Background Research

In the past two decades, extensive research into the amphibian malformation phenomena has been undertaken by scientists from government, academic, and non-profit sectors. Below we present information on the history of data collection from these diverse sources, all of which has been critical to obtaining a deeper understanding of the environmental factors driving patterns of amphibian malformation occurrence.

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North American Reporting Center of Amphibian Malformations

Some of the earliest work concerning amphibian malformations arose from the U.S. Geological Survey’s “North American Reporting Center for Amphibian Malformations” (NARCAM; Johnson et al. 2000). NARCAM was established in June 1997 following several months of discussions among federal and state agency staff, herpetologists, and other scientists, with the goal of facilitating the flow of information in two directions. First, scientists and the public could learn about the amphibian malformation phenomenon, including where occurrences had been found, the rates at which they were recorded, the species involved, and the types of malformations noted. Second, suspected or confirmed observations could be reported to NARCAM’s centralized database so that scientists could search for emerging patterns and trends in the type and incidence of malformations. Due to federal budget cuts, the NARCAM program was discontinued in 2002. See the “U.S. Fish and Wildlife Service” and “University of Colorado Boulder” sections to see how the NARCAM monitoring and reporting efforts paved the way for ongoing research projects.

U.S. Fish and Wildlife Service

In 2000, the U.S. Fish and Wildlife Service (USFWS) launched a nation-wide survey to determine the extent of malformed frogs and toads on National Wildlife Refuges. Their Amphibian Declines and Deformities web page provides more information about how this federal governmental agency continues to work towards conserving threatened and endangered amphibians. Recently, the USFWS was part of an unprecedented 10-year-study (Reeves et al. 2013) revealing encouraging results for frogs and toads on Refuges. Their research findings showed that, on average, less than 2 percent of frogs and toads sampled across 152 Refuges had physical malformations involving the skeleton and eyes; a lower rate than many experts feared based on earlier independent reports. It is important to recognize, however, that this study did not include amphibian surveys on private lands or other non-Refuge public lands. Reeves et al. (2013) revealed areas where sites with higher rates of abnormalities tended to cluster together geographically. Within these regional “hotspot” clusters—found in the Mississippi River Valley (northeast Missouri, Arkansas and northern Louisiana), the Central Valley of California, and in south-central and eastern Alaska—the frequency of malformations often exceeded the national average of 2 percent, affecting up to 40 percent of amphibians in some surveys. Their effort represents the first nation-wide survey of abnormal amphibians that uses standardized collection and evaluation methods.

University of Colorado Boulder

The Johnson Lab in the Department of Ecology and Evolutionary Biology at the University of Colorado has been conducting numerous scientific studies on the occurrence and causes of amphibian malformations for over a decade. Researchers in the lab focus on bringing a broad perspective to the amphibian malformation phenomenon by combining experiments, large-scale spatial and temporal field data, molecular tools and ecological modeling in their investigations. This group in particular has provided strong support for the role of the parasitic trematode, Ribeiroia ondatrae, in causing amphibian malformations in some species and geographic locations (particularly the western US).

Johnson, DH, Fowle, SC, and JA Jundt. (2000). The North American reporting center for amphibian malformations. Journal of the Iowa Academy of Science 107: 123-127.
Reeves, M.K., Medley, K.A., Pinkney, A.E., Holyoak, M., Johnson, P.T.J., and M.J. Lannoo. (2013). Localized hotspots drive continental geography of abnormal amphibians on U.S. wildlife refuges. PLoS ONE 8(11): e77467.