Population dynamics model of Euterpina acutifrons (Copepoda. Harpacticoida) coupling individual growth and larval development
Résumé
A mathematical model of population dynamics is proposed which embodies the principal biological processes involved in the energetic budget of Euterpina acutifrons Dana (Copepoda: Harpacticoida): ingestion, excretion, egestion, and reproduction. The model proposes functional connections between growth and development through the larval instars. The major hypotheses are: (1) weight and cumulated specific growth rate control the molting process; (2) molting occurs at fixed weights which are independent of temperature; (3) temperature influences only the ingestion process according to a constant Qlo rule. Simulations fit satisfactorily with the development of E. acutifrons followed experimentally in different conditions of temperature and food concentration. Growth was sigmoidal, the major weight increase being between stage C5 and adult. The model reveals Q l o values for growth and development between 10 and 25°C which are constant and similar, and higher than the Q , , for ingestion. According to the hypotheses put forward, growth is potentially exponent~al over a wide range of food and temperature. Equiproportional development was found for E, acutjfrons. The model is used to test the effects of vanation of food and predators on the recruitment of a population of E acutifrons. Because of the number and nonlinearity of interactions between biological processes governing development, only a sophisticated model incorporating both physiological and developmental processes is able to predict the effect of simultaneous external forcing variables on the population success.
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