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CA Press: Deformed frogs spark students' study


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Posted by W von Papinešu on January 21, 2003 at 18:06:24:

SONOMA INDEX-TRIBUNE (California) 21 January 03 Deformed frogs spark students' study (Patricia Henley)
Sparked by the fall 2001 discovery of a short-lived, multi-legged amphibian named Frogzilla, fifth-graders at El Verano Elementary have tested water samples, found more deformed frogs in local streams, questioned experts and developed their own theories about the cause.
"Some people think it's caused by the chemicals and some think its caused by the parasites. But we believe it's caused by (a chemical in) lawn fertilizer (and agricultural herbicides)," said Kristen Palmer, one of 27 students in Dave Neubacher's fifth-grade class. "The chemical runoff causes algae to grow in the creek, which attracts the snails. The snails have parasites, which attack the frogs where the legs are developing."
In addition to learning about the life-cycle and anatomy of frogs, the scientific approach to problem-solving, and the skills and care needed to gather and evaluate reliable testing samples, these youngsters have acquired a first-hand understanding of science in the real world.
"We learned that the colleges and a lot of scientists are fighting over this," said Dylan Orton. "One side thinks it's chemicals and one thinks it's parasites. They won't talk to each other, they just keep working. ... I think they would accomplish more if they would work together."
And these kids are determined that answers need to be found.
"If we just sit here doing nothing, then this could maybe affect humans, if people want to swim in the creek. ... We can't just wait. We have to do something," said fifth-grader Rueben Lopez.
The students are following up on research started last year, when then-fifth-grader Zachary McFarland brought his multi-legged bullfrog, Frogzilla, into Neubacher's classroom.
Neubacher and a group of students immediately went out to survey the two spots in a local creek where McFarland and his 6-year-old brother had found Frogzilla and other slightly-deformed frogs. Out of 35 bullfrogs caught on that expedition, 30 had more than the usual number of legs.
That set the classroom of fifth-graders into motion, studying books and the Internet, contacting scientists and government officials, working with the Sonoma Ecology Center staff to identify seven local monitoring sites to evaluate the percentage of deformities, gathering water samples for testing, and sending the deceased Frogzilla's body off for dissection and analysis.
However, all that activity yielded more questions than answers. Some experts told them definitively that the problem was parasites known as trematodes, which have been causing occasional frog deformities for thousands of years; others argued with equal conviction that the current deformities were produced by chemicals.
Last year's fifth-grade class graduated and went on to other pursuits, with the puzzle of Frogzilla and the other deformed bullfrogs still unresolved.
So this year's class of Neubacher's fifth-graders took up the challenge, building on the work done by the previous students and pursuing ideas of their own.
Last fall they continued monitoring the seven local stream sites, counting hundreds of frogs in the process.
"They were difficult to catch and the data collecting took days to gather the results," Neubacher said.
The students are keeping the exact monitoring locations a secret, so they won't be disturbed by outsiders eager to see deformed frogs.
At three of the seven sites, the kids found a total of 27 frogs with some form of minor deformities. One location (where Frogzilla was caught) had a deformity rate of 33.8 percent. The rate of deformed frogs at the other two sites was 1.3 percent and 24.7 percent.
And one of the locations that had deformed frogs also had "thousands of water snails around," according to a class report. Water snails are known to carry the trematode parasites.
The students also gathered water samples, testing some themselves and sending off others for laboratory analysis.
"When we work with the frogs and do the water samples and stuff, it kind of makes us feel like scientists, too," said student Courtney Haggard. "Just yesterday (Tuesday), we had the water samples and we put in chemicals like nitrate. It turns a color and you check it against a card."
"It's fun," added student Sam Livingston. "Although it may be hard work, it still is fun."
And they work well as a team.
"It's also fun watching someone in front of you doing stuff, taking water samples and stuff," said Max Wilson.
As part of their project, they checked newspapers and magazines for frog-related stories - and the names of experts - and scoured the Internet for information. The traditional answer is that the frogs' problems are caused by parasites.
Then one student brought in article in the San Francisco Chronicle highlighting frog research by University of California at Berkeley biology professor Tyrone Hayes, who asserted that the widespread frog deformities are caused by atrazine, a chemical widely found in the United States in fertilizer and herbicides, both for household and agricultural use.
According to online reports of Hayes' research, frog larvae are susceptible to atrazine, and surface water concentrations of this chemical tend to be highest during the first heavy spring rains - which is also when frogs spawn.
The chemical also apparently disrupts the frogs' sexual development; many of the frogs with deformities also have both male and female organs. Since they are unable to reproduce, the deformities could be contributing to another problem scientists are attempting to understand, the overall decline in the number of frogs worldwide.
The students attempted to contact Hayes directly, with no response.
They also visited a local hardware and garden store, to survey the wide range of on-the-shelf products containing atrazine.
However, the results of Frogzilla's dissection came back this year, clearly showing the presence of parasites. So the students sought an answer that would make sense of all the data - both the studies showing the potential role of atrazine and the damage known to be caused by the trematode parasites.
Another fifth-grader found an article on declining frog populations and listing three experts. That helped Neubacher's class make an e-mail connection with Carlos Davidson, a professor at California State University Sacramento.
Davidson agreed that the students' tentative theory - the presence of atrazine leading to more algae, more snails and more parasites - could be correct. However, he also forwarded an article by Joseph M. Kiesecker, a biologist at Pennsylvania State University, suggesting that chemical pollutants in the water could be lowering the frogs' resistance to the parasites.
So the students are continuing their research, looking for data either for or against their current theory. The frogs are hibernating through the winter months, so the students' stream work will intensify this spring, with the appearance of this year's tadpoles.
"This class is really into finding results," Neubacher said.



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