Imagine if found that a chemical in our food weakened our resistance to malaria and, when it entered the sewers after we washed it off our dishes, it actually caused mosquitoes to double their egg laying.  We’d call it a perfect storm.

That’s essentially the same situation facing amphibians because of atrazine, as reported in a Scientific American story about Northern Leopard Frogs. According to the story, “the culprit appears to be the common herbicide acting as a double-edged sword: It suppresses the frogs’ immune systems while boosting the population of snails that play host to parasitic worm larvae, the latter of which infect the weakened leopard frogs.”

Another way to explain it, according to the Christian Science Monitor, it this:

Atrazine reduced phytoplankton in the water, making more food and light available for algae. It also appears to speed snail reproduction. The snails, often carrying larvae of parasites harmful to frogs, feed on the increased amounts of algae. Then frogs feast on the snails. In addition, the atrazine deadens the frogs’ immune systems, leaving them less capable of countering the parasites.

Nice to see Joe Mendelson of Zoo Atlanta quoted in the coverage.



The effects of herbicide and fertilizer runoff on amphibians in rural areas has been reported before. We’re talking about frogs that develop extra limbs and other deformities. And of course, we’re talking about frogs dying. But a University of Pittsburgh study, funded by the National Science Foundation, shows that the active ingredient in popular pesticides like some Scotts Ortho products — it’s called malathion — is preventing tadpoles from maturing because it wreaks havoc with the food chain they need to grow. Here’s excerpt from Science Centric Web site which pulls its information from the Oct. 1 issue of Ecological Applications:

Gradual amounts of malathion that were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source. As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature.

“The chain of events caused by malathion deprived a large fraction of the leopard frog tadpoles of the nutrients they needed to metamorphose into adult frogs,’ said study author Rick Relyea, an associate professor of biological sciences in Pitt’s School of Arts and Sciences. “Repeated applications sustained that disruption of the tadpoles’ food supply. So, even concentrations that cannot directly kill tadpoles can indirectly kill them in large numbers.”

Here’s a thoughtful article on the issue from 2005: read here.


I came across a very long, very detailed and well written blog post from a Canadian (blogger name is gullyfourmyle) who contends amphibians are declining in large measure because of airborne toxins from our use of oil — and that, like a canary in a coal mine, they are warning humans to stop polluting. I’ve pasted the part about the frogs below, but the whole post can be found here.  


Frogs and people have a lot in common. Our mitochondria, the stuff that binds our cells together, is exactly the same. In fact every living thing on the planet has the same mitochondria. What that means to the average guy on the street without going into a long list of building blocks we share with our frog relatives, is that what affects frogs also affects us in much the same way. Essentially if something in the environment is killing them, you can rest assured we are at exactly the same risk, it may just take longer:

The world’s frogs, newts and toads are dying. They are being over-harvested for food, their homes are being destroyed, and most worryingly, entire species are disappearing for no apparent reason. That is the conclusion of more than 500 herpetologists around the world, reported in Science today. Stuart S., et al. Science, published online 10.1126/science.1103538 (2004).

“Time and again, scientists have visited woods filled with frog song just 3 or 4 years earlier, only to find them frogless. Now, researchers have finally caught a killer in the act–a new fungus that has turned up in 120 frogs and toads of 12 species in Australia and seven species in Panama during mass die-offs in relatively pristine areas. Fourteen scientists from Australia, the United States, the United Kingdom, and Canada will describe the fungus–from the phylum Chytridiomycota” – in the 21 July Proceedings of the National Academy of Sciences. Fungus May Drive Frog Genocide, Jocelyn Kaiser, WILDLIFE BIOLOGY, 3 July 1998

“There is the canary in the coalmine argument,” says Stuart. “Because of their sensitivity, amphibians are the first species we would expect to show adverse reactions to climate change and new emerging diseases.” Amphibians face a bleak future, Emma Marris, news@nature.com, October, 14, 2004

In 1993, a then unknown biologist by the name of Karen Lips who became internationally famous when her research into new species of amphibians found in Panama was made public. Her research was in a hitherto unexplored mountainous region of Panama where she was discovering new species of amphibians virtually one after the other. It was like finding her own Galapagos Islands. It was a different story when she returned to continue her research in 1997:
…imagine Karen’s shock when she returned to her research site in western Panama and discovered dead and dying frogs everywhere: “I’d been going to Fortuna, Panama, since 1993. In 1997, I returned to find all these dead frogs. They looked fine, like they went to sleep and didn’t wake up.” Frogs are food to so many snakes and birds, a herpetologist could spend many seasons in some places without seeing a dead frog lying on the ground.” Kim Y. Masibay, Science World, March 11, 2002

What ties these events together is air. Nothing associated with planet earth permeates our environment as completely as air and air is a vehicle for the transportation of material that can mix or float along and become one with what we consider our atmosphere. Airplanes take great advantage of the density of air, lift and speed to fly. The waste products of the energy consumed to make this happen are exhaust emissions. If you remove the passenger and cargo component of the aviation experience and equate what an airplane does as a cordless paint-gun, you have in our aviation system, a most complete mechanism for spraying a life dissolving chemical wash over the entire globe.

