Dynamic Energy Budget Theory - I

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

2. A TheoryofMetabolism • Whatismetabolism?

3. A TheoryofMetabolism • Whatismetabolism? • “Using resources (energy and materials) to make new cells, to repair old ones, and to get rid of wastes requires the assemblage of biochemical pathways that we call metabolism. Metabolism is a universal feature of life that links organisms with their environment, and with each other.”

4. A TheoryofMetabolism • Whatismetabolism? • “Using resources (energy and materials) to make new cells, to repair old ones, and to get rid of wastes requires the assemblage of biochemical pathways that we call metabolism. Metabolism is a universal feature of life that links organisms with their environment, and with each other.” • Whatshould a theoryofmetabolism look like?

5. A TheoryofMetabolism • Whatismetabolism? • Whatshould a theoryofmetabolism look like? • Itshouldbe a qualitativeandquantitativedescriptionofhoworganisms use massandenergy to do thethingstheyneed to do to stay alive

6. A TheoryofMetabolism • Whatismetabolism? • Whatshould a theoryofmetabolism look like? • Itshouldbe a qualitativeandquantitativedescriptionofhoworganisms use massandenergy to do thethingstheyneed to do to stay alive • Whichtypeofquestions can a theoryofmetabolismhelpyouwith?

7. A TheoryofMetabolism • Whatismetabolism? • Whatshould a theoryofmetabolism look like? • Whichtypeofquestions can a theoryofmetabolismhelpyouwith? • Whatistheminimumamountoffood (and habitat) a panda needs to survive? • Ifthetemperatureofoceanincreasesby 0.5ºC whatwillhappen to thesurvivalofthesardinelarvae?

8. EnvironmentalApplications • Toxicology • Which is the toxicity of the environmental concentration of a compound? • Which are the toxic effects of a compound? • Climate Change • Will an increase in 1ºC have a drastic impact on the distribution range of a species? • Waste water treatment plant • What are the necessary conditions to mantain an healthy microbian comunity in the biological reactors? • Fisheries Management • Whatisthesustainablefishing quota?

9. MinimataDisaster: Mercury Poisoning • Minamata is a small factory town dominated by the Chisso Corporation. The town faces the Shiranui Sea, and Minamata Bay is part of this sea. • Chisso Corporation started developing plastics, drugs, and perfumes through the use of a chemical called acetaldehyde in 1932. Acetaldehyde is produced using mercury as a compound, and was key component in the production of their products. • In the mid-1950's people begin to notice a "strange disease". Victimswere diagnosed as having a degeneration of their nervous ystems.

10. Human-made toxicants • Wide variety of uses • paints, detergents, solvents, pesticides, pharmaceuticals, polymers, … • probably some 100.000 compounds • Chemical industry is BIG business! • production value 2009: 3.4 trillion dollar (3.400.000.000.000 $) • equals the GDP of Germany • All are toxic, some are intended to kill • fungicides, insecticides, herbicides, nematicides, molluscicides, …

11. Human-made & natural toxicant Dioxins • e.g., 2,3,7,8-TCDD • human: paper and fiber bleaching, incineration of waste, metal smelting, cigarette smoke • natural: incomplete combustion of chlorine-containing things

12. Natural toxicants: defense Oleandrin • oleander (Nerium oleander) • gastrointestinal and cardiac effects, skin irritation, CNS effects (coma), death

13. Human-made vs. natural What is the difference? • Time scale • major increase after second world war • rapid development of new types of molecules • Spatial scale • amounts emitted • landscape and even global instead of local • Since 1970’s, most countries have programmes for environmental protection ...

14. Ecotoxicology • Daphnia reproduction test OECD guideline 211

15. Reproduction test

16. Reproduction test

17. Reproduction test wait for 21 days …

18. Range of Concentrations

19. EC50 NOEC Dose-response plot total offspring log concentration

20. If EC50 is the answer … … what was the question? “What is the concentration of chemical X that leads to 50% effect on the total number of offspring of Daphnia magna (Straus) after 21-day constant exposure under standardised laboratory conditions?” • What does this answer tell me about other situations? • (almost) nothing!

21. Organisms are complex… • Response to stress depends on • organism (species, life stage, sex, …) • endpoint (size, reproduction, development, …) • type of stressor (toxicant, radiation, parasites, …) • exposure scenario (pulsed, multiple stress, …) • environmental conditions (temperature, food, …) • etc., etc.

22. E.g., effect on reproduction

23. E.g., effect on reproduction

24. E.g., effect on reproduction

25. E.g., effect on reproduction

26. E.g., effect on reproduction • To understand an effect on reproduction … • need to know how food is used to make offspring • and how chemicals interfere with this process

27. Why is DEB important for toxicity? • The use of DEB theory allows extrapolation of toxicity test results to other situations and other species • To study the effects of toxicity on life-history traits, DEB follows naturally • food is used to fuel all traits over the life cycle • toxicants affect DEB parameters • should allow extrapolation to untested conditions • it is valuable for environmental risk assessment

28. Whatis DEB theory? • It captures thequantitativeaspectsofmetabolismatthe individual level for allspecies • Whythehope for generality? • universalityofphysicsandevolution • Entropyproductionis >=0 • widespreadbiologicalempiricalpatterns

29. A widespreadbiologicalempiricalfact: VonBertalanffygrowth • Growth as a function of time • Depends on length at birth, maximum length and growth rate • It was proposed in 1929 by Putter and in 1938 by Von Bertalanffy

30. A widespreadbiologicalempiricalfact:Kleiber’sLaw • Metabolism (respiration or heat production) as a function of mass • Metabolism increases with weigth raised to the power 3/4 • Max Kleiber originally formulated this basic relationship back in the 1930s.

