1 00:00:04,280 --> 00:00:05,680 In this series, 2 00:00:05,680 --> 00:00:09,280 I have travelled the length and breadth of the Great Barrier Reef... 3 00:00:13,520 --> 00:00:16,920 ..and used the latest techniques to watch its wildlife. 4 00:00:26,360 --> 00:00:30,040 But the reef has one more story to tell. 5 00:00:32,880 --> 00:00:35,560 The residents of this marine paradise 6 00:00:35,560 --> 00:00:39,600 have seen their habitat change rapidly within the last few decades. 7 00:00:41,240 --> 00:00:43,640 And time is running out for them. 8 00:00:48,280 --> 00:00:51,760 The Barrier Reef is facing one of the most serious challenges 9 00:00:51,760 --> 00:00:54,160 to its continued existence - 10 00:00:54,160 --> 00:00:56,080 the effect of human beings. 11 00:00:57,920 --> 00:00:59,640 But there is hope. 12 00:01:01,520 --> 00:01:04,440 This time, our research vessel, the Alucia, 13 00:01:04,440 --> 00:01:07,120 will be taking me to meet teams of scientists 14 00:01:07,120 --> 00:01:10,680 who are developing new ways to try and save it. 15 00:01:11,960 --> 00:01:14,720 And I'll be going to its deepest parts, 16 00:01:14,720 --> 00:01:16,720 where new discoveries are being made 17 00:01:16,720 --> 00:01:19,440 that might hold clues to its survival. 18 00:01:19,440 --> 00:01:22,720 Nobody has ever dived as deep as this before 19 00:01:22,720 --> 00:01:24,240 on the Great Barrier Reef. 20 00:01:26,240 --> 00:01:31,120 This is one of the greatest and most important ecosystems on the planet - 21 00:01:31,120 --> 00:01:34,000 and what happens here affects us all. 22 00:01:35,480 --> 00:01:39,240 So, what does the future hold for this complex wonder? 23 00:01:51,320 --> 00:01:54,160 I'm travelling along Australia's north east coast 24 00:01:54,160 --> 00:01:55,880 to look at one of the greatest 25 00:01:55,880 --> 00:01:59,600 and most splendid natural treasures that the world possesses - 26 00:01:59,600 --> 00:02:02,480 a chain of tropical islands and coral reefs 27 00:02:02,480 --> 00:02:05,760 that lies between the coast and the open ocean. 28 00:02:12,360 --> 00:02:15,480 I will never forget the first time I came here. 29 00:02:18,880 --> 00:02:20,920 YOUNGER DAVID: 'And what a world this was - 30 00:02:20,920 --> 00:02:23,800 'beneath me lay an endless landscape of coral, 31 00:02:23,800 --> 00:02:26,800 'of every conceivable colour and shape.' 32 00:02:38,400 --> 00:02:42,720 It was unimaginable then to think that we might ever lose the reef. 33 00:02:47,240 --> 00:02:51,160 But now, I've returned, and I can see that the reef is changing. 34 00:02:54,600 --> 00:02:58,880 In the last 30 years, almost half the coral has disappeared. 35 00:03:02,480 --> 00:03:06,680 The greatest concern now is that we might lose the reef altogether. 36 00:03:17,120 --> 00:03:20,280 Parts of the Great Barrier Reef still remain a mystery. 37 00:03:20,280 --> 00:03:22,760 Its immense size and remote depths 38 00:03:22,760 --> 00:03:25,680 make it extremely difficult to explore. 39 00:03:29,600 --> 00:03:32,920 But today, exciting new technology has made it possible 40 00:03:32,920 --> 00:03:37,320 to survey the entire reef from top to bottom. 41 00:03:37,320 --> 00:03:40,120 And that is revealing extraordinary things 42 00:03:40,120 --> 00:03:43,720 about the way in which the reef itself has evolved over time. 43 00:03:45,720 --> 00:03:47,800 By looking into the reef's past, 44 00:03:47,800 --> 00:03:50,640 we may discover something about its future. 45 00:03:52,360 --> 00:03:56,000 So, I'm meeting marine geologist Dr Robin Beaman. 46 00:03:58,600 --> 00:04:00,520 'He is on board the Alucia 47 00:04:00,520 --> 00:04:03,600 'and shows me some of his remarkable discoveries.' 