Mercury Exposure in the Common Loon (Gavia immer) at Isle Royale National Park, Michigan
Kaplan JD and Tischler KB. 2000. Mercury Exposure in the Common Loon (Gavia immer) at Isle Royale National Park, Michigan. BioDiversity Research Institute. Freeport, ME
Blood and feathers from loons were collected from populations from several inland lakes, including Sargent Lake on Isle Royale, and Lake Superior. Hg exposure – significantly greater in juvenile loons from ISRO than those from Lake Superior. In response to management concerns over the findings of elevated fish mercury levels on six inland lakes at Isle Royale, mercury concentrations in blood and feathers of the common loon (Gavia immer) were investigated. Mercury levels in Sargent Lake were compared to known moderate to low mercury sites on Lake Superior. At Isle Royale there was no significant difference in adult blood Hg levels between Sargent Lake and Lake Superior. Juvenile loons from Sargent Lake had significantly higher mercury levels than those from Lake Superior. Since juveniles are fed exclusively from the natal territory until fledling, we identify fledgling-aged juvenile as the most reliable indicator of Hg exposure in a specific waterbody. Interior lakes with elevated mercury levels hatched fewer chicks than Lake Superior territories. As a whole, Isle Royale adult loons showed moderate to low blood Hg levels in comparison with other sites in the Great Lakes region and North America. Ten percent of adult loons sampled at Isle Royale (n=29) had feather Hg concentrations at or above the risk level for toxic effects (>20 ug Hg/g). Eighty-three percent adult loons recaptured at Isle Royale after their original sampling showed increases in feather Hg levels.
- Type
- Published Report
- Authors
- Kaplan, Joseph; Tischler, Keren
- Date of Issue
- 2000-01-03
- Publisher
- BioDiversity Research Institute
- Units
- ARD , ISRO
- Keywords
- ARD_Park-Air-Info_Collection, biological indicator, Common Loon (Gavia immer), Contaminants, Deposition, Isle Royale National Park, Mercury, Mercury (Hg), Michigan, nest site location, piscivorous aquatic bird, Productivity, Territory, Toxicology, Toxics