Laughing Gull (Larus atricilla). Photo credit: courtesy of Jeffrey A. Spendelow, USGS Patuxent Wildlife Research Center

Although exposure to mercury is known to have toxic effects on birds, until recently, only limited information was available on the sensitivity of various species to mercury exposure. Recent studies conducted at the USGS Patuxent Wildlife Research Center have confirmed that clear differences exist in the sensitivity of various bird species to methylmercury. Although changes in the expression of multiple genes, including those associated with immune response, nervous system function, reproduction, egg fertilization, and development, have been reported in mammals, fish, and amphibians exposed to mercury, the molecular mechanisms that account for the observed differences in sensitivity in birds are unknown. To address this issue, we are conducting a study investigating the genomics of methylmercury in tissues collected from exposed bird embryos. Gene expression profiles of less sensitive species are being compared with those of more sensitive species. The results of this study will improve our understanding of species-specific and within-species differences in susceptibility to methylmercury in birds. Our goal is to identify a new analytical tool (gene profile) that would enable prediction of mercury’s effects in field-collected samples and in bird species that cannot be subjected to in-depth laboratory analyses of sensitivity.

For more information contact Natalie K. Karouna-Renier, Patuxent Wildlife Research Center.