1 00:00:05,662 --> 00:00:11,262 Thirty years ago a small and rare tropical plant was put into these tanks to grow. 2 00:00:12,079 --> 00:00:14,773 What came out was a monster. 3 00:00:17,201 --> 00:00:21,519 Today it is a potential threat to seas and oceans across the world. 4 00:00:23,085 --> 00:00:25,675 You could just tell as you came up to it there was trouble. 5 00:00:26,390 --> 00:00:32,871 It has a real insidious sort of creepy nature as if it's some sort of blob that's taking over at the bottom. 6 00:00:35,679 --> 00:00:38,643 Nobody knows where it may strike next. 7 00:00:39,564 --> 00:00:44,889 I don't believe that it's an exaggeration to say that this challenge is my worst nightmare 8 00:00:45,234 --> 00:00:49,177 and to the degree that people understand, it's their worst nightmare. 9 00:00:50,790 --> 00:00:54,819 This is the extraordinary story of how an insignificant algae 10 00:00:55,050 --> 00:01:00,849 grew to become something many scientists believe is capable of causing ecological damage across the globe. 11 00:01:02,619 --> 00:01:05,584 It's become known as the killer algae. 12 00:01:06,246 --> 00:01:10,909 It's like out of a horror movie, but it's real. 13 00:01:26,998 --> 00:01:33,172 Along the Pacific coast of southern California lie some of America's most popular holiday beaches. 14 00:01:34,611 --> 00:01:38,123 Thousands of people come here every year to ride the waves. 15 00:01:40,238 --> 00:01:44,958 Just behind the beaches are a series of lagoons, famous for water sports. 16 00:01:48,758 --> 00:01:55,867 It was here nine months ago that a team of divers found something totally unexpected on the seabed. 17 00:02:01,739 --> 00:02:05,294 It was a small plant they'd never seen before. 18 00:02:06,805 --> 00:02:09,453 They decided to find out what it was. 19 00:02:10,590 --> 00:02:15,900 I spent several days looking it up doing some research on it and when I finally found a photo 20 00:02:16,044 --> 00:02:21,686 as the picture downloaded onto my computer there was just a sinking feeling in my stomach. 21 00:02:22,636 --> 00:02:28,508 What marine biologist Rachael Woodfield had seen sent her rushing back to the lagoon. 22 00:02:36,034 --> 00:02:42,639 As she dived she was aware that if her suspicions were correct California faced a major problem. 23 00:02:45,590 --> 00:02:48,627 At first glance it looks like it's a nice round patch, 24 00:02:48,642 --> 00:02:53,765 but the more you investigate you see that deep down inside the eel grass there are many fingers of it 25 00:02:53,766 --> 00:02:58,082 spreading out into the eel grass sort of just creeping its way along the bottom. 26 00:02:59,492 --> 00:03:06,789 The American biologists knew that the plant had an awesome reputation for taking over and destroying whole ecosystems. 27 00:03:09,120 --> 00:03:14,690 We're assuming the worst case scenario that if we don't control it it's going to completely overtake this lagoon 28 00:03:14,805 --> 00:03:19,827 and if we're wrong I'd rather be wrong, over-estimating the impact than under-estimating it. 29 00:03:22,575 --> 00:03:28,778 The lagoon is directly linked to the sea. Their biggest fear was that it would escape into the Pacific 30 00:03:28,993 --> 00:03:31,857 and take over the entire Californian coast. 31 00:03:41,758 --> 00:03:45,370 A large area of the lagoon was cordoned off by the police, 32 00:03:45,801 --> 00:03:50,075 but no one knew how to destroy the plant, or stop it spreading. 33 00:03:53,126 --> 00:03:58,206 It had turned into California's biggest marine pollution scare for decades, 34 00:04:00,235 --> 00:04:03,646 yet this whole dramatic situation might have been avoided. 35 00:04:04,825 --> 00:04:10,423 In the early 1990s a European biologist had predicted just such a problem, 36 00:04:12,093 --> 00:04:15,173 but nobody at the time had listened to him. 37 00:04:22,756 --> 00:04:28,009 It all began twelve years ago, thousands of miles away, in Monaco. 38 00:04:28,556 --> 00:04:34,082 Here one day, French marine biologist Alexandre Meinesz went diving in the Mediterranean. 39 00:04:41,306 --> 00:04:45,120 Meinesz is an expert on the marine life of the Mediterranean. 40 00:04:47,523 --> 00:04:50,171 He knew that among the dozens of plants that live in it 41 00:04:50,632 --> 00:04:54,690 there is one key plant that is fundamental to the sea's ecosystem. 42 00:04:54,907 --> 00:04:57,814 It normally covers large areas of the seabed. 43 00:04:59,238 --> 00:05:02,635 It's a dark, grey/green sea grass called possidonia. 44 00:05:08,032 --> 00:05:13,486 Possidonia is a plant which provides food and shelter for a huge variety of fish and invertebrates, 45 00:05:19,113 --> 00:05:24,826 but that day as Alexandre Meinesz dived, nothing was as he expected it to be. 46 00:05:28,741 --> 00:05:34,468 The water was very clear. The sun was shining and the visibility was good. 47 00:05:35,231 --> 00:05:38,800 Then I saw straightaway that the seabed was bright green. 