VOA慢速英语2009-SCIENCE IN THE NEWS - Oldest Examples of Two Cor（在线收听）

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.

VOICE TWO:

And I'm Faith Lapidus. This week, we will tell about newly-found organisms that are said to be among the oldest living organisms on Earth. And, we will tell about the first complete report of bird populations in the United States.

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VOICE ONE:
　
Hawaiian coral that is more than 4,200 years old

A research team says it has found corals that are more than four thousand years old. The corals were discovered at the bottom of the Pacific Ocean, near the Hawaiian Islands. The team made the discovery with a vehicle designed to operate deep underwater. At depths of nearly four hundred meters, the researchers found the oldest examples of two species of coral. One is a kind of deep-water black coral called Leiopathes. The other was a gold coral, called Gerardia.

A report on the team's discovery was published recently in the Proceedings of the National Academy of Sciences.

VOICE TWO:

The team collected pieces of the coral and then used radio-carbon dating methods to find their age. The tests showed the organisms were, in fact, much older than reported in earlier estimates.

One of the researchers was Brendan Roark of Texas A-and-M University. He says the Leiopathes corals were shown to be about four thousand two hundred sixty-five years old. The Gerardia is believed to be about two thousand seven hundred forty-two years old.

The age of the corals would make them among the oldest living creatures in existence. Scientists know that some of the Bristlecone pines in northern California are also more than four thousand years old.

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Deep sea corals face numerous threats. They include illegal harvesting and activities linked to deep-sea fishing. Other threats include human pollution, acidification from carbon dioxide and rising temperatures in Earth's atmosphere.

Professor Roark says corals are important because they support many other forms of sea life. He says they also can show part of the ocean's ancient history. Corals have hard, stony skeletons that grow like tree trunks. The skeletons have growth rings that represent ocean water conditions at the time.

Professor Roark says knowing the age of the corals might help scientists understand earlier water conditions and ocean surface productivity. And, he says the discovery will add to what scientists know about Earth's changing climate.

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VOICE TWO:

We share our environment with many organisms. But few give us more pleasure than birds. Their beauty and songs have become part of our understanding of what a healthy environment should support.

Yet a report released in March shows that many kinds of American birds are in trouble. The report is called "The State of the Birds United States Two Thousand Nine." It says that nearly one third of about eight hundred bird species in the United States are threatened in some way.

VOICE ONE:

The report is said to provide the first complete study of American bird populations. It was based on three separate studies by a partnership of government agencies and environmental groups. The groups include the Cornell Lab of Ornithology, the National Audubon Society and the American Bird Conservancy.

Much of the information came from observations made by thousands of volunteers in more than four thousand places over forty years. The United States Fish and Wildlife Service led the effort to combine the information into one report.

VOICE TWO:
　
The Northern Bobwhite is a grassland bird that is close to disappearing

Interior Secretary Ken Salazar praised the report as an important scientific document on the health of American birds. But it is not only a warning about falling bird populations. The health of bird species tells researchers a lot about the condition of the environment.

The study grouped birds by the environments in which they live. It said grassland bird populations fell by about forty percent in forty years. That was the biggest drop reported. One reason for this is the disappearance of grasslands in the central United States. The report says only two percent of the grasslands that existed two centuries ago remain today.

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Birds depend on their environment to provide food and shelter. The report said loss of habitat is the biggest threat to American birds. Sixty-seven species are federally listed as endangered or threatened. But the report lists one hundred eight-four species that are considered in danger because of limited habitat, serious threats or falling populations.

The report also notes successes in bird conservation efforts. For example, the numbers of many wetland birds have recovered since measures were taken to protect more than twelve million hectares of wetlands.

One hundred thirty-nine wetland species have increased in number since the late nineteen-seventies. Pelicans, herons and geese are just a few of many recovering wetland species.

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The American Bald Eagle

Numbers of America's national bird, the bald eagle, have recovered largely because of measures to fight pollution. In nineteen seventy-two, the federal government banned most uses of the insecticide D.D.T. The chemical used to kill mosquitoes also caused bird egg shells to thin and break. Species like the bald eagle, peregrine falcon and osprey nearly disappeared. Now, their populations seem secure.

But threats to other species continue to grow. Land development and agriculture are just two uses of natural resources that change and destroy environments that birds need. The cutting of forests is threatening woodland species like the Northern Spotted Owl.

VOICE ONE:

In addition to loss of habitat, birds face many other man-made threats. The report says up to one billion birds die each year from flying into objects like power lines, windows and tall buildings.

Environmentalists are studying ways to reduce this number, but these efforts are only beginning.

Climate change is one of the least understood threats to birds. The report says temperatures are estimated to increase by several degrees Celsius in the next one hundred years. And sea levels could rise by one half meter.

Already, rising temperatures have had an effect on migratory birds. Studies show that some American Robins are appearing in their nesting areas two weeks earlier than thirty years ago. Other birds, like the red-winged blackbirds and eastern bluebirds, are laying eggs earlier because of warmer temperatures. The fear is that, as birds move to nesting areas earlier, they will arrive before food is available.

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The I'iwi of Hawaii

Birds native to one state are of special concern to wildlife experts. More than one third of all threatened or endangered bird species in America live on the Hawaiian Islands. Each island is home to a rich collection of animal and plant life. One hundred thirteen bird species are found nowhere else.

Seventy-one bird species have disappeared forever since people first arrived on the Hawaiian Islands one thousand seven hundred years ago. Today, thirty-one Hawaiian species are federally listed as endangered or threatened.

Non-native plants, animals and diseases are the main threats. Non-native animals like rats, cats and mongooses kill flightless birds and raid nests. Also, the loss of habitat to development and agriculture continue to endanger many rare species.

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Alicia King works for the Fish and Wildlife Service. She says the main message of the report is that conservation measures work when they are put in place. The successful recovery of some well-known species is evidence of this. But more needs to be done. She says there currently are not enough programs to study bird numbers and behavior.

Partnerships between public, private and tribal groups can help to provide the resources needed to protect America's birds. But Miz King says the American people are an important part of the solution, too.

Americans spend one hundred twenty-two billion dollars on watching wildlife each year. And, millions of Americans enjoy watching birds. But the economic value of wild birds is only part of their importance. They also represent a part of a healthy environment that cannot be replaced.

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VOICE TWO:

This SCIENCE IN THE NEWS was written by Mario Ritter and Brianna Blake, who was also our producer. I'm Faith Lapidus.

VOICE ONE:

And I'm Bob Doughty. Read and listen to our programs at voaspecialenglish.com. Join us again next week for more news about science in Special English on the Voice of America.