PARENT SESSION
PS1 - Wildlife Toxicology
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P007) Mercury in bald eagle blood, Chichagof Island, Alaska.
Rudis, Deborah*,1, Jacobson, Michael1, Bowman, Timothy2, 1 U.S. Fish & Wildlife Service, Juneau, AK, USA2 U.S. Fish & Wildlife Service, Anchorage, AK, USA
ABSTRACT- Klag Bay, on the outer coast of Chichagof Island, Alaska, is the location of the former Chichagof Mine, which operated as a gold and silver mine from 1906 to 1942. Ore was processed using mercury amalgamation. Sampling in 1986 by the U.S. Fish and Wildlife Service and in 1998 by U.S. EPA contractors found metal contamination (arsenic, cobalt, lead, mercury, silver and zinc) in sediment and marine biota. Because of the potential for biomagnification of some metals in bald eagles, Haliaeetus leucocephalus, we wanted to determine if metal concentrations in resident birds warranted concern. We trapped nine adult bald eagles in the spring of 2000 using floating herring lures. Blood samples were collected from seven males and two females. We also collected blue mussels, Mytilus trossulus, for metals analysis. We tested whole blood for a suite of metals, including total mercury and methylmercury (meHg). MeHg is the most toxic form of mercury and can bioconcentrate in fish, a primary food of eagles. MeHg can affect immune, genetic and enzyme systems in addition to the central nervous system. Total mercury in blood ranged from 0.68 - 5.10 ppm wet wt. (mean of 1.62), with meHg constituting approximately 48 to 89 percent. These total mercury concentrations were comparable to residues reported in bald eagles in from the western US. Consequences of low-level mercury contamination are not known. We did not collect information that would allow us to determine any health effects to eagles in our study. However, it appears from our data that Klag Bay bald eagles are bioaccumulating mercury. As, Cd, Cu, Pb, Se, and Zn were not detected at concentrations of concern in bald eagle blood. Blue mussel tissue concentrations of As, Ba, Cr, Hg, and Pb were generally high in comparison to mussel data from other undeveloped Alaska sites.
Key words: Bald eagle Haliaeetus leucocephalus, blood, metals, Alaska