Environmental changes affect salamander mating

By MELANIE LUTZ
Collegian Science Writer

Spring is in the air -- a time for warm weather, fresh flowers and romance. But humans aren't the only ones looking for love this time of year -- it's mating season for Pennsylvania salamanders. However, not as many of these amphibians will be mating here as usual.

William Dunson, a professor of biology who has conducted a 10-year study of salamanders in hundreds of central Pennsylvania ponds, said the decline in amphibian numbers has become an issue during the past five years. Acids and metals in the ponds that salamanders use for breeding and in the ground near those ponds have caused a decline of salamanders in the state, he said.

Dunson studied Jefferson salamanders, a species that breeds in early spring. He said these amphibians, which are convenient to use because they breed at this time and are available in central Pennsylvania, make excellent bioindicators of changes in the Earth's environment.

This is because amphibians are easily affected by environmental changes due to their thin skins and multiple habitats -- both land and water.

Dunson collected salamander eggs from the ponds and transplanted the salamander embryos to the laboratory, where he could study the effects of pH and metal concentration on them. He found that Jefferson salamanders were significantly affected by decreases in pH and increases in metals, such as aluminum.

He said these conditions may be due to the extremely acidic rain in the area. With a pH of 4, the rain in central Pennsylvania is 40 times more acidic than normal rainfall, he said.

"This is why so much research concerning acid rain is done at Penn State," he said.

Michael Horne, one of Dunson's students who graduated last semester, wrote a synopsis of the 10-year study of amphibian decline. In his synopsis he said the decline of the Jefferson salamanders is primarily due to the low pH and the elevated aluminum in some of the ponds but much remains to be learned about the details of the case.

Dunson said the decline of amphibians is a complex issue and there is also another problem -- the ground surrounding the ponds.

"The culprit is the groundwater," he said, adding that it is worse than the rain because it is even more acidic. Natural aluminum from the ground also contributes to the problem.

Dunson explained that the acid- and metal-rich water flows into ponds and kills the salamanders. When a salamander is placed in this groundwater, it will try to get out, he said. But it is still a mystery why the pH in the soil is so low.

Land development, pollution and ultraviolet light increases are all factors causing the decline in amphibians.

But even though things may not look so good for salamanders in Pennsylvania, Dunson said something has already been done to help.

That help is Congress' recent approval of the Clean Air Act, which sets industrial and public emissions standards, allowing the pH in rain to rise because of lowered pollution, Dunson said. But he does not know how rapidly it will affect the ground.

"We suspect that things will definitely improve," he said.