During the summers of 2006 through 2008, McMenamin, wearing hip waders and carrying a dip net, cataloged the amphibian lifeor lack thereofin and around 42 ponds that had been surveyed in 1992-1993. In that earlier survey, involving 46 ponds, 43 supported amphibian populations for at least one of the two years. But in the recent inspection, only 38 of those same ponds even contained water in summer.
In their fieldwork, the researchers were able to visit 31 of the 38 wet ponds (the remainder were off limits, to protect nesting trumpeter swans). Only 21 of them supported amphibian populations for even one of the three years they were checked, 2006-2008. In 15 years the number of ponds with frogs and salamanders had dropped drastically.
"That's when we really got alarmed, because the data just showed such a huge difference," Hadly said.
Historically, the pondsas small as backyard fish ponds, as large as small lakeshave been recharged during the summer by the groundwater in the soil. But the water table is dropping, the researchers say, as human-induced climate change produces a deadly combination of higher temperatures and less rain and snow. Moreover, the seasonal wetlands near the ponds, usually ideal amphibian habitat, are evaporating earlier in the spring, the result of an earlier snowmelt.
During the course of their study, the researchers witnessed the loss of four amphibian communities because of pond drying. Each event left hundreds of dried tiger salamander corpses behind. The ponds had dried rapidly, over just a few days, too fast for larvae to metamorphose and adults to migrate.
"Everybody can identify with the loss of glaciers, but in Yellowstone the decrease in lakes and ponds and we
|Contact: Dan Stober|