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Amazon, Ecuador

Glass Frogs Reveal the Crisis of Informal Mining in Ecuador

Like a crystal ball, gaze into the body of a glass frog and you just might get a glimpse of a monster that’s threatening the Ecuadorian Amazon: informal gold mining.

Glass frogs (Centrolenidae family) are tree-dwelling amphibians from South and Central America. Their skin is translucent, which means you can see through to their digestive and circulatory systems just by looking at their bellies.

Talag, a parish of Tena in Napo, an Amazonian province six hours from Quito, is where this story unfolds. In Napo, the signs of gold mining are everywhere. Enter the provincial capital, and you’ll see more than 100 excavators, which were seized from informal miners, deteriorating out in the open. Move into the urban area, and you’ll find the precious metal traded for $42 per gram. Above all, travel about 20 minutes from Tena, where gold flows through the waters of the Jatunyacu River, and you’ll be met by dozens of pits from mining activity on the riverbank, the result of mechanical arms and vibrating filtering machines called "zetas."

Mining activity in Napo has jumped by 300% since 2015, according to research published the Monitoring of the Andean Amazon Project (MAAP) in March 2023. Informal mining in particular grew since the start of the COVID-19 pandemic. The causes of this increase include the weakness of state environmental controls and a lack of transparency. 

This state of affairs was particularly noticeable between November 2020 and February 2021, when more than 2,000 gold panners began to dig up the earth in plain sight of the authorities, who only intervened after 104 days, seizing the machinery and closing the entrance to an area called "La Isla." The combined operations of security forces stopped the work of the informal miners, who moved on to other locations.

Among the environmental consequences of the mining, according to MAAP, is the fact that along the Yutzupino river, the drinking water for 25 communities is contaminated with mercury, cadmium, lead, zinc and arsenic, representing a grave threat to their health.
Against this backdrop of gold mining, the glass frog does its best to survive. Sixty-five of the 164 cataloged species of the Centrolenidae family live in Ecuador, and of them, at least 10 are critically endangered, especially those in the north of the country and the Amazon.

The translucency of the glass frog’s skin helps give the creature camouflage against its main predators such as snakes, owls and bird of prey, according to an analysis published in the journal Proceedings of the National Academy of Sciences (PNAS).

Among glass frogs, a subfamily of 37 members called Hyalinobatrachinae stands out, and in that group is a very special one: the Hyalinobatrachium yaku frog. That’s because their skin is so transparent that you can see its heart pumping blood to the rest of its body. The Hyalinobatrachium yaku frog lives in Napo and Orellana in the Amazon. Its name comes from its close relationship with water: “yaku” in Kichwa means water.

Its cataloging has been a complex task. It is not listed as an endangered species due to lack of data on its geographical distribution and population size. Even the huilli-huillis (“tadpoles” in Kichwa) are a mystery. What is known is that their young grow and develop entirely in the water and to do so, rivers and waterfalls must be pristine. (Remember: Frogs breathe through their skin.)

Juan Manuel Guayasamín is a biologist and research professor at the San Francisco University of Quito (USFQ) who, along with other scientists, christened this species in the 1990s. The first specimens were found in Ahuano-Napo, 40 minutes from Talag.


Interview with Juan Manuel Guayasamín


In his article "A Marvelous New Glassfrog," published in 2017 in the journal ZooKeys, he wrote: "The new species, Hyalinobatrachium yaku sp. n., is differentiated from all other congenerics by having small, middorsal, dark green spots on the head and dorsum, a transparent pericardium, and a tonal call that lasts 0.27–0.4 s, with a dominant frequency of 5219.3–5329.6 Hz.”  

The environmental threats that H. yaku faces include the destruction and/or pollution of its habitat due to mining and oil activities. Oil exploitation in Ecuador is centered in the provinces of Orellana and Sucumbíos, while mining is found in Napo.

In search of this glass creature

Our team — a journalist and photographer — endeavored to find the glass frog in its habitat. Days before, the biologist had told us that the search would be a fascinating experience, and he was not wrong at all.

"Glass frog? Yes, I've heard of it," said Juanito Alvarado, a Kichwa guide who met us in Talag. At the beginning of April 2023, we walked towards Dumbiki Wasi (The House of the Toucan), an eco-tourism business. The Talag river welcomed us. This body of water, about 20 meters wide, separated us from the jungle.


In the above interview, Juan Alvarado talks about his work as tourist guide in a jungle surrounded by mining


Donning rubber boots, we walked nearly 4 kilometers. The area boasts more than 14 waterfalls where frogs tend to hide.

The path was filled tangled roots. Our caravan was tiny compared to the army of leaf-cutter ants.

At night, we turned on our microphones and opened up our ears, and we were instantly amazed: A massive choir of birds, toads, monkeys and harpy eagles filled the air with song.

And as dawn broke, we heard the sound we had waited for: a sharp whistle. Below, compare the audio that we recorded during our expedition with audio from a 2016 expedition that Guayasamín participated in:


Sounds of the glass frog in Talag from April 2023.

