This investigation is determining whether amphibian diversity and abundance in the Green Bay ecosystem is notably low compared with similar sites elsewhere in Wisconsin. It is testing the hypothesis that chronic exposure of amphibian eggs to contaminants in water from Green Bay and its major tributary, the Fox River, reduces hatchability and survival of three particular species. Researchers are also checking for abnormal sex organs in amphibians raised in these waters. Results of this work will be used to assess the extent to which contaminants can explain the variation in amphibian species diversity and abundance in wetlands in the Green Bay ecosystem.

Work has progressed on three of four project objectives. Histological and functional biomarkers are being developed in a positive control experiment in which frogs are exposed to estrogen (b-estradiol). These biomarkers were used to assess the sexual development of ten distinct clutches of "clean" leopard frog eggs raised until the onset of metamorphosis in enclosures at two contaminated and two uncontaminated sites in the Green Bay ecosystem. Egg clutches were collected from one contaminated and two "clean" sites to test the hypothesis that chronic exposure to contaminants results in eggs with low viability.