🔗 Share this article The Galápagos Islands Lacked Any Native Amphibians. Then Hundreds of Thousands of Amphibians Arrived During her regular commute to the research facility, biologist the researcher crouches near a shallow water body covered by thick plants and collects a small plastic sound device. She had placed there through the night to capture the characteristic croaks of the Scinax quinquefasciatus, recognized by Galápagos scientists as an invasive species with effects that scientists are just beginning to understand. Although teeming with remarkable animals – including centuries-old large turtles, marine iguanas, and the famous finches that inspired Charles Darwin's theory of evolution – the island chain off the shoreline of South America had historically been devoid of amphibians. In the late 1990s, this shifted. Several tiny amphibians made their way from mainland the mainland to the archipelago, probably as hitchhikers on transport vessels. Fowler’s snouted tree frogs came in the 1990s and have taken hold on Isabela and Santa Cruz islands. Genetic studies indicate that, over the years, there have been multiple unintentional arrivals to the archipelago, and the frogs now have a firm presence on two locations: Isabela and Santa Cruz. The numbers is expanding so quickly that scientists have been finding it difficult to monitor, estimating numbers in the hundreds of thousands on each island, across developed and farming areas, but also in the protected Galápagos national park. When San José tagged frogs and attempted to recapture them in the following week and a half, she could find just one tagged frog from time to time, suggesting their populations were enormous. They calculated 6,000 frogs in a solitary pond. "Our estimates are still very low," says the researcher. "I am quite certain there are even more." Acoustic Chaos and Rising Worries The amphibians' abundance is clear from the sound disruption they create. "The number of frogs and the noise – it's truly insane," says the scientist. For the researchers, their nightly vocalizations are useful in determining their existence in remote areas, using recorders like the one near the workplace. But local farmers say the calls are so loud they keep them up at night. "During the rainy period, I regularly hear their croaks and they're extremely loud," says a local coffee farmer from Santa Cruz. "At first it was a shock, observing the first frogs in the area," says Larrea Saltos, who started noticing their large numbers about three years ago when one leaped on her hand as she was stepping out of her house. Ecological Impact Remains Unclear The sound isn't the primary problem, though. While the amphibians has been in the islands for almost 30 years, experts still know very little about its effect on the islands' precariously balanced terrestrial and aquatic environments. Researchers are finding out more about the amphibians, including that they can remain as tadpoles for as long as six months. On islands, it is very typical for non-native organisms to thrive, as they have none of their enemies. The Galápagos counts 1,645 introduced species, many of which are significantly affecting the safety of its endemic ones. A recent research indicates the invasive amphibians are hungry bug eaters, and might be disproportionately consuming rare insects found only on the islands, or reducing the nutrition of the region's rare avian species, affecting the food chain. Unusual Traits and Management Difficulties The Galápagos frogs have exhibited some atypical traits, including surviving in slightly salty water, which is rare for amphibians. Their metamorphosis process is also highly inconsistent, with some larvae turning into frogs very quickly and others taking a long time: San José witnessed one which remained as a larva in her lab for six months. "We truly don't know this aspect," she says, worried the tadpoles could be impacting the islands' clean water, a very limited commodity in Galápagos. More research is required to establish the optimal way to control the frogs without harming other organisms. Techniques to curb the amphibians in the beginning of the century were mostly ineffective. Conservation officers tried capturing large numbers by hand and slowly increasing the salinity of lagoons in vain. Studies indicates spraying coffee – which is extremely poisonous to amphibians – or using electrical methods could help, but these methods aren't always safe for other rare Galápagos organisms. Without answers to more of the basic issues about their lifestyle and effect, removing the amphibians might not even be the correct way to proceed, says the biologist. Financial Obstacles for Study While she hopes the increasing use of environmental DNA techniques and genetic analysis will help her team understand of the invader, funding for the research has been difficult to come by. "Everyone wants to give funding for preserving frogs," says the researcher. "But it's more difficult to find financial backing for an introduced frog that you might want to control."