Date of Award

12-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Wildlife and Fisheries Biology

Advisor

Bowerman, William W

Committee Member

Bridges , William C

Committee Member

Lanham , Drew

Abstract

Bald eagles (Haliaeetus leucocephalus) are a avian species used to monitor environmental contaminants such as mercury (Hg), methylmercury (MeHg), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCs) in North America. Populations of bald eagles nesting along the Great Lakes were very slow to recover after the ban of PCBs and OCs because these compounds were very persistent. Bald eagles at Voyageurs National Park (VNP) have been monitored since 1973 and provide an opportunity to assess temporal and spatial trends of persistent environmental contaminants. Nestling bald eagle feathers were analyzed for Hg concentrations for the past 12 years. Nestling bald eagle plasma samples were analyzed for PCBs and OCs for the past 14 years. The concentrations of total PCBs, total DDTs, 4,4'-DDE, and dieldrin in nestling plasma are reported here because there were greater than 50% of samples with detectable concentrations of these compounds. Hg concentrations at VNP ranged from non- detect (ND) to 34.97 mg/kg with 10% of nestling feather samples having concentrations of Hg below detectable limits. Hg concentrations in nestling feathers at VNP have decreased 77.4% since 1989. Total PCBs in nestling plasma ranged from ND to 280.08 μg/kg with 48.7% of nestling plasma samples having concentrations below detectable limits. Total PCBs in nestling plasma samples at VNP decreased 29.1% when the 5 year geometric means were compared from 1997 to 2001 and 2006 to 2010. 4,4'-DDE in nestling plasma ranged from ND to 68.30 μg/kg with 4.9% of nestling plasma samples having concentrations below detectable limits. 4,4'-DDE in nestling plasma samples at VNP decreased 24.09% when the 5 year geometric means were compared from 1997 to 2001 and 2006 to 2010. Dieldrin in nestling plasma ranged from ND to 48.61 μg/kg with 38.9% of nestling plasma samples having concentrations below detectable limits. Dieldrin in nestling plasma samples at VNP increased 50.25% when the 5 year geometric means were compared from 1997 to 2001 and 2006 to 2010. Hg, total PCBs, and 4,4'-DDE have decreased at VNP and any increases in are likely due to atmospheric sources. Dieldrin concentrations have increased causing reason to believe that a new source of dieldrin, possibly atmospheric, is present in the VNP ecosystem.

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