Skip to main content

Insensitivity to road salt: an advantage for the American bullfrog?


The health of freshwater ecosystems is negatively affected by a multitude of pollutants. In northern latitudes, road deicing agents enter nearby ponds and waterways elevating chloride concentrations in winter and spring. Few studies have examined how amphibians respond to road salt contamination and no study has focused on the response of an invasive amphibian. We examined the effects of NaCl, the most commonly used deicing agent, on the embryos and tadpoles of the American bullfrog, Lithobates catesbeianus, a species that is invasive in many regions around the world. In the first experiment, we exposed L. catesbeianus embryos to ecologically relevant levels of chloride for 60 days. The second experiment examined the indirect consequences of chloride contamination by exposing L. catesbeianus tadpoles to dragonfly larvae. Lithobates catesbeianus did not experience reduced survival, growth, or ability to evade predation in elevated chloride concentrations compared to controls. The lack of a response by L. catesbeianus suggests that its population growth will not be negatively impacted by road salt contamination. This result may be good news for L. catesbeianus, but raises concern for sympatric amphibians that have to contend with negative impacts of both chloride contamination and non-native L. catesbeianus.

This is a preview of subscription content, access via your institution.

Fig. 1


  • Abramoff, M. D., P. J. Magalhaes & S. J. Ram, 2004. Image processing with ImageJ. Biophotonics International 11: 36–42.

    Google Scholar 

  • Blaustein, A. R. & D. B. Wake, 1990. Declining amphibian populations: a global phenomenon? Trends in Ecology and Evolution 5: 203–204.

    Article  Google Scholar 

  • Bury, R. B. & R. A. Luckenbach, 1976. Introduced amphibians and reptiles in California. Biological Conservation 10: 1–14.

    Article  Google Scholar 

  • Casper, G. S. & R. Hendricks, 2005. Rana catesbeiana. In Lannoo, M. (ed.), Amphibian Declines: The Conservation Status of United States Species. University of California Press, California: 540–546.

  • Chambers, D. L., 2011. Increased conductivity affects corticosterone levels and prey consumption in larval amphibians. Journal of Herpetology 45: 219–223.

    Article  Google Scholar 

  • Christiansen, J. L., 1998. Perspectives on Iowa’s declining amphibians and reptiles. Proceedings of the Iowa Academy of Science 88: 24–27.

    Google Scholar 

  • Collins, S. J. & R. W. Russell, 2009. Toxicity of road salt to Nova Scotia amphibians. Environmental Pollution 157: 320–324.

    PubMed  Article  CAS  Google Scholar 

  • D’Itri, F. M., 1992. Prologue. In D’Itri, F. M. (ed.), Chemical Deicers and the Environment. Lewis, Boca Raton, FL.

  • Denoël, M., M. Bichot, G. F. Ficetola, J. Delcourt, M. Ylieff, P. Kestemont & P. Poncin, 2010. Cumulative effects of road de-icing salt on amphibian behavior. Aquatic Toxicology 99: 275–280.

    PubMed  Article  Google Scholar 

  • Dougherty, C. K. & G. S. Smith, 2006. Acute effects of road de-icers on the tadpoles of three anurans. Applied Herpetology 3: 87–93.

    Article  Google Scholar 

  • Environment Canada, 2001. Priority substances list assessment report for road salts. Canada Gazette, Part 1, December 1, 2001. Report number EN41-215/63E. Gatineau, Quebec, Canada.

  • Garner, T. W. J., M. W. Perkins, P. Govindarajulu, D. Seglie, S. Walker, A. A. Cunningham & M. C. Fisher, 2006. The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana. Biology Letters 2: 455–459.

    PubMed  Article  Google Scholar 

  • Gosner, K. L., 1960. A simplified table for staging anuran embryos and larvae with notes on identification. Herpetologica 1960: 183–190.

    Google Scholar 

  • Harless, M. L., C. J. Huckins, J. B. Grant & T. G. Pypker, 2011. Effects of six chemical deicers on larval wood frogs (Rana sylvatica). Environmental Toxicology and Chemistry 30: 1637–1641.

    PubMed  Article  CAS  Google Scholar 

  • Karraker, N. E., 2007. Are embryonic and larval green frogs (Rana clamitans) insensitive to road deicing salt? Herpetological Conservation and Biology 2: 35–41.

    Google Scholar 

  • Karraker, N. E., 2008. Impacts of road deicing salts on amphibians and their habitat. In Mitchell, J. C., R. E. Jung Brown & S. C. Walls (eds), Urban Herpetology. Society for the Study of Amphibians and Reptiles, Utah: 183–195.

