Radiocesium patterns in wood duck eggs and nesting females in a contaminated reservoir

Radionuclide releases from nuclear industry are an important ecological issue, particularly because these contaminants may directly affect animals and may be transferred to the hunting public through consumption. During 1991-92, we collected 13 clutches of wood duck eggs from nest boxes established in an abandoned reactor cooling reservoir. We examined whole-egg radiocesium (137Cs) levels and apportionment within egg components (albumen, yolk, and shell). Whole-egg concentrations averaged 0.113 Becquerel (Bq)/g wet mass (SE=0.01, n = 137) over 2 years. Albumen had the highest concentration of 137Cs (x = 1.096 Bq/g dry mass), followed by shell (x = 0.132 Bq/g dry mass) and yolk (x = 0.098 Bq/g dry mass). Levels of potassium (K), a chemical analog of Cs, suggested that contamination levels in yolk were disproportionally lower than those in albumen. Levels of 137Cs that appeared in these components may reflect temporal differences in the sythesis of yolk and albumen. Laying order did not relate to whole-egg 137Cs concentrations within clutches, but 137Cs concentrations in post-laying females were positively related to mean egg 137Cs levels in their respective clutches (r2 = 0.97). While female ducks and their eggs examined in this study would not have posed a health hazard to persons consuming them as food, we suggested that 137Cs levels in breeding female wood ducks and their clutches may be indicators of foraging habitat selection (both contaminated and uncontaminated) during the laying cycle. 23 refs., 2 figs., 2 tabs