探索全球两栖动物数量下降成因

A new study co-authored by University of Florida researchers on the endangered Ozark Hellbender giant salamander（娃娃鱼） is the first to detail its skin microbes, the bacteria and fungi that defend against pathogens. Published recently in the online journal PLoS One, the study details changes in the salamander's declining health and habitat, and could provide a baseline for how changing ecosystems are affecting the rapid decline of amphibians（两栖动物） worldwide.

"Scientists and biologists view amphibians as kind of a 'canary（金丝雀） in the coal mine' and their health is often used as a barometer for overall ecosystem health, including potential problems that may affect humans," said study co-author Max Nickerson, herpetology（爬虫学） curator（馆长，监护人） at the Florida Museum of Natural History on the UF campus.

More than 2 feet long, the Ozark Hellbender is the one of largest salamander species in the United States. Its unusual biological characteristics include the ability to regenerate injured or missing body parts.

In the new study, lead author Cheryl Nickerson, a professor at Arizona State University, along with NASA and UF scientists, cultured and identified microorganisms from abnormal and injured tissue on the salamanders searching for pathogens that may be causing the lack of regeneration and population decline.

The researchers found several potentially dangerous pathogens, including Aeromonas hydrophila, a bacterium scientists believe is associated with disease and death in both amphibians and fish.

While many different pathogens were found in the injured tissue, no single organism was found to be responsible for the lack of regeneration. Researchers believe the occurrence of abnormalities and injury in the Ozark Hellbender may have many contributing factors, including disease and habitat degradation, and say further study is needed.

"If you don't understand an amphibian's skin you don't understand the amphibians," Nickerson said.

Scientists have known about the remarkable powers of salamander regeneration for more than 200 years, but beginning in the 1980s, researchers noticed a sharp decline in the Ozark Hellbender population. They also found a specific population from the North Fork of Missouri's White River was declining dramatically and losing the ability to regenerate.

"We were finding animals with no legs that were still alive with flesh wounds or bones sticking out of limbs," Nickerson said.