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				The Silence of the Birds The brown tree snake has wiped out bird life on Guam. Will a new snake virus curb the crisis?
		Select text to jump ahead in the clip: ALDA: It's a tranquil scene on the coast. A couple of guys are diving... checking out life on the lagoon floor. People are boating. Actually, I know who that is out there. She's Rachel Woodfield, a marine biologist, and she's bringing in a bag of that weed the divers were looking at. Hiya, Rachel. Hiya. Hi. Is that it, there? This is it right here. ALDA: But the weed is not as nice as it might seem. We're at Agua Hedionda Lagoon just north of San Diego on the California coast. The divers out there are trying to get rid of every last shred of this stuff that they can find. It's calledCaulerpa taxifolia. It's an invasive weed that has the potential to literally smother California's native marine life to death. We know that because it's already killed off thousands of acres of coastal life in the Mediterranean. Caulerpais a classic example of the phenomenon that we're devoting this entire program to: alien species. Remember killer bees? They're dangerously aggressive African bees introduced to Brazil in 1957. Now they've spread north into California and the Southwest and beekeepers are trying to figure out how to cope with them. South American fire ants are another alien. They attack pets and wildlife and destroy native plants. Fire ants got to Mobile, Alabama, in the 1930s probably in soil used as ship ballast. Now they're in 14 states in the Southeast. What they all have in common is that somehow they've been transported from their home habitat to a part of the world where they did not evolve, where they're aliens. It's a great thing to be an alien because in your new environment there aren't any of the predators and competitors that you originally evolved with that make your life a constant struggle. So you can really run wild and grow like crazy and take over the place. Thousands of plants, animals, insects, fish and microbes have moved around the globe to become aliens. Almost always, it's humans who do the moving. Asian hydrilla, for example was first brought to the U.S. in the '50s as an aquarium plant. Now it clogs waterways all over the South. People always have carried things with them, of course either by accident or design. But now with global trade alien species are becoming an irresistible force. In the Great Lakes, many of the most common species are aliens including the notorious European zebra mussel. Most are recent arrivals. New Zealand now has as many alien plants as native around 1,700 of each. Hawaii is the same. It's thought that right now the U.S. has about 7,000 alien species of all kinds. Is that a bad thing? Sometimes the cost is obvious. For example, 20% of California is infested with Eurasian yellow star thistle. It's toxic to horses, and cattle won't walk on it so huge areas of rangeland are now useless. But ecologists argue that the greatest costs are less tangible. When species get mixed up in this great global exchange the sets of plants and animals called ecosystems can fall apart and disappear. We're going to lk at four alien species stories from around the world. Among them, they display all the classic ingredients. There's the 19th-century Harvard professor who thought he had the key to a better silkworm. There's the disease that was blown across the Atlantic to cause havoc in the Caribbean in coral reefs and maybe among people as well. We're going diving in the Mediterranean to see firsthand the damage that Caulerpa taxifoliacan do. And first, the story of a bird, a snake and a small island in the Pacific. WOMAN: Okay, this is... ALDA: This is the National Zoo in Washington, D.C. I'm heading for the tropical bird house in the company of Kathy Brader, the keeper. So, we have these birds that are housed inside. These are all different...? ALDA: There's one particular exhibit we're interested in. Now, this is our Guam exhibit. And in here we have our Guam rail and our brown tree snake. He's curled up on the top. Oh, yeah. And he is the cause of these guys' problems on Guam. ALDA: On the island of Guam in the western Pacific the forests are eerily silent. Guam has lost all three of its unique native bird species. Six other regional species are gone; just three others are hanging on. This is the culprit. You can see all the different locks and equipment we have on there to make sure that he cannot get out. Sometimes they hide a key, you know. (laughing) Well, fortunately I don't think we have that problem with the snake. And... let's just back up here a little bit. For us to have him here, we had to have a special permit and only have males, so there's no chance of... If one did get out, they can't reproduce. Because we don't need this problem here in the United States, you know, on the mainland. ALDA: You can be sure that if the brown tree snake did manage to get out the Guam rail would make an easy meal. Guam has