Contaminant Exposure, Food Web Transfer and Potential Effects on Ospreys (Pandion haliaetus) in Chesapeake Bay

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The last large-scale ecotoxicological study of ospreys (Pandion haliaetus) in Chesapeake Bay was conducted in 2000-2001 and focused on the U.S. Environmental Protection Agency designated Regions of Concern (ROCs; Baltimore Harbor/Patapsco, Anacostia/middle Potomac, and Elizabeth Rivers). From 2011-2013, ROCs, Susquehanna River and flats, James and Back Rivers were evaluated to determine spatial and temporal trends in osprey productivity and contaminants in eggs. Concentrations of p,p’-DDE were below the threshold associated with eggshell thinning. Total PCB concentrations in eggs from the Anacostia/middle Potomac were lower in 2011 than 2000, but remained unchanged in Baltimore Harbor. Polybrominated diphenyl ether flame retardants declined across study sites and five alternative brominated flame retardants were detected at low levels in osprey eggs. Concentrations of oxidized DNA (biomarker of oxidative stress) were slightly elevated on the Anacostia/middle Potomac and Baltimore Harbor/Patapsco Rivers, but no univariate contaminant predictors correlated with DNA damage. Pharmaceuticals and personal care products were also examined. An integrative modeling approach was used to evaluate bioaccumulation potential of pharmaceuticals using hypothetical screening-level exposure scenarios. A first-order kinetic exposure model was applied to estimate the average daily and cumulative 45-day dose of pharmaceuticals received by a nestling osprey. To complement the exposure model, water, fish and osprey nestling plasma samples were analyzed for 23 pharmaceuticals and an artificial sweetener (sucralose). Of the 18 analytes detected in water, 8 were found in fish plasma, and 1 in osprey nestling plasma (antihypertensive diltiazem). Diltiazem was detected at concentrations approximately 21.6 times greater in fish plasma than water and 4 times greater in osprey nestling plasma than fish. Diltiazem was found in all 69 osprey plasma samples (540–8,630 ng/L), with 41% of these samples exceeding maximum concentrations found in fish. Diltiazem levels in fish and osprey were below the human therapeutic plasma concentration (30,000 ng/L). Effect thresholds for diltiazem are unknown in ospreys at this time, and there was no evidence to suggest adverse effects. Overall, findings document continued recovery of the osprey population, declining levels of select persistent halogenated compounds, and modest evidence of oxidative genetic damage in nestlings.