Effects of carbaryl on species interactions of the foothill yellow legged frog (Rana boylii) and the Pacific treefrog (Pseudacris regilla)
- 269 Downloads
Amphibian species worldwide are being confronted with novel anthropogenic stressors such as contaminants and invasive species. While much work has been done to examine these factors individually, less is known about how these stressors might interact. No studies to this point have examined the potentially synergistic impacts between these two stressors on a threatened amphibian species. We present the results from three separate laboratory studies focusing on two species of frogs, the Pacific tree frog (Pseudacris regilla) and a federal species of concern, the foothill yellow legged frog (Rana boylii). These experiments examine the toxicity of an insecticide, carbaryl, on each species, on their competitive interactions, and on their interaction with a non-native crayfish predator (Pacifastacus leniusculus). R. boylii were more susceptible to pesticide exposure than P. regilla and exposure reduced their ability to compete. This differential effect of the pesticide resulted in a remarkable increase in mortality (50%) for R. boylii with an invasive crayfish predator present while P. regilla exhibited no change. These results add to concerns over the utility of single species toxicity tests in determining safe levels for environmental exposure and advocate for the use of multiple species tests that focus on key species interactions.
KeywordsPesticide Multiple stressors Predation Competition Sub-lethal effects
This work was supported by funding from the Environmental Protection Agency. We thank B. Shaffer and M. Johnson for input on previous versions of this manuscript. We also thank A. Lind and S. Kupferberg for assistance with R. boylii. K. Bryant was instrumental in conducting the work. This work was conducted under a permit from the California Department of Fish and Game.
- Datta, S., L. Hansen, L. McConnell, J. Baker, J. Lenoir & J. N. Seiber, 1998. Pesticides and PCB contaminants in fish and tadpoles from the Kaweah River Basin, California. Environmental Toxicology and Chemistry 60: 829–836.Google Scholar
- Gosner, K., 1960. A simplified table for staging anuran embryos and larvae with notes on identification. Herpetelogica 16: 183–190.Google Scholar
- Norris, L. A., H. W. Lorz, and S. Z. Gregory. 1983. Influence of forest and range land management on anadramous fish habitat in western North America: forest chemicals. USDA Forest Service General Technical Report PNW-149.Google Scholar