Worms and Flowers

Save the Frogs

Posted in Environment by Lzyjo on December 27, 2008

Year after year, scientists report mass die-offs of frog species worldwide, yet, little changes to protect these delicate amphibians from the well-known environmental threats that besiege them.

A 2002 National Geographic article and a recent NPR story point toward Atrazine, Malathion, and Esfenvalerate, a synthetic pyrethroid, as the root causes of physical defects threatening frog populations. Atrazine has already been banned in the European Union, since 2004 due to pervasive groundwater contamination, but remains the second most widely-used pre and post emergence herbicide in the U.S., next to Roundup, with over 77 Million pounds applied each year. Atrazine is cheap and most commonly used on corn crops, sorghum, and sugarcane.

Atrazine is a potent endocrine disruptor, even in low concentrations. The most egregious effect of Atrazine is it’s ability to demasculinize male frogs. “Atrazine-exposed frogs don’t have normal reproductive systems,” said Tyrone Hayes, the leader of a team from the University of California at Berkeley. “The males have ovaries in their testes and much smaller vocal organs.” Atrazine exposure caused levels of testosterone in male frogs to sink below those in healthy female frogs. Not only does Atrazine disrupt the reproductive systems of amphibians and humans, but it impairs organ development, causing deformed hearts, kidneys and digestive systems.

Some of the developmental effects of Atrazine can be explained by an overgrowth of trematodes, the parasitic worm that causes swimmer’s itch. When Atrazine is introduced into an aquatic environment, it kills algae floating on the surface, letting in more light for algae growing on the bottom. The bottom-growing algae is a food source for snail populations, which begin thriving in the altered conditions. In some cases, snail populations quadrupled, providing a host for the trematode. When developing tadpoles are exposed to trematode larvae, they form cysts in the frog’s body that alter later development, causing missing limbs, or in some cases duplicate limbs. Normally, a healthy frog would be able to resist, to some extent, a trematode infection, but the Atrazine has a detrimental effect on the frog’s immune system, so it can no longer protect itself.

Other studies have linked physical defects to increased ultraviolet radiation exposure from ozone layer depletion. A survey of frog habitat in Minnesota showed that frogs were less at risk for physical defects in wetlands where the habitat absorbs much of the UV light.

Chemical pollution is not the only threat to amphibians, it is global warming and a series of ecological chain reactions. A 2006 article from Live Science, explains a fungal phenomenon is responsible for a huge worldwide decline in frog populations over the past twenty years.

From Australia to the Caribbean, species are being wiped out by Chytridiomycota a primitive water-borne fungus that attacks the frog’s skin, causing excessive peeling, lethargy, and death. Scientists blame the increase in Chytridiomycota on increased cloud cover and altered day and night temperatures that provide the ideal breeding ground for the fungus. Scientists working during an outbreak after all the frogs died described the silence in the forest as eerie.

As gardeners with a special appreciation for the little creatures that inhabit our cultivated paradise, it behooves to do what we can to protect these essential and delicate creatures. I’ve seen a least one toad (?) around and I wish to provide a small sanctuary in my garden for those insect-eating creatures. A Frog Pond does not have to be large and can easily be inserted and maintained in a garden area. It takes little to maintain a frog pond as they do not need filtration, only shade, muck, and old leaves, which nature will provide.

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