Frogs have three areas of their bodies that can aid in gas exchange: skin, lungs, and the thin membranes lining the mouth and pharynx. Frogs can breathe through their skin while they are in wet places. They can also exchange gases between their blood vessels and with the outer environment. Unlike us they have mucus glands in their external skin tissue, they keep the skin moist. We have those same mucous glands but they line our nose and respiratory tract rather than our outer skin. Sweat glands are evolved mucous glands for land-lubbers. Frog skin absorbs a lot of dissolved oxygen from the ambient atmosphere.

The second respiratory surface is the thin membranes lining the mouth and pharynx. Our membranes exchange gases too, but not to the degree that those of frogs do.

The lungs are third respiratory surface, thin, elastic and lightweight, they are organs that inflate and deflate rhythmically, while the frog is at rest. Adult frogs have poorly developed lungs, due to their mostly motionless existence as they wait patiently for the next unsuspecting bug.

Now just imagine adding crude oil-derived solvents to the air the frogs must breathe. Solvents that turn their protective mucous to an acidic solution which then evaporates more quickly than pure water. You have a cooling and immobilizing effect that would tend to freeze the frog in place and strip it of its immune system (the mucous) at the same time. Since frogs live in environments that are thick with fungal spores, it is no stretch of the imagination to figure out what happens next is it?

From London Daily Mail:

On the toad to ruin: Thousands of tiny amphibians dice with death to flee polluted river

Residents in China’s Jiangsu Province were hopping mad when thousands of little toads took to the streets. 

ScienceDaily has summarized a new study published in Environmental Health Perspectives that shows atrazine harms the development of organs, such as the heart, in baby amphibians.  Other studies have pointed to problems that the common weed killer has caused with other stages of development, but this is the first to study the impact on organ morphogenesis, or organ development. The scientists did the experiment on Xenopus laevis, or African clawed frogs. That species is the one that was shipped around the world in the 1930s and 1940s for human pregnancy tests — and unwittingly carried with it the amphibian chytrid fungus. You decide if that’s ironical.

St. Louis Zoo chief Jefrrey Bonner has some one-on-one time with Kermit when the Assocation of Zoos & Aquariums brought the duo to the U.S. Capitol building to lobby for amphibian protection measures.

Our sex life started destroying amphibians when we exported the African clawed frog as a pregnancy test in the 1930s. A half century later, our use of the pill started changing the gender of frogs and salamanders. Read on…

The St. Louis Zoo’s Jeffrey Bonner (who also is chairman of Amphibian Ark) has written another very original article on the amphibian crisis,in the St. Louis Post-Dispatch. In this one he makes a connection between the spread of pollen (“the sex life of trees”) and the spread of the frog killing chytrid fungus (ultimately connected to the sex life of humans). It’s a fascinating observation, one I’ve not read before. The excerpt:

Several years ago, I attended a seminar in Washington. It was spring — cherry blossom time. I was sneezing like crazy. Our speaker also had allergies, and he apologized for his sniffles. Being a biologist, he explained it this way, “Sorry for all the sneezing. It seems I’ve become an inadvertent participant in the sex life of trees.” He was right, of course. We sneeze because we have an immune reaction to the pollen, or sex cells, which trees spread in the spring.

If frogs could speak, perhaps they’d say the same thing about amphibian chytrid. It would have taken forever for chytrid to spread out of South Africa had it not been for the actions of humans, harvesting infected frogs and air-mailing them around the planet for pregnancy tests. The frogs, it would seem, were an inadvertent participant in the sex lives of humans.

We can allow hundreds of amphibian species to face quietly into oblivion, or we can take action now to spare their lives. I hope the choice we make is the humane one.

Jeffrey Bonner is president of the St. Louis Zoo. He also is the chairman of the Amphibian Ark, the global effort to save 500 critically endangered species and place them in “protective custody” in zoos and aquariums around the world. 

Interestingly, Dr. Bonner earlier had written about modern birth control pills and their impact on amphibians — i.e., the heightened estrogen levels in our urine is reaching streams and deforming species. That story was extremely interesting, as well. In it, he wrote:

Of equal concern is many of the common drugs we consume. Their contents pass through our bodies, into sewage treatment plants and back into our rivers and streams. Estrogen, the active ingredient in many birth control pills, is one of these. In frogs, low levels of estrogen cause exposed tadpoles to become female; under normal conditions, half develop female and half develop male.