SPECIAL menu:   metabolism

  •    METABOLIC ALLOMETRY....     You can use this calculator to estimate metabolic rates and the necessary flow rate (in air or water) for respirometry, based on the maximum tolerable change in oxygen concentration and the size, taxa, and activity of the animal under study.

           The initial popup menu contains some very generalized equations, and also allows you to switch to submenus for specific taxa (arthropods, fish, birds, mammals, etc.).  For most taxa, several different equations are available from different literature sources.  You can also pick an approximate level of activity (resting, moderately active, etc.) -- but be aware that these are estimates based on the allometry of resting metabolism.  The effects of temperature can be included with the Q10 value and body temperature data (see next section for more detail).

  •   Q10 ADJUSTMENT…     This calculates the effect of temperature (Q10) on the rate of reactions or functions -- speed, power, metabolism, etc.   To do that, enter a base temperature and an adjusted temperature, the base value of the rate function, and the Q10 (the default is 2.2), and click the 'compute adjusted value' button.   Alternately, enter the base and adjusted temperatures and the base and adjusted rate values, and compute Q10 by clicking the 'compute Q10. button.   Q10 is the factorial change in rate across a 10 °C temperature change.   The temperature difference (base temperature to adjusted temperature) can be positive or negative.

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  •    CLOSED SYSTEM RESPIROMETRY...     This calculator computes rates of oxygen consumption (VO2) and/or carbon dioxide production (VCO2) in air or other breathable gas mixture in a closed system (i.e, the animal is sealed in an air-tight chamber for some time and metabolism is computed by the change in concentration of O2 and CO2 between initial and final gas samples). You need to enter:
    • chamber temperature, pressure, and relative humidity (when sealed, not at the end of measurements).
    • chamber volume
    • elapsed time (between taking the initial and final gas samples)
    • initial fractional concentrations of O2 (FiO2) and CO2 (FiCO2)
    • the change in concentration (in percent) of oxygen and/or CO2, and the respiratory quotient (RQ)
    If you measure only one of these two gas species, the program will use RQ to estimate the other. If you measure both O2 and CO2 concentration changes, the program will optionally use O2 in the calculation of VCO2. NOTE: it is assumed that sample gas is dried before measurement, and the default settings are:
    • Initial O2 concentration (FiO2) = .2095
    • Initial CO2 concentration (FiCO2) = .0004
    • CO2 is absorbed prior to O2 measurement
    • VCO2 is computed from VO2, if oxygen is measured, or from RQ otherwise

    Equations notes:
    • STP = standard temperature and pressure (0°C, 760 torr)
    • Δ[O2] = fractional change in O2 concentration
    • Δ[CO2] = fractional change in CO2 concentration
    • FeO2 = FiO2 - Δ[O2]
    • FeCO2 = FiCO2 + Δ[CO2]
    VO2 equations:
    • CO2 is absorbed: VO2 = STP volume * Δ[O2] /(1 - FeO2)
    • CO2 NOT absorbed, compute from Δ[CO2]: VO2 = STP volume * (Δ[O2] - (FeO2 * Δ[CO2])/(1 - FeO2)
    • CO2 NOT absorbed, compute from RQ: VO2 = STP volume * (Δ[O2] /(1 - FeO2 * (1-RQ))
    VCO2 equations: NOTE: at typical Δ[CO2], different equations have little effect on calculated VCO2
    • from RQ: VCO2 = STP volume * Δ[CO2]/(1 - FeCO2 * (1-(1/RQ)))
    • from VO2: VCO2 = STP volume * (Δ[CO2] - (FeCO2 * VO2))/(1 - FeCO2)

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