Model of copepod growth influenced by the food carbon : nitrogen ratio andconcentration, under the hypothesis of strict homeostasis

This study describes a model which addresses the processes of ingestion, as similation, respiration, excretion and growth of copepods as a function of the concentration of food and its elemental composition in terms of carbon (C) and nitrogen (N). Two experimental data sets are used to estimate sever al parameters of the model concerned with the influence of food quality. Th e results of the model suggest that the concentration of food and its quali ty (i.e. the C:N ratio) largely determine copepod growth. Both the experime ntal data sets and the model output show that low carbon relative to the ni trogen content of food does not limit the production of copepods. Comparing the results of the model to those of a previous model on bacteria suggests large differences between bacterial and copepod physiological responses to a variable quality of the substrate or food. The results of these models s uggest that the regeneration of ammonium performed by copepods always favor s regenerated primary production, whereas that performed by bacteria, depen ding on the quality of assimilated substrates, can favor or limit regenerat ed production.