Endangered blending turtles threatened by fungal disease

Biologists have been working for three decades on a recovery project for the Illinois-endangered blending turtle, whose numbers were declining due to an increase in predators and habitat destruction.

Now the species faces a new threat: a fungal disease that eats through the shell causing the Swiss cheese effect.

Recently, three wild bland tortoises in northeastern Illinois tested positive for the fungus. Chicago-area facilities that raised the turtles before they were released into the wild also learned that the water in the tubs of 40% of their habitats contained fungi.

“When we first learned about the fungus, the panic and fear is the way hatchlings are raised,” said Gary Glowacki, manager of conservation ecology for the Lake County Forest Preserve District.

“Looking at the bigger picture, we’re thinking we’re lucky we caught it early, and it will ultimately strengthen our recovery program,” Glowacki said. He has worked with Blanding’s turtles for more than two decades.

Since beginning in 1994, approximately 6,000 young Blending’s tortoises have been raised and released by biologists into northern Illinois wetlands.

Scientists at the University of Illinois discovered the fungus — naming it Amidomyces testavorans — after testing turtles with shell disease in the zoo’s collection. He later also confirmed that a wild population of endangered western pond turtles in Washington state also had a disease caused by the fungus. Shell disease can cause infection and premature death.

Although disease-causing agents such as fungi and viruses are commonly visible in the environment, “more fungal diseases have been appearing in wildlife recently,” says the Wildlife Epidemiology Laboratory at the University of Illinois’ Veterinary Clinical Laboratory. said Matt Allender, director of

The reasons are unclear, but may be due to climate change, deteriorating ecosystems, habitat loss and declining populations.

“A study published 10 years ago found that 75% of all emerging diseases in plants and animals were caused by fungi,” Allender said.

In Illinois, a fungus similar to that found in turtles is affecting other reptiles, including the state-endangered eastern Massasuga rattlesnake. Allender said the species experienced a 90% mortality rate in its last stronghold near Carlyle Lake in southwestern Illinois. Several species of snakes in Illinois, including the milk snake in Lake County, have tested positive for the fungus.

White nose syndrome, caused by a fungus, has killed millions of cave-hibernating bats across the eastern United States since the early 2000s. Brad Semmel, an endangered species recovery specialist with the Illinois Department of Natural Resources, said it also devastated the Illinois population in LaSalle County.

Scientific articles are reporting an increase in fungal diseases. Yale University School of the Environment Reported in 2016 That “an unprecedented global wave of virulent fungal infections is decimating entire groups of animals – from salamanders and frogs to snakes and bats.” One Article published in the American Society for Microbiology Cited an increase in fungal diseases in plants and humans in 2020.

In May, another fungus killed the endangered piping plover Monty, a popular fixture on Montrose Beach for the past three summers. But this fungus is different from the types found in turtles, snakes and bats, said Karen Terrio, chief of the University of Illinois Zoological Pathology Program who works with Allender.

Allender said that in the case of globally threatened species such as the blending turtle, the diseases could be devastating because the animal numbers have already declined significantly.


You. After off I. pathologists found the fungus in zoo animals, they decided to test Blanding’s tortoises in Illinois, even though they were showing no signs of disease. Allender said he caught the fungus early and that he hopes to stop the outbreak.

“All the stakeholders are on the same page. We are working to save the turtles,” Allender said. His team tests turtles, snakes and other reptiles for signs of disease in a state program called Wellness of Wildlife.

This summer, biologists plan to test the fungus in wetlands where Blanding’s turtles live in DuPage, Lake, Cook, Kane, McHenry, Will, Lee and Ogle counties.

Semmel said that Blanding’s recovery program, which he leads, “really has stalled immediately. We have to understand our actions better to see if it can put these populations at risk, if we can do this.” Presenting an emerging threat, we were not aware of it.

Blanding’s tortoises historically inhabited the northern two-thirds of Illinois.

“The conversion of natural land through urbanization and agriculture has greatly reduced the available habitat, such that in most cases, the remaining Blanding’s tortoise populations are small and highly fragmented by roads and development,” Semel said.


The species was listed as endangered by the state in 2009 because it had declined significantly in abundance and distribution and was dependent on a rare and vulnerable habitat.

“This is a species that has historically required sedge meadows and high-quality wetlands. They need uplands to lay eggs, shallow sedge meadows for summer pasture, and deep water for overwintering.” is needed,” Semel said.

According to Semmel, only six sites — in Lake, McHenry, Grundy, Carroll and Whiteside counties — remain in the state, where populations are viable. The range of the species also extends to New York, Wisconsin and Minnesota. The US Fish and Wildlife Service is assessing whether to list Blanding’s turtle as federally endangered.

