[vc_row][vc_column width=”1/2″][text_output]North America has an amazing, unique diversity of vertebrates, ranging from birds to mammals but also reptiles and amphibians. Sadly some members of these groups are being hit hard by several emerging infectious diseases that have led to massive declines and extinctions. Diseases caused by fungal agents are some of the most well-known culprits.
Bats in Canada and North America are being decimated by an introduced Eurasian fungus called Pseudogymnoascus destructans that causes a disease known as White-nose syndrome (Warnecke et al., 2012). This fungus attacks bats during hibernation and millions upon millions of bats have already died of the disease. The first study on treating the fungus with probiotics, a bacteria that inhibits the growth of the fungus, on living bats, seems to be promising.
Snakes in North America aren’t safe either. Another fungus, Ophidiomyces ophiodiicola, now dubbed as “Snake fungal disease” is eating the skin of snakes (keratin) and mortality rates are extremely high (Allender et al., 2015). See Snake Fungal Disease page for more info.
The most well-known fungal disease affecting wildlife is, of course, the chytrid fungus Batrachochytrium dendrobatidis or simply Bd which has led to enormous declines and extinctions of frogs and neotropical salamanders in the Americas, Australia and other places on the globe in the past decades (Berger et al. 1998). Bd has been called the most devastating wildlife disease ever and in 2013 we learned that it has a close relative that also has a deadly appetite for amphibians: salamanders to be exact.
Scientists from Ghent University Belgium identified a novel chytrid fungus in 2013 (Martel et al., 2013). They named it Batrachochytrium salamandrivorans (Bsal): the eater of salamanders. They traced its origins back to Asia where it co-evolved with the local salamander fauna for millions of years. Meaning, salamanders in Asia have adapted to the fungus. However, via the international pet trade Bsal hitched a ride to Europe where it made its way into Dutch fire salamander populations. This salamander species, as are all European newts and salamanders, are naive to the pathogen and die quickly when infected (Martel et al. 2014). Some of their American counterparts also appeared to be highly susceptible to the disease.
The pathogen is now spreading from its initial entry points in the Netherlands to Belgium and possibly other nearby countries. With North America being the salamander capital of the world (nearly 50% of all salamanders occur in North America) scientists fear that if Bsal is introduced in the Americas it will wreak havoc on a truly epic scale. But for the first time ever we have a chance to stop this from happening and with no mitigation or cure for Bsal in wild, infected populations this is a very welcome scenario indeed!
Yap et al. (2015) published their findings and recommendations on preventing Bsal from entering North America in Science. The authors created a map using a predictive model where they identified suitable habitat for Bsal and overlapped this with areas with high salamander diversity. The most important high-risk zones are the SouthEastern US (Appalachian mountains), the Pacific Northwest, the Sierra Nevada mountain range, and the highlands of Central Mexico. In addition, they identified the most likely entry points of Bsal, five US ports (Los Angeles, Tampa, New York, Atlanta, and San Francisco. All are very near to these vulnerable zones. From 2010 until 2014, 779,002 salamanders (of which 99% from Asia) came through these ports. Three Asian newts species have been identified as carriers of Bsal: blue-tailed fire-bellied newt (Cynops cyanurus), Japanese fire-bellied newt (Cynops pyrrhogaster), and the Tam Dao salamander (Paramesotriton deloustali). These two genera contribute for 91% of salamanders imported to North America.
Yap and her colleagues call for an immediate ban of salamander imports to North America. Protocols to stop Bsal have to be established and implemented first. For the time being a stop of salamander imports could have a very positive effect of introducing the disease. This could very well be a chance for us, like the title of the Science paper says, to avert a North American biodiversity crisis!
By Tariq Stark
Allender M.C., Raudabaugh D.B., Gleason F. H. , Miller A.N. 2015. The natural history, ecology, and epidemiology of Ophidiomyces ophiodiicola and its potential impact on free-ranging snake populations. Fungal Ecology
Berger, L., Speare, R., Daszak, P., Green, D. E., Cunningham, A. A., Goggin, C. L., Slocombe, R., Ragan, M. A., Hyatt, A. D., McDonald, K. R., Hines, H. B., Lips, K. R., Marantelli, G., and Parkes, H. 1998. Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America. Proceedings of the National Academy of Sciences, USA. 95: 9031-9036.
Martel, A.; Spitzen-van der Sluijs, A.; Blooi, M.; Bert, W.; Ducatelle, R.; Fisher, M. C.; Woeltjes, A.; Bosman, W.; Chiers, K.; Bossuyt, F.; Pasmans, F. (2013). “Batrachochytrium salamandrivorans sp. nov. causes lethal chytridiomycosis in amphibians”. Proceedings of the National Academy of Sciences of the United States of America 110 (38): 15325–15329.
T. A. Yap, M. S. Koo, R. F. Ambrose, D. B. Wake, V. T. Vredenburg. Averting a North American biodiversity crisis. Science, 2015; 349 (6247): 481 DOI: 10.1126/science.aab1052
Warnecke L, Turner JM, Bollinger TK, et al. Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(18):6999-7003. doi:10.1073/pnas.1200374109.
Yap, T.A., Koo, M.K., Ambrose, R.F., Wake, D.B., Vredenburg, V.T. 2015. Averting a North American biodiversity crisis. Science.[/text_output][/vc_column][vc_column width=”1/2″][text_output]Above: Photo © Sara Viernum[/text_output]
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