Tag Archives: Amphibian research

Guest post: A Herpetologist Chases Frogs with Tails

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We were so pleased to receive a guest post from Sara E. Viernum, a herpetologist with over 10 years of experience chasing snakes and salamanders around the U.S. When she’s not chasing reptiles and amphibians in the field, Sara is blogging about them on her website The Wandering Herpetologist, which is devoted to all things reptile and amphibian related. She currently resides in San Antonio, Texas, with her wonderful husband and her pet milk snake, Nyarla The Crawling Chaos. Sara also has a Facebook page.

For two field seasons in 2010 and 2011 I had the pleasure of hunting for aquatic amphibians in the Tillamook State Forest in Western Oregon. I was helping a friend with her graduate research focusing on the effects of fish passable culverts on aquatic amphibians. We spent many, many fun-filled hours crawling around in streams in the forest looking for Pacific giant salamanders (Dicamptodon tenebrosus), Columbia torrent salamanders (Rhyacotriton kezeri), and Pacific tailed frogs (Ascaphus truei).

Male Pacific tailed frog showing his "tail". Photo courtesy Sara Viernum.

The tailed frogs were such interesting amphibians. I had never seen these strange little frogs before we started the stream surveys. The tadpoles have specialized sucker mouths that they use to hold onto the rocks in the fast-flowing currents of the streams. They will also adhere to a collection bucket and your hand. If that’s not strange enough the adult males have a little “tail.” The “tail” is actually an extended cloaca that is used for internal fertilization. The Ascaphus frogs are the only frog species that have internal fertilization.

Pacific tailed froglets showing color variations. Photo courtesy Sara Viernum.

Tailed frogs are members of the Leiopelmatidae family (Tail-wagging frogs). There are only two species in this family found in North America – the Pacific tailed frog and the Rocky Mountain tailed frog (Ascaphus montanus). The family is considered to be one of the most primitive. The frogs cannot vocalize (call) and they do not have an external ear or a middle ear bone. Their closest relatives are the Leiopelma frogs from New Zealand which are also considered to be primitive frogs too.

Pacific tailed frog tadpole suctioned to Sara's hand. Photo courtesy Sara Viernum.

The Pacific tailed frogs could be quite common in some of the streams and were always a treat to find, although it was sometimes difficult to get to tadpoles to let go of your hand.

Pacific tailed frog tadpole showing its sucker mouth. Photo courtesy Sara Viernum.

Chemical Pollution in Your Backyard: Researching the Effects of Endocrine Disruptors in Suburbia

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We were so pleased to receive this guest post by Geoffrey Giller, who is a Master’s of Environmental Science candidate, 2013, at the Yale School of Forestry and Environmental Sciences. At Frogs Are Green, we have explored the issue of endocrine disruptors and their possible effects on frogs, as well as on humans. We look forward to learning the results of his research.

Geoffrey Giller environmental sciences Yale school

Geoff Giller readying nets for sampling at a golf course (Photo credit: Susan Bolden)

Frogs are threatened globally by a host of stressors, from habitat loss to climate change to infectious diseases. One threat receiving increased scientific attention is endocrine-disrupting chemicals (EDCs). These chemicals interfere with normal hormonal function. In 2002, Dr. Tyrone Hayes published a paper in Nature detailing the feminizing effects of the widely-used pesticide atrazine on male African clawed frogs. Since then, there has been increasing research showing similar effects of other EDCs on frogs and fish. There is also more and more evidence that endocrine disruptors are widely prevalent pollutants in the water bodies of the United States.

As a Master’s student at Yale’s School of Forestry and Environmental Studies, I want to further investigate the presence and effects of these EDCs. My advisor, Dr. David Skelly, recently published a paper showing that green frog hermaphrodites are most prevalent in suburban areas. While most research since Dr. Hayes’ paper has focused on agricultural areas, Dr. Skelly’s work indicated that there may be a significant source of EDCs causing these high rates of hermaphroditism (as demonstrated by the presence of egg cells in the gonads of male green frogs) in suburban areas.

photomicrographic frog cells

Testicular oocytes (egg cells in male gonads) from Skelly et al. 2010

This topic has implications both for frog conservation, as such sexual deformities likely inhibit frogs’ abilities to reproduce, and for human health, since suburban areas are much more densely populated than agricultural ones. But while the presence of these deformities has been confirmed, their cause has not. Dr. Skelly has hypothesized that the cause may be certain EDCs called synthetic estrogenic compounds; these chemicals are found in medications such as birth control pills as well as in some cosmetic products. The source of these chemicals would likely be septic tanks that leach chemicals into the groundwater; this contaminated groundwater then flows into nearby ponds, streams, and wetlands where frogs breed and live.

I am working with my fellow Master’s student, Max Lambert, to identify exactly what chemicals are present in the groundwater and pond water in suburban areas and what effect these chemicals are having on frogs. In collaboration with scientists at USGS, we will be installing sampling devices at 9 suburban sites, as well as three agricultural and three forested sites as comparisons. We will sample the groundwater and the pond water for a large range of chemicals including medications, synthetic estrogens, pesticides, and a host of other man-made compounds. This study will provide a list of the chemicals that may be responsible for the deformities in the frogs that we are observing.

