Modélisation des réponses d'une population de microinvertébrés d'eau douce à des polluants induisant des effets toxiques différents sur les organismes

Titre du congrès :5th SETAC World Congress
Ville du congrès :Sydney
Date du congrès :03/08/2008

Toxic effects of ionizing radiation on survival, reproduction, and other vital functions (nutrition, respiration, and energy allocation) of the freshwater microcrustacean Daphnia magna are increasingly well-described under laboratory controlled conditions. Different radionuclides (natural U, Am-241 and Cs-137, representing respectively dominant chemotoxicity, internal alpha contamination and external gamma irradiation) showed contrasted effects on energy budget of organisms. However, their consequences are still difficult to measure at the population level in a broader ecological context because in natural biota, populations are constantly subject to variable environmental conditions which may alter their capacity to cope with toxic stress. We present a model which simulates population dynamics of Daphnia exposed to different pollutants, including radionuclides (based on our experiments) and stable heavy metals (Cd, Cu... using data from the literature). The model is individual-based and describes the acquisition of energy from food and its allocation towards survival, growth and reproduction. Further experiments at different food levels aim at testing how natural constraints, such as variable food conditions, might influence responses of organisms and populations to radiological and chemical pollutants.