Modelkey: VUA-TB, WP Effect-3

Modelkey: VUA-TB, WP Effect-3 Bas Kooijman Dept theoretical biology Vrije Universiteit Amsterdam Bas@bio.vu.nl http://www.bio.vu.nl/thb/ Palma, 2005/03/02-04

Research effort by VUA-TB 2005/02 – 2009/02: PhD student (vacancy!!) Primary task: modelling effects in canonical communities/ biofilms support in experimental design and data analysis collaboration with UFZ (Mechthild Schmitt Janssen, Christina Klünder) ECT (Thomas Knacker, Markus Liebig) 2006/02 – 2008/02: Postdoc (vacancy) Primary task: modelling effects in food chains support in decisions what to measure and data analysis collaboration with VUA (Bert van Hattum)

Education effort by VUA-TB 2005/02 – 04: DEB tele course Topic: metabolic organization of organisms 2005/03/07 – 12: DEBtox crash course Topic: effects of toxicants on metabolic organisation Participation: Mechthild Schmitt Janssen, Christina Klünder, Markus Liebig, Bert van Hattum DEB = Dynamic Energy Budget

assimilation  maintenance costs defecation feeding food faeces growth costs assimilation reproduction costs reserve  hazard to embryo somatic maintenance  7 maturity maintenance  1-  maint tumour induction 6 maturation reproduction u endocr. disruption growth 7  lethal effects: hazard rate Mode of action affects translation to pop level 8 maturity offspring structure tumour 6 Modes of action of toxicants

Models for toxic effects • Tree model components: • kinetics • external concentration  internal concentration • example: one-compartment kinetics • change in target parameter(s) • internal concentration  value of target parameter(s) • example: linear relationship • physiology • value of parameter  endpoint (survival, reproduction) • example: DEB model

Hazard rate Definition: instantaneous death rate (dim: time-1) Interpretation of hazard rate times time increment: probability of death, given to be alive Relationship with survival probability for : Examples for :

DEB-based effects on reproduction • Indirect effects • indicator: effects on onset of reproduction • decrease of assimilation rate (food intake, digestion) • increase of specific maintenance costs • increase of costs for synthesis of biomass (structural) • Direct effects • indicator: no effects on onset of reproduction • increase of costs for the synthesis of offspring • decrease of survival probability at birth

Food chains n=2 glucose mg/ml Escherichia coli mm3/ml h = 0.064 h-1, Xr = 1mg ml-1, 25 °C cell vol, m3 Data from Dent et al 1976 Dictyostelium mm3/ml cell vol, m3 Kooijman & Kooi,1996 Nonlin. World3: 77 - 83 time, h time, h

1-species mixotroph community Mixotrophs are producers, which live off light and nutrients as well as decomposers, which live off organic compounds which they produce by aging Simplest community with full material cycling

Canonical community Short time scale: Mass recycling in a community closed for mass open for energy Long time scale: Nutrients leaks and influxes Memory is controlled by life span (links to body size) Spatial coherence is controlled by transport (links to body size)

biomass detritus nutrient consumer producer decomposer nutrient 1-spec. vs canon. community biomass 1-species: mixotroph community Total nitrogen Total carbon detritus nutrient consumer 3-species: canonical community Total nitrogen Total carbon producer decomposer Total carbon Total nitrogen

Modelkey: VUA-TB, WP Effect-3