Double Whammy: Snake carries killer fungus

blunt-headed tree snake

Researchers recently confirmed that the fungus causing the lethal disease chytridiomycosis is present on nonamphibian carriers, such as this blunt-headed tree snake, in natural environments. (Photo courtesy of STRI)

The blunt-headed tree snake (Imantodes cenchoa) not only eats frogs and their eggs, it also carries the killer fungus that has wiped out more than 100 amphibian species worldwide.

A new study by Vanessa Kilburn and David Green from Canada’s McGill University with the Smithsonian Tropical Research Institute’s Roberto Ibáñez, in-country director of the Panama Amphibian Rescue and Conservation Project, confirms for the first time that the fungus causing the lethal disease chytridiomycosis is present on nonamphibian carriers in natural environments.

The team surveyed 13 species of lizards and 8 species of snakes from sites across Panama using a genetic test to identify fungal DNA in samples taken from the reptiles’ skin with a cotton swab. They found evidence of the disease on up to 32 percent of lizards (Anolis humilis) and on three different species of snakes.

The irony of a frog-eating snake that carries a killer frog disease is that it may eliminate its own food supply, leading to its own demise.

Beth King, Smithsonian Tropical Research Institute

Conserving Frogs and Identifying an Invader in Panama

A group of researchers at the Smithsonian Tropical Research Institute confirmed this frog's identity as the "greenhouse frog," Eleutherodactylus planirostris. (Photo courtesy of STRI)

A team of dedicated amphibian caretakers, volunteers and Smithsonian scientists assembled their field gear, chytrid swab kits and swamp boots. Preparation was imperative for the week-long field expedition to the remote tropical rainforest in the Darien Province of eastern Panama. The team’s intention was to survey the site, still relatively untouched by fungal amphibian disease, and to collect individuals of species targeted for conservation at the captive rearing and breeding facility at the Smithsonian Tropical Research Institute (STRI). As had been the case in the last expeditions to these little-studied places, there was also a high probability of finding new species.

But storms made it impossible to land a plane at the site, so the trip was canceled. Disappointed, the team went back to work at the captive-breeding facility.

At the same time, another group of researchers at STRI identified another species of frog. Instead of being “new” to biology, this was an invader, native to the islands of the Caribbean, but new to Panama. In late 2008, herpetologists heard unusual calls in the gardens of suburban Panama City. A lack of local knowledge and individuals for comparison made definite identification difficult at first, so a genetic technique called DNA barcoding was employed to finally confirm the frogs’ identity as the “greenhouse frog,” Eleutherodactylus planirostris. Since then, many more individuals have been collected, confirming their presence.

DNA barcoding complements the more traditional techniques of identifying species based on body shape and size. Barcoding uses standardized snippets of mitochondrial genes that vary between species but not within individuals of the same species. DNA from the greenhouse frog was compared to sequences available in large worldwide databases like GenBank, kind of like matching the picture of a criminal to one of the faces in a line-up of suspects.

In 2010, a group of scientists working at STRI published a paper on amphibian diversity established using DNA barcoding. The paper and study came in the wake of massive frog species die-offs in central Panama caused by the fungal disease chytridiomycosis. “This is the first time that we’ve used genetic barcodes—DNA sequences unique to a given species—to characterize an entire amphibian community,” said Eldredge Bermingham, STRI director and co-author. “STRI has also done barcoding on this scale for tropical trees on in our forest dynamics-monitoring plot in Panama. The before-and-after approach we took with the frogs tells us exactly what was lost to this deadly disease in this area—33 percent of their evolutionary history.”

Applying a technique like barcoding in new places results in new knowledge and also raises many more questions than it answers.  What will the effect of the loss of so many frog species be on the insects that the frogs ate and on the snakes and birds that ate the frogs?  How did an invasive frog species arrive in Panama City from the Caribbean?  More updates soon….from Panama!

