- Thousands of amphibians are dying in the Americas because of the lethal fungus Batrachochytrium dendrobatidis (Bd), which causes a disease called chytridiomycosis.
- Some of the most affected species are from the Atelopus genus, known as harlequin frogs, also called “jewels of the neotropics” because of their vibrant colors.
- Active since 2019, the Atelopus Survival Initiative (ASI) brings together scientists from 15 countries working to prevent the disappearance of harlequin frogs; of the 99 known species, half may already be extinct.
- Human health is also at risk: In Central America, extinction of amphibians has resulted in up to 90% more malaria cases because one of the important roles the frogs play is to control other populations, including mosquitoes.
At a conference on herpetology — the branch of zoology studying reptiles and amphibians — at the end of the 1980s, researchers from numerous countries began to tell of disappearing and shrinking frog and toad populations. It was found not to be an isolated situation: the same phenomenon was happening in many forests and mountains across the American continent.
After a number of analyses, the scientists found that thousands of amphibians were becoming victim to a lethal fungus originating in Asia called Batrachochytrium dendrobatidis, or Bd, which causes a disease called chytridiomycosis. Asian amphibians are resistant to the fungus, but not those on the other continents.
Among the many amphibian species decimated in recent decades by Bd are those in the genus Atelopus, commonly known as harlequin frogs.
Found in a region stretching from Costa Rica to Bolivia and from Ecuador to French Guiana, including the Brazilian Amazon, these frogs measure a mere 2-3 centimeters (0.8-1.2 inches) in length. Their colors, however, can only be described as showy. They are covered in some of the most vibrant found in nature — hot pink, orange, neon yellow and purple — earning themselves the moniker “jewels of the neotropics.”
“The fungus has been horrible, devastating to the Atelopus. Of the 99 species we know, four are extinct in nature and [as many as] 40 may also be extinct — most of them because of the chytridiomycosis associated with habitat destruction,” says biologist and amphibian specialist Luis Fernando Marin da Fonte.
Marin da Fonte is a Brazilian researcher and head of the Atelopus Survival Initiative (ASI), which was created in 2019 to work toward saving harlequin frogs from extinction. The unprecedented project has drawn together 57 organizations from 15 nations including Brazil. The scientists realized they would be more successful working together than separately.
“As an incredibly diverse amphibian group facing a series of threats, harlequin frogs need innovative solutions coming from a group of individuals and organizations with diverse knowledge and capacities,” says Lina Valencia, founder of ASI and co-president of the International Union for Conservation of Nature (IUCN) Amphibian Specialist Group’s Atelopus Task Force. Valencia is also coordinator of Andean nations at the North American NGO Re:wild.
Micro-endemic populations are the most vulnerable
Not only are amphibians having to deal with the highly lethal Bd fungus, their physical characteristics also make them more susceptible to changes in climate. Marin da Fonte explains that amphibians breathe through their skin and, as they have no way of regulating their body temperature, depend on the temperature of their environment to do this. “In extreme heat, mammals can perspire and reduce their metabolism to compensate for lost energy. Amphibians can’t do this, so if the temperature outside is too hot, they will probably die.”
This is why amphibians tend to live in humid places away from exposure to extreme heat. Their permeable skin is also sensitive to pollution and the presence of agrotoxins or other forms of pollution in rivers and streams.
And in the case of deforestation or other types of habitat destruction, some mammals and birds can flee to other regions. Frogs, toads and tree frogs, however, cannot, and they end up dying.
In the case of harlequin frogs, what makes these threats even more serious is that many of their species are micro-endemic, meaning some populations are so small that they are found only in one specific region. When they face threats such as chytridiomycosis, destruction of their habitat or a sudden rise in temperature, they stand a greater risk of extinction.
Most of the harlequin frog species described until today are found in Colombia, Ecuador and Peru, numbering 41, 24 and 19, respectively. But more than 75% of these species live at high altitudes, some with snowy peaks 4,500 meters (14,760 feet) above sea level.
There is some speculation that the fungus is more severe in cold climates than in hotter, more humid ones like Amazonia, where Bd has not affected the animals as much as it has in the Andes.
Fewer frogs, more malaria
Amphibians are the most threatened vertebrates on Earth. Still, they are not the animals that receive the most funding for conservation, nor are they the animals appearing in major campaigns by global environmental protection organizations. After all, not so many people think frogs are “beautiful” or “cute.”
“Mammals and birds get all the attention. They are more charismatic,” states Marin da Fonte. “And no one needs convincing that it’s important to protect a panda, a lion or a giraffe.”
This is why, aside from field research and preservation strategy planning, one of ASI’s focuses is on environmental education because society’s view of these animals needs to be transformed.
One of the first steps to reaching this goal was taken during a meeting held in Colombia last year, which gathered researchers from around Latin America. The location was carefully chosen: Colombia’s Sierra Nevada de Santa Marta where, for some still unknown reason, the harlequin frogs seem to be more resistant to Batrachochytrium dendrobatidis.
At ASI’s first meeting held in person following the COVID-19 pandemic, much material was released to engage people in the fight to protect harlequin frogs. Publications included a book in Portuguese, Spanish and English with information and illustrations on the species as well as videos and songs produced and recorded by the Colombian band Jacana Jacana.
“We chose four very endangered species from four different countries for this project: Panama, Ecuador, Colombia and Brazil. The Brazilian frog chosen was Atelopus manauensis, endemic to Manaus,” tells Pedro Peloso, biologist and researcher at the Emílio Goeldi Museum in the state of Pará and one of the professionals involved in ASI.
The scientists say it is essential that these materials reach the general public, not just the scientific community.
“We were able to reach children with the book. And the music is a much more entertaining and interesting way to tell the story than writing a scientific article or a text that will only be read by people already working to protect amphibians,” says Marin da Fonte. “And when you work with children, you overcome prejudices. The idea that frogs are disgusting and poisonous is a cultural issue that is passed from generation to generation. It’s much easier to break this paradigm with children.”
It is still unknown whether, in the long term, harlequin frogs will become immune to Batrachochytrium dendrobatidis. However, recent studies are already showing how the important role that amphibians play in controlling the populations of other animals in their ecosystems like mosquitoes is being affected.
A scientific article published in Environmental Research Letters in 2022 warned that there has been a jump in malaria cases in humans in Central America. In the eight years following the significant losses of amphibians caused by Bd, there has been an increase in the disease equal to approximately one extra case for every 1,000 people, meaning a rise from 70% to 90%.
For those needing more justification to fight for the preservation of these beautiful and rare neotropical jewels, this serves as a very worrisome one.
Banner image: An Atelopus hoogmoedi harlequin frog, native to the Northern Amazon. Populations have been found in the Guianas and the Brazilian states of Amapá and Roraima. Photo courtesy of Jaime Culebras/ASI.