Where Have All the Frogs Gone?!

Around the world, amphibians are on the decline from disease, and according to USF biologist Jason Rohr, this reduction could be a warning that other species may be at-risk from a variety of factors.

"We are in the midst of a sixth mass extinction and amphibians are the most threatened vertebrate taxon on the planet," he says."They have become the ‘poster child' for this mass extinction." And unlike past mass extinctions, this one is driven by humans, he says.

Studies published by Rohr and colleagues in the journal Nature and in Proceedings of the National Academy of Sciences reveal that chemical pollution can increase often deadly trematode (parasitic flatworm) infections in a declining amphibian species.

"The combination of atrazine, a widely used herbicide, and phosphate, a primary ingredient in fertilizers, accounted for 74 percent of the variation in larval trematode abundance in the frogs," said Rohr, an assistant professor in the Department of Integrative Biology. "These agrochemicals increase trematode infections by augmenting snail intermediate hosts - the source of trematodes that infect amphibians - and suppressing amphibian immune responses."

Like canaries used to gauge the safety of air in coal mines, amphibians are thought to be the "canaries" in our freshwater environments; reductions in their health can warn that subsequent species declines and degradation of ecosystem services might be in store.

Click here to read the complete article in USF Magazine (page 33).