48 00:05:48,296 --> 00:05:53,937 I said to myself this isn't possible, there shouldn't be any brilliant green seaweed here. 49 00:05:55,823 --> 00:06:00,601 Where Meinesz had expected to find the usual variety of Mediterranean sea life 50 00:06:00,817 --> 00:06:03,278 all he could see for hundreds of metres 51 00:06:03,465 --> 00:06:07,883 was a dense and bright green mat of weed he'd never seen before. 52 00:06:10,099 --> 00:06:16,633 As he studied the extraordinary new plant he realised it was a giant variant of a tropical algae 53 00:06:16,634 --> 00:06:23,728 called caulerpa taxifolia yet how could a tropical plant survive in the colder waters of the Mediterranean? 54 00:06:25,484 --> 00:06:29,125 He decided to try and find out what was going on. 55 00:06:33,816 --> 00:06:40,407 Back in the laboratory he compared the taxifolia with other specimens of the same family of algae from around the world. 56 00:06:42,393 --> 00:06:47,272 : I have a few specimens that I collected myself several decades ago in the Red Sea 57 00:06:47,603 --> 00:06:54,007 and here is Tahiti in Polynesia. They are all small, whatever depth they come from 58 00:06:54,252 --> 00:06:59,058 not very long, not very wide and the runners are always very thin, 59 00:06:59,203 --> 00:07:03,880 so I realised straightaway that what was growing in the Mediterranean 60 00:07:03,923 --> 00:07:08,240 was something absolutely exceptional, that had never been seen before. 61 00:07:10,946 --> 00:07:16,702 This new plant was bigger, tougher and more vigorous than any other specimen of caulerpa 62 00:07:17,509 --> 00:07:21,020 and it normally lived thousands of miles away in the Tropics. 63 00:07:23,985 --> 00:07:27,957 It's a giant in comparison with what can be found in tropical seas. 64 00:07:28,273 --> 00:07:34,519 I realised that it was different from anything else in the world. I was absolutely astonished. 65 00:07:34,678 --> 00:07:40,261 It was something strange. I did some more research but everything confirmed my first impression. 66 00:07:40,794 --> 00:07:48,364 It was an alien. Something abnormal, supernatural, was beginning to develop in the Mediterranean. 67 00:07:52,912 --> 00:07:59,344 It was growing so fast and densely it was swamping the dark green native possidonia. 68 00:08:01,949 --> 00:08:03,892 There was something else too. 69 00:08:04,496 --> 00:08:10,497 The coastal waters of the Mediterranean are normally home to some 600 species of animals and plants, 70 00:08:10,856 --> 00:08:16,555 yet the seabed around the mysterious new algae was almost devoid of other marine life. 71 00:08:20,124 --> 00:08:24,412 I immediately felt that the whole Mediterranean was in danger. 72 00:08:24,728 --> 00:08:31,895 This was a very adaptable plant. It seemed able to alter the ecology of large areas of the sea. 73 00:08:35,766 --> 00:08:38,630 It seemed like something out of science fiction. 74 00:08:39,048 --> 00:08:44,919 What was a gigantic tropical algae doing flourishing in the Mediterranean? 75 00:08:52,115 --> 00:08:57,498 Charles-Francois Boudouresque is one of France's leading experts on Mediterranean animal life. 76 00:09:01,340 --> 00:09:07,111 Alexandre Meinesz telephoned me several times to say he'd made an incredible discovery. 77 00:09:09,269 --> 00:09:12,047 He asked me to come to Nice to see it. 78 00:09:13,486 --> 00:09:16,465 I said yes, yes, but later. 79 00:09:17,846 --> 00:09:23,387 It took him a year to persuade me to come and see the colonies of caulerpa taxifolia. 80 00:09:27,201 --> 00:09:31,518 When he saw it Boudouresque was also shocked by the invasion. 81 00:09:32,224 --> 00:09:37,433 He immediately agreed to investigate whether the algae was harming the sea's animal life. 82 00:09:38,772 --> 00:09:42,341 The animal he chose as a test case was the sea urchin 83 00:09:42,657 --> 00:09:46,126 which lives on plants and is easy to observe in the laboratory. 84 00:09:49,536 --> 00:09:52,415 He set up a simple experiment. 85 00:09:56,445 --> 00:10:00,762 Here is an urchin that has been fed on native Mediterranean algae. 86 00:10:06,835 --> 00:10:11,670 The mouth normally faces downwards and we turn it over. 87 00:10:13,714 --> 00:10:16,506 We put it with its mouth facing upwards. 88 00:10:19,313 --> 00:10:24,465 We know that a sea urchin that is in good health takes about one minute to turn back over again, 89 00:10:25,227 --> 00:10:27,731 to return to its natural position. 90 00:10:37,705 --> 00:10:44,742 Almost immediately the urchin began to put out little suckers, wave its spines and struggle to turn itself over. 91 00:10:49,131 --> 00:10:52,369 In less than a minute it had completed the manoeuvre. 92 00:10:58,125 --> 00:11:02,672 There, what an athlete. It's a very good athlete. 93 00:11:07,363 --> 00:11:12,429 In another jar Boudouresque had urchins fed exclusively on the new algae. 94 00:11:14,616 --> 00:11:19,092 These urchins have been fed for a long time on caulerpa taxifolia. 