JIM LEHRER: What's killing the world's coral reefs, and what can be done to save them? Many scientists think the devastation caused by the recent tsunami might have been less severe if the coral reefs in South Asia had been in better shape and more able to protect the coastlines. Betty Ann Bowser has our Science Unit report.
BETTY ANN BOWSER: On the Great Barrier Reef off the coast of Australia, marine researcher Mary Wakeford methodically takes measurements and underwater pictures to see if the corals that live there are growing or continue to die.
Scientists all over the globe are watching what's happening here because this is the largest coral reef system in the world, stretching out some 1,400 miles. Wakeford's boss is Australian Institute of Marine Science Biologist Terry Done, an expert on coral reefs.
TERRY DONE: I'm quite worried that in a few decades there may be far poorer reefs.
BETTY ANN BOWSER: Ten thousand miles away in the oceans off the Florida Keys, Marine Sanctuary Manager Billy Causey and Biologist Kim Ritchie also examine the coral. And like his colleagues half a world away, Causey doesn't like what he sees.
BILLY CAUSEY: Some days I come out here and I just want to cry. And I've been visiting this reef for well over 30 years, and I've seen enormous decline in the last 15 years.
BETTY ANN BOWSER: The coral reefs of the world are disappearing at alarming rates. Some scientists are so concerned that they believe if nothing is done coral reefs will be gone from the Earth in 50 years. Marine biologist Sylvia Earle is executive director of the Global Marine Program for Conservation International.
SYLVIA EARLE: The rule of thumb that I keep hearing, and I trust the evaluation here, is that half of the coral reefs worldwide are either gone-- that is based on what it was before; human activity and exploitation's severely depleted them or either gone or on the way out and severely degraded.
BETTY ANN BOWSER: Corals are living animals, spineless creatures called polyps. They use calcium carbonate in the ocean to create a skeleton blanketing their soft, fragile bodies, and the limestone formed by those polyps grow into huge structures and become what we call coral reefs.
They're home to thousands of species of big and small fish, giant clams, schools of sharks, spiny lobsters, and eels. Coral reefs also provide food for hundreds of developing countries, they give coastlines a protective barrier, and they generate millions of dollars in revenue for fishermen and the tourist industry. Marine biologist Earle says there's also another big- picture value.
SYLVIA EARLE: People need to understand that coral reefs as a reflection of the health of the ocean as a whole is an indication that our life support system, the ocean, is in trouble. And if it's in trouble, we're in trouble.
BETTY ANN BOWSER: Marine scientists around the world say coral reefs are dying because of what they call "the big three"-- over fishing, pollution from the land, and global warming. Billy Causey knows the dangers of the big three from experience. As manager of the Florida Keys National Marine Sanctuary for 21 years, he's watched with alarm at what over fishing has done.
BILLY CAUSEY: We no longer have some of the larger species out there, larger grouper or snapper. We've seen changes in shifts in the overall reef fish population from a more healthy pristine area to areas that are degraded in some instances. We've also seen a great deal of habitat destruction, either from direct impacts, from boat groundings or anchors or problems coming from overuse, too much use on some of the reefs.
BETTY ANN BOWSER: But even those who never dive or swim on a reef in the Florida Keys can have a big impact on them. Over the last 20 years, thousands of people have moved to South Florida, creating a construction boom. More people has meant more pollution in the canals and along the beaches of the Keys.
It's not uncommon now for entire swimming areas to be closed down from the sewage that leaks into the water from the 25,000 septic tanks people use up and down the coast. Marine biologists like Jim Leichter have been trying to figure out how the nutrients produced by the pollution are impacting the reefs.
JIM LEICHTER: We do know that sewage is going into the waters. We can see decreased water clarity. We really don't know how the nutrient sources from shore, at least in my opinion, whether and how those are reaching and impacting the outer reef tract.
BETTY ANN BOWSER: He's hoping to find out as an aquanaut in the only underwater lab in the world. Located in 60 feet of water about ten miles off the Florida Keys, Aquarius is operated by the University of North Carolina at Wilmington and owned by the National Oceanic and Atmospheric Administration, or NOAA. Steven Miller is Aquarius's director.
STEVEN MILLER: If you're a coral reef biologist, you've got to dive; you've got to spend time in the environment that you're studying. And conventional scuba diving is really limited. You work from the surface; you have maybe an hour a day. Imagine trying to do your job if all you had was an hour a day. Aquarius, because of the special type of diving we do, called saturation diving, gives scientists really unlimited time to work underwater studying the coral reefs.
