As Temps Rise, Amphibians May Vanish

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Red-eyed tree frogs inhabit areas near rivers and ponds in rainforests from southern Mexico, through Central America, to Northern Colombia.
Corbis

THE GIST

- Many animals and plants may be unable to move to suitable locations as the climate changes.

- The unpredictable nature of climate change is one of the biggest obstacles.

- Scientists might need to help more species breed and migrate to help them survive.

As the climate heats up, scientists expect all sorts of animals to move to cooler places. But that may be easier said than done.

When researchers mapped out the escape routes that a variety of amphibians would need to take in the coming decades to adapt to changing climate conditions, they uncovered some serious trouble.

Because of unpredictable rises and dips in temperature, many salamanders, frogs and newts will get stuck in unfavorable conditions along their travels -- enough to threaten their survival.

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The findings are likely to apply not just to amphibians, but also to insects and other types of animals as well as plants. The study adds fire to a longstanding debate among conservation biologists and wildlife managers.

Some experts argue that threatened species need to be bred in captivity or that animals should be moved to places that will foster their survival. Others cite infamous examples like the invasive cane toad in Australia and argue that introducing species to new environments is simply a recipe for disaster.

"What conservationists have been planning for some time is that we might be able to use green habitat corridors so species can jump from place to place quite easily," said Regan Early, a climate change ecologist at the University of Évora, in Portugal. "We're finding it isn't going to be that simple. If we put corridors in place, we are going to have to do a lot of work to help species along."

"I don't think there is a silver bullet," she added. "We are going to be faced with a lot of hard decisions about what we want to do. We can either act and do things we might not be happy with, or not act and see a lot of species that we're used to seeing every day start to disappear."

"We need to decide what it is we want form our environment and how we're going to manage it."

Amphibians are perfect subjects for studies on climate change, Early said, because they are extremely sensitive to changes in temperature. Because frogs and related creatures are so small, they are also limited in how far they can move at a time. So they can't easily escape from conditions that become inhospitable to them.

Early and colleagues looked at 15 amphibian species: Two types of newts, two types of frogs and 11 varieties of salamanders, all native to the western United States.

Armed with detailed information about the survival needs of each species, the researchers used climate projections to map out the routes they would need to take to survive climate changes. The study plotted data in 10-year increments, from 1990 to 2100.

Resulting maps showed that four of the 15 species will end up going extinct, without any suitable places to go in the future, the researchers report today in the journal Ecology Letters. A large potential range will continue to exist for six other species, but they will be able to access just half of that range. Four species are likely to become vulnerable or endangered as a result of climate changes.

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The biggest obstacles facing the amphibians are not mountain ranges and other physical barriers, the study found. Instead, it's the unpredictable nature of projected climate changes that threatens them most. Instead of getting gradually and consistently warmer, temperatures will roller coaster in ways too extreme for amphibians to deal with.

"Every time it gets warmer, they can move, but when it gets cooler again, they can't move far enough and they get stuck," Early said. "It's like taking two steps forward and one step back."

Butterflies, reptiles, plants and all sorts of other life forms face the same issues, said John Wiens, an evolutionary ecologist and herpetologist at Stony Brook University in New York. And that's on top of the challenges they already have to deal with, including habitat destruction and diseases.

The new study emphasizes, at the very least, how important it is to maintain corridors for species to move through when environmental conditions change, Wiens said. He added that, while conservationists talk about helping species breed and migrate, the only ultimate solution might be to slow or reverse the rate of climate change.

"This just shows that, even under the best case scenarios where you have corridors, how hard it might be" for species to survive, Wiens said. "Even if the habitat is perfectly intact, it might be almost impossible."