Coordinated Studies of Ultraviolet Radiation and Amphibians in Lentic Wetland Habitats

Abstract

The recent depletion of stratospheric ozone hasresulted in increased terrestrial ultraviolet-B radi-ation (UV-B, 280–320-nm wavelengths) and isamong the most dramatic examples of humanactivities affecting global ecosystems. Because thenegative effects of UV-B on biological systems arewell-known, increased exposure represents a clearthreat to human health and ecosystems worldwide(Helbling and Zagarese 2003). In 1987, respondingto this threat, representatives from 24 nationssigned the Montreal Protocol, the first in a series oflandmark global agreements designed to preservestratospheric ozone by reducing industrial produc-tion of ozone-depleting compounds (Morrisette1989). These actions have slowed the rate of ozonereduction; however, stratospheric ozone concen-trations are presently at their lowest levels everand, even assuming complete global compliancewith the Montreal Protocol, are not expected toapproach pre-CFC-release levels for 15–45 years(Weatherhead and others 2000).Through the 1970s and 1980s, as UV-B levelsreaching the surface of the earth increased,amphibian species disappeared from many loca-tions worldwide (Middleton and others 2001). Astrong link between amphibian declines and UV-Bhas not yet been demonstrated, but researchershave begun to evaluate patterns of habitat occu-pancy and declines for evidence of UV-Bs influ-ence in nature (Adams and others 2001; Davidsonand others 2001, 2002; Middleton and others 2001)and to assess the risk that UV-B currently poses forwild amphibians (Palen and others 2002). Al-though the causes of specific amphibian declinesand disappearances are usually unclear, a numberof field experiments have shown that UV-B presentin natural sunlight can increase mortality andmalformation rates in embryos of some amphibians(reviewed in Corn 2000; Blaustein and others2003; Licht 2003). In January 1999, biologists fromthe U.S. Environmental Protection Agency (EPA),National Park Service (NPS), U.S. Geological Sur-vey (USGS), and academia convened in Duluth,Minnesota, USA, to discuss how to evaluate therisk that UV-B poses to natural amphibian popu-lations and to design a research project using theParks Research and Intensive Monitoring of Eco-systems Network (PRIMENet).PRIMENet is a joint EPA–NPS program estab-lished to assess the effects of environmentalstressors on ecological systems nationwide (http://www.forestry.umt.edu/research/MFCES/pro-grams/primenet/). PRIMENet encompasses 14national park sites at which UV-B levels aremonitored continuously by Brewer spectropho-