95 00:11:23,740 --> 00:11:31,799 We do the same experiment with them. We turn them over and measure the time they take to right themselves. 96 00:11:34,604 --> 00:11:39,425 The time they took to turn over crept up from two minutes, to five, to twenty. 97 00:11:40,102 --> 00:11:45,801 Boudouresque suspected the urchins were finding the taxifolia inedible and were starving to death. 98 00:11:49,571 --> 00:11:57,069 After a month on an exclusive diet of taxifolia the turning over time had reached 30 minutes. 99 00:11:58,896 --> 00:12:03,516 It soon became clear that some even preferred to die rather than eat the algae. 100 00:12:06,006 --> 00:12:11,043 The findings were very disturbing. If the new algae took over the Mediterranean 101 00:12:11,488 --> 00:12:18,540 would other animals which feed on plants react in the same way? Would the whole food chain be disrupted? 102 00:12:21,231 --> 00:12:26,829 What, the French researchers wondered, was the plant's secret weapon that stopped the urchins eating it? 103 00:12:29,117 --> 00:12:34,370 Meinesz sent samples to a number of European labs specialising in plant toxins. 104 00:12:40,112 --> 00:12:46,401 At the Max Planck Institute in Germany they began analysing the chemical composition of the caulerpa samples. 105 00:12:47,294 --> 00:12:49,409 The findings were unexpected. 106 00:12:53,093 --> 00:12:57,339 Many plants employ a chemical defence mechanism to ward off predators, 107 00:12:57,814 --> 00:13:02,606 but most use a variety of different toxins in relatively small quantities. 108 00:13:04,017 --> 00:13:07,283 The mysterious new algae turned out to be different. 109 00:13:07,772 --> 00:13:14,594 It is very special because caulerpa taxifolia is nearly entirely relying on one component, 110 00:13:14,882 --> 00:13:22,135 that it is basing its whole chemical defence on. Usually plants use a multitude of different components 111 00:13:22,207 --> 00:13:25,790 that have all different target animals. 112 00:13:26,395 --> 00:13:30,813 Caulerpa taxifolia uses another strategy. It uses only one component, 113 00:13:31,087 --> 00:13:34,238 but this component is produced in a very high amount. 114 00:13:37,548 --> 00:13:43,894 It was the sheer concentration of the toxin in the plant that marked it out as something very unusual. 115 00:13:45,305 --> 00:13:52,242 The toxin is called caulerpenine and the concentration was higher than in any other algae Pohnert had ever analysed. 116 00:13:54,443 --> 00:13:58,703 Pohnert discovered that although the toxin was not lethal to humans or animals, 117 00:13:58,962 --> 00:14:06,388 it made the plant almost totally inedible and if nothing would eat it there was nothing to stop the algae's advance. 118 00:14:09,380 --> 00:14:15,324 If it took over, the Mediterranean's animal life would be forced to flee or starve to death. 119 00:14:28,780 --> 00:14:33,629 Alexandre Meinesz now believed he was dealing with not just any invasive plant, 120 00:14:33,932 --> 00:14:37,357 but an exceptionally harmful and vigorous organism. 121 00:14:40,898 --> 00:14:46,122 As the algae continued to spread, growing at twice the speed of indigenous plants, 122 00:14:46,222 --> 00:14:52,655 he worried that the situation could rapidly get out of control unless something was done to stop it. 123 00:15:01,693 --> 00:15:03,103 There was one hope. 124 00:15:03,736 --> 00:15:09,003 The colony of algae lay directly under the walls of one of Europe's most prestigious marine research 125 00:15:09,004 --> 00:15:14,860 and conservation organisations: the Monaco Oceanographic Museum. 126 00:15:15,651 --> 00:15:18,947 Meinesz felt sure the Museum would help him. 127 00:15:24,459 --> 00:15:28,460 It would take money, resources and government involvement, 128 00:15:28,461 --> 00:15:32,446 but Meinesz was confident the Museum would be able to persuade the French authorities 129 00:15:32,447 --> 00:15:35,526 to eradicate the algae before it spread further. 130 00:15:38,922 --> 00:15:40,821 He was in for a shock. 131 00:15:51,081 --> 00:15:57,931 The Museum is run by Professor Francois Doumenge, one of France's most influential marine biologists. 132 00:16:00,464 --> 00:16:06,969 He is Director of an institution which, for nearly a century, has championed oceanographic conservation 133 00:16:07,343 --> 00:16:11,387 and preserved the riches of the sea in a series of palatial galleries. 134 00:16:12,250 --> 00:16:19,302 Meinesz approached the Museum with his concerns, but the Museum's Director had a very different view of the situation. 135 00:16:20,093 --> 00:16:26,396 He simply didn't believe the invasion of caulerpa taxifolia was dangerous or unnatural. 136 00:16:29,951 --> 00:16:35,880 The development of tropical species in the Mediterranean is an old story. 137 00:16:38,398 --> 00:16:44,011 Some species date back to the opening of the Suez Canal and are now well known. 138 00:16:45,551 --> 00:16:52,343 So there have been tropical species in the Mediterranean since the end of the 19th century. 