A skin-eating fungus from Europe could decimate Appalachian salamanders

The Southern Appalachian Mountains are a global biodiversity hotspot for salamanders. Dr. Deb Miller and Dr. Matt Gray lead the Amphibian Disease Laboratory at the University of Tennessee and are examining various strategies to prevent a deadly salamander fungus from entering the United States through the international pet trade. . They are also conducting research to learn more about the disease and looking into potential strategies to reduce the spread of the fungus should it enter the country.

Why do the Appalachian Mountains have so many salamanders?

The intersection of North Carolina, Tennessee, and Georgia is a global biodiversity hotspot for salamanders. Tennessee, for example, has about 60 species, more than the entire European continent.

The Southern Appalachian Range is one of the oldest mountain ranges in the world, so for many species there have been plenty of opportunities to evolve over a long period of time. Temperate conditions and high altitudes create a forest system with lots of moisture and accumulated bedding. Over time, this creates the perfect habitat for salamanders.

What is the fungus that threatens salamanders?

Batrachochytrium salamandrivorans, or Bsal, is the second chytrid mushroom that has been discovered. The first chytrid fungus that many people have heard of is called Batrachochytrium dendrobatidis, or Bd, and has been associated with the decline of more than 500 amphibian species globally and over 100 species with extinctions.

Bsal fungus specifically attacks a salamander’s outer skin, but we’re finding that it can attack frog skin as well. The skin is one of the most important organs in an amphibian’s body. It is so important because some salamanders do not have lungs and therefore the skin is a major source of respiration for them. It also maintains the right amount of hydration so that their body systems, including the heart, can function properly.

The name salamandrivorans literally means that he eats the salamander. In fact, it destroys the skin with a fungal coating. The skin stops working and the animal shuts down and dies.

The fungus has not yet entered North America, but what has been its effect on amphibians in Europe?

The discovery of a new chytrid fungus in Northern Europe was very alarming. It was discovered in 2010 and since then, populations of salamanders across Europe have seen a steep decline. There is now research indicating that it may have actually been introduced to Germany and spread from there.

It has been found in Southeast Asia that it infects salamanders but has no effect on them. It seems he lives there with the salamanders. But it is believed to have been introduced to Europe through the international pet trade. We have not yet detected Bsal here in North America or anywhere else in the Western Hemisphere, but we are concerned that the pet trade is the most likely route for introduction here.

What measures are being taken to prevent him from entering the United States?

The United States has been quite proactive in its response to Bsal. The US Fish and Wildlife Service approved in 2016 a moratorium on the import of some 200 species of salamanders that could serve as possible hosts of the Bsal. This effectively blocked most of the salamander trade entering our country. However, since then, we have learned that frogs can also be infected with Bsal, which makes up 95% of the trade, so the threat of introduction to the United States remains.

There has been very limited oversight for Bsal in the pet industry and we are working on partnerships that would expand sampling for Bsal. It is also in the interest of the industry because it threatens captive populations and their profits.

What is your research focused on?

As for the pathology, we are looking at a few different things. One, what does it do to the body besides peeling off the skin? What is the critical point at which we might be able to do something? And are there any opportunistic bacteria or other pathogens that play a role in the disease?

In terms of research on transmission and disease intervention strategies, we’ve looked at what happens if it enters a pond system here. Could we go into that pond system and reduce the density of salamanders, just like humans do with social distancing during the pandemic?

Bsal spreads through water, but also through direct contact, so we reduce the pathogen’s ability to swim or salamanders to meet by increasing the number of plants around their habitat, and therefore the complexity of the habitat.

We are also looking into plant-based fungicides. Salamander skin contains many natural microbes and we are looking to integrate their natural microbiome on their skin to aid in the defense of this pathogen. So we collaborate with colleagues from different universities to investigate all these questions.

What role do salamanders play in this ecosystem?

It has been estimated that in a typical pond system, amphibians can consume over a million insects in a year, including mosquitoes. They consume both adults and larvae before they can bite you or transmit a zoonotic disease. Both tadpoles and salamander larvae love to eat the small mosquito larvae, which are very nutritious. They play a role similar to that of bats in the air.

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