no native snakes so the birds developed no natural defenses against them. Horatio, as he's called, doesn't even recognize the nearby snake as a danger. It's the mealworms that interest Horatio. BRADER: We use them as a protein supplement but we also kind of use them as a treat. As a treat? Yeah. You know, no wonder these birds are extinct. Come here, Horatio. ALDA: Horatio is descended from the last 21 Guam rails that were brought in from the wild in the mid-1980s for captive breeding. ALDA: Do you hope to reintroduce them? BRADER: Yes, but there's literally millions of these snakes and we can't just go and re-release them with the snakes still being the problem. When we can solve that problem is to reintroduce these birds back into Guam. We want them in the wild. NEWSREEL ANNOUNCER: Here in the South Pacific theater air transport bucks fog, mountains and Japs in the routine performance of its duties. ALDA: It was the disruption of war that led to the devastation of most of Guam's wildlife-- birds, bats, flying foxes and small mammals. The island was occupied by the Japanese, fought over and became an important air-transport hub. Sometime in the 1940s a few brown tree snakes must have stowed away on flights maybe from New Guinea or the Solomon Islands and made it to Guam-- the first snakes ever on the island. Today, Guam is infested with brown tree snakes maybe one or two million of them-- up to 20 snakes per acre in some areas. It's the highest snake density in the world and a major nuisance for people. Their bite is only mildly poisonous-- about like a bee sting-- but the snakes short out power lines; they get into buildings and attack anything-- wildlife, pets, chickens, and children, too. Secured in double cages at the National Zoo there's a large research collection of brown tree snakes including females, collected in Guam by veterinarian Don Nichols. He's been bitten maybe half a dozen times. You need to move quickly once they know you're here but I'm just going to grab the snake by the head and secure the head, which is where all the weapons are and then pull it on out. And as you can see these are very long and slender which is adapted for life in the trees. And if my hand were a tree branch then it could actually extend its body out as much as 67% out into the air. With a lot of snakes that are not adapted to life in the trees you can actually grab them by the tail and hold them up like this and the snakes can't get to you if you hold it away from your body. But this snake can, huh? But this snake has the ability. Its muscles are so strong that it can actually come right back up like this and if I were to let go of the head it could come up and nail me, or maybe even... Or maybe even me. ALDA: Guam is still a major hub so the fear is the snake could stow away again and jump to other snake-free islands, like Saipan or Hawaii. There are rings of traps around the seaport and airport. Cargoes are checked constantly but in spite of the vigilance, there are leaks. So far the snake has been caught on eight other Pacific islands including Hawaii, where 14 are known to have arrived. One snake was even caught in Corpus Christi, Texas. It's only a matter of time before a new population gets established somewhere so the search is on for some way to control-- even eradicate-- the snakes on Guam. At the National Zoo Don Nichols and Elaine Lamirande are working on a radical idea: find a disease which just affects snakes. These samples all came from snakes that died from a virus infection. Called paramyxovirus, it regularly crops up in captive snakes which live close together. NICHOLS: This one looks a little rambunctious so I'm going to use the snake hook. ALDA: Don Nichols had the idea that paramyxovirus could be made to spread among Guam's dense snake population. Right now they're seeing how different strains of virus sent here from around the world, affect the brown tree snake. The snake gets a shot of anesthetic which takes about 15 minutes to take effect. NICHOLS: Now I give it a few jiggles and make sure there's no movement. Yeah. You can see. I still will make sure I got control of her head but she's... quite asleep at this stage. ALDA: Then a dose of one of the paramyxovirus strains is injected into the snake's windpipe causing a pneumonia-like disease within two or three weeks. Don says these viruses pose no risks for people because they're active only in cold-blooded reptiles. Our high body temperature kills the virus off. NICHOLS: Let the fluid trickle down into the lung. ALDA: So far they've tested 16 strains of the virus, looking for one that will kill the snake only after a delay, so there's time for the infection to spread to other snakes. There's no getting around the fact that this project is about killing animals-- figuring out the best way to give them a really bad case of pneumonia. That's something that an animal lover like Don is acutely aware of but for him, it's the lesser of two evils. How do you answer somebody who questions whether or