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Dynamic Energy Budget Theory - I

Dynamic Energy Budget Theory - I. Tânia Sousa with contributions from : Bas Kooijman. Energy flows vs. Mass flows. Fluxes. Parameters. =. State Variables. Exercises.

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Dynamic Energy Budget Theory - I

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  1. DynamicEnergy Budget Theory - I Tânia Sousa withcontributionsfrom : Bas Kooijman

  2. Energyflows vs. Massflows • Fluxes • Parameters = • StateVariables

  3. Exercises • What wouldbetheexpression for a parameterthatistheequivalentof for thesomaticmaintenanceassociatedwith volume? • Suggestions: • Write as a functionof - energyspent in themaintenanceofstructurebuiltwith 1 unitof reserve energy per unit time - energyspent in themaintenanceofmaturitybuiltwith 1 unitof reserve energy per unit time

  4. A DEB organismAssimilation, dissipationandgrowth • Metabolism in a DEB individual. • Rectangles are state variables • Arrows are flows of foodJXA, reserveJEA, JEC, JEM, JET, JEG, JER, JEJor structureJVG. • Circles are processes • The full square is a fixed allocation rule (the kappa rule) • The full circles are the priority maintenance rule. Feeding ME- Reserve Mobilisation Assimilation Offspring MER MaturityMaintenance Reproduction Growth SomaticMaintenance Maturation MH - Maturity MV - Structure

  5. 3 types of aggregated chemical transformations • Assimilation: X(substrate)+M  E(reserve) + M • linked to surface area • Dissipation: E(reserve) +M  M • somatic maintenance: linked to surface area & structural volume • maturity maintenance: linked to maturity • maturation or reproduction overheads • Growth: E(reserve)+M  V(structure) + M • Compounds: • Organic compounds: V, E, X and P • Mineral compounds: CO2, H2O, O2 and Nwaste

  6. Exercises • Obtain theaggregatedchemicalreactions for assimilation, dissipationandgrowthconsideringthatthechemicalcompositions are: food CH1.8O0.5N0.2, reserve CH2O0.5N0.15, faeces CH1.8O0.5N0.15,structure CH1.8O0.5N0.15and NH3. • Identify in theseequationsyXE, yPEandyEV. • Constraintsonthe yield coeficients • Degreesoffreedom

  7. Exercises • What istherelationshipbetweentheseequationsand, ,,, , and . • Compute the total consumptionof O2. • Writeit as a functionof, and . • Compute theaggregatechemicaltransformation • Thestoichiometryoftheaggregatechemicaltransformationthatdescribestheorganismhas 3 degreesoffreedom: anyflowproducedorconsumed in theorganismis a weightedaverageofanythreeotherflows

  8. Exercises • Write theenergy balance for eachchemical reactor (assimilation, dissipationandgrowth) • Compute the total metabolicheatproductionas a function of , and . • Iftheorganismtemperatureisconstantthenthemetabolicheat must beequal to theheatreleased • Indirectcalorimetry (estimatingheatproductionwithoutmesuringit) : Dissipatingheatisweighted sum ofthreemassflows: CO2, O2andnitrogeneouswaste (Lavoisier in the XVIII century).

  9. Dissipating heat Steam from a heap of moist Prunus serotina litter illustrates metabolic heat production by fungi

  10. Heat increment of feeding • Definition: • O2consumption that is associated with assimilation per unit of ingested food • Strange name relates to common practice to take pT+ JOwhich generally does not hold true • Exercise: What is the relationship between O2 consumption and heat production

  11. Metabolic rates: the effect of temperature • Allmetabolic rates dependontemperatureandalldependonthesameway (evolutionaryprinciple) Daphnia magna reproduction young/d ln rate ingestion 106 cells/h growth, d-1 • TheArrheniusrelationshiphasgoodempiricalsupport • TheArrheniustemperatureisgivenbyminustheslope: thehighertheArrheniustemperaturethe more sensitiveorganisms are to changes in temperature aging, d-1 104 T-1, K-1

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