–Charlie Hruska, Columbia University and Panama Amphibian Rescue and Conservation Project volunteer

Q&A with Dr. Eric Baitchman: Through a vet’s eyes

Dr. Eric Baitchman

Dr. Eric Baitchman of Zoo New England treats a frog for the deadly chytrid fungus. (Photo courtesy of Zoo New England)

Dr. Eric Baitchman, Zoo New England director of Veterinary Services, is the lead veterinarian for the Panama Amphibian Rescue and Conservation Project. We spent some time talking to Dr. Baitchman about his interest in amphibians and what he has learned from his participation in this vital conservation project. Here’s what he told us:

When did you first develop an interest in amphibians? What sparked this interest?

I can’t really say when or what it was that sparked my interest in amphibians. I’ve always been drawn to their diversity of shape, colors and habits, as well as to the types of environments that amphibians usually occupy. Amphibian life histories are fascinating as well, spending the first part of their lives in the water as tadpoles, undergoing metamorphosis, and then growing in to terrestrial adults–no other vertebrate undergoes such dramatic changes in their life cycle.

What has been the most rewarding aspect about your participation in the Panama Amphibian Rescue and Conservation Project?

The work with the rescue project is truthfully a culmination of every reason I became a veterinarian in the first place. It is most rewarding to me to apply my skills as a veterinarian to make a meaningful impact on the conservation of entire species. The individual animals we care for in the rescue project represent what may amount to the last survivors for each of their species, entrusted in our care to assure their continued existence on this planet. I can’t imagine how anyone could find more reward from their work than that!

Has your work in Panama affected your veterinary approach at Zoo New England?

I have learned a great deal about amphibian medicine and their normal physiology through my work in Panama. Virtually everything I’ve learned there, I’ve been able to apply at home when caring for the amphibians in our own collection at Zoo New England, as well as advising other zoos on amphibian medicine through my role as an amphibian veterinary advisor for institutions accredited by the Association of Zoos and Aquariums.

If there is one thing that people should know about amphibians, what is it?

Unfortunately, people should know the danger amphibians are in all over the world. Amphibians everywhere are declining at alarming rates–so much so, that not since the extinction of the dinosaurs has there been this great a loss of species from a single taxon of animals.

What are simple things that people can do to help improve the lives of amphibians in the wild, including those in their own backyard?

There are many ways that you can make a difference and help improve the lives of amphibians. Here are some simple ways that everyone can help: recycle to keep waterways clean; use biodegradable and other “green” cleaning products to keep phosphates and other chemicals out of the water; keep chemicals out of water run-off by not fertilizing your grass or using pesticides; be mindful of your water use, especially in the summer when there is a higher risk of droughts (shallow water is more concentrated in pollutants than free-running water); and don’t put anything down a storm drain as it usually drains directly to a river or pond.

Brooke Wardrop, Zoo New England

Mission Critical: Amphibian Rescue

Toad Mountain harlequin frog (Atelopus certus)

The Smithsonian Channel documentary follows as three rescue project scientists search for the vanishing Toad Mountain harlequin frog. (Photo by Brian Gratwicke, Smithsonian Conservation Biology Institute)

We’re excited to announce that next week “Mission Critical: Amphibian Rescue” will be airing for the first time on the Smithsonian Channel! The documentary follows three of the project’s frog rescuers, Brian Gratwicke, Edgardo Griffith and Bob Chastain, into the Panamanian rain forest to collect the vanishing Toad mountain harlequin frog (Atelopus certus). Their adventure—including their triumphs and challenges—are captured on film, in addition to the promising recent developments in finding a cure for the deadly chytrid fungus.

The documentary will air on Smithsonian Channel at 8 pm (eastern) on Wednesday, Oct. 12. For information and a preview, check out the Smithsonian Channel’s website.

In addition, the Smithsonian’s National Zoo will be hosting a premiere for the documentary in its Visitors’ Center on Tuesday, Oct. 11. The reception starts at 6 p.m. and the movie will air at 7 p.m. and will be followed by a lively panel discussion with the stars of the documentary! Attendees will also have a chance to participate in an auction that includes frog artwork, books and more! If you live in the D.C. area and are interested in attending, please email Lindsay Renick Mayer at renickmayerl@si.edu.

And a big thanks to Black Dinah Chocolaters for supplying delicious treats!

