| | Accession Number | 5004297 |
| | Title | The Role of Pesticides in Declining Amphibian Populations in the Sierra Nevadas |
| | Project Description | The Role of Pesticides in Declining Amphibian Populations in the Sierra Nevadas Status: Active |
| | Starting Date: 000630 Ending Date: 031230 Several species of amphibians are declining in the |
| | Sierra Nevada Mountains of California. These include the red-legged frog (Rana aurora), mountain |
| | yellow-legged frog (R. muscosa), Cascade frog, foothills yellow-legged frog(R. boylii), Yosemite |
| | toad (Bufo canorus) and others. The populations most severely affected are those living at high |
| | elevation in presumably pristine National Parks and federal lands (Yosemite, Sequoia, Lake Tahoe |
| | Mgmt Basin). The red-legged frog is listed by the Fish and Wildlife Service as threatened and the |
| | mountain yellow-legged frog is proposed for listing. Several factors such as habitat loss, |
| | introduced predators and increased ultraviolet radiation have been proposed as contributors to |
| | these declines. However, a growing body of information clearly suggests that pesticides are a |
| | principal factor. According to this data, westerly winds from the coast sweep past the intensely |
| | agricultural Central Valley of California and carry insecticides into the pristine higher elevations. |
| | Pesticides have been found repeatedly in rainfall and snow of the National Parks. Recently, |
| | depressed cholinesterase and body residues of pesticides in Pacific treefrogs (Hyla regilla), a |
| | sentinel species for the rarer frogs, has been found to match the declines very closely. Up to 86% |
| | of some populations had measurable levels of endosulfans and 30%+ of other populations had |
| | detectable levels of chlorpyrifos or diazinon. This research is of considerable interest to the U.S. |
| | Fish and Wildlife Service because of its mission of dealing with endangered species and to the |
| | National Park Service on whose lands the problems are most expressed. The current study has |
| | three main objectives: a) determine the extent of reduced cholinesterase activity and pesticide |
| | residues in Hyla regilla and ponds as they relate to declines in Bufo and Rana species; b) conduct |
| | translocation experiments to compare the survivorship of tadpoles in waters suspected of being |
| | contaminated by pesticides; and c) quantify the sensitivities of Hyla regilla and Rana aurora or |
| | Rana muscosa to pesticides suspected of affecting anuran populations in the Sierras through |
| | standard toxicity tests. |
| | Keywords | amphibians, california, chlorpyrifos, declining populations, diazinon, endosulfan, hyla, pesticides, |
| | population effects, rana, sierra nevada mountains, |
| | Principal | Donald W Sparling, USGS Patuxent Wildlife Research Center: don_sparling@usgs.gov; G. |
| | Investigators | Fellers, Western Ecology Research Center: gary_fellers@usgs.gov; Deborah Cowman, |
| | Department of Fisheries and Wildlife, Texas A&M University: d-cowman@tamu.edu; |
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