1. Dynamic Energy Budget (DEB) theory by Elke, Svenja and Ben

2. Outline  What is DEB? Basic concepts and rules  Example: Food limitation  Toxicants in DEB  Example: increasing costs for reproduction, decreasing ingestion rate  But...  Why do we use DEB?

3. What is DEB? Quantitative theory; ‘first principles’ time, energy and mass balance Life-cycle of the individual links levels of organisation: molecule  ecosystems Comparison of species body-size scaling relationships; e.g., metabolic rate Fundamental to biology; many practical applications (bio)production, (eco)toxicity, climate change, … Kooijman (2010)

4. Why is DEB cool?

5. Effects on reproduction

9. Focus on energy budgets  Organisms must obey conservation laws for mass and energy  Reduced repro/growth must be reflected in budget  growth and reproduction are linked processes  need to understand how food is used to fuel these processes Currently, approaches based on energy budgets are the only ones to do this!

10. Basic rules and concepts

11. Energy budget … growth reproduction feeding maintenance maturation

12. Entire life cycle … feeding reproduction

13. DEB allocation rules foodfaeces reserves assimilation structure somatic maintenance  1-  maturity offspring maturity maintenance

14. Energy budget … growth reproduction feeding maintenance maturation 5% ad libitum

15. Energy budget … growth reproduction feeding maintenance maturation 50% limiting

16. Energy flows... foodfaeces reserves structure maturity offspring XP A = X – P S = k M V G = κ C – k M V C J = k J H R = (1 – κ) C – k J H

17. for embryos … reserves structure somatic maintenance  1-  maturity maturity maintenance

18. for juveniles … foodfaeces reserves assimilation structure somatic maintenance  1-  maturity maturity maintenance

19. for adults … foodfaeces reserves assimilation structure somatic maintenance  1-  gametes maturity maintenance reproduction buffer periodic release of eggs

20. Example: food limitation

21. Food limitation Jager et al. (2005)

22. DEB in toxicants

23. Toxicants in DEB external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time life-history traits one-compartment model, accounting for changes in body size

24. Toxicants in DEB external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time DEB parameters in time life-history traits ingestion rate maintenance rate coeff. egg costs etc. …

25. Toxicants in DEB external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time DEB parameters in time DEB model DEB model life-history traits

26. Toxicants in DEB external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time DEB parameters in time DEB model DEB model effects in time Affected DEB parameter has specific consequences for life cycle

27. external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time mixture toxicity Extrapolation external concentration (in time) toxico- kinetics toxico- kinetics internal concentration in time DEB parameters in time DEB model DEB model effects in time time-varying concentrations temperature food limitation

28. Modes of action … Standard DEBtox assimilation, maintenance, growth costs, repro costs, hazard to embryo Based on resource allocation contrasts common use (‘narcosis’, ‘uncoupling’) a MoA has a specific effect patterns on various traits effects on traits are linked!  effect on length always accompanied by effect on repro  growth affects toxicokinetics which affects toxicity  in principle, other endpoints can be included (respiration, product formation, …)

29. Examples

30. Potential targets time body length time cumulative offspring Pentachlorobenzene Alda Álvarez et al. (2006)

31. Potential targets foodfaeces reserves structure maturity offspring maturity maintenancesomatic maintenance assimilation  1- 

32. Potential targets time cumulative offspring time body length Chlorpyrifos Crommentuijn et al. (1997), Jager et al. (2007)

33. DEB analysis of data Simultaneous fit size and repro data MoA: decrease in ingestion rate 050100150 1 2 3 4 5 6 7 8 9 time (days) body length 80 120 160 200 050100150 0 5 10 15 20 25 30 35 40 time (days) cumulative offspring per female 80 120 160 200

34. DEB analysis of data Assume size-dependent feeding limitation (Jager et al, 2005) 80 120 160 200 80 120 160 200

35. What’s different? effects data individuals effects data individuals population consequences population consequences model parameters model parameters extrapolated parameters extrapolated parameters DEB-less DEB

36. What’s the use of DEB?  In-depth interpretation of effects on individual all endpoints over time in one framework indicates experimental ‘problems’ mechanism of action of compound  DEB is essential for inter- and extrapolation e.g., extrapolation to field conditions ‘repair’ experimental artefacts  Natural link with different population approaches simple (e.g., Euler-Lotka and matrix models) more complex (e.g., IBM’s)

37. But …  Strong (but explicit) assumptions are made on metabolic organisation on mechanisms of toxicity  Elaborate DEB models require strong data growth, repro and survival over (partial) life cycle e.g., Daphnia repro protocol extended with size  Almost every analysis raises more questions difficult to perform on routine basis Interesting point raised by DEB3 … hatching time and hatchling size can be affected by stress

38. Why do we use DEB?  Ben  Svenja  Elke

39. Thanks to Tjalling Jager for his nice slides! Courses International DEB Tele Course 2011 Symposia 2nd International DEB Symposium 2011 in Lisbon More information: http://www.bio.vu.nl/thb