Q & A with Dr. Vance Vredenburg: Chytrid in Asia

Chytrid study

Dr. Vance Vredenburg swabs frogs to test for chytrid. (Photo courtesy of Vance Vredenburg, San Francisco University)

A new study published on Aug. 16 in the journal PLoS ONE found that Batrachochytrium dendrobatidis (Bd), the fungus that causes chytridiomycosis, is indeed present in Asia, but at significantly lower levels than anywhere else in the world. In fact, researchers found that just more than two percent of the individuals they tested were positive and that the fungus was present only in the Philippines, Kyrgyzstan, Laos, Indonesia, Malaysia and South Korea. Now scientists want to know why.

An international research team conducted this study between 2001 and 2009, examining more than 3,000 amphibians, most of which were frogs, from 15 Asian countries. It was the first large-scale investigation of the disease conducted in Asia.

We spoke with Dr. Vance Vredenburg of San Francisco University, one of the researchers from the study and a leading expert in this disease. Here’s what he had to say:

1)  This was the first comprehensive survey of chytrid in Asia. Why do you think this hasn’t been done before?

I think expense is probably a huge hindrance on research. Our study was conducted in 15 countries and our data was collected by a large number of field personnel. The cost of analyzing the samples is not cheap–costs range from $5 to $30 per sample, depending on where and how they are analyzed. We ran nearly 3,500 samples.

2)    What do your findings mean in the battle against chytrid, and what is your next step?

Our findings provide an important milestone because they are the first broad survey for Bd across a vast continent that harbors a large amount of amphibian diversity. Our hope is that researchers will now be able to return to many of these sites and see if the dynamics of the pathogen host system change and if so, in what direction. Our next step will be to follow up on as many sites as possible.

3)    Were you surprised by the findings? Why or why not?

Yes. I was surprised by how low the prevalence was across what appears to be such perfect habitat for this pathogen.

Hylarana similis

This frog, Hylarana similis, is native to the Phillipines and is a species now infected by chytrid. (Photo courtesy of Rafe M. Brown, University of Kansas)

4)   Why do you think that frogs in Asia aren’t being wiped out at the same rate as frogs in the neotropics?

There are only a few possibilities. We describe them in detail in the discussion [in the paper], but in short, either Bd is only just emerging in Asia and thus we haven’t seen mass die-offs due to chytridiomycosis yet, or it is endemic and there are either abiotic or biotic influences holding the pathogen at bay. We still don’t have the answer to this.

5)   If this outbreak in Asia is relatively recent, where did it originate on the continent?

We discovered one–and only one–place out of 300 sites where an outbreak may be occurring, at a site in the Philippines.

6)   The Philippines are a series of Islands. If you believe there is or is going to be an outbreak there, how did it get there and how can it spread to other places in the world?

We propose that human trade is involved, specifically that farms raising American bullfrogs could be the source of Bd that could then spread to wild frogs [if some escape]. We don’t know where it originated or how it spread for sure.

7)   Are there Asian amphibians other than frogs that appear to be affected by chytrid?

Asia has a rich fauna of both salamander and caecilians, but to date we do not know if they are affected by Bd. Our study did not sample caecilians and includes only a small number of salamanders.

8)   A few amphibian species, such as bullfrogs, are said to be carriers of Bd, but rarely seem to die from it. What exactly allows a species to be a “carrier,” or is there still not enough information known about that?

We don’t yet know how bullfrogs (Rana catesbeiana) are able to survive Bd infections without showing symptoms of chytridiomycosis.

9)   Do you believe that these Asian frogs that seem to be less affected may be carriers as well?

 We need more information to assess this. My guess is that there are probably some species that can sustain infections just like American bullfrogs and could act as carriers.

10)  What other threats do frogs in Asia face and what is being done to address those threats?

 The two major threats in Asia are habitat destruction and hunting and gathering amphibians to eat.

