Past Meeting, Feb 2021: Gregory Wier & Carter Farmer – Chytrid fungus and its detrimental effect on amphibians0
February 21, 2021 by lancasterherp
The Lancaster Herpetological Society wants to thank everyone that attended the digital meeting last evening. Carter Farmer and I talked about the chytrid fungus that has been plaguing amphibians around the world. If you missed the meeting, you can watch the presentation on Youtube.
Amphibian populations have been on the decline around the globe since the 1970s, and many of these declines cannot be attributed to obvious human intervention. It was not until 1998 that a chytrid fungus was characterized that grows on amphibian skin (1), disrupts their ability to osmoregulate, and can eventually lead to death by cardiac arrest (2). The fungus, Batrachochytrium dendrobatidis (Bd), has been found on every continent that has amphibians and has been linked to many of the mass declines. According to a recently published report (3), Bd is responsible for the greatest documented loss of biodiversity attributable to a pathogen in the world. Most of these declines have been in Central America and South America, where there is a large diversity of amphibians, many of which are confined only to a very small geographic range. These species are very susceptible to outside threats like Bd. Genomic sequencing work has shown that Bd has four distinct lineages that vary in their ability to cause disease. The sequencing work also convincingly places the origin of the fungus in Asia, where amphibians have likely co-evolved with it and no longer suffer mass die offs (4). This gives hope that many frog species showing declines around the world may eventually develop a resistance to the fungus, so long as they do not go extinct first. Excitingly, there have been several instances of frog species being rediscovered, years after being declared extinct, like the Heredia Robber Frog (Craugastor escoces) in Costa Rica (5).
While Bd originated in Asia, it has spread around the globe, no doubt transferred by humans, whether for the pet trade, the food industry, or for medical research. Because of this, it is important for herpetologists to disinfect their boots and equipment before and after visiting sites looking for amphibians. Soak your equipment in a 1:20 dilution of bleach in water for 2-5 minutes and let them dry. Bleach degrades quickly, so you should use fresh bleach to prepare the solution. While Bd is thought to be fairly prevalent in North America, any effort to help limit its spread is valuable. Towards this end, in 2013, a second Batrachochytrium species was discovered causing local extinctions of fire salamanders in the Netherlands (6), and named Batrachochytrium salamandrivorans (Bsal). Presently there is no evidence that Bsal has been introduced to North America, but since this country is a hotspot for salamanders, its introduction could be detrimental. This makes it all the more important that you disinfect your boots and equipment when going out into the field. It is only a matter of time until Bsal makes it to North America, and if we are diligent, we can prevent it from spreading and putting our salamanders at risk.
Once again, thanks to everyone who attended the talk. Stay tuned for more information about next month’s meeting!
- Berger, L. et al. Proc. Natl Acad. Sci. USA 95, 9031–9036 (1998).
- Voyles, J., et al. Science. 2009 Oct 23;326(5952):582-5.
- Scheele, BC; et al. Science. 2019 Mar 29;363(6434):1459-1463.
- O’Hanlon, SJ; et al. Science. 2018 May 11;360(6389):621-627.
- Jiménez, R.; et al. Amphibia-Reptilia 2017, 38.
- Martel, A. et al. Proc. Natl Acad. Sci. USA 110, 15325–15329 (2013).
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