not you're being cruel to them? Well, I mean it's all a matter of your priorities and I'm the first person to admit... I actually like snakes, and I like them where they belong. But these things are... are a pest species in an area and they're causing all kinds of havoc. They're threatening other islands. And it may not be the most humane way to kill them but it's the only way you can do it on a broad scale. ALDA: There was an attempt on Guam to persuade people to eat the snakes. It never caught on, and anyway no approach involving catching individual snakes is going to make a dent in a population of millions. Don is convinced that only a biological control agent that can perpetuate itself-- like a disease or a parasite-- could have much effect. But could biological control carry its own risks? Don't viruses reproduce rapidly? Don't they have a chance to mutate and attack other species eventually? My biggest concern would be whether or not it could adapt... mutate and adapt to the native lizards. ALDA: Don says that paramyxovirus has never been known to jump to lizards and of course they'll do tests before any virus release. But biological control inevitably carries risks and that's a measure of how difficult it is to tackle the problems created by alien species. The original problem occurred when some snakes got on airplanes and flew to Guam. Now, if you infect the snakes in Guam and an infected snake gets on an airplane and flies to some country where that virus could hurt those snakes isn't that a danger? NICHOLS: There is a chance of that happening. However, one of the key things is that these viral diseases are very density-dependent. In other words, high populations, dense populations-- easy for the viruses to spread around. But in the native range of these things it's very difficult to find the snakes. They're very low-density, so... It's not a zero-percent chance, I'm not saying... No, no, I mean, my mind is racing because it just seems to me that every time we do something to fix something that we did wrong 50 years ago we create a new problem for somebody 50 years from now. ALDA: The hope, of course, is that we've learned how not to create new problems. If the virus project is approved the small island of Rota, 35 miles north of Guam may hold the best hope for the return of Guam's wildlife. It's still free of snakes so there are birds here that are extinct on Guam. Over the last few years, more than 200 Guam rails bred in zoos from the 21 birds captured in the 1980s have been released here. Two-zero-eight-five. ALDA: They're breeding successfully so they can provide a wild nucleus from which Guam itself can be repopulated if Don Nichols' virus works. Guam's wildlife can never be fully restored but without snakes, it can return to something like the balance that once existed. And at the same time, the threat of similar devastation spreading to other islands can be averted.

				Green Invader Alien algae are smothering native marine life and livelihoods in the Mediterranean. And now it's in San Diego as well.
		Select text to jump ahead in the clip: ALDA: How long have you been studying thisCaulerpa? MAN: More than ten years. Ten years. ALDA: We're in a small towjust down the coast from Nice in the south of France. Alex Meinesz, a biology professor from Nice University is taking me out fishing. In those ten years, how much has it increased? ALDA: As with thousands of places like it around the Mediterranean Sea this town depends on a mix of fishing and tourism for its livelihood. On peut monter? FISHERMAN: Okay. Okay, thanks. Bonjour. FISHERMAN: Bonjour. Patrick. Patrick, Alan. Alex, bonjour. Mais alors, au commencement... ALDA: We're on the Verg family boat. The waters around here have been fished for generations-- until now, that is. They don't fish here anymore. We had to persuade them to set their net out last night just so we could film the result. And the result is this. ALDA: There's some. MEINESZ: Caulerpa. Yeah. Caulerpa. Look. PATRICK: On arrte un peu, uh? Look-- and thisCaulerpa clogs the nets and the fish see the nets, and there is no fishes. Oh, I see. So it hurts fishing... it hurts fishing just because... They see the nets. It calls attention to the nets. ALDA: The weed, calledCaulerpa taxifolia,doesn't belong here. It's a tropical plant common in the Caribbean and other warm waters. The northern Mediterranean gets cold in the winter but somehow theCaulerpais surviving and thriving-- nothing can touch it. MEINESZ: When you broke it, there comes a kind of juice out of, you see? Does that juice have anything in it that keeps away predators? Yes, absolutely that are terpenes, caulerpenynes. And this is a kind of toxic matter and a repellent matter. So the fish don't eat it. So it repels fish, and does it... so... in this area, nothing is a natural predator. No. You see all the leaves are entire. Nothing... Nothing has been eating it. No, no eating trace. Yeah. On y va? On y va. (laughing) Holy moly! He really jumps in! ALDA: Alex took us