Amphibian Population Declines and Contaminants:

Selected Literature



This site is dedicated to presenting the scientific literature on the possible role of contaminants in global amphibian population declines. The site focuses on five areas: papers directly about contaminants and amphibian population declines, contaminants impacts on amphibian immune systems impacts, contaminant transport to remote locations where declines have occurred, synergistic effects and review papers.


Not included here is the vast literature on laboratory studies of lethality of chemicals to amphibians which is well covered by the Environmental Protection Agencies’ ECOTOX database. Also not included are many papers which demonstrate simple sub-lethal effects of contaminants such as reduced survival, which may indicate real impacts of contaminants on wild amphibian populations, but represent mechanisms that are unlikely to be responsible for the phenomenon of rapid amphibian population declines. The focus of this site is thus narrower than the broad topic of contaminants and amphibian conservation.


This site was inspired by a similar site on amphibian declines and disease.


If you have suggestions for additional papers to include click here for submittal info.




Angermann, J. E., G. M. Fellers, and F. Matsumura. 2002. Polychlorinated biphenyls and toxaphene in Pacific tree frog tadpoles (Hyla regilla) from the California Sierra Nevada, USA. Environmental    Toxicology and Chemistry 21:2209-2215. [pdf]


Aston, L. S., and J. N. Seiber. 1997. Fate of summertime airborne organophosphate pesticide residues in the Sierra Nevada mountains. Journal of Environmental Quality 26:1483-1492.


Bishop, C. A. 1992. The effects of pesticides on amphibians and the implications for determining causes of declines in amphibian populations. Occasional paper. Canadian Wildlife Service. Ottawa.


Blais, J. M., D. W. Schindler, D. C. G. Muir, L. E. Kimpe, D. B. Donald, and B. Rosenberg. 1998. Accumulation of persistent organochlorine compounds in mountains of western Canada.  395:585-588.


Blaustein, A. R., J. M. Romansic, J. M. Kiesecker, and A. C. Hatch. 2003. Ultraviolet radiation, toxic chemicals and amphibian population declines. Diversity & Distributions 9:123-140.[pdf]


Boone, M., C. Davidson, and C. M. Bridges. In press. Evaluating the Role of Pesticides in Amphibian Declines in H. Heatwole, and J. Wilkinson, editors. Decline and Conservation of Amphibians.


Boone, M.D., R.D. Semlitsch, E.E. Little, and M.C. Doyle. 2007. Multiple stressors in amphibian communities: interactive effects of chemical contamination, bullfrog tadpoles, and bluegill sunfish. Ecological Applications 17:291-301.


Boone, M. D., D. F. Cowman, C. Davidson, T. B. Hayes, W. A. Hopkins, R. A. Relyea, L. Schiesari, and R. D. Semlitsch. 2005. Chapter 6, Evaluating the Role of Environmental Contamination in Amphibian Population Declines in C. Gascon, J. P. Collins, R. D. Moore, D. R. Church, J. McKay, and J. M. III, editors. Amphibian Conservation Action Plan. The World Conservation Union (IUCN), Gland, Switzerland. [pdf]


Boone, M.D., R.D. Semlitsch, J.M. Fairchild, and B.B. Rothermel. 2004. Effects of an insecticide on amphibians in large-scale experimental ponds. Ecological Applications 14:685-691. [pdf]


Boone, M.D., and R.D. Semlitsch. 2003. Interactions of bullfrog tadpole predators and an insecticide: predation release and facilitation. Oecologia 137:610-616. [pdf]


Boone, M. D., and C. M. Bridges. 2003. Effects of pesticides on amphibian populations. Amphibian conservation:152–167.


Boone, M. D., and S. M. James. 2003. Interactions of an insecticide, herbicide, and natural stressors in amphibian community mesocosms. Ecological Applications 13:829-841. [pdf]


Boone, M. D., and R. D. Semlitsch. 2001. Interactions of an insecticide with larval density and predation in experimental amphibian communities. Conservation Biology 15:228-238. [pdf]


Boone, M. D., and R. D. Semlitsch. 2002. Interactions of an insecticide with competition and pond drying in amphibian communities. Ecological applications 12:307-316. [pdf]


Bridges, C. M., and E. E. Little. 2005. Toxicity to amphibians of environmental extracts from natural waters in National Parks and Fish and Wildlife Refuges. Alytes 22:130-145.


