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Metabolic products within a DEB context

This course focuses on the relationship between respiration and energy use within the context of Dynamic Energy Budget (DEB) theory. It explores the definitions and calculations of products in a DEB context using examples and data analysis. The course also discusses the application of DEB theory in marine ecology, aquaculture, and fisheries sciences.

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Metabolic products within a DEB context

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  1. Metabolic products within a DEB context Laure Pecquerie Laboratoire des Sciences de l’Environnement Marin UMR LEMAR, IRD laure.pecquerie@ird.fr 21st -22nd April 2015, DEB Course 2015, Marseille

  2. Respiration in bioenergetic models • The conceptual relationship between respiration and use of energy has changed with time. • Von Bertalanffy identified it with anabolic processes, • while e.g. a Scope For model relates it to catabolic processes • DEB theory relates it to the three transformations : assimilation, dissipation and growth (which all have an anabolic and a catabolic components) • DEB theory defines O2 consumption and CO2 production as product “formations” and not as mechanistic processes (ie fluxes driving the dynamics of the state variables)

  3. Outlinelecture 1 (Tue. 21. ) and 2 (Wed. 22.) • [A bit of networking] • Definition of products in a DEB context • Example : Torpedo marmorata • Univariate data t-L, L-W • Respiration data L-JO • Steps to calculate the respiration rate from the standard DEB expressed in an energy-length-time framework • Hard to believe at first (for me!) but true (and we gained a lot of insights from it) : otoliths and other biocarbonates are also DEB products

  4. 2005 2015 and next! • Participant of the Brest group of the 2005 DEB telecourse : 10th DEB anniversary for Jonathan, Fred, me and a few others you’ll meet • Changed the direction of my anchovy PhD project • Helped me getting an interview for a post-doc position in Santa Barbara with Roger Nisbet • Got me a job in Brest ! • Brest group: DEB applications inmarine ecology, aquaculture and fisheries sciences: 16 people! 3 assistant professors, 6 researchers, 2 associated researchers, 1 post-doc, 4 PhD students + 5 Master and PhD students in the US, Peru and Mexico  Call for Post-docs and PhD’s  contact us! Grand merci : Bas, Roger, Brest group – Jonathan, Fred, Marianne, Cédric and Véro - , and Starrlight, Dina and Gonçalo for taking me on board

  5. Respiration rate as a function of length Allometric model = 2 parameters R = aLb = 0.0516 L2.437 Daphnia pulex(Kooijman, 2010)

  6. Respiration rate as a function of length Allometric model = 2 parameters R = aLb = 0.0516 L2.437 DEB model = same number of parameters but parameters with measureable dimensions R = aL2 + bL3= 0.0336 L2 + 0.01845 L3 Daphnia pulex(Kooijman, 2010)

  7. Respiration rate as a function of length Assimilation proportional to L2 Dissipation prop to L3 Growth prop. to L2 and L3 R = aLb = 0.0516 L2.437 R = aL2 + bL3= 0.0336 L2 + 0.01845 L3 Daphnia pulex(Kooijman, 2010)

  8. Respiration in DEB theory • Weighted sum of L2 and L3 processes as product formation is a weighted sum of : • Assimilation (L2), • Dissipation(L3 - and L2) and • Growth (L3 and L2) • Definition of Dissipation : sum of somatic maintenance, maturity maintenance, development and reproduction overheads For embryos and juveniles For adults

  9. Definition of products in a DEB context

  10. Product formation can occur during one, two or all the three DEB transformations : assimilation, dissipation and growth

  11. Torpedo marmorata example • Constant food and temperature = 15°C • Weight, length and respiration data from birth to max age • Time (d), Wet weight (g) , Total length (cm), Respiration rate (mg O2 /h) • Let’s start with the first 2 univariate datasets: t-L and L-W

  12. t-L and L-W predictions • Defined inpredict_Torpedo_marmorata.m • Lw as a function of t? • Constant food  von Bertalanffy growth L_w = L_wi – (L_wi – L_wb) * exp( -r_BT * t) • L_wi? L_wb? r_BT? t? • Ww as a function of Lw ? • Constant food  constant reserve density • Ww = Ww_V + Ww_E (+ Ww_ER)

  13. predict_Torpedo_marmorata.m • t = time from birth to max age : defined in mydata_Torpedo_marmorata.m • Parameters • v: primary parameter defined in pars_init_Torpedo_marmorata.m • T_A : environmental parameter • k_M, L_m, g, k, v_Hb: computed in parscomp_st.m • del_M : auxiliary param defined in pars_init_Torpedo_marmorata.m • Environment • X  f: treated as paramdefined in pars_init_Torpedo_marmorata.m • T  TC_tL: calculated by tempcorr.mTC_tL = tempcorr(temp.tL, T_ref, T_A); • Initial conditions : at E_Hb defined in pars_init_Torpedo_marmorata.m • L_b (NOTA : E_b = f [E_m]L_b, E_Rb = 0) calculated by get_lb.mpars_lb = [g; k; v_Hb] • Lw_b = get_lb(pars_lb, f) * L_m/ del_M; • Von Bertalanffy parameters • rB = 1 / (3 kM+ 3 f L_m / v) • Lw_i = f * L_m / del_M

  14. predict_Torpedo_marmorata.m • Calculation • EL = Lw_i - (Lw_i - Lw_b) * exp( - TC_tL * r_B * tL(:,1)); • Ww_V = (EL * del_M)^3  assumption that d_V = 1 g/cm^3 for wet weight • Ww_E = (EL * del_M)^3 * f * wwith w = m_Em* w_E * d_E/ d_V/ w_V;

  15. L-JO predictions • Hold your breath, we’ll dive deeper into DEB notations!

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