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Integrating Monitoring and Genetic Methods To Infer Historical Risks of PCBs and DDE to Common and Roseate Terns Nesting Near the New Bedford Harbor Superfund Site (Massachusetts, USA)
Citation:
Nacci, D., M. Hahn, S. Karchner, Saro Jayaraman, C. Mostello, K. Miller, C. Blackwell, AND I. Nisbet. Integrating Monitoring and Genetic Methods To Infer Historical Risks of PCBs and DDE to Common and Roseate Terns Nesting Near the New Bedford Harbor Superfund Site (Massachusetts, USA). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 50(18):10226-10235, (2016).
Impact/Purpose:
This manuscript describes experimental studies that contribute to our understanding of the ecological risks associated with chronic contaminant exposures to wildlife populations. Here, we assessed the magnitude and projected effects of an important class of highly toxic environmental pollutants, PCBs. We used archived and newly collected samples of tern eggs nesting near a PCB-contaminated Superfund site to assess temporal patterns of contamination that might reflect the influence of the Superfund site. We used published laboratory studies and novel genetic information and functional assays to estimate the toxic effects of contamination to measured and related species of terns. Results of these studies demonstrate the value of molecular tools to diagnose and predict effects of chemical stressors and characterize the mechanisms and costs of toxic chemical stressors by wild populations. General impacts from this contribution include improved understanding by managers and scientists of links between human activities, natural dynamics, ecological stressors and ecosystem condition.
Description:
Common and roseate terns are migratory piscivorous seabirds with major breeding colonies within feeding range of thepolychlorinated biphenyl (PCB)-contaminated New Bedford Harbor (NBH, MA, USA) Superfund site. Our longitudinal study shows that before PCB discharges into NBH ceased (late 1970s), tern eggs had very high but variable PCB concentrations. However, egg concentrations of PCBs as well as DDE (1,1-bis(p-chlorophenyl)-2,2-dichloroethene), the degradation product of the ubiquitous global contaminant DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane), have since declined. Rate constants for temporal decline of PCB congeners in tern eggs varied inversely with log10KOW (n-octanol−water partition coefficient), shifting egg congener patterns away from those characterizing NBH sediment. To estimate the toxic effects on tern eggs of PCB dioxin-like congener (DLC) exposures, we extrapolated published laboratory data on common terns to roseate terns by characterizing genetic and functional similarities in species aryl hydrocarbon receptors (AHRs), which mediate DLC sensitivity. Our assessment of contaminant risks suggests that terns breeding near NBH were exposed historically to toxic levels of PCBs and DDE; however, acute effects on tern egg development have become less likely since the 1970s. Our approach demonstrates how comparative genetics at target loci can effectively increase the range of inference for chemical risk assessments from tested to untested and untestable species.