139 00:16:56,113 --> 00:17:02,114 Doumenge argued that algae like taxifolia are constantly moved around the world by sea currents 140 00:17:02,574 --> 00:17:08,201 and frequently lie dormant in the water for years until a temperature change brings them to life. 141 00:17:11,367 --> 00:17:16,692 Doumenge suggested Meinesz was worrying about nothing. The growth of the taxifolia was not a danger, 142 00:17:17,008 --> 00:17:20,678 merely a sign of the evolving character of the Mediterranean Sea. 143 00:17:24,247 --> 00:17:26,995 Eight to ten thousand years ago 144 00:17:27,413 --> 00:17:34,608 the sea was 120 metres lower than it is now and three to five degrees cooler, 145 00:17:35,429 --> 00:17:43,761 so the Mediterranean should be seen as a basin which changes very rapidly on the geological timescale. 146 00:17:45,143 --> 00:17:50,841 Its current state is simply an intermediate state, a transitory phase. 147 00:17:54,655 --> 00:18:00,124 Doumenge passed on his thoughts to the French Ministry of the Environment who breathed a sigh of relief. 148 00:18:00,829 --> 00:18:04,729 If the algae was not dangerous but part of a pattern of global change 149 00:18:05,118 --> 00:18:10,745 there was not much the French government could be expected to do against such a fundamental, natural occurrence. 150 00:18:14,990 --> 00:18:20,085 Over the next 18 months the algae spread, as Meinesz had feared it might. 151 00:18:20,747 --> 00:18:25,928 In 1990 there were sightings at Cap Martin, four kilometres east of Monaco, 152 00:18:26,129 --> 00:18:30,719 and at Toulon, almost 200 kilometres in the opposite direction. 153 00:18:33,683 --> 00:18:40,058 By late 1991 there were some dozen patches of the algae dotted along the French Riviera. 154 00:18:50,320 --> 00:18:54,479 It confirmed all my fears. The algae was beginning to spread. 155 00:18:54,998 --> 00:19:01,301 I could no longer keep quiet. I absolutely had to tell the media to try to make the people aware of it. 156 00:19:06,352 --> 00:19:13,389 By the early 1990s, with the press finally involved, the French Ministry of the Environment stepped in. 157 00:19:14,109 --> 00:19:19,131 It sent a research ship to the affected area of the Mediterranean to see what was going on. 158 00:19:23,146 --> 00:19:28,068 At long last there was official recognition that something might be wrong. 159 00:19:28,975 --> 00:19:33,954 The man in charge of the government's research effort was marine biologist Thomas Belsher. 160 00:19:44,071 --> 00:19:48,705 Belcher sent down divers to chart the taxifolia beds. 161 00:19:51,426 --> 00:19:58,362 The progress of caulerpa taxifolia can be followed by an underwater video camera 162 00:19:58,363 --> 00:20:01,413 which is a few metres above the seabed 163 00:20:05,356 --> 00:20:09,040 and each time we see some caulerpa we mark it. 164 00:20:11,732 --> 00:20:16,740 This allows us to make accurate maps of the observations. 165 00:20:19,460 --> 00:20:25,806 Almost immediately Belsher found that Meinesz, if anything, had underestimated the size of the infestation 166 00:20:25,907 --> 00:20:27,562 and the rate it was growing. 167 00:20:32,526 --> 00:20:38,686 Belsher's divers investigated further. It was, as Meinesz had already observed, 168 00:20:38,816 --> 00:20:44,184 bigger, faster growing and denser than any algae ever seen before. 169 00:20:44,788 --> 00:20:47,954 Belsher's maps revealed that the Mediterranean seabed 170 00:20:48,026 --> 00:20:52,429 was being transformed faster than at any time in recent history. 171 00:20:54,933 --> 00:21:01,582 We had never seen an alga introduced into a marine ecosystem that had grown so quickly. 172 00:21:06,964 --> 00:21:10,921 The seriousness of the situation was reinforced by other researchers 173 00:21:10,922 --> 00:21:17,124 who now established that fish populations around the invasive taxifolia beds were measurably falling. 174 00:21:19,181 --> 00:21:23,067 In some places fish numbers had dropped by up to 50%. 175 00:21:24,448 --> 00:21:29,859 Fish, like urchins, appeared to find the taxifolia too toxic to eat. 176 00:21:36,696 --> 00:21:42,121 The French authorities, still only half convinced this was a problem they could do anything about, 177 00:21:42,437 --> 00:21:46,668 commissioned a series of small-scale experimental eradictions. 178 00:21:48,222 --> 00:21:53,791 It soon became clear that destroying the plant was going to be much more difficult than anybody had expected. 179 00:21:55,388 --> 00:21:59,216 Divers were sent down to dig up patches of algae by hand, 180 00:21:59,360 --> 00:22:03,534 but it was like trying to trim a football pitch with a pair of scissors. 181 00:22:05,808 --> 00:22:08,916 This algae is very difficult to eradicate. 