Bridges, C. M., and M. D. Boone. 2003. The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development. Biological Conservation 113:49-54. [pdf]


Bridges, C.M., and R.D. Semlitsch. 2001. Genetic variation in insecticide tolerance in a population of southern leopard frogs (Rana sphenocephala): implications for amphibian conservation. Copeia 2001: 7-13.


Bridges, C. M., and R. D. Semlitsch. 2000. Variation in Pesticide Tolerance of Tadpoles among and within Species of Ranidae and Patterns of Amphibian Decline. Conservation Biology 14:1490-1499.[pdf]


Budischak, S. A., L. K. Belden, and W. A. Hopkins. 2008. Effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles. Environ Toxicol Chem:1.[pdf]


Carrera, G., P. Fernandez, J. O. Grimalt, M. Ventura, L. Camarero, J. Catalan, U. Nickus, H. Thies, and R. Psenner. 2002. Atmospheric Deposition of Organochlorine Compounds to Remote High Mountain Lakes of Europe. Environ. Sci. Technol. 36:2581-2588. [pdf]


Carrera, G., P. Fernandez, R. M. Vilanova, and J. O. Grimalt. 2001. Persistent organic pollutants in snow from European high mountain areas. Atmospheric Environment 35:245-254. [pdf]


Christin, M. S., Ménard, L., Gendron, A.D., Ruby S., Cyr, D., Marcogliese, D., Rollins-Smith, L., and Fournier, M. 2004. Effects of agricultural pesticides on the immune system of Xenopus laevis and Rana pipiens. Aquatic Toxicology 67:33-43.


Christin, M. S., A. D. Gendron, P. Brousseau, L. Menard, D. J. Marcogliese, D. Cyr, S. Ruby, and M. Fournier. 2003. Effects of agricultural pesticides on the immune system of Rana pipiens and on its resistance to parasitic infection. Environmental Toxicology and Chemistry 22:1127-1133.


Cory, L., P. Fjerd, and W. Serat. 1970. Distribution patterns of DDT residues in the Sierra Nevada mountains. Pesticide Monitoring Journal 3:204-211.


Cowman, D. F. 2007. Pesticides and amphibian declines in the Sierra Nevada Mountains, California. Texas A & M. Ph.D. dissertation. [link]


Daly, G. L., Y. D. Lei, C. Teixeira, D. C. G. Muir, L. E. Castillo, and F. Wania. 2007. Accumulation of current-use pesticides in neotropical montane forests. Environmental Science and Technology. 41:1118-1123.[pdf]


Datta, S. 1997. Studies on the atmospheric transport and deposition of polychlorinated biphenyls and pesticides in aquatic ecosystems of the Sierra Nevada. University of California, Davis. Ph.D. dissertation. 


Datta, S., L. Hansen, L. McConnell, J. Baker, J. LeNoir, and J. N. Seiber. 1998. Pesticides and PCB contaminants in fish and tadpoles from the Kaweah River Basin, California. Bulletin of Environmental Contamination and Toxicology 60:829-836. [pdf]


Davidson, C., M. Benard, H. B. Shaffer, J. Parker, C. O'Leary, J. M. Conlon, and L. A. Rollins-Smith. 2007. Effects of chytrid infection and carbaryl exposure on survival, growth and antimicrobial peptide defenses in foothill yellow-legged frogs (Rana boylii). Environmental Science and Technology 41:1771-1776. [pdf]


Davidson, C., and R. Knapp. 2007. Multiple stressors and amphibian declines: dual impacts of pesticides and fish on yellow-legged frogs. Ecological Applications 17:587-597. [pdf]


Davidson, C. 2004. Declining downwind: Amphibian population declines in California and historic pesticide use. Ecological Applications 14:1892-1902.[pdf]


Davidson, C., H. B. Shaffer, and M. Jennings. 2002. Spatial tests of the pesticide drift, habitat destruction, UV-B and climate change hypotheses for California amphibian declines. Conservation Biology 16:1588-1601. [pdf]


Davidson, C., H. B. Shaffer, and M. R. Jennings. 2001. Declines of the California red-legged frog: climate, UV-B, habitat and pesticides hypotheses. Ecological Applications 11:464-479.[pdf]


Fellers, G. M., L. L. McConnell, D. Pratt, and S. Datta. 2004. Pesticides in mountain yellow-legged frogs (Rana muscosa) from the Sierra Nevada mountains of California, USA. Environmental Toxicology and Chemistry 23:2170-2177.[pdf]


