PH25 Wildlife Ecotoxicology II
Exhibit Hall
8:00 AM - Thursday
(PH301) Unusually High Concentrations of Strontium in Eggshells of Passerine Birds: Toxicological Implications.
Mora, Miguel1, Taylor, Robert2, Brattin, Bryan3, 1 U.S. Geological Survey, Texas A&M University, College Station, Texas, U.S.A.2 Trace Element Research Lab, Texas A&M University, College Station, Texas, U.S.A.3 Trace Element Research Lab, Texas A&M University, College Station, Texas, U.S.A.
ABSTRACT- Previously, Mora et al. (2003a, b) reported elevated concentrations of Sr in a few eggshells of yellow-breasted chats (Icteria virens) from Arizona. Geological studies indicate that some regions in Arizona contain unusually high concentrations of Sr in stream sediments. In this study, we investigated whether the occurrence of high Sr levels in bird eggshells was more widely distributed in Arizona and the potential toxicological significance of such Sr levels. We collected 40 eggs from 10 passerine birds in 4 regions of Arizona. The eggshells were washed with water and acetone to remove egg content residues and then were analyzed for inorganic elements with ICP optical emission spectrometry and hydride generation atomic fluorescence. Concentrations of Sr in eggshells ranged from 70 to 1360 
g/g dw with an overall mean of 684 g/g dw for the 4 regions in the state. 23 % of the eggshells had Sr concentrations greater than 1,000 g/g dw, and over half of these eggshells were from species collected in the lower San Pedro River. The other region with high concentrations of Sr was Camp Verde. The species with greater concentrations of Sr were Bell′s vireo (Vireo bellii), yellow warbler (Dendrocia petechia) and brown headed cowbird (Molothrus ater). There was a significant positive correlation between Sr and Ca (P < 0.01, r2 = 0.44), but Ca was not significantly correlated with Ba (P > 0.05, r2 = 0.22). Mean Sr/Ca ratios were 2.27 ± 0.96 and Ba/Ca 0.17 ± 0.09, and mean eggshell thickness was 0.01 ± 0.0017. Eggshell thickness tended to increase with the amount of Ca; however, thickness was not significantly correlated with Ca or Sr. To our knowledge, these are among the highest levels of Sr that have been reported in bird eggshells in North America. Few studies suggest that high concentrations of Sr could be embryotoxic to chickens or reduce hatching success. Considerable transport of eggshell solids and minerals into the embryo occurs during the latter half of incubation. It is possible that Sr in the shell may become mobilized and perhaps affect later stage embryos resulting in reduced hatching success or inhibit transport of Ca necessary for bone development, thus resulting in beak deformities. This study provides additional information on the role of the avian eggshell in sequestering metals and metalloids.
Key words: Eggshell, Strontium, Birds, Metals