Contaminant Exposure, Food Web Transfer and Potential Health Effects on Chesapeake Bay and Delaware Bay Waterbirds

Science Center Objects

Chesapeake and Delaware Bays are the largest estuaries on the east coast of the United States.  They support extensive fisheries and provide critical habitat for many species of wildlife.  These Bays are surrounded by vast agricultural andindustrialized regions, with urbanized areas, all of which are a source of pollution that can affect natural resources.  We have long monitored contaminants in this region, and in some instances our research has led to the mitigation of harmful effects.

The Challenge: Agricultural, industrial and urban activities have had major effects on waterbirds in Chesapeake and Delaware Bays. Some legacy pollutants (PCBs, organochlorine pesticides, flame retardants, metals) pose a potential threat to wildlife in some locations. Pharmaceuticals, personal care products, and endocrine disrupting compounds have been detected in water and fish tissue, yet knowledge of effects on wildlife is limited.

The Science: A re-evaluation of contaminant exposure in ospreys nesting in Chesapeake Bay (Regions of Concern: Baltimore Harbor/Patapsco, Anacostia/middle Potomac and Elizabeth Rivers; Susquehanna and James Rivers) and Delaware Bay (Cape Henlopen, DE north to Bristol, PA) was undertaken between 2011- 2015. In Chesapeake Bay, organochlorine pesticides and their metabolites declined over time, but PCBs remained high in some locations like Baltimore Harbor. Concentrations of polybrominated diphenyl ether flame retardants have declined since 2000, but remain elevated in the vicinity of wastewater treatment plants. There was evidence of DNA damage in industrialized and urbanized locations. Overall, osprey productivity in Chesapeake Bay remains adequate to maintain a stable population. A suite of pharmaceuticals and the artificial sweetener sucralose were quantified in water, and fish and osprey plasma. Of the 24 analytes, 18 were detected in water, 8 in fish plasma, but only one diltiazem (pharmaceutical for blood pressure management) in osprey nestling plasma. In fish and osprey plasma, levels of pharmaceuticals were below human therapeutic concentrations. Similar work was conducted in Delaware Bay in 2015, and findings indicate that osprey productivity is adequate and sample analyses are currently underway.

The Future: This research is expanding our knowledge of ecotoxicological hazards to waterbirds in Chesapeake and Delaware Bays, and may have implications for human health. Data will be used by regulatory and resource management agencies to prioritize contaminants of concern, and develop management actions to mitigate pollution. Even though empirical concentrations of drugs in the present study are below human therapeutic levels, there are limited data for wildlife which makes interpretation challenging. Findings are contributing to the improvement of environmental quality, ecosystem integrity, and sustainability of Chesapeake and Delaware Bays.