🔗 Share this article The Galápagos Islands Had No Indigenous Amphibians. Until Countless Numbers of Amphibians Invaded On her daily walk to the research facility, biologist the researcher stoops near a small pond surrounded by thick plants and retrieves a small plastic sound recorder. The device was left there overnight to record the characteristic calls of the Scinax quinquefasciatus, known by local scientists as an non-native threat with effects that experts are starting to comprehend. Despite abounding with unique animals – including ancient giant tortoises, swimming lizards, and the well-known birds that sparked Darwin's theory of evolution – the island chain off the coast of Ecuador had long remained free of amphibians. In the late 1990s, this changed. Several small tree frogs traveled from continental Ecuador to the islands, probably as hitchhikers on transport vessels. The invasive species came in the 90s and have taken hold on multiple Galápagos islands. Genetic research suggest that, through time, there have been multiple accidental arrivals to the archipelago, and the frogs now have a strong presence on two locations: multiple locations. The numbers is growing so rapidly that scientists have been struggling to monitor, estimating populations in the hundreds of thousands on every island, across developed and agricultural areas, but also in the protected natural reserve. When San José marked amphibians and attempted to find them in the subsequent 10 days, she could find only a single marked frog from time to time, indicating their populations were enormous. They estimated six thousand frogs in a single pond. "Our estimates are still very low," states the researcher. "I am pretty sure there are additional numbers." Deafening Noise and Rising Worries The amphibians' abundance is evident from the sound chaos they cause. "The number of frogs and the noise – it's truly insane," says San José. For the scientists, their nocturnal vocalizations are useful in determining their existence in far-flung areas, using audio devices like the one outside San José's office. But nearby farmers say the sounds are so raucous they prevent sleep at night. "During the rainy period, I regularly hear their croaks and they're extremely loud," says a local coffee farmer from Santa Cruz. "Initially it was a shock, seeing the first frogs in the region," says the farmer, who started noticing their abundance about three years ago when one jumped on her palm as she was walking out of her house. Ecological Impact Remains Unclear The sound isn't the fundamental problem, though. While the amphibians has been in the islands for almost three decades, scientists still know very little about its effect on the archipelago's delicately balanced terrestrial and aquatic ecosystems. Researchers are finding out more about the amphibians, including that they can stay as larvae for as long as half a year. On archipelagos, it is very typical for non-native species to prosper, as they have none of their enemies. The islands counts 1,645 invasive types, many of which are seriously disrupting the safety of its native ones. A 2020 research indicates the invasive amphibians are hungry insect consumers, and might be disproportionately eating uncommon insects found only on the islands, or depleting the nutrition of the region's uncommon avian species, disrupting the food chain. Unusual Traits and Control Challenges The island frogs have shown some atypical characteristics, including living in brackish water, which is rare for frogs. Their metamorphosis process is also extremely inconsistent, with some tadpoles becoming frogs very quickly and others taking a long time: the researcher witnessed one which stayed as a larva in her laboratory for six months. "We truly don't know this part," she says, concerned the tadpoles could be impacting the region's clean water, a very limited commodity in the islands. Additional studies is required to establish the best way to control the frogs without harming other organisms. Techniques to control the frogs in the beginning of the century were largely ineffective. Park rangers tried collecting large numbers by hand and slowly raising the salinity of lagoons in vain. Research suggests applying caffeine – which is extremely poisonous to amphibians – or using electrical methods could assist, but these approaches aren't always secure for other uncommon Galápagos species. Without answers to more of the fundamental issues about their lifestyle and effect, culling the amphibians might not even be the right way to proceed, says the biologist. Financial Obstacles for Research While she expects the increasing use of environmental DNA methods and DNA analysis will assist her team make sense of the invasive species, funding for the project has been hard to obtain. "Everyone wants to give funding for preserving frogs," says the researcher. "But it's more difficult to find funding for an invasive frog that you might want to manage."