Decadal re-evaluation of contaminant exposure and productivity of ospreys (Pandion haliaetus) nesting in Chesapeake Bay Regions of Concern

The last large-scale ecotoxicological study of ospreys (Pandion haliaetus) in Chesapeake Bay was conducted in 2000–2001 and focused on U.S. EPA-designated Regions of Concern (ROCs; Baltimore Harbor/Patapsco, Anacostia/middle Potomac, and Elizabeth Rivers). In 2011–2012, ROCs were re-evaluated to determine spatial and temporal trends in productivity and contaminants. Concentrations of p,p′-DDE were low in eggs and below the threshold associated with eggshell thinning. Eggs from the Anacostia/middle Potomac Rivers had lower total PCB concentrations in 2011 than in 2000; however, concentrations remained unchanged in Baltimore Harbor. Polybrominated diphenyl ether flame retardants declined by 40%, and five alternative brominated flame retardants were detected at low levels. Osprey productivity was adequate to sustain local populations, and there was no relation between productivity and halogenated contaminants. Our findings document continued recovery of the osprey population, declining levels of many persistent halogenated compounds, and modest evidence of genetic damage in nestlings from industrialized regions. [Display omitted] •This study documents the continued recovery of the Chesapeake Bay osprey population.•Osprey eggshells have nearly returned to pre-DDT-era thickness.•Organochlorine pesticides are low in eggs, but PCB levels seem unchanged in industrialized areas.•PBDE flame retardants have declined in eggs, but seem to peak near wastewater treatment plants.•There is some evidence of genetic damage in nestling blood samples in the most industrialized areas. While the Chesapeake Bay osprey population has recovered, concentrations of some persistent contaminants in eggs remain unchanged, and there is some evidence of genetic damage in nestlings.