Forson, D. D., and A. Storfer. 2006. Atrazine increases ranavirus susceptibility in the tiger salamander, Ambystoma tigrinum. Ecological Applications 16:2325-2332. [pdf]


Gendron, A. D., D. J. Marcogliese, S. Barbeau, M. S. Christin, P. Brousseau, S. Ruby, D. Cyr, and M. Fournier. 2003. Exposure of leopard frogs to a pesticide mixture affects life history characteristics of the lungworm Rhabdias ranae. Oecologia 135:469-476. [pdf]


Gilbertson, M., G. D. Haffner, K. G. Drouillard, A. Albert, and B. Dixon. 2003. Immunosuppression in the northern leopard frog (Rana pipiens) induced by pesticide exposure. Environmental Toxicology and Chemistry 22:101-110.[pdf]


Grimalt, J. O., P. Fernandez, L. Berdie, R. M. Vilanova, J. Catalan, R. Psenner, R. Hofer, P. Appleby, B. O. Rosseland, L. Lien, J. C. Massabuau, and R. W. Battarbee. 2001. Selective Trapping of Organochlorine Compounds in Mountain Lakes of Temperate Areas. Environmental Science and Technology 35:2690-2697. [pdf]


Hageman, K. J., S. L. Simonich, D. H. Campbell, G. R. Wilson, and D. H. Landers. 2006. Atmospheric deposition of current-use and historic-use pesticides in snow at national parks in the western United States. Environmental Science & Technology 40:3174-3180.[pdf]


Hatch, A. C., and A. R. Blaustein. 2000. Combined Effects of UV-B, Nitrate, and Low pH Reduce the Survival and Activity Level of Larval Cascades Frogs (Rana cascadae). Archives of Environmental Contamination and Toxicology 39:494-499. [pdf]


Hayes, T. B., P. Case, S. Chui, D. Chung, C. Haeffele, K. Haston, M. Lee, V. P. Mai, Y. Marjuoa, and J. Parker. 2006. Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact? Environmental Health Perspectives 114:40.[pdf]


Hayes, T. B., A. Collins, M. Lee, M. Mendoza, N. Noriega, A. Stuart, and A. Vonk. 2002. Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses. Proceedings of the National Academy of Sciences of the United States of America 99:5476–5480.[pdf]


Hopkins, W. A., S. E. DuRant, B. P. Staub, C. L. Rowe, and B. P. Jackson. 2006. Reproduction, embryonic development, and maternal transfer of contaminants in the amphibian Gastrophryne carolinensis. Environmental Health Perspectives 114:661.[pdf]


James, S.M., E.E. Little, and R.D. Semlitsch. 2005. Responses of two amphibian species to chronic cadmium exposure as tadpoles in aquatic outdoor mesocosms. Environmental Toxicology and Chemistry 24:1994-2001. [pdf]


James, S.M., E.E. Little, and R.D. Semlitsch. 2004. Effects of multiple routes of cadmium exposure on the hibernation success of the American toad (Bufo americanus). Archives of Environmental Contamination and Toxicology 46:518-527. [pdf]


James, S.M., E.E. Little, and R.D. Semlitsch. 2004. The effect of soil composition and hydration on the bioavailability and toxicity of cadmium to hibernating juvenile American toads (Bufo americanus). Environmental Pollution 132:523-532.


Kerby, J. L., and A. Storfer. 2009. Combined effects of atrazine and chlorpyrifos on susceptibility of the tiger salamander to Ambystoma tigrinum virus. EcoHealth.


Kiesecker, J. M. 2002. Synergism between trematode infection and pesticide exposure: A link to amphibian limb deformities in nature? Proceedings of the National Academy of Sciences of the United States of America 99:9900-9904.[pdf]


LeNoir, J. S., L. L. McConnell, G. M. Fellers, T. M. Cahill, and J. N. Seiber. 1999. Summertime transport of current-use pesticides from California's Central Valley to the Sierra Nevada mountain range, USA. Environmental  Toxicology and Chemistry 18:2715-2722. [pdf]


McConnell, L. L., J. S. LeNoir, S. Datta, and J. N. Seiber. 1998. Wet deposition of current-use pesticides in the Sierra Nevada mountain range, California, USA. Environmental Toxicology and Chemistry 17:1908-1916. [pdf]


Mills, N. E. and R.D. Semlitsch. 2004. Competition and predation mediate the indirect effects of an insecticide on southern leopard frogs. Ecological Applications 14:1041-1054. [pdf]


