Modelkey: VUA-TB, WP Effect-3 Bas Kooijman Dept theoretical biology Vrije Universiteit Amsterdam 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

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

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 time, h glucose Escherichia coli Dictyostelium mg/ml mm 3 /ml cell vol,  m 3 X 0 (0)0.433mg. ml -1 X 1 (0)0.361X 2 (0)0.084mm 3.ml -1 e 1 (0)1e 2 (0)1- X K1 0.40X K g1g1 0.86g2g k M k M2 0.16h -1 k E1 0.67k E2 2.05h -1 j Xm1 0.65j Xm Data from Dent et al 1976 h = h -1, X r = 1mg ml -1, 25 °C Kooijman & Kooi,1996 Nonlin. World 3:

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)

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