Note: original title using the term fertilizer was corrected to read atrazine

Leopard frog
Courtesy Heather Dietz

What is happening to our frogs?

A recent study showed that atrazine in pond water could lead to a higher population of snails, which harbor parasites that also infect frogs. For the study, Lucinda Johnson and her colleagues at UMD collected leopard frogs from 18 wetlands near St. Cloud, Minnesota. The researchers found a positive correlation between the amount of atrazine in a wetland and the number of parasites in that wetland's frogs. The parasite in question is a tiny worm called a trematode. They can have a negative effect on frog populations.

How atrazine effects frogs

More fertilizer = more pond scum (periphyton)
More periphyton (snail food) = more snails
More snails = more snail parasites (trematodes)
More trematodes = more trematode larva attacking tadpoles
Larva infested tadpoles and frogs have lower survival rates when atrazine is present

The trematode worm that infects the frogs gets passed to frog-eating birds like herons and egrets. Inside the birds, the worms develop to adulthood. The adults produce eggs that are released into water with the birds' feces. The eggs hatch, develop into larvae, and burrow into snails. After further development, they burrow their way out again and swim in search of tadpoles. They infect them, the tadpoles turn into frogs, and the cycle continues.

Learn more about atrazine and frogs

Source articleUMNews: The tadpoles tale .
Article in Nature: Agrochemicals increase trematode infections in a declining amphibian species

Tags : Lucinda Johnson, leopard frogs, frogs, freaky frogs, fertilizer, ecosystems, deformities, atrazine, water, environment

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Lemur leaf frog: Frogs are threatened by a fungus that can kill up to 90 percent of amphibians in a stream and lead to decimation of the rest of an ecosystem.
Courtesy Scott Connelly/UGAResearchers studying an amphibian-killing chytrid fungus (Batrachochytrium dendrobatidis) spreading through the streams of Central America, are using the opportunity to investigate the effects that the loss of frogs have on a stream’s overall ecology.

Chyrtid fungus has been spreading southeast through Central America destroying amphibian populations along the way. Scientists from the University of Georgia in Athens set up two separate study areas – one in a stream that had been invaded by the fungus, and another unaffected stream that was in the path of the spreading outbreak.

What they discovered is how important tadpoles are in keeping a stream’s ecology in balance. The tadpoles, it seems, stir up quiet pockets of the stream as they hunt for food, an activity that keeps sediment suspended in the water from settling to the bottom. This allows more sunlight to reach the algae growing there which, in turn, processes it into an energy source that is the base of the stream’s food chain.

“Many things that live in the stream depend on algae as a base food resource,” said lead author Scott Connelly, a doctoral student from the UGA Odum School of Ecology. “And we found that the system was more productive when the tadpoles were there.”

Although the algae increased by as much as 250 percent in some cases, the lack of agitation from the decimated tadpole population allowed more sediment to cover the bottom and stifle the algae’s processing of sunlight and nutrients into a food source for the rest of the stream’s fauna.

The scientists have been able to save infected frogs in captivity by applying a fungicide, but so far they have been unable to restore ecosystems damaged by the fungus because a widespread application of the fungicide would also kill any beneficial fungi.

The results of the study appeared last week in the online version of the journal Ecosystems.

UGA press release
Story on ScienceDaily
More on the amphibian extinction crisis
All about tadpoles

Tags : frogs, ecosystems, ecology, biology, amphibians

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