An investigation of mercury levels in the food web of Isle Royale National Park, Michigan: Report for the aquatic subproject Sargent and Richie Lakes Summer 1998 - Summer 1999
Gorski PR, Cleckner LB, Hurley JP, Armstrong DE, Garrison PJ, Sierszen ME. 2002. An investigation of mercury levels in the food web of Isle Royale National Park, Michigan: Report for the aquatic subproject Sargent and Richie Lakes Summer 1998 - Summer 1999. University of Wisconsin, Madison
Recent data have shown that 6 of the inland lakes of Isle Royale National Park contain northern pike with mercury (Hg) concentrations exceeding health consumption advisory levels (> 500 ng/g weight). The purpose of this study was to assess Hg concentration in various components of the aquatic ecosystem. Our working hypothesis is that elevated Hg concentrations in water, sediments, or organisms of the lower food chain could account for differences in Hg concentrations observed in northern pike between advisory and non-advisory lakes. In 1998 and 1999, water, sediment, zooplankton, macro invertebrates, and fishes from one advisory lake, Sargent Lake, were collected for total Mg and methyl mercury analysis. Comparison samples were also collected from a non-advisory lake, Lake Richie. The lakes have similar physical and watershed characterisitics and both lakes develop anoxic hypolemia during the summer with associated increases in methyl mercury. Counter to expectations, Lake Richie had slightly higher average Hg concentrations in open water samples, and also higher suspended particulate matter, dissolved organic carbon, chlorophyll a, and blue green algal pigment concentrations. Both lakes have Hg concentrations similar to other lakes in the Upper Midwest. The historical record provided by sediment cores suggests atmospheric inputs have been the main external source of Hg to both lakes.
- Type
- Published Report
- Authors
- Gorski, P; Cleckner, L; Hurley, J; Armstrong, D; Garrison, P; Sierszen, M
- Date of Issue
- 2002-01
- Publisher
- University of Wisconsin, Madison
- Units
- ARD , ISRO
- Keywords
- Aquatic, ARD_Park-Air-Info_Collection, blue green algae, chlorophyll a, Contaminants, Deposition, Dissolved Organic Carbon, Fish, Isle Royale National Park, Macro invertebrates, Mercury, Mercury (Hg), Michigan, Sediment, Toxics, Water Quality, Zooplankton