Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study Links Pesticides, Declining Frog Population

14.08.2009
Researchers discover that the same chemicals that make California's Central Valley so successful as a farming area also make the nearby Sierra Mountains deadly for frogs.

Don Sparling, associate professor of zoology at Southern Illinois University Carbondale, tapped a few grains of salt from a shaker of into his hand, demonstrating how little pesticide it takes to kill off a population of frogs.

“This would be enough to make about 250, 8-liter doses,” the researcher said, referring to no more than a dozen grains of salt in his palm. “And this would be enough to kill every frog in there.”

Researchers have known since the mid 1990s that amphibian populations around the world are declining. Loss of habitat -- up to 95 percent of wetlands have been drained for the “corn desert” in states such as Iowa and Illinois -- and a virulent fungus, known as chytrid, are two big reasons. But a third reason, the one Sparling investigates, involves contaminants such as pesticides.

Sparling has been involved with the issue for years. The second edition of his textbook and reference, “Ecotoxicology of Amphibians and Reptiles,” is due out early next year. His most recent study was published in the August edition of “Environmental Toxicology and Chemistry.”

Sparling, along with other researchers, recently discovered that the same chemicals that make California’s Central Valley so successful as a farming area also make the nearby Sierra Mountains deadly for frogs. Specifically, the study looked at Pacific tree frogs and foothill yellow-legged frogs, both of which are native to the mountain meadows and are declining in population.

Sparling and the team found neurotoxin pesticides are finding their way up out of the valley and into the snow and eventually the streams where the frogs live and breed.

And the results are devastating.

Using laboratories at SIUC, Sparling and his graduate students found that as little as 0.3 parts per billion of endosulfan -- the active ingredient in many pesticides -- in water is enough to kill half of the frogs living in it.

“At 0.8 parts per billion, we lose all of them,” Sparling said, referring to the tiny amount of salt in his hand. “We always thought there was an association between pesticides and declining amphibian populations, and we’re building up a body of evidence to show this is the case.”

Sparling’s research studies the effects of “environmentally realistic” amounts of pesticides on amphibians, such as frogs. California’s Central Valley, with its great diversity of farming and heavy use of chemicals, along with its nearby mountains and declining amphibian populations, provided the perfect opportunity.

“The Central Valley is an extremely intense agriculture area, with everything from grapes to peaches, to nuts and tomatoes grown there,” Sparling said. “Along with that, you have literally hundreds of thousands of pounds of active-ingredient pesticides, this is before it’s diluted, applied each year in this area.”

Sparling and his colleagues looked at whether the pesticides were involved in the amphibian population declines there. A main question they faced involved finding out how the chemicals worked their way up out of the valley and up into the Sierras.

Using sampling techniques, the team found the chemicals were indeed making their way into the frogs’ environment, most likely by wind.

“These pesticides are applied by airplanes and we found that the wind would blow some of it up into the mountains, for instance,” Sparling said. “In other cases, these chemicals would volatize after being applied, turning into a gaseous state, which could also be picked up and spread into the mountains by wind.”

Timing was also a major factor in the damage caused by the chemicals.

Chemicals applied in late winter and early spring would find their way into snows packed in the cooler mountain region. As the snow melted each year, the chemical released into the streams just as frogs begin to breed.

“As soon as ice is out of those streams, frogs start breeding,” Sparling said. “The newly hatched frog larvae are at their most vulnerable right at this time, when the chemicals are getting into the water.”

Chemical exposure causes death and abnormalities in the tadpoles, in some cases causing their signature long tail to develop off-center, resulting in an animal capable of swimming only in a tight circular “corkscrew” pattern that makes it easy pickings for a hungry fish. It also causes drastic differences in the rate of growth and other problems.

“The sub-lethal effects of chemicals are probably even more important than outright killing,” in terms of affecting the population, he said. “It’s more insidious.” Contamination levels far below the lethal range may cause such effects.

The foothill yellow-legged frog is especially susceptible to the chemicals such as endosulfans, which kill by essentially overloading the nervous system and rendering breathing muscles useless. Europe and Australia each have banned the use of the chemical as a pesticide, and the U.S. Environmental Protection Agency also is studying the issue, Sparling said.

Sparling is optimistic humans can find ways to both farm on a large enough scale to feed the population and protect non-pest animals.

“To produce crops to provide for the world we have to use pesticides, and I’m not anti-pesticide,” he said. “But it’s important for us as scientists, agriculturalists and environmental protectors to make sure we continue developing pesticides that are as protective as possible of non-target animals as can be, both in the chemicals we use and application methods.”

Sparling continues working on the issue, helping graduate students examine the effects of the interaction of the chemicals -- the cocktail neurotoxins -- on frog populations, looking at whether they interfere with one another, synergize or have an additive effect. He also is looking at the effect of each chemical on the mountain yellow-legged frog, a relative of the foothill yellow-legged frog that lives at higher elevations.

Monitoring the frog populations’ health is critical to humans as they seek to protect the environment from unintended consequences.

“Frogs are like the canary in the coal mine. They serve as early alarms for the environment,” Sparling said. “They also provide a large and important link between the aquatic and terrestrial environments. If amphibians go, a huge link will be gone.”

Tim Crosby | Newswise Science News
Further information:
http://www.siu.edu

More articles from Agricultural and Forestry Science:

nachricht Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>