Contaminants in Bald Eagle Nestlings at Apostle Islands National Lakeshore, Mississippi National River and Recreation Area, and the St. Croix National Scenic RiverwayData Summary, 2006-2008

Route, B.; Key, R.

From 2006 through 2008 the National Park Service Great Lakes Inventory and Monitoring Network assessed levels of targeted environmental contaminants in bald eagle (Haliaeetus leucocephalus) nestlings in and adjacent to the Apostle Islands National Lakeshore, Mississippi National River and Recreation Area, and St. Croix National Scenic Riverway. A total of 200 bald eagle nestlings were handled of which 194 were sampled for contaminants. Of the 194 nestlings sampled, 111 plasma and 108 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 telomers). Seventy-six plasma and 78 feather samples were archived for future analysis. Herein we provide a summary of samples analyzed. All study areas had > 1.0 young per occupied territory, considered the threshold for a healthy bald eagle population. 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). The percent of territories that were successful ranged from 62.5% in 2008 at Apostle Islands to 100% in 2007 on the lower St. Croix River. Contaminant levels varied between study areas and years. The geometric mean (mean geo) mercury levels in feathers ranged from 2.67 ug/g in nestlings on pools 3&4 of the Mississippi River in 2008 to 7.88 ug/g on the upper St. Croix Riverway in 2006. Mean (mean geo) lead levels in feathers were lowest on the Apostle Islands in 2006 (0.07 ug/g) and highest in the lower St. Croix River in 2006 (0.99 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 were found in seven Lake Superior nestlings in 2006 and 2007 and in one nestling from the Mississippi National River and Recreation Area in 2006; DDE was found in all nestlings sampled and at high levels in nestlings from the Apostle Islands in 2006 (mean geo = 28.9 ug/L). Nestlings on islands furthest out in to Lake Superior had among the highest DDE levels all three years. Levels of DDE were lowest on the upper St. Croix River in 2006 (mean geo = 2.53 ug/L). Levels of PCBs were lowest on the upper St. Croix River in 2006 (mean geo = 10.01 ug/L) and highest on the lower St. Croix in 2006 (mean geo = 136.06 ug/L). Polybrominated diphenyl ethers (PBDEs), a group of chemicals of increasing concern, ranged from mean geo of 1.39 ug/L in the lower St. Croix River in 2006 to mean geo of 14.56 ug/L along the south shore of Lake Superior in 2008. Generally, spatial patterns of PBDEs were similar to PCBs across the study areas. Perfluorinated compounds (PFCs), another group of chemicals of increasing concern, were found in all samples and the primary telomer was PFOS (64% of all samples by volume). We found PFOS at very high levels in nestlings on the lower St Croix River (mean geo = 1550.27 ug/L) and in the Mississippi National River and Recreation Area (mean geo = 1234.17 ug/L) in 2006 and on pools 3&4 in 2008 (mean geo = 1480.56 ug/L). PFOS was generally low on the upper St. Croix Riverway (mean geo = 13.94 ug/L in 2007) and at moderate levels on the Apostle Islands. A second PFC telomere, PFDS, comprised 30% of all samples by volume and its distribution was similar to PFOS in 2008 - the only year it was analyzed for. Interestingly, PFOA, a PFC telomer of high interest due to its toxicity and pervasiveness around the world, was found at very low levels in nestling plasma in our study areas (< 1% of the 16 PFCs by volume); yet this telomer was higher in two of the three years in nestlings from the outer islands of the Apostle Islands.

Contaminants in Bald Eagle Nestlings at Apostle Islands National Lakeshore, Mississippi National River and Recreation Area, and the St. Croix National Scenic RiverwayData Summary, 2006-2008

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