Sara Bloom Leeds, Smithsonian’s National Zoo

The Fascinating Wyoming Toad

Wyoming toads

At around six weeks, the toadlets look like miniature (half-inch) versions of the adults. (Courtesy of Cheyenne Mountain Zoo)

A North American toad is fighting its own battle with chytrid, a battle just as devastating as the one frogs in Panama are facing. The Wyoming toad (Anaxyrus baxteri) is one of the most endangered anurans (frog or toad) in North America. Historically, they were found in the Laramie Basin of southern Wyoming. Up until the mid 1970s, they were common throughout this region, but since then, the population drastically declined. Major threats are loss of habitat, pesticide usage and chytrid fungus. In 1994, the last wild toads were rescued from extinction when they were collected and sent to a captive breeding facility. One day, their tadpoles could be released back into the wild, thanks to Cheyenne Mountain Zoo (CMZ), and other zoos and federal facilities now breeding Wyoming toads.

The CMZ Amphibian Propagation and Research Center is a bio-secure area and closed to zoo guests to help keep chytrid fungus and other diseases out of the breeding population. CMZ’s Wyoming toad population for 2011 consists of 17 males and 17 females. However, due to limited space for tadpoles, not all of the toads are bred each year. The Wyoming toad studbook keeper and population manager determine what the best matches are to maximize and maintain genetic diversity. CMZ also monitors the overall health of each toad and decides whether they are fit for reproduction.

During most of the year, CMZ’s goal is to keep the toads healthy and growing with exceptional water quality, properly supplemented feeder insects and regularly changed UV bulbs. As spring approaches, we confirm our recommended pairings and prepare for something somewhat disconcerting for an animal keeper–we have to chill our toads in the refrigerator! In order for them to breed successfully, the toads require a period of cool hibernation as would be experienced in the wild. This is a very delicate time for them because their immune systems are suppressed.

Amphibian Propagation Center

Cheyenne Mountain Zoo's Wyoming toad room in the Amphibian Propagation Center. (Courtesy of Cheyenne Mountain Zoo)

A few days prior to hibernating, the toads are not given food. As their metabolism slows, so does their digestive tract, and undigested food could make them sick. Their room is slightly cooled from 75 degrees to 65 degrees and the lights are turned off the day before entering the hibernaculum, which is basically a fancy refrigerator. Each tank of toads has its own tub filled with wet gravel, carbon, sand and moss. The toads are weighed, placed in the tubs and the temperature is set to 52 degrees. The next day, it’s turned down to 45 degrees, the following day to 41 degrees and finally, down t

o a chilly 38 degrees. The toads will remain at this temperature for 35 days, misted with chilled water to maintain humidity and checked on about twice a week. We have to limit the number of checks to reduce the amount of environmental disturbance.

After 35 days, the toads are slowly warmed up in reverse order of the cool down. It’s believed the hibernation helps produce the natural hormones that would trigger reproductive behavior in the wild. The toads are placed back in their normal husbandry tanks and offered a few insects. They should be ready for breeding the next day.

Many species of amphibians are not able to be bred in a captive environment. For the Wyoming toad, it was discovered they require supplemental hormones in addition to hibernation in order to reproduce. The females are given their first hormone injection in the morning and placed in a breeding tank. Six hours later, the males are given a hormone injection and the females their second. The breeding tank has about one-and-a-half inches of water and some plastic floating plants. A recording of Wyoming toad breeding calls is played for 24 hours while the pairs are together. (Hear a sample of the Wyoming toad call) By the next morning, the female should have hopefully produced eggs fertilized by the male.

On June 1, 2011, six pairs of Wyoming toads were placed together at CMZ, and all of them produced eggs! Unfortunately, two of the egg masses were infertile, but in total, CMZ had about 2,000 tadpoles. 1,792 of them were released back into the wild in Wyoming. Based on valuable genetics, CMZ held back 60 tadpoles for future breeding.

Wyoming toad

A Wyoming toad in the wild. (Courtesy of Cheyenne Mountain Zoo)

Each year, staff from CMZ, other zoos and U.S. Fish and Wildlife Service survey Mortenson National Wildlife Refuge for offspring from previous released Wyoming toads. This is a non-public access refuge, and reintroductions were stopped at this site in 2005 due to chytrid. The site allows us to see if the population could continue even though chytrid was present. Tadpoles are now released at a different location, which prevents us from confusing recently released animals with those naturally produced in the wild.

Length, relative size, weight, habitat conditions, temperature and wind speed are just some of the data recorded during the survey. Most importantly, though, is collecting a swabbed sample from each found toad to see if chytrid is present. The toads are also given a microchip under their skin for permanent identification, enabling us to know how many different toads are found. If a microchipped toad is caught again, a scanner will tell us.