Small Frog size of fingernail

Max Lambert with a peeper (Photo credit: Hannah Erin Bement)

In addition to the water testing, we will be surveying three types of frogs—American toads, gray tree frogs, and pickerel frogs—for similar sexual deformities. By combining the data from our water testing with the rates of deformities in frogs at these same ponds, we will be able to say which chemicals are likely causing deformities, and which are not. This information will be crucial for the future regulation of these chemicals.

The main stumbling block of this project is the cost. EDCs can have significant biological effects when present at very low concentrations; however, doing water testing for such low concentrations of chemicals requires highly specialized equipment. While some of our costs are covered by our collaboration with USGS, we still need to raise some funds. For more information on our project, and for a chance to help us out with this research, please go here: http://www.petridish.org/projects/estrogens-in-your-backyard-the-chemical-ecology-of-suburbia. This website allows researchers to raise necessary resources through “crowdfunding,” or multiple small donations from a large number of people. We are close to our target funding amount, but could use a little more help. Take a look at our page (as well as the various rewards for different donation amounts), and we would be incredibly grateful for your support!

If You Can Make It Here: New frog species discovered in NYC

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Last week’s discovery of a new frog species in New York City was one of our favorite recent amphibian news stories. The story was picked up by newspapers both across the country and worldwide, from the BBC to the News Pakistan. We especially liked the story, not only because we are both native New Yorkers, born within an hour’s drive of where this frog was discovered, but also because it was discovered by a scientist from New Jersey (our adopted state.)

So here’s the story, as reported by the New York Times and New Jersey Newsroom.com:

While doing research in Staten Island (one of New York City’s boroughs) in 2009, Jeremy A. Feinberg, a doctoral candidate in ecology and evolution at Rutgers University, heard an unusual frog call.  Instead of the “long snore” or “rapid chuckle” he would normally expect from a  leopard frog, he heard instead a short, repetitive croak. Feinberg suspected this frog might be a new species. He teamed up with Cathy Newman, a geneticist completing a master’s degree in genetics at the University of Alabama, to test the frog’s DNA.

Jeremy Feinberg

Newman compared this frog’s DNA with the DNA of southern and northern leopard frogs, which range widely north and south of New York City. These frogs look quite similar to each other, but the results indicated that this frog’s lineage was genetically distinct.

Newly discovered leopard frog in NYC. Photo by Brian Curry, Rutgers University

Feinberg believes this leopard frog once inhabited Manhattan and the other boroughs. He has found specimens in the Meadowlands and the Great Swamp National Wildlife Refuge in New Jersey, as well as in Putnam and Orange Counties in New York. Some frogs were also collected in central Connecticut.

What’s unusual about this finding is that new frog species are usually found in the remote rainforests of Indonesia and similar places, and not within the shadow of one of the world’s most densely populated urban areas.

The New York Times has asked readers to come up with a name for this new frog. They have listed some attributes of this frog to give you inspiration for a name, including the fact that the geographic center of the frog’s range is Yankee Stadium in the Bronx.

How about The Green Bomber? After all, there are Yankee fans all over the tri-state area.

More information about the discovery:

The findings are to be published in an issue of the journal Molecular Phylogenetics and Evolution, but are currently available online. Much of the genetic analysis was performed in Professor  H. Bradley Shaffer’s laboratory at the University of California at Davis, where he worked until recently.

Photo of Jeremy Feinberg, courtesy of New Jersey Newsroom.com

Listening to Frog Songs to Understand Climate Change

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At Frogs Are Green, we’ve always been interested in the interconnections between frogs and the Earth. How is climate change affecting amphibian populations? Are we listening to what frogs are telling us about the health of our planet?

Recently, we read an intriguing article in the Deccan Herald (India), about how a team of scientists in India are literally listening to frogs to understand the effect of climate change on amphibian populations.

Three scientists, K.S. Seshadri with T. Ganesh, and S. Devy, were doing research 100 feet above the ground in the canopy of the evergreen forest in the Kalakad Mundanthurai Tiger Reserve. While getting drenched with rain, they heard a cacophony of frog songs. Intrigued by the songs that the rains triggered, they initiated a program to study frog calls to both monitor populations and to study the affect of climate change on frogs.

Volunteer examines the monkey-proof enclosure for equipment to record frog calls. Photo credit: K. S. Seshadri

Amphibian Meterologists

Frogs can tell us a lot about the weather. Their skin is extremely thin and sensitive; they respond to even small changes in atmospheric moisture and temperature. The scientists reasoned that an analysis of sound recordings, combined with readings from climate data loggers, could help improve our understanding of the impact of climate change.

Climate change seems to underlie many of the threats facing frogs worldwide. By monitoring the frog calls, an activity calendar for each of the indicator species can be made. This long-term monitoring will be invaluable in understanding the greater impact of climate change and also might help to save frog species.

Work station studying frog calls, high up in the forest canopy. Photo credit K. S. Seshadri

As the Deccan Herald put it: “Will the croak alarm finally wake us from our ignorant slumber? The answer lies in the future.”

For more information:

“What Frogs Tell Us About the Planet,” Decclan Herald, India

“Frog song and climate science,” Ashoka Trust for Research in Ecology and the Environment