Patterns of Radiocesium Contamination in Eggs of Free-Ranging Wood Ducks

Abstract

Studies of biological consequences of nuclear industrial contaminants in the environment increase in importance as the potential for exposure of wildlife populations rises. Thus, we examined levels of radiocesium (cesium-137) contamination in wood duck eggs from a Department of Energy nuclear facility in South Carolina during 1990. Radiocesium levels in individual eggs from 5 locations on the site ranged from below detectable concentrations to a maximum of 2.21 Bq/g wet mass. Eggs from an abandoned reactor cooling reservoir contained the greatest burdens; mean egg concentrations there were more than an order of magnitude higher than those from other locations studied. Eggs from a second radionuclide releases, all contained similar low radiocesium levels that were, on average, below detection limits. Variation in radiocesium concentrations of eggs from the most contaminated cooling reservoir was partitioned into within- and among-clutch variation. Approximately 33% of the variation in radiocesium content occurred among eggs laid by the same female, and may have resulted because females fed in both contaminated and uncontaminated habitats during egg formation. Radiation dose rates to developing wood duck embryos, resulting from internal and external sources examined in this study, were below those expected to affect hatchability or any other aspect ofmore » the breeding biology of these birds. Wood ducks and their eggs may be useful as bioindicators of radiocesium uptake, but we caution that local foraging patterns could cause variation in contaminant deposition within clutches. 45 refs., 1 fig., 2 tabs.« less