182 00:22:09,852 --> 00:22:16,299 You can see that the roots are as fine as hair and have fruits that may give rise to new plants, 183 00:22:16,730 --> 00:22:18,630 so to eliminate it by hand 184 00:22:18,688 --> 00:22:23,307 you have to remove much more than what you see. You have to remove everything underneath as well 185 00:22:23,437 --> 00:22:27,999 - the mud, the sand - because there might be little bits not visible to the eye. 186 00:22:30,531 --> 00:22:37,223 They tried freezing it to death with blocks of dry ice. It was never a match for the scale of the problem. 187 00:22:40,950 --> 00:22:44,649 They even tried sucking it up with an underwater vacuum cleaner. 188 00:22:46,649 --> 00:22:52,981 The trials quickly showed that it would take an army of divers many years to make an impact on the algae. 189 00:22:55,284 --> 00:23:01,170 By 1994 new sightings showed that the taxifolia had spread even further, 190 00:23:02,465 --> 00:23:05,747 yet there was something very puzzling about the way it was spreading. 191 00:23:06,998 --> 00:23:12,611 It was not just expanding into the neighbouring seabed, it was leaping from one bit of coast to another, 192 00:23:12,999 --> 00:23:16,755 establishing new colonies hundreds of miles apart. 193 00:23:22,541 --> 00:23:25,750 Meinesz knew that if the authorities were to slow its spread 194 00:23:26,182 --> 00:23:30,974 they needed to understand what lay behind this apparently erratic pattern of growth 195 00:23:37,479 --> 00:23:41,292 but there were those who still believed he was worrying about nothing. 196 00:23:41,595 --> 00:23:47,509 The Director of the Monaco Museum, Francois Doumenge, continued to suggest Meinesz was over-reacting. 197 00:23:49,840 --> 00:23:57,453 In my opinion if we'd taken time to consider the problem, if we'd tackled it with greater scientific calmness 198 00:23:57,454 --> 00:24:04,073 and not incidentally concluded that it was a catastrophe, we'd have realised there was not much to worry about. 199 00:24:07,038 --> 00:24:12,895 Meinesz went back to the lab. He suspected the key to understanding the plant's erratic spread 200 00:24:13,125 --> 00:24:15,485 lay in knowing how it reproduced. 201 00:24:16,478 --> 00:24:21,112 What we wanted to know right at the start is how this species reproduces. 202 00:24:21,443 --> 00:24:28,624 You have to take a little bit of juice that is in this caulerpa, put it on the slide and look at it under a microscope. 203 00:24:31,215 --> 00:24:37,864 The sticky juice of the taxifolia contains microscopic particles called gametes or reproductive cells. 204 00:24:38,224 --> 00:24:42,253 These are normally male and female and act like sperm and egg. 205 00:24:45,852 --> 00:24:51,320 Theoretically you should find two types of gametes, reproductive organs inside the juice. 206 00:24:51,738 --> 00:24:58,861 The gametes are very small. They measure five microns. The male gamete is the same size as the female gamete, 207 00:24:59,149 --> 00:25:04,027 but there is a small difference - the female gamete has a red dot, a stigma. 208 00:25:06,445 --> 00:25:13,007 Meinesz studied slides of the juice of the taxifolia looking for the red dot that identifies the female gamete. 209 00:25:16,792 --> 00:25:20,274 He couldn't find a single female gamete. 210 00:25:20,750 --> 00:25:25,599 We looked in vain for female gametes on the specimens from the Mediterranean. 211 00:25:25,959 --> 00:25:32,319 There were no female gametes, so no fusion between the two gametes, no sexual reproduction. 212 00:25:34,838 --> 00:25:37,918 There could be only one explanation. 213 00:25:39,774 --> 00:25:44,149 The taxifolia in the Mediterranean was spreading not through sexual reproduction, 214 00:25:44,422 --> 00:25:49,747 but by a process known as vegetative reproduction. It's a form of cloning. 215 00:25:52,538 --> 00:25:58,683 It was an important breakthrough that finally made sense of the strange spread of the taxifolia. 216 00:26:06,310 --> 00:26:11,304 It meant that any tiny fragment of the algae separated from the main plant 217 00:26:11,520 --> 00:26:16,888 contained all the genetic material necessary to grow an exact replica of the parent plant 218 00:26:18,384 --> 00:26:20,442 to create a clone. 219 00:26:23,392 --> 00:26:30,271 It's as if a piece of human hair, or a flake of skin dropped on the ground could grow into a complete human being. 220 00:26:33,321 --> 00:26:39,121 Meinesz now realised that it would only take an infinitesimally small fragment of the taxifolia 221 00:26:39,409 --> 00:26:43,309 picked up by the anchor of one of the thousands of boats that criss-cross the sea 222 00:26:44,532 --> 00:26:48,734 to start a new colony of plants hundreds of miles away. 223 00:26:54,102 --> 00:27:00,780 By 1997 a new map of the colonies of the algae seemed to confirm this hypothesis. 224 00:27:02,132 --> 00:27:05,816 it had jumped further along the coasts of France and Italy, 225 00:27:06,247 --> 00:27:13,385 it had even leapt across to the coast of Croatia. It was eight years since Meinesz had first raised the alarm. 