The role of intracellular components in food chain dynamics

The dynamics of a simple food web, including multiple substrates and predat or-prey interactions, is studied. An individual-based model is presented th at describes the intracellular composition of the biomass of each populatio n with two components: reserves and structural biomass. The model describes the simultaneous uptake of multiple substrates via specific carriers and t heir assimilation into reserve energy via multiple assimilation pathways. T he available energy is used for maintenance and growth. Parameters are esti mated by curve-fitting data from the literature under the condition that th e elemental balances and the enthalpy balances are met. The proposed model provides an adequate description of the macromolecular composition of bioma ss. The model is not too complicated to be of use in the study of food webs . The consequences of the presence of intracellular components in a food we b on its long-term dynamics are investigated with bifurcation analysis. (C) 2000 Academie des sciences/ Editions scientifiques et medicales Elsevier S AS.