M9 PM Multiple Stressors in Amphibian and Reptile Ecotoxicology
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 339-340

(FEL-1117-839123) Amphibian Declines in the Sierra Nevada mountains of California: why are we worried about contaminants?

Fellers, Gary¹, Kleeman, Patrick¹, ¹ Western Ecological Research Center, USGS, Point Reyes National Seashore, Point Reyes, CA, USA

ABSTRACT- Since 1991, we have visited >6,000 field sites throughout California to evaluate the presence and abundance of pond-breeding amphibians. We have found that most, if not all, species of pond-breeding amphibians in the Sierra Nevada mountains of California are declining. Cascades frogs (Rana cascadae) are almost entirely gone from Lassen Volcanic National Park, mountain yellow-legged frogs (Rana muscosa) are gone from large portions of Sequoia NP, and Yosemite toads (Bufo canorus) are now hard to find in many formerly occupied areas of Yosemite NP. The preponderance of data suggest that contaminants are playing a significant role in these, and other declines. Prevailing winds move pesticides from the valley into the Sierra Nevada. An experimental reintroduction of mountain yellow-legged frogs in Sequoia NP failed. Pond-breeding amphibians in watersheds that face the highly agriculturalized Central Valley of California have experienced the most dramatic declines. A series of studies comparing contaminants levels in frog and tadpole tissue, sediment, air, snow, and water in coastal and mountain parts of California strongly support the view that contaminants are playing a role in amphibian declines.

Key words: frog, amphibian, contaminant, decline