BETTY ANN BOWSER: One of the things Aquarius scientists are seeing is disease, a major cause of coral death in the Keys.
BILLY CAUSEY: In a month's time frame it appears to me that I'm seeing more coral diseases here. We saw black band disease, we saw a number of different types of diseases that scientists are still working on, and it was very disturbing to me.
BETTY ANN BOWSER: Of all the things that are killing the coral reefs, it is global warming that has scientists around the world most concerned because it is actually heating up the water. Even a subtle temperature increase of one degree can kill the microscopic algae inside the corals, which turns the coral bright white.
TERRY DONE: The science tells us that it is climate change which is killing coral reefs. The water is getting hotter; the corals are basically being cooked by these very hot waters because they live right close to the edge of their tolerance already. And we hope that they can adapt fast enough, but it may be a forlorn hope. There's no evidence that they are really likely to adapt as quickly as we would hope.
BETTY ANN BOWSER: Experts like Done say the science is clear: They know what is killing coral reefs of the world. The question for them now is: what people do with that knowledge. Paul Marshall is a biologist with the Great Barrier Reef Marine Park Authority.
PAUL MARSHALL: Science is essential to saving coral reefs, but science doesn't actually result in change. The agents of change are risk-management agencies, policy-makers, and the people who use the reef day to day.
BETTY ANN BOWSER: Last summer Australia took the science and did something unprecedented. The government set aside more than one-third of the Great Barrier Reef, and made it off- limits to fishing. New regulations to halt the flow of land-based pollution onto the reef were also imposed. From now on, in this new, so-called "no-take zone," an area half the size of Texas, visitors may look but they may not touch.
In 1989, Australia experimented with setting aside about five percent of the Great Barrier Reef. Wheeler Reef was in that original set-aside. Nothing has been taken away from here in 15 years. We interviewed Terry Done 60 miles off the Australian coast at low tide, when Wheeler Reef forms a sandbar for a few hours a day. Done says the health of this reef is evidence that set asides work.
TERRY DONE: What I'm seeing here is a reef which is, to my way of looking it's intact - as well as being stunningly beautiful, it's somehow ecologically intact; it's got all the -- all the options open to it for feedback, symbiosis, redundancies. If one species goes down, there's very likely something with a similar function will be able to come up.
BETTY ANN BOWSER: The American coral reefs off the coast of Florida are big business; they're the number one diving and sport-fishing destination in the world, supporting a $1 billion a year tourist industry.
But the U.S. has no national ocean policy regulating its coral reefs. And when marine scientists tried to get the federal government to protect reefs off the Florida coast, the idea was met with angry opposition. John Ogden is a Florida marine scientist.
JOHN OGDEN: The original advisory council, which was a cross section of Florida citizens, sat down together and we butted heads for six years over this thing. Our lives were threatened. My windshield was broken; my tires were slashed by angry people with no other way to express their anger than striking out at somebody.
BETTY ANN BOWSER: In 1990, the federal government created the Florida Keys National Marine Sanctuary. But Ogden says even with protection, there's a free-for-all atmosphere.
JOHN OGDEN: We have been living. It is exactly like the land -- the Oklahoma land rush of 1879. Everybody's out there. "I'm going to get mine." "I own it, it's mine, but I have no responsibility for it." And that has to change. We have to become stewards of this, as we are in fact of the land.
BETTY ANN BOWSER: Causey knows an expanded no-take zone would not guarantee survival of Florida's coral reefs. But he thinks it would take some of the pressure off.
BILLY CAUSEY: If we were able to set 33 percent of the Florida Keys National Marine Sanctuary aside, and protect the corals that are more resilient to protect corals for future generations, that would be a major management step forward; and it is something that would benefit our coral reefs enormously.
BETTY ANN BOWSER: Terry Done thinks Australia is off to a good start, but hopes it's not too late.
TERRY DONE: Without global climate change, it would be a reasonable expectation for us to think that reefs would be continuing to suffer their natural disturbances and bounce back to something like we've expected to see in our lifetimes. And what scientists are concerned about with global warming is that that ability to bounce back will be taken away simply because the insults will become too frequent and too severe.
STEVEN MILLER: If we lose coral reefs, you know, it's the same answer: What happens if we lose the rain forests? You know, what do we lose? We lose a lot. We lose something -- we lose the most dramatic and spectacular ecosystem on this planet. When it's gone, it's gone.
BETTY ANN BOWSER: In the past two years, two American blue ribbon commissions have called on the federal government to establish a national policy for the oceans.
JIM LEHRER: In a future report, we'll look at why the medical world is interested in the world's coral reefs.