Above: The California newt is a salamander species endemic to California, in the Western United States. Photo courtesy John Clare via Flickr/Creative Commons.
by ELIZABETH DAUT
Last week, the U.S. Fish and Wildlife Service (USFWS) acted to protect native amphibians from a newly-described and potentially lethal fungus. The culprit—called Batrachochytrium salamandrivorans, or Bsal—has all but wiped out some salamander populations in Europe. And researchers are worried the U.S. could be next.
The movement of Bsal from overseas to the U.S. may likely be hastened by international trade, which is a well-known factor contributing to the spread of infectious diseases (Fèvre et al. 2006). For example, outbreaks of foot and mouth disease, which devastated the livestock industry in Europe, were spread by the international transport of live farm animals. In the case of Bsal, research has confirmed that Asian salamanders, which are imported primarily for the exotic pet industry, are carriers of the fungus. As carriers, these species are resistant to the disease but are able to transmit the fungus to susceptible wild salamanders.
The USFWS has good reason to worry. From 2004 to 2014, nearly 2.5 million live salamanders comprising roughly 60 species were imported into the U.S. Wild salamander populations are at high risk of being exposed to Bsal through the release of imported, infected salamanders (Yap et al. 2015). Although to date, Bsal has not been identified in the U.S. (Berger et al. 2016), a similar fungus—Batrachochytrium dendrobatidis, or Bd—has devastated many amphibian species in the U.S. and worldwide, some to the point of extinction (Woodhams et al. 2011).
That’s a concern that cannot be overstated. The U.S. is a global hotspot for salamander diversity, with roughly 40 percent of the more than 650 living species. Many native salamanders are endemic to the U.S.—i.e., not found anywhere else in the world—and are already threatened (USFWS 2016). Despite being rarely seen, salamanders are considered keystone species. They are highly abundant in many terrestrial and aquatic systems and important contributors to nutrient cycling as predators of arthropods and prey for other vertebrates.
Disease surveillance and regulation in the U.S. are stringent and effective when pathogens harmful for agriculture or humans are involved. However, less attention is spent on regulating animal imports for potential pathogens harmful for native wildlife. But things are now changing.
In a bold new step to halt the spread of Bsal to the U.S., the USFWS adopted an interim rule to ban commercial importation from overseas and interstate transportation across state lines of 201 salamander species.
Under the Lacey Act, the USFWS has the authority to regulate trade in wild animals they determine as injurious to humans, agriculture, or native wildlife. Typically, the Lacey Act has been used to prevent the introduction or spread of invasive vertebrate species, such as pythons in the Everglades (USFWS 2012). This is only the second time that the USFWS has amended the Lacey Act to prevent introduction of a potential pathogen (Bsal) by regulating import and trade of its host species (salamanders). The 201 species listed as injurious under the new USFWS ruling include species from 20 genera known to be susceptible to or carriers of Bsal.
With the looming fungal threat, the USFWS opted for an interim rule that took effect on 28 January 2016, instead of a typical proposed rule, which would have allowed salamander imports to continue while providing an opportunity for public comment. Interested persons are still encouraged to submit written comments on the interim rule before mid-March. Visit the Federal eRulemaking Portal here, search for Docket No. FWS–HQ–FAC–2015–0005, and follow the instructions for submitting comments (USFWS 2016).
The interim rule is an important step toward protecting native salamander populations, but there’s still much work to be done to shield U.S. wildlife from introduced diseases spread through commercial trade. At the National Socio-Environmental Synthesis Center (SESYNC), I’m working with researchers at the University of Maryland to investigate the disease risks associated with importation of exotic animals and—now that the USFWS has taken action on Bsal—to identify the next big potential threats facing native wildlife. Our hope is that this research will provide the scientific, evidence-based knowledge necessary to inform policies that best prioritize disease threat and ensure social and economic benefits from trade.
Berger, L., Roberts, A.A., Voyles, J., Longcore, J.E., Murray, K.A., Skerratt, L.F., 2016. History and recent progress on chytridiomycosis in amphibians. Fungal Ecology 19, 89–99.
Fèvre, E.M., Bronsvoort, B.M.d.C., Hamilton, K.A., Cleaveland, S., 2006. Animal movements and the spread of infectious diseases. Trends in Microbiology 14, 125–131.
USFWS. 2012. Salazar announces ban on importation and interstate transportation of four giant snakes that threaten everglades. U.S. Fish and Wildlife Service. <http://www.fws.gov/southeast/news/2012/003.html> (22 December 2015).
USFWS, 2016. Injurious wildlife species: listing salamanders due to risk of salamander chytrid fungus. Federal Register, Vol. 81, No. 8 Rules and Regulations.
Woodhams, D., Bosch, J., Briggs, C., Cashins, S., Davis, L., Lauer, A., Muths, E., Puschendorf, R., Schmidt, B., Sheafor, B., Voyles, J., 2011. Mitigating amphibian disease: strategies to maintain wild populations and control chytridiomycosis. Frontiers in Zoology 8, 8.
Yap, T.A., Koo, M.S., Ambrose, R.F., Wake, D.B., Vredenburg, V.T., 2015. Averting a North American biodiversity crisis. Science 349, 481–482.