Sounds of the glass frog in Ahuano-Napo in 2016.


We lit up the spot with our lanterns and searched along the edge of the river, peering at the underside of leaves where the males tend to perch and sing, as we had been instructed to do at the Jambatu Amphibian Research and Conservation Center in Quito during a previous visit. We located harlequin frogs, one of the most endangered groups in the world. H. yaku was in the area, although we didn’t get the shot we so longed to take with our cameras.

Early in the morning, Alvarado led us to an area of high ground, where we trekked 10 kilometers. The green expanse stretched as far as the eye could see, but the jungle canopy was peppered with holes. "It's the mining," he said.

In 2018, the presence of gold attracted the first mining operations, both informal and those conducted by Chinese transnational companies. The suspicion that the entire area was sitting on gold deposits triggered the rush in 2020 and 2021.

Miners used backhoes to dig pits up to 10 meters deep. The earth that has been removed was then processed through "zetas," which classify stony materials using water pressure.

Mercury is used in the final stage of the process to form a blend known as "golden sponges," which is then stored in a deposit called "the box," which the miners guard with their life (literally).

The heavy metal used in Napo comes from Peru and costs 300 dollars for a 2,500-milliliter bottle, says Pepe Moreno. "An informal miner uses at least one bottle per day," he added.

According to data from the Mining Control Agency, it takes 5 grams of mercury to have one of gold. "It also requires moving 6 tons of earth and more than 1,000 liters of water," Moreno calculated.

In Napo, almost a kilogram of gold is produced daily by informal methods as well as by the more than 43 mining concessions that the government has granted in the area, according to a November 2022 article from the national news site Primicias.

The organization Napo Resiste, which translates to “Napo Resists,” calculated that the more than 2,000 panners extracted between 6 and 8 grams of gold per person per day over the course of those 104 days, which would represent about 13 million dollars. "And the worst thing is that the communities aren’t seeing any benefit — a road, a school, people are just leaving," Moreno insisted.

"The Island" is now part of the concession granted to the Chinese company Terraearth. Informal mining activity has extended to the mountain range that connects with the Sardinas, Pioculín and Sapallo rivers, Moreno said, all of which surround the Talag parish, where areas to wash minerals have also appeared.

The glass frog is flanked by mining. After two days of searching, we returned home. H. yaku had stayed hidden in the canopy, but our guide promised to keep looking. 

Almost a month later, we received a photo of the upper part of the inside of a cave, where you could see a transparent bag full of eggs.

"They’re glass frog eggs," Guayasamín confirmed. In early July, we returned to Napo, this time to the vicinity of the Cotundo parish, 18 kilometers from Tena. There, we explored a long slope that ended in a waterfall, bathing the rocks below. After an hour, we found two bags of crystalline eggs full of tadpoles and, just 30 centimeters away in the mud, a glass frog.

Scientists Guayasamín and Andrea Terán, from the Jambatu Center, confirmed that it was a specimen of Rulyrana flavopunctata. We didn't find H. yaku, but we did find a close cousin. A cousin that, according to the Bioweb page of the Catholic University of Ecuador, suffers from a lack of studies of its populations.

The Amazon's glass frog continues to reproduce. It is urgent that new journalists and scientists publicize the threats they face.

In 2018, the World Wildlife Fund (WWF) determined in the document "Healthy Rivers, Healthy People" that “mercury pollution is irreversible and difficult to contain (...), it can cause significant damage in terms of neurological and developmental aspects in different species."

By 2020, threats to the survival of harlequin and nurse frogs, which are endangered, were the main argument in the legal battle against large-scale mining in Llurimagua in the Toisán mountain range (North Sierra-Imbabura). On that occasion, Ecuadorian environmental organizations determined that a change in the PH level in the water generates abnormalities in tadpoles and "a progressive reduction in the richness, diversity and abundance of amphibians."

There is still no specific study on the effects of mercury on glass frogs in Ecuador, Terán said. Glass frogs, these transparent wonders, cling to life in waterfalls and rivers, despite everything and everyone.

Some trivia about a peculiar frog

  • A study published in the journal Science mentions that glass frogs can concentrate blood in their liver during the day. How they can do this without generating clots is being studied.
  • The biologist Guayasamín was the one who gave the genus Sachatamia its name, which means forest and rain in Kichwa.
  • Gold, one of the threats to this species, has also made its way into the scientific name of a frog: Hyalinobatrachium aureoguttatum.
  • Sometimes, the frog’s name comes from the location where its found, such as Hyalinobatrachium guairarepanense, which lives in the Coast Mountain Range (Venezuela).
  • In the case of the species called Laura's Glassfrog, its name refers to the scientist Diego Cisneros Heredia's grandmother. No better tribute than that.
  • Nymphargus colomai was named in recognition of scientist Luis Coloma, director of the Jambatu Center.

Read the original Spanish-language story here.

This story was produced with support from the Earth Journalism Network. It was first published in Radio Pichincha on July 17, 2023. It has been lightly edited for length and clarity.

Banner image: Glass frog in the forest /  Credit: Angélica Mendoza.