226 00:27:13,716 --> 00:27:17,084 Now nowhere in the Mediterranean seemed safe. 227 00:27:20,537 --> 00:27:23,631 But even as the new figures were being assimilated 228 00:27:24,336 --> 00:27:28,639 there was a dramatic discovery which was to throw new light on the algae's origins 229 00:27:28,999 --> 00:27:34,108 and confirm Meinesz's fears that there was something very unnatural about the plant. 230 00:27:37,562 --> 00:27:40,440 It happened here at the University of Geneva. 231 00:27:42,383 --> 00:27:46,686 Olivier Jousson is a specialist in DNA sampling. 232 00:27:46,931 --> 00:27:52,817 He realised the only way to prove whether the gigantic taxifolia in the Mediterranean was a natural invasion 233 00:27:53,090 --> 00:28:00,171 was to trace its origins. If he could match its DNA to the DNA of any tropical taxifolia 234 00:28:00,286 --> 00:28:05,610 then the theory of the Monaco Museum that it had naturally drifted in from the Tropics was probably right. 235 00:28:09,281 --> 00:28:15,512 I realised that the main problem with caulerpa was that nobody knew where it had come from. 236 00:28:19,816 --> 00:28:24,637 He set about processing dozens of samples of taxifolia from all over the world, 237 00:28:24,809 --> 00:28:29,817 including the Red Sea and areas of the Pacific. Nothing matched. 238 00:28:31,816 --> 00:28:37,356 Each time the DNA fingerprint was slightly different from the Mediterranean strain. 239 00:28:40,076 --> 00:28:41,126 It was a mystery. 240 00:28:43,745 --> 00:28:46,954 Eventually there was only one strain left to try. 241 00:28:54,178 --> 00:28:56,164 It was a perfect match, 242 00:28:59,560 --> 00:29:04,065 but this was not a wild plant; it had been bred by humans. 243 00:29:04,539 --> 00:29:09,260 It was a sample of caulerpa taxifolia taken from an aquarium tank. 244 00:29:15,088 --> 00:29:21,362 For years a very peculiar strain of caulerpa taxifolia has been used to decorate tropical fish tanks. 245 00:29:21,808 --> 00:29:28,040 It appeared that it was this human bred, artificial strain which had escaped into the Mediterranean. 246 00:29:33,235 --> 00:29:36,833 Jousson's discovery proved, beyond reasonable doubt, 247 00:29:36,890 --> 00:29:41,165 that the taxifolia in the Mediterranean had not drifted in from the Tropics. 248 00:29:41,710 --> 00:29:47,409 Monaco's argument that what was happening was part of a natural cycle of change in the sea did not hold up. 249 00:29:50,719 --> 00:29:57,828 It wasn't long before people also realised that if the findings were right the most obvious source of the alien invasion 250 00:29:58,418 --> 00:30:01,886 was the one place that was certain it had come from elsewhere: 251 00:30:04,159 --> 00:30:07,742 the Monaco Oceanographic Museum. 252 00:30:13,557 --> 00:30:17,514 The Museum was known to have had taxifolia in its tropical tanks 253 00:30:17,759 --> 00:30:22,608 and was also directly above the site of the first known infestation. 254 00:30:25,646 --> 00:30:29,718 Yet to suggest that the Museum was, albeit unwittingly, responsible 255 00:30:29,934 --> 00:30:33,474 carried huge political and scientific implications. 256 00:30:35,992 --> 00:30:42,742 It meant the Institute had somehow unknowingly allowed material from its aquarium tanks to get into the sea. 257 00:30:44,051 --> 00:30:48,901 Worse, the most likely time for all this to have happened was in the early 1980s 258 00:30:49,189 --> 00:30:54,413 when the Museum had been run by a man with an international reputation for marine research: 259 00:30:56,398 --> 00:30:58,140 Jacques Cousteau. 260 00:31:00,313 --> 00:31:06,789 For years he'd been the father of French marine biology, a hero of marine conservation. 261 00:31:07,753 --> 00:31:13,941 The irony was that to accuse the Monaco Museum of even accidentally releasing a rogue alga into the sea 262 00:31:14,316 --> 00:31:20,159 was to hold some of the most famous names in marine conservation responsible for what many now regarded 263 00:31:20,173 --> 00:31:22,389 as an ecological disaster. 264 00:31:25,670 --> 00:31:30,059 The Museum flatly denied any link between the taxifolia in its tanks 265 00:31:30,246 --> 00:31:35,729 and the taxifolia below its walls and questioned the validity of the DNA findings. 266 00:31:39,025 --> 00:31:46,782 I think that the tests that were performed didn't use either the safest or best known methods. 267 00:31:49,272 --> 00:31:58,482 What we need for an accurate answer is much more detailed, much finer genetic studies, 268 00:31:58,684 --> 00:32:04,613 using a much bigger range of samples than was practical before. 269 00:32:08,786 --> 00:32:15,204 Doumenge's was a controversial point of view. Even Jacques Cousteau, when he later found out about the issue, 270 00:32:15,334 --> 00:32:19,291 told the French Minister of Environment that there might be cause for concern, 271 00:32:22,414 --> 00:32:29,926 but with so much taxifolia in the sea the exact source of the original infestation had become less important. 