Toxic Snow Takes Toll on Tadpoles

This release can be found in the USGS Newsroom at:

Contamination in U.S. Private Wells.

Toxic Snow Takes Toll on Tadpoles

Pesticides can travel hundreds of miles and turn up in some unexpected

places. Scientists from the USGS and Southern Illinois University are

linking declines in frog populations in the Sierra Nevada mountains with

pesticides used on farms in the San Joaquin Valley. These pesticides can

travel by wind to contaminate the snow falling in the Sierra Nevada. When

the snow melts in the spring, pesticides in the runoff contaminate areas

where foothill yellow-legged frogs and Pacific treefrogs breed. In the

study, the pesticides endosulfan and chlorpyrifos slowed tadpole growth and

development. Chlorpyrifos also affected functioning of the nervous system,

and endosulfan caused developmental abnormalities. These factors can alter

behavior and make tadpoles more vulnerable to predators. The full report

can be read at the USGS Western Ecological Center Web site. For more

information contact Gary Fellers at gary_fellers@usgs.gov or (415)

464-5185.