An Update on Frogs, Contaminants, and Disease Research

POWERPOINT AND VIDEO WITHHELD AT SPEAKER'S REQUEST

FELLERS, GARY M.
USGS Western Ecological Research Center, Point Reyes National Seashore, Point Reyes, CA,
gary_fellers@usgs.gov

An Update on Frogs, Contaminants, and Disease Research

A fungal disease (chytridiomycosis), first described in 1999 and possibly introduced from Africa, has been closely associated with amphibian die-offs in the Sierra Nevada and elsewhere, but it is not clear whether the chytrid fungus is a primary cause of the declines or whether it gets a foothold when amphibian populations are under stress. Chytrid fungus in Yosemite National Park was reported in Rana muscosa in 2001 (Fellers et al.). In 2005, I began a detailed study of two watersheds in Yosemite and one at Point Reyes National Seashore to determine the distribution of chytrid fungus in native amphibian tadpoles. In a series of related studies, data from contaminants research suggest that pesticides are playing a significant role in amphibian declines in the Sierra Nevada. Studies comparing contaminants levels in frog and tadpole tissue with concentrations in sediment, air, snow, and water in coastal and mountain regions of California strongly support the view that contaminants are playing a significant role in amphibian declines.