Amphibians continue to disappear, and not just in the Celery Bog

by Justin Mack, Journal and Courier

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frogFor Arnold Lishin, the frogs and toads that call it home help make West Lafayette’s Celery Bog special.

From their unmistakable chirps and croaks, to the ripples they leave in the water as they dart from spot to spot in the marsh, Lishin said the bog wouldn’t be quite the same without them.

“On quiet nights you can really hear them, loud and clear,” said Lishin, a Lafayette resident who makes regular trips to walk the trail and take wildlife photos.

“They are hard to see, but you can spot quite a few if you’re patient. You have to be careful not to scare them off if you want to see them, but it’s always a treat when they show up.”

Showing up is no longer a certainty.

According to a recent study by the U.S. Geological Survey, populations of frogs, salamanders and toads have been vanishing from places where they live at a rate of 3.7 percent a year.

At that rate, they will disappear from half of their inhabited sites nationwide in 20 years.

The study, which is the first-ever estimate of how fast some amphibians are disappearing from United States habitats, covered a nine-year period. Researchers analyzed 34 sites and 48 species.

Lishin said in his opinion, the most troubling part of the analysis is that no solid reason for the decline was identified, nor did researchers offer any solutions.

“It’s like there is nothing we can do,” he said.            

The study shows that even species believed to be relatively stable and widespread are declining. The declines are occurring in amphibian populations everywhere, from Louisiana and Florida swamps to the Sierras and the Rockies.

The more threatened species, deemed “Red-Listed” in an assessment by the global organization International Union for Conservation of Nature, disappeared from their studied habitats at a rate of 11.6 percent a year.

If the rate observed holds steady, Red-Listed species would disappear from half of their habitats in about six years.

“Amphibians have been a constant presence in our planet’s ponds, streams, lakes and rivers for 350 million years or so, surviving countless changes that caused many other groups of animals to go extinct,” saidSuzette Kimball, director of the geological survey. “This is why the findings of this study are so noteworthy: They demonstrate that the pressures amphibians now face exceed the ability of many of these survivors to cope.”

Jason Hoverman, an assistant professor in vertebrate ecology at Purdue University, said amphibian populations have been declining rapidly for decades, noting a 2003 study published in the scientific journal Diversity and Distributions that argues that the species have been vanishing globally since the late 1950s.

The geological survey’s study is just the first assessment that attempted to quantify the situation.

Hoverman points to habitat loss from changing environments and population growth as the prime culprit.

“We’ve seen amphibians lose 50 percent of their habitat in the last 200 years, so it really comes down to that,” he said. “Beyond habitat loss, which is the No. 1 problem, there are is chemical contaminants, diseases and invasive species.

“I think in terms of contaminants, pesticides are a big problem, so anything we can do to limit our use of pesticides will help. Another thing is when you observe mortality events, notify the (Department of Natural Resources) or the people at Purdue. ... Being able to get out there and get that information is going to help.”

Hoverman added that while the reported 3.7 percent rate is certainly reasonable, it shouldn’t be considered an across-the-board rate for all environments.

“The estimate probably is on the high end. ... The USGS study is one of the most complex in terms of its scope, when it comes to estimating amphibian population, but I think (the decline) is going to be kind of region-specific as well,” he said.

“In places where there is a lot of human growth, there is more habitat loss, so in those places we are losing amphibians pretty rapidly. But I’d say in other areas, like here, we’re not putting as much stress on the population.”

The study offered other surprising insights. For example, declines occurred even in lands managed for conservation of natural resources, such as national parks and national wildlife refuges.

Ecologist Michael Adams, the lead author of the study, said declines of amphibians in these protected areas are particularly worrisome because they suggest that some stressors — such as diseases, contaminants and drought — transcend landscapes.

“Even though these declines seem small on the surface, they are not,” he said. “Small numbers build up to dramatic declines with time. We knew there was a big problem with amphibians, but these numbers are both surprising and of significant concern.”

Amphibians seem to be experiencing the worst declines documented among vertebrates, but Adams said all major groups of animals associated with freshwater are having problems.
He added that the study gives officials a point of reference that will enable them to track what’s happening in a way that wasn’t possible before.

Rob Chapman, an Extension forest wildlife specialist in the Department of Forestry and Natural Resources at Purdue, said one of the most important things people can do to slow the declines is to be mindful of the substances and animals brought into the wild.
“Anything we can do to protect our water quality can help … preventing weird substances from going into the waterway and not flushing pharmaceuticals down the drain can really filter out those water quality issues,” he said.

“And if you buy an exotic amphibian at the pet store, do not release it in the wild. Turning loose an exotic amphibian in North America can expose native species to disease. If you have a pet that you have to get rid of, finding an new owner or euthanasia may be the best options.”