31. A widespreadbiologicalempiricalfact:IndirectCalorimetry • Indirect calorimetry calculates heat that living organisms produce from their production of carbon dioxide and nitrogen waste and from their consumption of oxygen. • Lavoisiernoted in 1780 that heat production can be predicted from oxygen consumption this way, using multiple regression.

32. Basic concepts in DEB Theory • Consistencywithotherscientificknowledge (thermodynamics, evolution, etc) • Consistencywithempirical data • Life-cycleapproach: embryo, juvenileandadult • Occam’srazor: the general modelshouldbe as simple as possible (andnot more)

33. Basic Concepts in DEB Theory • The individual: time andspatialscales Volume log10m3 30 Life span log10a earth 20 10 life on earth whale whale 0 bacterium ATP molecule -10 bacterium -20 water molecule -30

34. A DEB organism • Metabolism in a DEB individual. • The boundary of the organism • Rectangles are state variables ME- Reserve MV - Structure MH - Maturity

35. DEB model: theStateVariables • What defines a DEB organism? • Biomass • Mv - MassofStructure • ME- MassofReserve • Life-Cycleapproach: differentlifestages • MH- LevelofMaturity (itrepresentsneithermassnorenergy) • Whataboutotherpossiblesstatevariablessuch as age?

36. Why not age as a state variable? Trichopsis vittatus These gouramis are from the same nest, they have the same age and lived in the same tankSocial interaction during feeding caused the huge size differenceAge-based models for growth are bound to fail; growth depends on food intake

37. DEB model: Reserve andStructure • Stronghomeostasis • Reserve & Structurehaveconstantaggregatedchemicalcomposition • Why more than 1 statevariable to define thebiomass? • Theaggregatedchemicalcompositionoforganismsisnotconstant – itchangeswiththegrowth rate • Whynot more than 2 statevariables to define biomass? • Two are sufficient (in animalsandbacteria) to capture thechange in aggregatedchemicalcompositionwiththegrowth rate • Stronghomeostasis -> highercontrolovermetabolism

38. Whynot use thousandsofchemicalspeciesandchemicalreactions to define theorganism? • Metabolismatthechemicallevelisverycomplex • Itisnotpossible to imposemassconservationwithoutmodelingallchemicalreactions (whichisimpossible).

39. DEB model: Reserve andStructure • Weakhomeostasis • Atconstantfoodorganismstend to constantaggregatedchemicalcomposition • Empiricalsupport: growingbiomasstends to constantchemicalcompositionatconstantfood • Weakhomeostasis -> highercontrolovermetabolism

40. DEB model: Maturity • LifeStages (darkblue) andtransitions (light blue) • Essentialswitchpoints for metabolicbehavior • Birth (startoffeeding) • Puberty (startofallocation to reproduction) • Switchpointssometimes in reversedorder (aphids) embryo juvenile adult baby infant weaning fertilization birth death puberty MHb- thresholdofmaturityatbirth MHp- thresholdofmaturityatpuberty

41. Life-stages: Metamorphosis

42. MHb - Extremes in relative maturity at birth Didelphus marsupiales (Am opossum) ♂, ♀ 0.5 + 0.5 m, 6.5 kg At birth: <2 g; ab = 8-13 d 10-12 (upto 25) young/litter, 2 litters/a Ommatophoca rossii (Ross Seal) ♂ 1.7-2.1 m, 129-216 kg ♀ 1.3-2.2 m, 159-204 kg At birth: 1 m, 16.5 kg; ab = 270 d

43. Notation 1

44. Notation 2 General Indices for compounds Indices for transformations

45. A DEB organism • 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 Feeding ME- Reserve Assimilation MV - Structure MH - Maturity

46. Feeding & Assimilation • Feeding: theuptakeoffood • Assimilation: conversionofsubstrate (food, nutrients, light) into reserve(s) • Dependsonsubstrateavailability& structuralsurfacearea (e.g. surfaceareaofthegut) - surfacemaximumassimilation rate -yield of reserve onfood • Empiricalpattern: theheatincrementoffeedingsuggeststhatthere are processes onlyassociatedwithfoodprocessing • Stronghomeostasisimposes a fixedconversionefficiency • Consistencywithotherfields: masstransfer (needed for acquisition, digestionandfoodprocessing) isproportional to area

47. Feeding rate • Iffoodavailabilityisconstant (orabundant) feedingincreasesproportional to areaor L2 (for isomorphs) Filtration rate, l/h Mytilus edulis Data: Winter 1973 Length, cm

48. Intra-taxon predation: efficient conversionyEX a high yield of reserve on food Hemiphractus fasciatus is a frog-eating frog Beroe sp is a comb jelly-eating comb jelly Solaster papposus is a starfish-eating starfish Chrysaora hysoscella is a jelly fish-eating jelly fish Coluber constrictor is a snake-eating snake Euspira catena is a snail-eating snail

49. Intra-taxon predation: efficient conversionyEX a high yield of reserve on food Asplanchna girodi is a rotifer-eating rotifer Didinium nasutum is a ciliate-eating ciliate Esox lucius is a fish-eating fish Acinonyx jubatus is a mammal-eating mammal Enallagma carunculatum is a insect-eating insect Falco peregrinus is a bird-eating bird

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