Spatial patterns of persistent contaminants in bald eagle nestlings at three national parks in the upper Midwest: 2006-2009

Route, Bill; Rasmussen, Paul; Key, Rebecca; Meyer, Michael; Martell, Mark

During 2006 through 2009 the National Park Service Great Lakes Inventory and Monitoring Network and its partners assessed levels of targeted environmental contaminants in bald eagle (Haliaeetus leucocephalus) nestlings at sites in and adjacent to the Apostle Islands National Lakeshore, Mississippi National River and Recreation Area, and St. Croix National Scenic Riverway. Adjacent study areas were added when funds were available; these included the entire Wisconsin south shore of Lake Superior and a section of the Mississippi River below Minneapolis-St. Paul, Minnesota, to the southern end of Lake Pepin. A total of 288 bald eagle nestlings were handled, and 154 plasma and 142 breast-feather samples were analyzed for six contaminants: total mercury, lead, DDT (and metabolites DDE and DDD), total PCBs (75 congeners), total PBDEs (9 congeners), and total PFCs (16 analytes). We also archived 123 plasma and 121 feather samples for possible future analysis. All study areas averaged >1.0 young per occupied bald eagle nest. The Apostle Islands had the lowest productivity (1.0 in 2008) and the Mississippi National River and Recreation Area had the highest (2.2 in 2006 and 2009). The percent of territories that were successful ranged from 63% at Apostle Islands in 2008 to 100% at the lower St. Croix River (2007 and 2009) and the Mississippi National River and Recreation Area (2008). Contaminant levels varied between study areas and years. The geometric mean (Xgeo) mercury levels in feathers ranged from 2.69 ug/g in nestlings on Pools 3&4 of the Mississippi River in 2008 to 7.96 ug/g on the upper St. Croix Riverway in 2006. Mean (Xgeo) lead levels in feathers were lowest on the Apostle Islands in 2006 (0.0700 ug/g) and highest in the lower St. Croix River in 2006 (1.03 ug/g). Generally, lead was highest in the lower St. Croix River and along the Mississippi River and lowest on the Apostle Islands and the upper St. Croix Riverway. Trace levels of DDT in blood were found in seven nestlings from Lake Superior in 2006 and 2007 and in two nestlings from the Mississippi National River and Recreation Area - one in 2006 and one in 2009; DDE was found in all nestlings sampled and at high levels in nestlings from the Apostle Islands in 2006 (Xgeo=29.7 ug/L). Nestlings on islands furthest from the mainland had among the highest DDE levels all four years. Levels of DDE were lowest on the upper St. Croix River in 2006 (Xgeo=2.70 ug/L). Levels of PCBs were lowest on the upper St. Croix River in 2006 (Xgeo=10.0 ug/L) and highest on the lower St. Croix in 2006 (Xgeo=139 ug/L). Polybrominated diphenyl ethers (PBDEs), a group of chemicals of increasing concern, ranged from Xgeo of 1.39 ug/L in the upper St. Croix River in 2006 to Xgeo of 16.8 ug/L in the Mississippi National River and Recreation Area in 2007. Generally, spatial patterns of PBDEs were similar to those of PCBs across the study areas. Perfluorinated compounds (PFCs), another group of chemicals of increasing concern, were found in all samples, and the primary analyte was PFOS (68% in Mississippi River sample sites and 53% in Lake Superior sample sites by volume). We found PFOS at very high levels in nestlings on the lower St Croix River (Xgeo=1580 ug/L) and in the Mississippi National River and Recreation Area (Xgeo=1250 ug/L) in 2006. PFOS was generally low in eaglets from the upper St. Croix Riverway (Xgeo=13.4 ug/L in 2007) and at moderate levels on the Apostle Islands (146-174 ug/L). Another PFC analyte, PFDS, made up 26% of the PFC volume in eaglet plasma from the Mississippi River study areas but <1% of volume in Lake Superior eaglets. PFOA, another PFC a analyte of high interest due to its toxicity and pervasiveness around the world, was found at very low levels in plasma from nestlings in our study areas (<1% of the 16 PFCs by volume); yet it was consistently at its highest levels in nestlings from the Apostle Islands (4.97 ug/L in 2008).

Spatial patterns of persistent contaminants in bald eagle nestlings at three national parks in the upper Midwest: 2006-2009

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