"We were there before, during and after the extinction event and were able to look at the ecosystem and measure how it changed," said Pringle, Distinguished Research Professor in the Odum School and study co-author. "Very rarely have scientists been able to do that with respect to any organism."
The chytrid fungus responsible for declines has steadily marched southeast across Costa Rica and through much of Panama like a storm front, killing up to 90 percent of frogs in afflicted streams. In 2003, the team set up research sites on two streams in the pristine and lush highlands of Panama. One study site had already suffered a catastrophic amphibian decline, while the other had a healthy population but, based on its location, was directly in the path of the fungal disease.
In the first stage of their research, Connelly and Pringle assessed ecosystem changes that occur when tadpoles are experimentally excluded from small areas of both the healthy stream and the frogless stream. They found that the absence of the tadpoles resulted in more sediment and less productive algae.
In late 2004, frogs in the formerly healthy stream began dying. The team reassessed the stream and found that impact of the frog die-off was even greater than they had predicted in their exclusion studies. "We predicted the direction of the change," Pringle said, "but underestimated its magnitude."
The UGA research team is continuing to monitor the health of the streams to get valuable, long-term data. So far the str
|Contact: Sam Fahmy|
University of Georgia