Cheyenne Mountain Zoo is very proud to be an important participant in the Wyoming toad recovery program!

Jeff Baughman, Conservation Center keeper, Cheyenne Mountain Zoo

Mamoni Valley: A Rescue Mission

It isn’t every day that one gets to travel to the heart of one of Panama’s richest rain forests on a rescue mission to save some of Panama’s most endangered amphibians. A brief two-hour drive from Panama City brought us to a facility run by Earth Train called the Mamoni Valley. I was lucky enough to be able to shadow leading herpetologists, Brian Gratwicke and Roberto Ibáñez, on one of their field expeditions to rescue endangered frogs.

One of the main objectives for our expedition to Mamoni Valley was to rescue a rapidly declining harlequin frog called Atelopus limosus and to launch the Global Amphibian Bioblitz, a citizen-science initiative to document as many amphibian species on the planet as possible. Hours of sweaty hiking up and down a mountain track in the dark brought us to a cool, clear stream where we began our search for frogs. After studying each passing leaf fruitlessly, and slipping and falling in the stream a few times, I found myself impressed at how much skill and patience it actually takes to capture frogs. But the numerous hours of careful searching in the streams both day and night turned out to be well worth the effort because we found some beautiful Atelopus limosus along with 13 other species of glass frogs, poison dart frogs, toads, rocket frogs and some spectacular snakes. We bagged each frog we collected and swabbed them individually. Each swab will be tested for the deadly amphibian chytrid fungus back at the Smithsonian Tropical Research Institute lab.

Each day when we returned from our 5-6 hour expeditions, there was always a feeling of success in the air, because we did find few Atelopus limosus, but it was always slightly reserved. Although I thought the number of frogs we had collected was fantastic, I learned quickly that the team had encountered many more frogs on previous visits to the site. It was extremely sobering for me to look at the worried faces of the experts sitting next to me as they explained that at current rates of decline it would be unlikely that we would find any more Atelopus limosus next year, and that I was in a very privileged position of being able to see a rapidly declining species in the wild, because few people will ever have that opportunity again.

This Amphibian Rescue Mission to Mamoni Valley not only taught me a great deal about the grave dangers that many amphibians face, but it also gave new perspective on how important it is to save these beautiful, endangered frogs before it’s too late. If you would like to help the global amphibian effort – try to mount your own amphibian expedition to a nearby park or pond and then share your photos on the Global Amphibian Blitz website!

Meryl Monfort is a volunteer for the Panama Amphibian Rescue and Conservation Project and is working on developing education and outreach for the project.

Chytrid spreading fast and furiously

This week we broke the news that chytridiomycosis, a rapidly spreading amphibian disease, has reached a site near Panama’s Darien region, leaving us little time to save the species there at risk of extinction. Here’s an updated map of how the pathogen is moving through the neotropics:

Chytrid spread
Chytridiomycosis has been linked to dramatic population declines or even extinctions of amphibian species worldwide. Within five months of arriving at El Cope in western Panama, chytridiomychosis extirpated 50 percent of the frog species and 80 percent of individuals.

Conservationists have been fretting for years about what might happen to Eastern Panama’s 120-odd amphibian species when chytrid hits. Chytrid is a disease that cannot tolerate extremely hot temperatures, so it tends to be most devastating in cooler mountainous regions of the tropics that remain cool and moist year-round. The mountainous regions of Eastern Panama are one of the last remaining strongholds of naïve amphibian populations in the New World, and species that tend to have a highland distribution and small ranges are the most vulnerable to extinction.

Press release: Smithsonian Scientists Find Deadly Amphibian Disease in the Last Disease-free Region of Central America

Toad Mountain harlequin frog (Atelopus certus)

The Panama Amphibian Rescue and Conservation Project has established an assurance colony for two species endemic to the Darien, including the Toad Mountain harlequin frog (Atelopus certus), shown here. (Brian Gratwicke, Smithsonian Conservation Biology Institute)

Smithsonian scientists have confirmed that chytridiomycosis, a rapidly spreading amphibian disease, has reached a site near Panama’s Darien region. This was the last area in the entire mountainous neotropics to be free of the disease. This is troubling news for the Panama Amphibian Rescue and Conservation Project, a consortium of nine U.S. and Panamanian institutions that aims to rescue 20 species of frogs in imminent danger of extinction.

