Abstract
The IUCN has assessed almost 6,500 species of extant amphibians, of which 32% have been listed as threatened (assessed as critically endangered, endangered, or vulnerable). An additional 24% are of unknown risk, which could increase the number of threatened amphibian species to as high as 56%.1 Potential threats to amphibian populations include habitat loss and degradation, climate disturbances, human exploitation, invasive species, and infectious diseases.
Unexplained widespread declines in amphibian populations were first noted in the late 1980s and early 1990s. Many of these declines were later attributed to chytridiomycosis, an emerging infectious disease which causes dermal lesions and mortality in amphibians.2,3 Chytridiomycosis is caused by the fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal).4,5 Spread of Bd or Bsal to naïve populations has been associated with precipitous declines in over two hundred species.3 Chytridiomycosis was first described in 1998 and attributed to Bd in 1999.4,6 Bd has been detected globally in all areas where amphibians reside and has been found to cause disease in all three orders of amphibians (Anura, Caudata, and Gymnophiona).2,3 Severity of disease varies among species, with anurans being the most sensitive.3 Bsal was first described in 2013.5 It is endemic to Asia and has recently been found in Europe in both wild and captive populations of salamanders.5,7 Import of salamanders for the pet trade is believed to be the source of Bsal in Europe.7 To date, Bsal has only been found to cause disease in caudates, but data is limited.5 Surveillance for Bsal outside of Europe has been inadequate, prompting a call for action from a number of organizations in North America and Europe.8
North America is home to 48% of the world's salamander species.9 The highest diversity of salamanders is found in the eastern United States, making it a salamander biodiversity hotspot and a region of concern should Bsal invade North America.8,9 On January 12, 2016, the U.S. Fish and Wildlife Service listed 201 species of salamanders as injurious, prohibiting the importation and interstate transportation of these species. The regulation was enacted due to the concern that Bsal "poses an imminent threat to U.S. native salamander populations".10
In the fall of 2016, wild salamanders from 3 sites in southeastern Virginia were tested for Bd and Bsal. The sampling included 7 species and 91 individuals. Samples collected from individuals in close proximity were pooled to reduce handling of salamanders, resulting in 57 samples. All samples tested negative for Bd and Bsal. Additional and continual surveillance is needed to monitor for Bsal around the U.S. as well as in Canada and Mexico. Early detection of Bsal in North America and a swift response are necessary to protect endemic salamander populations.8,9
Acknowledgements
The authors wish to thank the Virginia Zoo, the Virginia Herpetological Society, and the Fresno Chaffee Zoo Wildlife Conservation Grant for support of this project. San Diego Zoo Amphibian Disease laboratory (USFWS permit: MA92338B-0) conducted the Bd and Bsal analyses. All sampling was approved by Virginia Department of Game and Inland Fisheries (057639), Department of Conservation and Recreation (RCP-CBR01-16), Sandy Bottom Nature Park (073016-07), and the Virginia Zoo IACUC (16-006) before the start of the project.
* Presenting author
+ Student presenter
Literature Cited
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