    Google Scholar 

  • Karraker, N. E., J. P. Gibbs & J. R. Vonesh, 2008. Impacts of road de-icing salt on the demography of vernal pool-breeding amphibians. Ecological Applications 18: 724–734.

    PubMed  Article  Google Scholar 

  • Kats, L. B. & R. P. Ferrer, 2003. Alien predators and amphibian declines: review of two decades of science and the transition to conservation. Diversity and Distributions 9: 99–110.

    Article  Google Scholar 

  • Kiesecker, J. M. & A. R. Blaustein, 1997. Population differences in responses of red-legged frogs (Rana aurora) to introduced bullfrogs. Ecology 78: 1752–1760.

    Google Scholar 

  • Kupferberg, S., 1997. Bullfrog (Rana catesbeiana) invasion of a California river: the role of larval competition. Ecology 78: 1736–1751.

    Google Scholar 

  • Lake County Health Department, 2012. Lake Reports, Lakes Management Unit, Waukegan, IL.

  • Levesque, R., 2007. SPSS Programming and Data Management: A Guide for SPSS and SAS Users, 4th ed. SPSS Inc., Chicago, IL.

    Google Scholar 

  • Lewis, W. M. Jr., 1999. Studies of environmental effects of magnesium chloride deicer in Colorado. Colorado Department of Transportation, Denver. Report No. CDOT-DTD-R-99-10.

  • Marsalek, J., 2003. Road salts in urban stormwater; an emerging issue in stormwater management in cold climates. Water Science and Technology 48: 61–70.

    PubMed  CAS  Google Scholar 

  • Moriarty, J. J., 1998. Status of amphibians in Minnesota. In Lannoo, M. J. (ed.) Status and Conservation of Midwestern Amphibians. University of Iowa Press, Iowa: 166–168.

  • National Research Council, 1991a. Highway deicing: comparing salt and calcium magnesium acetate. National Research Council, Traffic Research Board, Special Report No. 235, Washington, DC.

  • National Research Council, 1991b. Road salt use in the United States. National Research Council, Transportation Research Board, Washington, DC.

    Google Scholar 

  • Oberts, G. L., 1986. Pollutants associated with sand and salt applied to roads in Minnesota. Water Resources Bulletin 22: 479–483.

    Article  CAS  Google Scholar 

  • Petranka, J. W. & E. J. Doyle, 2010. Effects of road salts on the composition of seasonal pond communities: can the use of road salts enhance mosquito recruitment? Aquatic Ecology 44: 155–166.

    Article  CAS  Google Scholar 

  • Pfaff, J. D., 1993. Method 300.0. Determination of inorganic anions by ion chromatography. Environmental monitoring systems laboratory. Office of Research and Development, U.S. Environmental Protection Agency, Ohio.

  • Sanzo, D. & S. J. Hecnar, 2006. Effects of road de-icing salt (NaCl) on larval wood frogs (Rana sylvatica). Environmental Pollution 140: 247–256.

    PubMed  Article  CAS  Google Scholar 

  • Stebbins, R. C., 1985. A Field Guide to Western Reptiles and Amphibians, 2nd ed. Houghton Mifflin Company, Boston, MA.

    Google Scholar 

  • Turtle, S. L., 2000. Embryonic survivorship of the spotted salamander (Ambystoma maculatum) in roadside and woodland vernal pools in southeastern New Hampshire. Journal of Herpetology 34: 60–67.

    Article  Google Scholar 

  • Van Meter, R. J., C. M. Swan, J. Leips & J. W. Snodgrass, 2011. Road salt stress induces novel food web structure and interactions. Wetlands 31: 843–851.

    Article  Google Scholar 

  • WSDOT., 2012. Statewide snow and ice plan, 2012–2013. Washington State Department of Transportation.

Download references


We thank David Matlaga, Joseph Frumkin, Kyle Livengood, and Natalie Marioni for assistance in the field and the lab. We are grateful for funding from the Illinois Toll Highway Authority to complete this project.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Tanya Hawley Matlaga.

Additional information

Handling editor: Lee B. Kats

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Matlaga, T.H., Phillips, C.A. & Soucek, D.J. Insensitivity to road salt: an advantage for the American bullfrog?. Hydrobiologia 721, 1–8 (2014).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Amphibian
  • Deicing agents
  • Dragonfly larvae
  • Lithobates catesbeianus
  • Sublethal effects
  • Survival