🔗 Share this article The Galápagos Islands Lacked Any Native Amphibians. Until Countless Numbers of Amphibians Arrived On her regular commute to the research facility, scientist Miriam San José crouches near a shallow water body surrounded by thick vegetation and collects a compact plastic audio device. The device was left there overnight to record the characteristic croaks of the Scinax quinquefasciatus, known by local scientists as an non-native species with consequences that experts are starting to comprehend. Despite abounding with remarkable animals – including centuries-old large turtles, swimming iguanas, and the famous finches that sparked Charles Darwin's evolutionary theory – the Galápagos archipelago near the shoreline of Ecuador had historically been free of frogs and toads. During the 1990s, this changed. Several small amphibians made their way from mainland Ecuador to the archipelago, probably as hitchhikers on transport vessels. The invasive species came in the 90s and have taken hold on Isabela and Santa Cruz islands. Genetic research suggest that, through time, there have been multiple unintentional arrivals to the islands, and the amphibians now have a strong foothold on two locations: Isabela and Santa Cruz. The population is growing so rapidly that scientists have been struggling to keep track, calculating populations in the millions on each island, across developed and farming areas, but also in the protected natural reserve. When the biologist tagged frogs and attempted to recapture them in the subsequent week and a half, she could find just one tagged frog occasionally, indicating their populations were enormous. They calculated 6,000 frogs in a solitary pond. "The calculations are still very low," says San José. "I'm pretty sure there are additional numbers." Acoustic Chaos and Rising Worries The amphibians' abundance is clear from the acoustic disruption they create. "The amount of frogs and the sound – it's really incredible," says San José. For the scientists, their nightly vocalizations are helpful in determining their existence in remote areas, using recorders like the one near San José's workplace. But local farmers say the sounds are so raucous they prevent sleep at night. "In the wet season, I regularly hear their calls and they're extremely loud," says a local coffee farmer from Santa Cruz. "At first it was a surprise, observing the initial frogs in the region," says Larrea Saltos, who started noticing their large numbers about three years ago when one jumped on her hand as she was walking out of her house. Environmental Consequences Stays Unclear The noise isn't the primary problem, however. While the species has been in the Galápagos for almost 30 years, scientists still know limited information about its impact on the islands' precariously balanced land and water environments. Researchers are finding out more about the amphibians, including that they can remain as tadpoles for as long as half a year. On islands, it is very common for non-native organisms to prosper, as they have few of their natural predators. The islands counts over sixteen hundred introduced types, many of which are significantly affecting the safety of its native ones. A recent research indicates the invasive amphibians are voracious bug eaters, and might be disproportionately eating rare bugs found only on the islands, or depleting the food sources of the region's rare birds, affecting the ecosystem balance. Unique Characteristics and Control Challenges The Galápagos frogs have shown some atypical traits, including living in brackish water, which is uncommon for amphibians. Their metamorphosis process is also extremely variable, with some tadpoles becoming frogs very quickly and others taking a extended period: the researcher witnessed one which remained as a tadpole in her lab for half a year. "We truly don't know this aspect," she says, concerned the larvae could be affecting the islands' freshwater, a very limited commodity in Galápagos. Additional studies is required to establish the best way to manage the frogs without harming other species. Methods to curb the amphibians in the beginning of the century were largely ineffective. Conservation officers tried capturing significant quantities by manual methods and gradually raising the salinity of lagoons in without success. Research indicates applying caffeine – which is highly toxic to amphibians – or using electrocution could help, but these methods aren't always safe for other uncommon island organisms. Without solutions to more of the fundamental questions about their biology and effect, removing the amphibians might not even be the right way to proceed, says San José. Financial Obstacles for Study While she hopes the increasing use of environmental DNA methods and genetic examination will help her group make sense of the invasive species, funding for the research has been hard to obtain. "Everyone wants to give support for preserving frogs," says San José. "But it's more difficult to find funding for an invasive frog that you might want to manage."