Pesticides and amphibian population declines in California, USA
Sparling DW, Fellers GM, McConnell LL. 2001. Pesticides and amphibian population declines in California, USA. Environmental Toxicology and Chemistry. 20(7):1591–1595
Several species of anuran amphibians have undergone drastic population declines in the western United States over the last 10 to 15 years. In California, the most severe declines are in the Sierra Mountains east of the Central Valley and downwind of the intensely agricultural San Joaquin Valley. In contrast, coastal and more northern populations across from the less agrarian in declines of these species. Using Hyla regilla as a sentinel species, we found that cholinesterase (ChE) activity in tadpoles was depressed in mountainous areas east of the Central Valley compared with sites along the coast or north of the Valley. Cholinesterase was also lower in areas where ranid population status was poor or moderate compared with areas with good ranid status. Up to 50% of the sampled population in areas with reduced ChE had detectable organophosphorus residues, with concentratins as high as 190 ppb wet weight. In addition, up to 86% of some populations had measurable endosulfan concentrations and 40% had detectable 4,4'-dichlorodiphenyldichloroethylene, 4,4'-DDT, and 2,4'-DDT residues.
- Type
- Journal Article
- Authors
- Sparling, Donald; Fellers, Gary; McConnell, Laura
- Units
- KLMN , PORE , SIEN , YOSE
- Keywords
- chlorpyrifos, DDT, Declining amphibians, diazinon, Endosulfan, foothill yellow legged frogs, Herpetology (Amphibians/Reptiles), Hyla regilla, Marin County, mountain yellow legged frogs, Pacific Treefrog, Pesticide, Pesticide effects, Point Reyes, Red legged frogs, Tadpoles, Yosemite toads