Reeder, A. L., M. O. Ruiz, A. Pessier, L. E. Brown, J. M. Levengood, C. A. Phillips, M. B. Wheeler, R. E. Warner, and V. R. Beasley. 2005. Intersexuality and the Cricket Frog Decline: Historic and Geographic Trends. Environmental Health Perspectives 113:261. [pdf]


Relyea, R. A., N. M. Schoeppner, and J. T. Hoverman. 2005. Pesticides and amphibians: the importance of community context. Ecological Applications 15:1125-1134. [pdf]


Relyea, R. A. 2004. Growth and survival of five amphibian species exposed to combinations of pesticides. Environmental Toxicology and Chemistry 23:1737-1742. [pdf]


Relyea, R. A. 2004. Synergistic impacts of malathion and predatory stress on six species of North American tadpoles. Environmental Toxicology and Chemistry 23:1080-1084. [pdf]


Relyea, R. A. 2003. Predator cues and pesticides: A double dose of danger for amphibians. Ecological Applications 13:1515–1521. [pdf]


Relyea, R. A., and M. Mills. 2001. Predator-induced stress makes the pesticide carbaryl more deadly to gray treefrog tadpoles. Proceedings of the National Academy of Sciences of the United States of America 98:2491-2496. [pdf]


Rohr, J. R., T. R. Raffel, S. K. Sessions, and P. J. Hudson. 2008. Understanding the net effects of pesticides on amphibian tremetode infections. Ecological Applications 18:1743-1753. [pdf]


Rohr, J. R., A. M. Schotthoefer, T. R. Raffel, H. J. Carrick, N. Halstead, J. T. Hoverman, C. M. Johnson, L. B. Johnson, C. Lieske, and M. D. Piwoni. 2008. Agrochemicals increase trematode infections in a declining amphibian species. Nature 455:1235. [pdf]


Rohr, J. R., A. A. Elskus, B. S. Shepherd, P. H. Crowley, T. M. McCarthy, J. H. Niedzwiecki, T. Sager, A. Sih, and B. D. Palmer. 2004. Multiple stressors and salamanders: effects of an herbicide, food limitation, and hydroperiod. Ecological Applications 14:1028-1040. [pdf]


Semlitsch, R.D., C.M. Bridges, and A.M. Welch. 2000. Genetic variation and a fitness tradeoff in the tolerance of gray treefrog tadpoles (Hyla versicolor) to the insecticide carbaryl. Oecologia 125:179-185.


Sparling, D. W., and G. M. Fellers. 2007. Comparative toxicity of chlorpyrifos, diazinon malathion and their oxon derivatives to larval Rana boylii. Environmental Polution 147:535-539. [pdf]


Sparling, D. W., Bishop, C. A. and Linder, G., 2000.  The current status of amphibian and reptile ecotoxicological research.  Pp. 1-13 in  "Ecotoxicology of Amphibians and Reptiles", ed by D. W. Sparling, G. Linder, and C. A. Bishop.  Society of Environmental Toxicology and Chemistry, Pensacola.


Sparling, D. W., G. M. Fellers, and L. L. McConnell. 2001. Pesticides and amphibian population declines in California, USA. Environmental Toxicology and Chemistry 20:1591-1595.  [pdf]


Sparling, D. W., G. Fellers, and L. McConnell. 2001. Pesticides are involved with population declines of amphibians in the California Sierra Nevadas. Scientific World Journal 1:200-201.


Sparling, D. W., Linder, G. and Bishop, C. A., 2000.  "Ecotoxicology of Amphibians and Reptiles".  SETAC Press, Pensacola.


Storrs, S.I., and R.D. Semlitsch. 2008. Species variation in somatic and ovarian development: predicting susceptibility of amphibians to estrogenic contaminants. General & Comparative Endocrinology 156:524-530. [pdf]


Taylor, S. K., E. S. Williams, and K. W. Mills. 1999. Effects of malathion on disease susceptibility in Woodhouse's toads. Journal of Wildlife Diseases 35:536-541. [pdf]


Vilanova, R., P. Fernandez, C. Martinez, and J. O. Grimalt. 2001. Organochlorine pollutants in remote mountain lake waters. J Environ Qual 30:1286-1295. [pdf]


Zabik, J. M., and J. N. Seiber. 1993. Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada Mountains. Journal of Environmental Quality 22:80-90.


Zaga, A., E. E. Little, C. F. Rabeni, and M. R. Ellersieck. 1998. Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians. Environmental Toxicology and Chemistry 17:2543-2553.


Last update July 14, 2009.