Several decades ago, researchers in northern Illinois found that when female Blanding’s tortoises laid eggs, predators such as raccoons, whose numbers are increasing in the state, promptly dug up and ate them.

“There was no successful breeding going on,” Semmel said. They did not find any young turtles that could start breeding at the age of 10.


The head-start project began in McHenry and DuPage counties. Biologists don the wading boots at the time of egg laying and collect the females, taking care not to harm them. They bring the females to a laboratory to lay eggs and then return them to the wild. Semmel said female blanding turtles take no part in raising the young — they lay and release the eggs — so taking the eggs doesn’t harm them.

The biologists then raise the hatchlings until the shells are hard enough and the young are large enough to be released into the wild without being hunted. Today, turtle-hatching facilities are located at the Peggy Notbart Nature Museum and Shedd Aquarium in Chicago, Brookfield Zoo, the Cosley Zoo in Wheaton, the McHenry County Conservation District, and the Lake County Forest Preserve District.

“We are producing positive results year after year,” Semel said. “Survival is increasing, and captive-bred turtles are starting to breed in the wild. We thought that if we’re successful, we might start adding some other populations to Illinois.”

That’s not going to happen, at least for now.

Terrio said the fungus affecting Blending’s tortoises is the same one that causes shell lesions in aquatic turtles in zoological collections across the country and in Washington state.

“Western ponds are pockets of turtle populations where more than 80% of them have shell disease,” Terrio said.

Allender said his team has been testing Blanding’s turtles for various diseases for the past six years. Over the winter, they decided to test samples taken from wild turtles over the years for the newly emerged fungus.

“We didn’t want the Blanding’s tortoise to go the way of the Western Pond Turtle,” he said.

Blanding’s turtle hatchling facilities are now establishing biosafety protocols such as requiring staff to work with turtles that are positive and negative for the fungus before using gloves when handling turtles.


“Conservation is the overarching principle of ecology: do no harm,” Glowacki said. “It is a scary thought to think that you may be doing more harm than good. We are at this crossroads. How do we continue to reap the benefits of all our efforts? It adds a new wrinkle.”

Paying members of the public have been notified to adopt the turtle in the Lake County Forest Conservation District program, and many have agreed to donate money to outbreak prevention, Glowecki said.

Terio said drugs have been identified that can treat turtles with the fungus.

“But the question is, how do you deliver that drug to the turtle? Can we do it as an implant or as a slow-release capsule? He said.

His department is also working on other strategies, including filtration systems that, like a filter on a fish tank, use different wavelengths of light to target the fungus.

“We wanted to see which of these methods of filtration might be best for not only reducing fungus levels but also for promoting overall turtle health,” Terrio said. But they need to be careful not to create a completely sterile environment, which Terrio said is “often not healthy.”

Shedd Aquarium is studying how head-start projects can be done to help endangered turtles avoid spreading the fungus. The aquarium houses eight Western Pond Turtles from the Washington State Recovery Program, which is similar to Blending’s Turtle Program in Illinois.

Allender said his team is working with a bland tortoise that came from a homeowner who was illegally raising it in a pond in the backyard. That turtle tested positive for the fungus.

“Within the last two months, we got our first negative test on a turtle, which we’ve been treating for eight or nine months,” he said. Treatment includes drugs, inhalers, and other methods, but further testing is needed to see what works best, according to Allender.


He said it could take a long time before a treatment for blending tortoises is readily available in the wild.

“I am concerned about treatment options. We have developed new treatments to reduce snake fungal diseases, mortality and disease rates. But tortoise shell fungal disease is much more problematic,” Allender said.

Terrio said biologists are wondering, “Why are we now suddenly starting to see the numbers of these different fungi? They’ve all come up over the past few decades.”

Terrio said causes could include climate change and poor ecosystems, and humans are responsible. “It is our responsibility to do everything we can to help the wildlife affected by these changes,” she said.

The case of Blanding’s turtle also illustrates the complexities of helping endangered species recover.

“It’s such a multi-faceted approach,” Semmel said. “People used to think, we will not hunt them anymore. That was the most direct way. Then we realized they needed a place to live. Let’s do housing management. Then you realize, we have climate change and time may be off for some species. For example, Corner blue butterflies lay eggs before their food is available.

“Now we’ve added health assessments. … Diseases will be a really important component in understanding how to recover endangered species,” Semmel said.

Sherrill DeVore is a freelance journalist.

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