The answers to some questions are not really answers, but more questions. Elizabeth Davidson, a pathologist at Arizona State University, does research on a lethal salamander virus. She is one of a large group of scientists from around the world who are working together to find out what has triggered the decline of amphibians in places as far and wide as North and Central America and Australia. Her particular study area has turned up a few exciting answers, and enough questions to keep this global group of biologists busy for years.
Davidson's research entered the amphibian conservation realm somewhat serendipitously. She had heard about massive numbers of tiger salamanders dying in Arizona's San Rafeal Valley from fellow ASU biologist Jim Collins, who was studying the salamanders' ecology. Davidson and research assistant James Jancovich, curious about what was killing the animals, accompanied Collins to the San Rafeal Valley during a dieoff in 1995. They found ponds full of dead salamanders apparently killed by a bacterial infection called "red leg" disease.
Assuming that the bacteria were to blame for the deaths, Davidson and Jancovich took samples back to the laboratory for further study. What they would find later would open a minefield of unanswered questions.
In the laboratory, they had no trouble isolating the bacterium causing red leg and plenty of other bacteria. "But we were isolating the same bacteria from healthy animals, too. That was one of my first clues that we were barking up the wrong tree," says Jancovich. If healthy animals harbored the same bacteria, why weren't they dying? Davidson and Jancovich began to suspect that the bacteria were simply opportunists preying on already-sick animals, and that a different agent was the real culprit.
Davidson sought the help of colleague Frank Morado, a marine pathologist at the National Oceanographic and Atmospheric Administration in Seattle. The damage Morado saw in the infected tissu
Contact: James Hathaway
Arizona State University