标题：Effects of Incident UV-B Radiation on Periphyton in Four Alpine Freshwater Ecosystems in Central Colorado: Impacts on Boreal Toad Tadpoles (Bufo boreas)
摘要：Field experiments using mylar shielding were conducted to determine the impacts of UV-B on food quality in four western boreal toad breeding ponds located in central Colorado. The breeding ponds were located at elevations ranging from 2971 m to 3272 m, an elevational range associated with at least a 5% change in UV-B exposure. The protein concentration in algae decreased with increased exposure to UV-B, chlorophyll a concentration was not affected by UV-B exposure, and community composition of algae was affected. Densities of Chlorophyta and Xanthophycease increased and densities of Diatomaceae and Cyanophyta decreased under mylar shielding. Not all members of taxonomic groups reacted the same. These data are interpreted to mean that food quality available to boreal toad tadpoles is poorer as a result of increased exposure to UV-B. Poorer food quality can impact the ability of these toads to complete their life cycle and thus can impact recruitment to adult populations.
