Contaminants Research
Effects of Contaminant Exposure on Top Predators

Objectives

Measure the contaminant exposure and reproductive health of piscivorous wildlife inhabiting Wisconsin aquatic systems contaminated by toxic substances.

Background

Despite the ban of toxic substances such as polychlorobiphenyls (PCBs) and organochlorine pesticides (i.e., DDT, dieldrin, etc.) in agriculture and industry, they persist in the biota and sediment of many aquatic ecosystems. These systems contain important nesting and foraging habitat for wildlife. Aquatic habitats are also contaminated with mercury, mostly through atmospheric deposition. Furthermore, the low pH of acidified northern Wisconsin lakes increases the bioavailability of mercury within lake ecosystems. For example, fish mercury content prompts fish consumption advisories on more than 300 of these lakes.

The bioaccumulation of PCBs, pesticides, mercury, and other toxic substances can impair the productivity of top predator wildlife. In the Great Lakes region, bald eagles, osprey, loons, mink, and otter represent several affected species. While bald eagles, osprey, and common loon populations have recovered from post-World War II declines, these species remain on Wisconsin's "threatened" and/or "watch" list. These top predators can serve as bioindicators to ecosystem health.

Documenting mercury levels in selected lakes, the impacts on loon reproduction, and factors affecting mercury exposure will determine the magnitude of this threat. Additionally, monitoring the health and productivity of piscivorous wildlife in habitats affected by industry and/or agriculture will provide an early warning of future population threats.

For more information on this topic please contact:Michael Meyer (608) 219-7520