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QUANTIFYING ULTRAVIOLET RADIATION DOSE RELATIVE TO WETLAND HABITAT VARIABLES FOR THE ASSESSMENT OF RISK TO AMPHIBIANS
Citation:
Diamond, S A., P. C. Trenham, G T. Ankley, J E. Tietge, G. S. Peterson, M. J. Adams, P. S. Corn, B. Hossack, R. A. Knapp, R. Breen, R. Breen, D. Fagre, N E. Detenbeck, K. Tonnesen, T. M. Jicha, C M. Elonen, AND L E. Anderson. QUANTIFYING ULTRAVIOLET RADIATION DOSE RELATIVE TO WETLAND HABITAT VARIABLES FOR THE ASSESSMENT OF RISK TO AMPHIBIANS. Presented at USEPA Science Forum 2002, Meeting the Challenges, Washington, DC, May 1-2, 2002.
Description:
Ultraviolet B radiation (UV-B) has increased globally over the last several decades due to reduction of stratospheric ozone. UV-B may also increase when climate change alters cloud cover, rainfall, and distributions of vegetation. In aquatic systems, these factors can also interact to change the concentration and composition of dissolved organic carbon (DOC), a strong absorber of UV-B. Because UV-B can be extremely toxic, even small increases are of great concern. This concern, and the suggestion that amphibians are in worldwide decline, has fostered the hypothesis that UV-B radiation may be affecting amphibian populations. We are addressing this hypothesis in two ways: 1) Assessment of risk in which experimentally-determined UV-B dose/effect levels were compared with estimated wetland doses; and 2) Landscape-level surveys in which the relationship between amphibian distributions and estimated UV-B doses are examined. Both approaches involve characterization of the UV-filtering capacity of wetland water and the degree to which landscape reduces the dose of solar radiation reaching each wetland. These data are modified by, and combined with, extensive modeling that incorporates the effect of ozone, clouds, landscape, location, specific date, and exposure duration. Data were collected in collaboration with the National Park Service, USGS, and academic researchers, including the University of Minnesota's Natural Resource Research Institute. Over 1000 wetlands in six National Parks and in northern Minnesota and Wisconsin were studied. Of the 26 wetlands studied in the Midwest, UV-B dose exceeded the experimental thresholds for mortality or malformation in three of them. UV-B dose estimates and amphibian distribution information (as well as numerous habitat variables) for 1026 wetlands in the National Parks are being statistically analyzed to determine if a relationship exists between the level of UV-B exposure and the presence of amphibians. This research is innovative in its incorporation of all the factors essential for UV-B dose estimation, its broad geographic coverage, the number of wetlands studied, and its applicability to many environmental issues, and will provide invaluable information to environmental researchers and decision makers alike.