By Kevin Kelly
A new study led by the U.S. Geological Survey and published this week offers compelling evidence that amphibian populations across the country are declining at a rate of almost 4 percent per year.
Urbanization, pesticide use, changing weather patterns and disease all represent threats to amphibians, but how each threat impacts these species varies from region to region, according to the study.
“Implementing conservation plans at a local level will be key in stopping amphibian population losses since global efforts to reduce or lessen threats have been elusive,” Evan Grant, a U.S.G.S. research wildlife biologist who led the study, said in a news release.
The Kentucky Department of Fish and Wildlife Resources has tracked amphibian populations for years and this spring initiated its own statewide study to monitor these species for diseases. Plans call for visiting 50 sites across seven ecological regions over the next two years.
“We’ve done a lot of surveys, and through those we know we have robust populations of amphibians,” said Iga Stasiak, wildlife veterinarian with Kentucky Fish and Wildlife. “We generally don’t have a lot of information about amphibian health in Kentucky. What we’re focused on with this study is identifying disease, which is the first step in preventing its spread.”
Among the threats facing amphibian populations worldwide is the lethal chytrid fungus. A close relative of it now is taking aim on salamander populations in Europe. This new fungus – known generally as salamander chytrid fungus – could have serious effects if it turns up in the U.S. Chytrid fungus causes an infectious, and often fatal, skin disease in amphibians.
“It would be potentially devastating if we had an introduced pathogen such as the salamander chytrid fungus,” Stasiak said. “Some experimental studies have shown that a number of salamander species found in Kentucky and North America are susceptible, including the Eastern newt.”
Kentucky is home to 35 types of salamanders. The Eastern newt is most common in the forested areas of eastern and southern Kentucky but can be found across the state, said John MacGregor, state herpetologist with Kentucky Fish and Wildlife.
Biologists conducting the study are collecting newts and tadpoles at each monitoring site.
“We set minnow traps in a wetland and leave them overnight,” said Maggie Smith, wildlife health technician with Kentucky Fish and Wildlife. “Newts cruise around looking for prey, usually beetles or some type of invertebrate, and they’ll just kind of crawl into that trap. We also do dip netting. You’re just looking for a deepish pond that’s fairly permanent, and scouting for muddy areas with lots of vegetation because that’s what they like.”
Once collected, each specimen is swabbed and then immediately returned to the water. The samples are sent to the USGS National Wildlife Health Center in Wisconsin for testing. Newt samples will be tested for chytrid fungus and salamander chytrid fungus, and tadpole samples will be tested for chytrid fungus and ranaviruses.
“The reason we’re sampling tadpoles is because that life stage and the ranid family of frogs appear to be most susceptible to those agents,” Stasiak said. “We’ve had die-offs reported in Kentucky but we’ve never documented a disease-related die-off in Kentucky.”
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The public can help prevent the transmission of diseases to amphibian populations by following some simple guidelines, starting with not releasing captive exotic or native species of amphibians into the wild.
“You could be spreading a disease or pathogen unknowingly by releasing them,” Stasiak said. “When we go into the field, we have a decontamination protocol and we disinfect our equipment and our boots with a diluted bleach solution before going from one pond to another.
“We certainly encourage people to appreciate wildlife and spend time outdoors, but it’s best to not move them from one place to another and to also be mindful of your boots and your equipment.”
Kentucky Fish and Wildlife offers additional information about how to prevent the spread of chytrid fungi on its website at fw.ky.gov.
Stasiak hopes to continue the monitoring long term to track any changes in amphibian populations across Kentucky.
“Prevention is an important facet of wildlife health and often overlooked,” she said. “Often we’re very action oriented but prevention is equally important. Early detection is part of that. If we can detect a disease early on in the population we’re more likely to be able to potentially implement management actions to prevent its spread.”
Kevin Kelly is a writer for Kentucky Afield magazine, the official publication of the Kentucky Department of Fish and Wildlife Resources. An avid angler with a passion for muskellunge and stream fishing, his journalism career has included stops at daily newspapers in Cincinnati, St. Petersburg, Fla., and Charleston, S.C. Get the latest from Kelly and the entire Kentucky Afield staff by following them on Twitter: @kyafield.
The Kentucky Department of Fish and Wildlife Resources manages, regulates, enforces and promotes responsible use of all fish and wildlife species, their habitats, public wildlife areas and waterways for the benefit of those resources and for public enjoyment. Kentucky Fish and Wildlife is an agency of the Tourism, Arts and Heritage Cabinet. For more information on the department, click here.