into the shallow water near the town's bathing beach. Everything below was covered by theCaulerpa:rocks, sand, mud. There's nothing else down here-- no other plants, barely a fish. It's a classic example of an alien that just takes over-- like the brown tree snake in Guam. Nothing eats it, and nothing competes with it. It's full, huh? Yeah, there's a lot of it down there. All the bottom is covered. ALDA: TheCaulerpaarrived here about nine years ago. Advancing at an inch a day, it has ruined the fishing and it'll soon clog the town beach. It's the same disastrous story spread out along a thousand miles of Mediterranean coast. Caulerpais easily spread. It's carried along in fishing nets and there are millions of small boats in the Mediterranean all with anchors. MEINESZ: A little piece like this I put this in the water after six months, you have three square meters with this little piece. Any part of this? Any part, any part. ALDA: With its rapid spread from fragments and its cold-water survival Caulerpain the Mediterranean is behaving in ways that shocked marine plant experts like Alex. After years of investigation Alex is pretty certain he knows how this disaster happened. This is the aquarium at the famous Monaco Oceanographic Museum where Jacques Cousteau was once director. In the early 1980s, the museum along with several other European aquaria started using a decorative and easy-to-grow plant in their tropical tanks. The plant was Caulerpa taxifolia. It's still used here today, as it is around the world. Alex believes that somehow some fragments ofCaulerpa were released from the tanks into the sea. A museum diver first sawCaulerpa right outside the building on the bottom in 1984. It covered just one square yard. By 1989, when Alex first saw it, it covered two acres. By 1990 it was at nearby Cap Martin next year Toulon, a hundred miles away and now it's found from Spain to Croatia. With no natural enemies to hold it back theCaulerpahas been steadily smothering Mediterranean sea life. In the shallow areas, there's normally a complex community of over a thousand different species: algae, shellfish, worms and fishes, all based on meadows of native sea grass. In the darker depths, there's a different balance with the grass giving way to red sea fans. This is the steep 100-foot rock wall off Cap Martin once a favorite spot for scuba divers. The film is from 1996, shot as theCaulerpawas taking hold. Alex has been diving here every year since theCaulerpaarrived. As the alien plant advances, it blocks out light-- from the red sea fans, for example, which die off. Alex has seen the same process repeated all over the rock wall. Did this all originate with the Monaco aquarium? Genetic analysis has shown theCaulerpais a mutant strain unique to aquariums-- including Monaco-- and not found in the wild. But we'll never know for sure how it first got loose. In the summer of 1999 our underwater cameraman swam down the rock wall at Cap Martin to record the progress of theCaulerpa. The wall is now completely covered. The last sea fans are dying. The wall is essentially a biological desert. Once again, we're looking atCaulerpa growing in an aquarium. But there's something else-- it's a kind of slug and it's eating the weed. The result: all over the tank, ghostly white fronds of weed with their toxic juice sucked right out by the slugs. The slugs are being studied in his lab at the University of Nice by Alex Meinesz. In his view, they represent the single best hope for controllingCaulerpa taxifoliain the Mediterranean. We've jumped 4,000 miles across the Atlantic to the Indian River in Florida. Alex's slugs came from here, collected by Cecilia Miles a marine biologist from Florida State University. HereCaulerpais eaten and controlled by the highly specialized slugs as it is further south all over the Caribbean. The hope is that slugs from Florida-- the northern extreme of their range-- might be hardy enough to survive the Mediterranean winter. In the summer of '99 Cecilia collected and packed a batch of Florida slugs for shipment to Alex in Nice. The slugs had their own air supply for the flight and were escorted across the Atlantic by a French grad student. See you, Cecilia. Bye-bye. Thank you. ALDA: Here you were a student ofCaulerpa... ALDA: Alex has been studying different slugs for years. The Florida batch had been in residence at Nice University for about two weeks when I visited. I study on theCaulerpasince... ALDA: His work with slugs andCaulerpa is done on a shoestring budget in a makeshift lab behind the biology building. The Monaco Aquarium connection makes this a very political subject so research grants have been hard to come by. ALDA: So you've got a chance to see who's working out. Yes, who studies biology. Come in, please, come in. So... they're in there. I don't see any slugs. Yes... here! ALDA: Oh, yeah, yeah, yeah! Now, is he eating now? Yes, I think so. So these slugs really like that toxic stuff. Yes, ah, yes. They need the toxic because they take the toxins