 Dynamic Energy Budget Theory - I Tânia Sousa with contributions from :Bas Kooijman

 Energy flows vs. Mass flows  Fluxes  Parameters  State Variables

 Exercises

  Metabolism in a DEB individual.  Rectangles are state variables  Arrows are flows of food J XA, reserve J EA, J EC, J EM, J ET, J EG, J ER, J EJ or structure J VG.  Circles are processes  The full square is a fixed allocation rule (the kappa rule)  The full circles are the priority maintenance rule. A DEB organism Assimilation, dissipation and growth M V - Structure Feeding M H - Maturity Assimilation M E - Reserve Mobilisation Offspring M ER Somatic Maintenance Growth Maturity Maintenance Reproduction Maturation

  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: CO 2, H 2 O, O 2 and N waste 3 types of aggregated chemical transformations

  Obtain the aggregated chemical reactions for assimilation, dissipation and growth considering that the chemical compositions are: food CH 1.8 O 0.5 N 0.2, reserve CH 2 O 0.5 N 0.15, faeces CH 1.8 O 0.5 N 0.15, structure CH 1.8 O 0.5 N 0.15 and NH 3.  Identify in these equations y XE, y PE and y EV.  Constraints on the yield coeficients  Degrees of freedom Exercises

  The stoichiometry of the aggregate chemical transformation that describes the organism has 3 degrees of freedom: any flow produced or consumed in the organism is a weighted average of any three other flows

 Exercises  Indirect calorimetry (estimating heat production without mesuring it) : Dissipating heat is weighted sum of three mass flows: CO 2, O 2 and nitrogeneous waste (Lavoisier in the XVIII century).

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

  Definition:  O 2 consumption that is associated with assimilation per unit of ingested food  Strange name relates to common practice to take p T+  J O which generally does not hold true  Exercise: What is the relationship between O2 consumption and heat production Heat increment of feeding

 Metabolic rates: the effect of temperature  The Arrhenius relationship has good empirical support  The Arrhenius temperature is given by minus the slope: the higher the Arrhenius temperature the more sensitive organisms are to changes in temperature ln rate 10 4 T -1, K -1 reproduction young/d ingestion 10 6 cells/h growth, d -1 aging, d -1 Daphnia magna  All metabolic rates depend on temperature and all depend on the same way (evolutionary principle)