272 00:32:32,301 --> 00:32:39,511 Scientists now realised that wherever the aquarium breed had come from they were dealing with an extremely invasive plant. 273 00:32:41,022 --> 00:32:43,426 It was also remarkably adaptable. 274 00:32:44,735 --> 00:32:48,981 In the aquaria it had developed a new and distinctive DNA fingerprint 275 00:32:49,168 --> 00:32:53,183 and changed its characteristic so it could survive in cooler water. 276 00:32:54,234 --> 00:32:59,486 I ask myself a question that in my opinion was really incomprehensible: 277 00:32:59,918 --> 00:33:05,201 how can this algae, which only lives in the Tropics where it's always 20 degrees, 278 00:33:05,446 --> 00:33:08,856 withstand winters when it's 13 degrees? 279 00:33:09,504 --> 00:33:11,432 How could it stay alive? 280 00:33:13,361 --> 00:33:19,017 A search for an answer lay in tracing the aquarium plant to its original source. 281 00:33:25,895 --> 00:33:31,522 The trail led back from Monaco, through France, to Germany and a zoo in Stuttgart. 282 00:33:34,458 --> 00:33:41,063 Here, during the 1970s, aquarium staff at the Wilhelmina Zoo had made a curious discovery. 283 00:33:43,193 --> 00:33:49,352 At the time people everywhere had been trying to find a plant that could be used to decorate tropical fish tanks. 284 00:33:49,970 --> 00:33:54,561 The world's leading aquaria imported wild specimens from the four corners of the globe, 285 00:33:54,950 --> 00:33:59,224 but nothing seemed to survive in the artificial environment of a tank, 286 00:34:00,749 --> 00:34:05,254 but then at the Wilhelmina Zoo, something unexpected happened. 287 00:34:06,491 --> 00:34:12,780 A newly imported strain of wild caulerpa taxifolia from the Pacific suddenly blossomed and flourished. 288 00:34:13,457 --> 00:34:16,162 It rapidly turned into the Zoo's wonder plant. 289 00:34:18,335 --> 00:34:25,243 At the time nobody asked how, or why, it had suddenly flourished. Now they did. 290 00:34:28,207 --> 00:34:35,301 The question of the nature of this algae gave me a lot of food for thought and there are only two hypothesis. 291 00:34:40,583 --> 00:34:45,376 First hypothesis: someone selects a bunch of caulerpa in the wild 292 00:34:45,664 --> 00:34:49,779 which is slightly abnormal, more resistant to the cold, 293 00:34:49,952 --> 00:34:56,212 and it is this one that is grown in an aquarium and find its way into the Mediterranean. 294 00:34:57,494 --> 00:35:01,595 In other words, a collector in the 1970s had, by accident, 295 00:35:01,754 --> 00:35:05,985 selected an unusually big and robust sample of the plant in the wild 296 00:35:06,244 --> 00:35:10,331 and it was this exceptional plant which had been grown in the Stuttgart Zoo, 297 00:35:10,951 --> 00:35:13,354 but there was also a second possibility. 298 00:35:17,455 --> 00:35:22,751 The second hypothesis: something happens in the aquarium to modify the plants. 299 00:35:22,851 --> 00:35:29,241 For some reason there is a change in its genetic structure, a mutation, a change in the chromosomes. 300 00:35:29,400 --> 00:35:31,386 It could be one of several things. 301 00:35:34,869 --> 00:35:40,683 Aquarium tanks use chemicals and lights to artificially recreate the natural balance of the sea. 302 00:35:41,360 --> 00:35:46,224 Could this man-made brew have caused the original wild strain to change, 303 00:35:46,325 --> 00:35:50,628 or mutate, into a more invasive plant than its wild cousin? 304 00:35:55,550 --> 00:35:59,291 To this day nobody has ever solved the mystery. 305 00:35:59,679 --> 00:36:04,097 The discovery was anyway rapidly overtaken by a new concern. 306 00:36:05,565 --> 00:36:11,278 Throughout the 80s and 90s the German-bred algae had been sent to aquaria around the world. 307 00:36:11,624 --> 00:36:17,222 It had become the most popular aquatic plant on earth. It was everywhere. 308 00:36:19,006 --> 00:36:23,137 If it could escape from one tank and survive, it could escape from others, 309 00:36:23,424 --> 00:36:28,346 and if it could flourish in the Mediterranean it could flourish in dozens of other seas. 310 00:36:31,728 --> 00:36:36,405 The super algae that Alexandre Meinesz had warned France about twelve years before 311 00:36:36,764 --> 00:36:40,477 was now potentially a world problem. 312 00:36:55,085 --> 00:37:00,568 California, with a huge trade in exotic plants, was always a likely victim. 313 00:37:05,892 --> 00:37:12,598 Ironically after the genetic discoveries in Europe, the US Department of Agriculture had listed caulerpa taxifolia 314 00:37:12,599 --> 00:37:16,167 as a noxious weed and banned sales and imports, 315 00:37:19,376 --> 00:37:23,362 but the country's aquaria already housed huge quantities of it. 316 00:37:23,363 --> 00:37:27,421 It was only a matter of time before some of it escaped into the wild. 317 00:37:29,983 --> 00:37:32,990 Last year this is just what happened. 318 00:37:34,386 --> 00:37:39,221 Caulerpa taxifolia was found in a coastal lagoon in southern California. 