and they stock it in them and then the fishes doesn't eat it. Oh... Oh, I see! Oh, oh, so the slugs use the toxins to keep the fish away from them! Exactly, exactly, exactly. ALDA: The slugs have other highly specific adaptations toCaulerpa. They needCaulerpacells as part of their own metabolism and they have a special tooth which matches onlyCaulerpacell structure. Alex argues that the slugs are so exquisitely adapted to their one food that releasing them into the Mediterranean to control the invasion biologically would present a very low risk. I asked him about this. How do we know the slugs that you bring in won't adapt and find some other way to live in addition toCaulerpa? When the slug have no moreCaulerpa they cannot, in one generation, say "Ah, we shall change our tooth, our mouth our toxin, to eat other things." (laughing) You understand? That takes a lot of plastic surgery! You understand? Sure, sure! When there isCaulerpa, they eatCaulerpa. No problem, no problem. When they see there is no more Caulerpa,it is too late. It is too late. ALDA: Alex's slugs may be the only way to go. All kinds of nonbiological control methods have been tried like releasing poisonous copper from underwater electrodes... or simply scraping the weed off... vacuuming it up... freezing it with dry ice... scalding it with hot water... or cutting off its sunlight. But there's nothing that's practical on a large scale except the slugs. I asked Alex again is it really smart to release the slugs into such a paradise of food? All of a sudden, they're dining out every night. They're going to Maxim's every night and they're doing pretty well. Now you're liable to have some pretty fat, happy, healthy slugs around looking for trouble. No, no. You ever have a prairie ofCaulerpa with many slugs in it and then they control theCaulerpa and it is finished, that we think. But what you want? Do you want to have a Mediterranean Sea full withCaulerpa without any control method? We must have a predator for this invader. Without predator, theCaulerpa-- that is a risk that we see now. We can see, you have see it when we snorkeling. You see with the fishermen. It covered all the bottom and expands every year. So what do we do? Do we nothing or do we try this? ALDA: If you can't get rid of it, if the slugs don't work if the slugs are too dangerous, if the slugs work but governments won't let you use the slugs what will theCaulerpado? What will happen to the Mediterranean? What happen is exactly the same that happened since ten years. It extends. It extends every year, in new country, new regions. And we think that this algae is able to colonize most of the region of all the Mediterranean Sea. ALDA: Now fast-forward two years and 7,000 miles. We're back at the California lagoon where we began this program. Just like in France, the alienCaulerpahere is untouched by any natural enemy. It's capable of smothering the native eelgrass. The patch of bright greenCaulerpa was first noticed in the year 2000 suspiciously close to a storm drain outlet. Caulerpais widely used in home aquariums so someone probably dumped one out into a drain somewhere in the area. Getting rid of theCaulerpahere and in one more spot near Los Angeles is now the responsibility of Rachel Woodfield who works for an environmental consulting firm. Where did you first find Caulerpaaround here? Right out here in the eelgrass beds. We were monitoring the success of the native eelgrass beds and came across this bright green terror growing in there. We weren't sure what it was at first. We've all heard ofCaulerpa in the Mediterranean but to make the relation that this isthekiller algae-- it took us a little while to figure it out. Was it widespread by the time you first discovered it? It had spread throughout this small harbor area. It covers about five acres. So we built this boom around it to keep all the boats out and people who might want to come in and see it and might potentially spread it. ALDA: They decided to try killing off theCaulerpa a few square feet at a time-- something it's too late for in the Mediterranean. Portable frames are covered with plastic tarps which are sealed to the lagoon floor with sandbags. The underwater tent is then given a dose of chlorine and left for a few days. Everything inside is killed-- Caulerpaand native eelgrass-- but so long as they get all theCaulerpa only eelgrass will grow back. After a year, it seems to be working. We're at a manageable point right now. We have two infestations. They're deep back inland in lagoons. There's calm water. We're able to have the luxury to put these tarps down and deal with it and keep an eye out for it before it gets offshore. Is this the major threat or the only threat right now from an alien species in this... in these waters? This certainly is not the first exotic species that this lagoon has seen. However, this is the first species that really has the potential to cause some serious, serious harm to our coastline and that is at a state that is manageable.

