These are not good times for Minnesota's frogs and the news isn't getting any better.
Besides the old standbys of pollution and habitat loss, the amphibians have also been threatened by two diseases fatal to them.
Or it was two, until research published Tuesday said scientists have learned a third disease is killing them – and Minnesota is one of the states where it's caused a big die-off.
The U.S. Geological Survey says frogs (and their cousins, salamanders) are among the most threatened groups of animals on the planet. Alarm bells about their shrinking numbers have been ringing for years and scientists with the USGS and other agencies are trying to learn what's behind it.
The new paper published in the journal Nature says a disease called SPI (it stands for severe Perkinsea infections) has caused frog die-offs in 10 states. It says five of those states, including Minnesota, have had really big ones – where 95 percent of the frogs in an area die.
What is this disease?
The researchers say SPI is carried by a tiny parasite. In fact it's as small as they get, just one cell (it's a kind of protist called Perkinsea).
And it actually kills them before they're even frogs, while they're still tadpoles. It causes their organs to fail and they never make it out of the tadpole stage to froghood.
The USGS shared this photo of a tadpole with the organ failure the disease causes.
The researchers say SPI is serious enough that it can cause extinction of frogs in local areas. (The study does not mention where in Minnesota they found the 95 percent die-off.)
The scientists say they found the disease in 11 different kinds of frogs. They're not really sure how common it is because most frog researchers around the country have not been checking for it. That will change, though, now that this new study is out.
Most of the states where SPI caused die-offs are on the Atlantic or Gulf coasts. But there were three exceptions: Minnesota, Oregon, and Alaska.
SPI is not known to have any effect on people or their pets, Science Daily says.
Why frogs matter
One of the really cool things about frogs is that they eat mosquitoes. They eat other stuff, too, but the lead author of the study published in Nature Tuesday, Marcos Isidoro Ayza, says pest control is one of their greatest values to people.
They're also part of the food chain, so no frogs would mean less food for animals like herons, hawks, snakes, and big fish.
Another reason scientists like them is that the frog population is a good measure of how healthy the environment is in the places where they live. "Like the proverbial canary in a coal mine," Isidoro Ayza says, "amphibians let us know when something in our environment is going awry."