PARENT SESSION
OOS 2: Anthropogenic Disturbances to Western Alpine Lakes: Past, Present, and Future .
Organized by: JE Saros and CE Williamson
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room E 143.
UV impacts on alpine amphibians: Linking UV tolerance with field exposure.
Palen, Wendy*,1, Schindler, Daniel1, Clauser, Aaron2, Williamson, Craig2, 1 University of Washington, Seattle, WA2 Lehigh University, Bethlehem, PA
ABSTRACT- Increasing UV-B radiation due to stratospheric ozone depletion is among the most studied anthropogenic stressors to alpine ecosystems. High elevation ecosystems receive greater fluxes of UV-B and have little landscape vegetation to moderate this radiation compared to lowland systems. As such, aquatic organisms in alpine areas may be particularly sensitive to increasing levels of UV-B. Amphibians have received disproportionate attention in the literature related to UV-B impacts in alpine lakes, with nearly 100 studies documenting direct mortality through DNA damage, indirect mortality though increased susceptibility to predators and pathogens, and changes in behavior. While many of these studies have been invoked in support of the often cited link between increasing UV-B and declining amphibian populations, very little is known about how differences in species′ physiological sensitivity to UV-B translate into risk for populations distributed over heterogeneous landscapes. Building on previous work establishing the importance of dissolved organic matter (DOM) for the optical characteristics of amphibian breeding sites, we conducted a series of experiments in sub-alpine ponds of Olympic National Park (WA) to determine the levels of UV-B exposure required for embryonic mortality in sites spanning a gradient of DOM concentrations. We link the results of these field experiments for two amphibians to laboratory-based studies of UV-B photorepair ability and field surveys of egg exposure to estimate the thresholds of DOM required for UV-B protection. Our results demonstrate that oviposition behavior in the field compliments differences in species′ physiological tolerances to UV-B. These predictions give a first approximation for evaluating the risk increasing UV-B poses to amphibians at the large spatial scales relevant to population dynamics.
Key words: amphibian declines, risk-analysis, UV-B radiation, dissolved organic matter