Chytridiomycosis has been linked to dramatic population declines or even extinctions of amphibian species worldwide. Within five months of arriving at El Cope in western Panama, chytridiomychosis extirpated 50 percent of the frog species and 80 percent of individuals.

“We would like to save all of the species in the Darien, but there isn’t time to do that now,” said Brian Gratwicke, biologist at the Smithsonian Conservation Biology Institute and international coordinator for the Panama Amphibian Rescue and Conservation Project. “Our project is one of a few to take an active stance against the probable extinction of these species. We have already succeeded in breeding three species in captivity. Time may be running out, but we are looking for more resources to take advantage of the time that remains.”

The Darien National Park is a World Heritage site and represents one of Central America’s largest remaining wilderness areas. In 2007, Doug Woodhams, a research associate at the Smithsonian Tropical Research Institute, tested 49 frogs at a site bordering the Darien. At that time, none tested positive for the disease. In January 2010, however, Woodhams found that 2 percent of the 93 frogs he tested were infected.

“Finding chytridiomycosis on frogs at a site bordering the Darien happened much sooner than anyone predicted,” Woodhams said. “The unrelenting and extremely fast-paced spread of this fungus is alarming.”

The Panama Amphibian Rescue and Conservation Project has already established captive assurance colonies in Panama of two priority species endemic to the Darien—the Pirre harlequin frog (Atelopus glyphus) and the Toad Mountain harlequin frog (A. certus). In addition, the Smithsonian’s National Zoo maintains an active breeding program for the Panamanian golden frog, which is Panama’s national animal. The Panamanian golden frog is critically endangered, according to the International Union for Conservation of Nature, and researchers have not seen them in the wild since 2008.

Bd infection

Chytridiomycosis is a rapidly spreading amphibian disease that attacks the skin cells of amphibians (shown here) and is wiping out frog species worldwide. (Doug Woodhams, Smithsonian Tropical Research Institute)

“We would like to be moving faster to build capacity,” Gratwicke said. “One of our major hurdles is fundraising to build a facility to house these frogs. Until we jump that hurdle, we’re limited in our capacity to take in additional species.”

Nearly one-third of the world’s amphibian species are at risk of extinction. While the global amphibian crisis is the result of habitat loss, climate change and pollution, chytridiomycosis is at least partly responsible for the disappearances of 94 of the 120 frog species thought to have gone extinct since 1980.

“These animals that we are breeding in captivity will buy us some time as we find a way to control this disease in the wild and mitigate the threat directly,” said Woodhams, who was the lead author of a whitepaper Mitigating Amphibian Disease: strategies to maintain wild populations and control chytridiomycosis. This paper, published in Frontiers in Zoology, systematically reviews disease-control tools from other fields and examines how they might be deployed to fight chytrid in the wild. One particularly exciting lead in the effort to find a cure is that anti-chytrid bacteria living on frog skin may have probiotics properties that protect their amphibian host from chytrid by secreting anti-fungal chemicals. Woodhams recently discovered that some Panamanian species with anti-chytrid skin bacteria transmit beneficial skin chemicals and bacteria to their offspring. The paper, Social Immunity in Amphibians: Evidence for Vertical Transmission of Innate Defenses, was published in Biotropica in May.

“We are all working around the clock to find a cure,” Gratwicke said. “Woodhams’ discovery that defenses can indeed be transferred from parent to offspring gives us hope that if we are successful at developing a cure in the lab, we may find a way to use it to save wild amphibians.”

The Smithsonian Conservation Biology Institute serves as an umbrella for the Smithsonian Institution’s global effort to understand and conserve species and train future generations of conservationists. Headquartered in Front Royal, Va., SCBI facilitates and promotes research programs based at Front Royal, the National Zoo in Washington, D.C., and at field research stations and training sites worldwide.

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Media only: contact Lindsay Renick Mayer, Smithsonian’s National Zoo, 202-633-3081