiology underlying that interpretation and the methodology used to determine Pcrit remain topics of active debate. The debate remains unresolved in part because Pcrit, as defined above, is a purely descriptive metric that lacks a clear mechanistic basis. Here we redefine Pcrit as the PO2 at which physiological oxygen supply is maximized and refer to these values, thus determined, as Pcrit-α. The oxygen supply capacity (α) is a species- and temperature-specific coefficient that describes the slope of the relationship between the maximum achievable metabolic rate and PO2. This α is easily determined using respirometry and provides a precise and robust estimate of the minimum oxygen pressure required to sustain any metabolic rate. To determine α, it is not necessary for an individual animal to maintain a consistent metabolic rate throughout a trial (i.e. regulation) nor for the metabolic rate to show a clear break-point at low PO2. We show that Pcrit-α can be determined at any metabolic rate as long as the organisms’ oxygen supply machinery reaches its maximum capacity at some point during the trial. We reanalyze published representative Pcrit trials for 40 species across five phyla, as well as complete datasets from six additional species, five of which have not previously been published. Values determined using the Pcrit-α method are strongly correlated with Pcrit values reported in the literature. Advantages of Pcrit-α include: 1) Pcrit-α is directly measured without the need for complex statistics that hinder measurement and interpretation; 2) it makes clear that Pcrit is a measure of oxygen supply, which does not necessarily reflect hypoxia tolerance; 3) it alleviates many of the methodological constraints inherent in existing methods; 4) it provides a means of predicting the maximum metabolic rate achievable at any PO2, 5) Pcrit-α sheds light on the temperature- and size-dependence of oxygen supply and metabolic rate and 6) Pcrit-α can be determined with greater precision than traditional Pcrit.

scholarly journals Kinetic bottlenecks to chemical exchange rates for deep-sea animals – Part 1: Oxygen

2012 ◽  
Vol 9 (10) ◽  
pp. 13817-13856 ◽  
Author(s):  
A. F. Hofmann ◽  
E. T. Peltzer ◽  
P. G. Brewer
Keyword(s):  
Hydrostatic Pressure ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Deep Sea ◽  
Oxygen Supply ◽  
Ocean Warming ◽  
Physico Chemical ◽  
The World ◽  
Supply Potential ◽  
The Impact

Abstract. Ocean warming will reduce dissolved oxygen concentrations which can pose challenges to marine life. Oxygen limits are traditionally reported simply as a static concentration thresholds with no temperature, pressure or flow rate dependency. Here we treat the oceanic oxygen supply potential for heterotrophic consumption as a dynamic molecular exchange problem analogous to familiar gas exchange processes at the sea surface. A combination of the purely physico-chemical oceanic properties temperature, hydrostatic pressure, and oxygen concentration defines the ability of the ocean to supply oxygen to any given animal. This general oceanic oxygen supply potential is modulated by animal specific properties such as the diffusive boundary layer thickness to define and limit maximal oxygen supply rates. Here we combine all these properties into formal, mechanistic equations defining novel oceanic properties that subsume various relevant classical oceanographic parameters to better visualize, map, comprehend, and predict the impact of ocean deoxygenation on aerobic life. By explicitly including temperature and hydrostatic pressure into our quantities, various ocean regions ranging from the cold deep-sea to warm, coastal seas can be compared. We define purely physico-chemical quantities to describe the oceanic oxygen supply potential, but also quantities that contain organism-specific properties which in a most generalized way describe general concepts and dependencies. We apply these novel quantities to example oceanic profiles around the world and find that temperature and pressure dependencies of diffusion and partial pressure create zones of greatest physical constriction on oxygen supply typically at around 1000 m depth, which coincides with oxygen concentration minimum zones. In these zones, which comprise the bulk of the world ocean, ocean warming and deoxygenation have a clear negative effect for aerobic life. In some shallow and warm waters the enhanced diffusion and higher partial pressure due to higher temperatures might slightly overcompensate for oxygen concentration decreases due to decreases in solubility.

Sign in / Sign up

Export Citation Format

Share Document