Environmental concerns increasing infectious disease in amphibians, other animals

July 18th, 2012 in Biology / Ecology
Infection with trematodes in this leopard frog caused extra legs to grow. (Photo by Pieter Johnson, courtesy of Oregon State University)


Infection with trematodes in this leopard frog caused extra legs to grow. (Photo by Pieter Johnson, courtesy of Oregon State University)

Climate change, habitat destruction, pollution and invasive species are all involved in the global crisis of amphibian declines and extinctions, researchers suggest in a new analysis, but increasingly these forces are causing actual mortality in the form of infectious disease.

Amphibians are now, and always have been hosts for a wide range of , including viruses, bacteria and fungi, scientists said in a review published in B.

But in recent decades, disease seems to have taken a more prominent role in causing mortality. Because of multiple stresses, many induced by humans, amphibians now succumb to diseases they may historically have been better able to resist or tolerate.

"There's more and more evidence of the role of disease in the , in both amphibians and other types of animals," said Andrew Blaustein, a distinguished professor of zoology at Oregon State University and author of the recent analysis.

"It's normal for animals to deal with infectious organisms, often many of them simultaneously," he said. "But in the face of pollution, a reduced immune response, , evolving pathogens and many other stresses in such a short period of time, many species now simply can't survive."

The current of amphibians - which existed even before dinosaurs roamed the Earth - may be more than 200 times the background rate of extinction, the scientists note in this report. From an , amphibians that survived for hundreds of millions of years may be undergoing a major .

Because they have both terrestrial and aquatic life stages amphibians are exposed to various environmental forces more than some other animals, scientists say, and a higher percentage of them are threatened with extinction than are birds or mammals. However, similar concerns may become apparent in many animal species, including humans, as environmental changes and stresses grow, they said.

Among the observations in this report:

These forces are complex, the researchers noted. The effects of climate change on amphibian disease, for instance, my cause some pathogens to increase in prevalence and severity, while others decline.

Understanding the driving forces behind these changes, the scientists said, will be important not only to address but also to deal with emerging infections in many other plants and animals, including humans. Such impacts can affect wildlife conservation, economic growth and human health.

Provided by Oregon State University

"Environmental concerns increasing infectious disease in amphibians, other animals." July 18th, 2012. http://phys.org/news/2012-07-environmental-infectious-disease-amphibians-animals.html