District tests for fungus deadly to amphibians

  • DuPage forest district ecologist Dan Thompson swabs a frog to test for a deadly fungal disease in amphibians.

    DuPage forest district ecologist Dan Thompson swabs a frog to test for a deadly fungal disease in amphibians. Courtesy of the Forest Preserve District of DuPage County.

 
By Deb Humiston
Forest Preserve District of DuPage County
Posted5/3/2016 1:07 PM

Every day for seven weeks in the spring, Forest Preserve District of DuPage County ecologist Dan Thompson and a few volunteers don hip waders and scour select marshy areas at Waterfall Glen Forest Preserve in Darien in search of amphibians.

When they find one, they collect two swab samples, one from the back and one from the belly. The back swab tests for cortisol, a stress indicator, but the belly swab tests for chytridiomycosis, also known as chytrid, an infectious, potentially deadly disease in amphibians caused by the aquatic fungal pathogen Batrachochytrium dendrobatidis.

 

Not a threat to humans, chytridiomycosis thickens the outer layers of skin on amphibians, affecting their ability to absorb water and electrolytes. It's found on every amphibian-inhabited continent on the planet and has been linked to serious population declines.

Frogs and salamanders can carry and spread the fungus to other amphibians without showing signs of the disease themselves.

Since 2014 researchers have been testing amphibians for chytridiomycosis in DuPage, Cook, Lake, McHenry, Will, DeKalb and Boone counties to determine the prevalence of the disease in northern Illinois. The research team is led by Allison Sacerdote-Velat, a reintroduction biologist at Lincoln Park Zoo; Mary Beth Manjerovic, a wildlife disease ecologist at the zoo; and Rachel Santymire, director of the zoo's Davee Center for Endocrinology and Epidemiology.

To date, chytridiomycosis has been prevalent in 30 to 32 percent of the tested amphibians, Sacerdote-Velat said, although "in DuPage we've only found positives along sites within the East Branch DuPage River and Des Plaines River watersheds."

"Each year we learn more from the results of our studies here in Illinois, which gives us a better understanding of chytrid and its distribution and effect on the region," Thompson said.

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"It's important research because amphibians are sensitive to environmental changes. They're our early warning system, our 'canary in the coal mine.' Populations are declining globally at an alarming rate, and it's a problem we can't ignore."

The public can help limit the spread of the chytrid pathogen by cleaning boots, waders and other gear exposed to water before entering different bodies of water. They should soak shoes in a solution of 4 percent bleach for five minutes, clean off any dirt and then thoroughly rinse them.

At the very least, since the fungus is waterborne, people should clean waders or other footwear and make sure they dry completely. Additionally, people should never release pet amphibians into the wild. In addition to Batrachochytrium dendrobatidis, the animals can harbor other pathogens harmful to wild populations.

"The more we understand about the spread of this disease, the better we'll be able to combat it and protect our amphibian populations in DuPage County," said Joe Cantore, forest district president.

"Collaborations such as this are critical to providing a clearer picture and better understanding of what's happening with amphibian populations in Illinois," said Forest Preserve District Commissioner Linda Painter, District 3.