Bullfrogs and other amphibians are especially vulnerable to agrochemicals because they live in both water and on land at different life stages.
Oregon State University/Lynn Ketchum
A first-of-its-kind "meta-analysis" from Oregon State University researchers looks at the link between pesticides and fertilizers and amphibians -- and what that means for the rest of the ecosystem.
If you want to dig into the science and methodology, the OSU Extension Service does a nice job explaining it all.
- WATCH Oregon Field Guide: Amphibian Declines Driven by Complex Causes
One of the interesting aspects of this study is the way it connects the dots from pesticide and fertilizer use to things people care about ... like controlling mosquitoes and making sure the whole circle-of-life thing works as it should.
1. The Agrochemicals: carbamate insecticides, herbicides like atrazine and inorganic or chemical fertilizers are used a lot during the spring. That's when new crops need the help getting started and surviving threats from weeds and insects.
2. The Amphibians: Those same springtime applications coincide with the time of year when the next generation of frogs, salamanders and toads are in the egg or larval and tadpole stages. They live in ponds, other waterways, or on the ground -- putting them in direct exposure to the chemicals.
3. What Happens To Amphibians: Contact with these chemicals decreases amphibians' survival and make them more susceptible to predation. These chemicals also hinder the production of amphibian offspring later in life.
4. What Happens To the Ecosystem: When you disrupt frog, toad and salamander populations, you undermine biodiversity. You also set off a domino effect throughout the ecosystem. Birds, snakes and fish eat amphibians. Reduce their population and you've reduced the number of meals available for these predators -- and in turn, for the species that prey on them. And these amphibians aren't just food. They help the environment through their roles as grazers, herbivores and predators of pests, such as mosquitoes.
Tiffany Garcia. Credit: OSU
The study's announcement concludes that timing is critical when it comes to reducing the effects of pesticides and fertilizers on amphibians.
"Farmers can be, and often are, the best naturalists we have," said Tiffany Garcia, a co-author of the study and an associate professor of wildlife science within OSU’s College of Agricultural Sciences. "Mixing agricultural production with wildlife management is vital to the survival of amphibians, especially with agricultural intensity growing to feed our booming global human population."
-- David Steves