华纳国际

Climate Change, Invasive Species Threaten Everglades


14 December, 2019

Everglades National Park, in the American state of Florida, is home to a large number of different kinds of wildlife. There are, for example, more than 360 species of birds.

The Everglades is the only place in the world where freshwater alligators and saltwater crocodiles live together, some say.

A great egret sits on top of a dead tree in the Florida Everglades, near South Bay, Fla. Friday, Jan. 14, 2005, as the sky turns darks as a thunderstorm moves across the area.
A great egret sits on top of a dead tree in the Florida Everglades, near South Bay, Fla. Friday, Jan. 14, 2005, as the sky turns darks as a thunderstorm moves across the area.

But the park is facing problems, including climate change and invasive species.

Environmental problems

Over the last century, about half of the Everglades has disappeared.

What survives is not really a natural ecosystem. It depends on a large network of human-made waterways, dams, pump stations and other water-control structures.

It is what the U.S. Army Corps of Engineers calls a "highly managed system." Critics call it a "Disney Everglades."

New information about the speed of climate change has led some to question how much of the Everglades can ever be saved.

"I tend to think that everything can be saved," says Fred Sklar of the South Florida Water Management District, which is responsible for much of the Everglades' infrastructure. "Restored is another question."

Tiffany Troxler is a director of Florida International University's Sea Level Solutions Center. She recently showed reporters from the Associated Press some of the environmental problems. These include evidence of the collapse of a thick soil that supports the ecosystem.

"You can think about these soils as your bank account," she said. "In the condition that this marsh is [in] right now, the outlook is not good."

A lack of fresh water and an increase in sea water have caused salt levels to rise in the marshes, Troxler and others say. This appears to be slowing or stopping plant growth.

Earlier this year, a group that includes the Corps of Engineers and the National Park Service issued its latest Everglades System Status Report.

It reads, "The Florida Everglades is struggling to survive in the face of sustained pressure from human activities" and the increasing effects of climate change.

Invasive species

But climate change is only one of the problems facing the Everglades. Invasive species are another.

Of all the invasive species in the Everglades, the Burmese python is the most difficult to deal with. No one is quite sure how a huge snake native to Southeast Asia arrived in South Florida. Many believe the first pythons escaped — or were released — in the late 1970s. Estimates of their population run into the hundreds of thousands.

Scientists suspect the python is responsible for the disappearance of up to 99 percent of the marsh rabbits, raccoons and other small animals in the national park.

Scientist Ian Bartoszek heads the Conservancy of Southwest Florida's snake research and removal program. Since 2013, he has been using pythons to catch pythons.

Every two weeks, he flies over the Everglades, picking up the signal of radio devices placed in 25 snakes. The hope is that these so-called "Judas snakes" will lead his team to others, especially females of reproductive age.

In the past six years, the conservancy team has removed more than 500 pythons with a combined weight of about 5,900 kilograms. However, Bartoszek thinks a total removal of the Burmese python is impossible.

Bartoszek noted that the Burmese pythons seem "to be adapting and evolving [in] real time here in the Everglades ecosystem." He added that it may be more correct to call them Everglades pythons. "Because they're ours now. They're here," he said.

Some hopeful signs

Still, there are some hopeful signs.

Some adaptation is taking place. Scientists have found evidence that local wood storks, a kind of bird, are eating non-native African jewelfish.

And the endangered Everglades snail kite has been eating a rare kind of mollusk, another invasive species in the area.

Perhaps the most hopeful development of all is the ongoing $578 million project to restore 103 square kilometers of the Kissimmee River Basin.

Since the destruction of some dams, part of the river has returned to its natural path. The wetlands are spreading and the numbers of wildlife are increasing in that area.

Thomas Van Lent, vice president of science and education at the Everglades Foundation, recently took a boat trip on a three-kilometer part of the restored river.

"And there were snail kites everywhere," he says. "It's just amazing to see the effects."

I'm John Russell.

And I'm Jill Robbins.

Allen G. Breed reported on this story for the Associated Press. John Russell adapted it for Learning English. Caty Weaver was the editor.

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Words in This Story

ecosystem – n. everything that exists in a particular environment.

Judas - n. one that betrays another

managed – adj. describing something that is controlled (such as a business, department, sports team, etc.)

tend v. used to describe what often happens or what someone often does or is likely to do — followed by to + verb

infrastructure – n. the basic equipment and structures (such as roads and bridges) that are needed for a country, region, or organization to function properly

marsh – n. an area of soft, wet land that has many grasses and other plants

adapt v. to change your behavior so that it is easier to live in a place or situation

evolve – v. to change or develop slowly often into a better, more complex, or more advanced state : to develop by a process of evolution

amazing – adj. causing great surprise or wonder : causing amazement

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