				The Silken Tree Eaters Scientists wage a desperate struggle to save America's forests from deadly insects.
		Select text to jump ahead in the clip: ALDA: We're in the New York City borough of Queens to witness the death of a tree. (chain saw buzzing) ALDA: One of the cemetery's prized mature maples is coming down. It was doomed anyway, and this is why. MAN: What we have here is a larval Asian long-horned beetle. If we just pull him out of here... You can see they're quite sizable. They have large mandibles well suited for the environment inside a log and chewing its way through the hardwood. ALDA: The Asian long-horned beetle is as big a threat to America's forests asCaulerpais to our marine life. In late summer each female distributes a couple of hundred eggs around several trees. The beetles arrived in the mid-1980s in wooden packing materials from China so as usual with alien species they have no natural enemies here. Right now they're just confined to the New York City and Chicago areas but already 7,500 trees have had to be destroyed. The damage is done in the spring when the larvae hatch and eat their way out emerging as adult beetles to begin the cycle again. The tree cannot survive the process. You don't see much on the outside sometimes and then when you flip it you see what type of damage this is capable of. Our goal is total eradication of this insect from North America. (chain saw buzzing) ALDA: Eradication means cutting up every infected tree picking out the larvae chipping the remains and burning the chips. And then every apparently healthy tree within 700 feet gets a dose of systemic insecticide just in case there are larvae inside. Like withCaulerpa, we still have a shot at halting this alien invasion. The dominant hardwood in the eastern American forests was once chestnut until it was almost wiped out by chestnut blight-- a fungus from Japan-- in the 1880s. As a result, oaks took over but they're being devastated by the gypsy moth from Europe. So now maples are coming to predominate. But they're one of the favorite foods of the Asian long-horned beetle. It would be the worst-ever pest of American forests. It's a pest of about 18 different species of hardwood trees in the northeast forest including all of your maples, your elms, horse chestnuts willows, poplars, birch, ash trees. So you're talking about a sizable percentage of the natural forest in the Northeast. And the possibility of spread outside of the... if you would, the ornamental situation now from a backyard pest to a forest pest, would be catastrophic. ALDA: Many people in the Northeast have firsthand experience of a continuing forest catastrophe. The gypsy moth regularly defoliates and kills large swaths of oak forest in an ever-expanding area. It's costly and destructive. It leads to large-scale pesticide use and it's plain disgusting, too. The gypsy moth has been a classic story of alien invasion for over a hundred years. This film was made 50 years after Etienne Trouvelot, a Harvard astronomer had accidentally released a group of gypsy moths from his home in Medford, a Boston suburb. He'd imported the moths from Europe in the hope of establishing an American silk industry. The first big defoliation took place in Medford in 1880 ten years after the release. There were more or less constant attempts to prevent the moth from spreading including extensive use of toxic lead arsenate sprays. But by the late 1920s it infested 40,000 square miles of New England, New York and Canada. Victory was declared several times but the gypsy moth proved unstoppable. Today, it's all over the Northeast and still on the move. From this lab on Cape Cod the U.S.D.A. continues to battle the gypsy moth as they have for a hundred years. Inside labs sealed with airlocks they keep gypsy moths and about 40 other aliens which might be the next invader. They even have some Asian long-horned beetles here. They're determined not to be caught off guard again. MAN: The gypsy moth is fully entrenched in the United States. We will never eradicate it. The goal now is to slow that natural spread. You can eliminate some pesticide use and save some dollars by not letting u