Maternal transfer of contaminants to eggs in common grackles (Quiscalus quiscala) nesting on coal fly ash basins

Abstract

Coal combustion is a major source of trace elements to the environment. Aquatic disposal of wastes from this process can result in reproductive failure in many wildlife species, but little is known regarding impacts on avian fauna. Individual eggs were collected from common grackles (Quiscalus quiscala) nesting in association with coal fly ash settling basins and a reference site to determine if females from the contaminated site transfered trace elements to their eggs. Whole clutches were also collected from both sites to examine inter- and intra-clutch variability of maternally transferred contaminants. Selenium was the only trace element found in significantly higher concentrations in ash basin eggs (x = 5.88 +/- 0.44 microg/g DW) than in reference eggs (x = 2.69 +/- 0.13 microg/g DW). Selenium concentrations in eggs from the ash basins were above background levels, but did not exceed higher proposed Se toxicity thresholds. Inter- and intra-clutch variation was higher for ash basin clutches than reference clutches. The relationship between selenium concentrations and laying order (estimated by egg mass) was not statistically significant, but increased Se concentration in the second egg of most ash basin clutches followed by declining concentrations in subsequent eggs suggested that further examination of this pattern might be warranted.