Effets de l'irradiation chronique alpha interne sur le budget énergétique individuel de Daphnia magna et conséquences pour la dynamique de population

Titre du congrès :SETAC Europe 17th Annual Meeting Ville du congrès :Porto Date du congrès :20/05/2007

Until now, biological effects of alpha-emitting radionuclides such as Am-241 have been poorly studied at chronic low dose in invertebrates. In this study, the freshwater microcrustacean Daphnia magna was chronically exposed to waterborne Am-241 on a range of dose rates. Daphnids showed an increased respiration and a reduction in body mass after 23 days of exposure to 0.8 mGy/h. While fecundity remained unchanged, individual mass per egg was significantly smaller compared to the control and neonates showed significantly reduced resistance to food limitation. Possible effects of Am-241 on population dynamics were tested. A 10-week multigeneration experiment examined whether the observed reduction in per-offspring investment resulted in reduced growth, fecundity, survival, and/or delayed deposition of the first brood in two subsequent generations. Results were integrated into a population model and predicted increasing delay in population growth with increasing exposure to alpha radiation.