319 00:37:41,596 --> 00:37:47,208 Could have been simply a case of where the individual was cleaning his aquarium in his front yard, in his 320 00:37:47,453 --> 00:37:53,598 , in, in the street and as, and he had the algae in the aquarium and, and pieces of it floated down the gutter, 321 00:37:53,599 --> 00:37:58,979 got into the storm drain and then were just discharged into the lagoon because there is a, there is a, 322 00:37:59,238 --> 00:38:04,103 a storm drain outlet right here, very close to where the infestation is. 323 00:38:14,162 --> 00:38:20,710 The Americans, determined to avoid the Mediterranean experience, knew they had to act fast. 324 00:38:20,911 --> 00:38:25,804 Within weeks they'd settled on a radical campaign of eradication. 325 00:38:32,093 --> 00:38:36,986 The chosen weapon was chlorine which kills everything in its path. 326 00:38:40,713 --> 00:38:44,728 The chlorine is pumped down through a pipe from tanks on the surface 327 00:38:44,916 --> 00:38:51,694 into a tarpaulin which has been spread over the algae and held down at the sides with pegs and sandbags. 328 00:38:54,082 --> 00:39:00,026 Everything under the tarpaulin is killed - plants, fish, crustaceans. 329 00:39:00,961 --> 00:39:03,681 It's a price the Americans are willing to pay. 330 00:39:04,861 --> 00:39:13,496 No matter what level, how harsh the chemical response is, if we're effective 331 00:39:14,561 --> 00:39:22,735 it's hard to believe that that could be as bad as not being effective and having a whole coastline smothered by this algae. 332 00:39:25,225 --> 00:39:28,506 The chlorine, with an approximate strength of household bleach, 333 00:39:28,563 --> 00:39:33,701 acts almost immediately. Within hours the taxifolia is dead. 334 00:39:35,255 --> 00:39:39,961 It's an extreme solution, but it seems to be working in California. 335 00:39:43,977 --> 00:39:50,251 In Europe, however, after 15 years the infestation of taxifolia has spread too far. 336 00:39:50,856 --> 00:39:57,073 Poison is simply impractical and the scale of the destruction of wildlife would be completely unacceptable. 337 00:39:59,649 --> 00:40:03,434 Here an even more radical solution is now being considered. 338 00:40:04,441 --> 00:40:10,658 It's more controversial than poison, it's more drastic than most people will accept. 339 00:40:17,882 --> 00:40:25,077 It's a tiny tropical slug, the only known creature in the world that kills taxifolia as it eats it. 340 00:40:26,272 --> 00:40:30,417 At the University of Nice, Meinesz stumbled on it by accident. 341 00:40:33,540 --> 00:40:41,239 I heard from an American Professor in Florida who told me there was a slug that fed exclusively on caulerpa. 342 00:40:42,606 --> 00:40:49,428 To begin with I didn't take him very seriously. I couldn't believe that these little slugs could make much difference 343 00:40:49,528 --> 00:40:52,493 to the enormous amount of caulerpa we've got here. 344 00:40:53,860 --> 00:40:59,070 Then, by accident, we imported some of them in a bunch of caulerpa from the Caribbean, 345 00:40:59,444 --> 00:41:04,438 so we began studying them and looking at their potential as a biological weapon 346 00:41:04,682 --> 00:41:08,841 against caulerpa taxifolia and we have a few hopes. 347 00:41:11,532 --> 00:41:18,526 The slug is unique in producing an enzyme which enables it to eat the plant and neutralise the toxin. 348 00:41:21,318 --> 00:41:25,895 What is extraordinary is the way these slugs eat the caulerpa. 349 00:41:26,499 --> 00:41:32,975 They don't chew it as we eat salad. They make a small hole and suck out the juice. 350 00:41:37,738 --> 00:41:42,933 It's like a vampire sucking out the juice and leaving a dying husk. 351 00:41:43,364 --> 00:41:49,336 By the time the slug has finished its meal the plant is dead and the toxin has been neutralised. 352 00:41:50,027 --> 00:41:56,906 Meinesz's plan is to release thousands of these tropical slugs into the sea to attack the taxifolia beds, 353 00:42:00,303 --> 00:42:03,368 but it's not nearly as straightforward as it sounds. 354 00:42:03,670 --> 00:42:10,232 The French authorities are understandably wary of introducing yet another alien species into the Mediterranean 355 00:42:10,880 --> 00:42:15,226 and have so far refused permission to test the slugs in open water, 356 00:42:17,529 --> 00:42:23,458 yet Meinesz is sure the slug has evolved such a specialised and exclusive dependence on taxifolia 357 00:42:23,789 --> 00:42:26,279 it won't attack anything else. 358 00:42:29,531 --> 00:42:37,058 All the studies we've done tell us that there would be no danger if these little slugs were released into the Mediterranean. 359 00:42:39,864 --> 00:42:46,973 It could be that this small creature is all that separates the Mediterranean from massive environmental damage, 360 00:42:48,124 --> 00:42:52,743 yet it would be the ultimate irony if the sea were saved from caulerpa taxifolia 361 00:42:53,189 --> 00:42:59,290 only to be decimated in turn by a tiny slug called elysia subornata.