48 00:04:04,960 --> 00:04:08,080 This is a depth model of the Great Barrier Reef - 49 00:04:08,080 --> 00:04:10,160 of the entire Great Barrier Reef. 50 00:04:10,160 --> 00:04:12,600 And there's a whole lot of different tools we use, 51 00:04:12,600 --> 00:04:14,920 the main one being multibeam echosounders, 52 00:04:14,920 --> 00:04:17,440 so it gives you a scan of the seafloor 53 00:04:17,440 --> 00:04:22,040 and we can actually map great areas of the continental shelf. 54 00:04:22,040 --> 00:04:24,360 This white part is land? 55 00:04:24,360 --> 00:04:25,520 That's right. 56 00:04:25,520 --> 00:04:30,160 So, everything that's coloured rainbow colours is under water. 57 00:04:30,160 --> 00:04:33,920 'By combining computer modelling and deep sea surveying, 58 00:04:33,920 --> 00:04:36,160 'Beaman has discovered new evidence 59 00:04:36,160 --> 00:04:39,600 'that the reef has already experienced great changes.' 60 00:04:42,160 --> 00:04:44,240 As a scientist - as geological scientists - 61 00:04:44,240 --> 00:04:46,560 we're trying to understand how the Great Barrier Reef 62 00:04:46,560 --> 00:04:48,600 has responded to changes in the past 63 00:04:48,600 --> 00:04:51,640 and there are clues there as to what the Great Barrier Reef has done, 64 00:04:51,640 --> 00:04:55,400 so if I zoom back, you can see, geologically, 65 00:04:55,400 --> 00:04:57,880 it's gone through some dramatic changes. 66 00:05:01,320 --> 00:05:05,280 Beaman's scans showed traces of an ancient reef 67 00:05:05,280 --> 00:05:08,080 that thrived over the last half million years 68 00:05:08,080 --> 00:05:11,760 and is now hidden along the edge of this great drop-off. 69 00:05:14,120 --> 00:05:18,200 This earlier reef existed long before the one we know today. 70 00:05:18,200 --> 00:05:20,840 It lay up to 70 metres deep 71 00:05:20,840 --> 00:05:24,600 and stretched nearly unbroken for more than 500 miles. 72 00:05:27,520 --> 00:05:30,920 It's been described as the world's largest fossil. 73 00:05:33,000 --> 00:05:36,360 This is what the older Great Barrier Reef looked like. 74 00:05:36,360 --> 00:05:38,200 And we call these "drowned reefs" - 75 00:05:38,200 --> 00:05:41,160 they're drowned in the sense that the water over them is so deep 76 00:05:41,160 --> 00:05:43,000 that the reef no longer grows. 77 00:05:45,160 --> 00:05:48,320 These ancient reefs were drowned by dramatic climate changes 78 00:05:48,320 --> 00:05:50,480 that caused sea levels to rise. 79 00:05:52,160 --> 00:05:55,280 This last happened less than 14,000 years ago. 80 00:05:56,920 --> 00:06:00,000 So, water released from the melting icecaps 81 00:06:00,000 --> 00:06:03,560 - is going to start flooding across here, is it? - That's right. 82 00:06:03,560 --> 00:06:06,320 The sea level was high enough to actually inundate 83 00:06:06,320 --> 00:06:08,760 and cover these old limestone hills 84 00:06:08,760 --> 00:06:12,080 and created the Great Barrier Reef that we know today. 85 00:06:12,080 --> 00:06:15,040 So, the changes that we're seeing going on now 86 00:06:15,040 --> 00:06:18,080 are nothing new, in terms of change. 87 00:06:18,080 --> 00:06:21,400 I mean, the Barrier Reef has always been changing. 88 00:06:21,400 --> 00:06:23,000 We do find it's quite robust. 89 00:06:23,000 --> 00:06:24,880 It has actually reformed, 90 00:06:24,880 --> 00:06:30,160 despite these catastrophic changes that have occurred. 91 00:06:31,320 --> 00:06:36,360 It's been exposed and flooded at least four times that we know of. 92 00:06:36,360 --> 00:06:38,200 To us, it's astounding. 93 00:06:41,480 --> 00:06:44,960 This new insight into the ancient history of the reef 94 00:06:44,960 --> 00:06:48,560 shows that, given enough time, it can regenerate. 95 00:06:53,080 --> 00:06:56,200 It seems that if seawater is clear and warm, 96 00:06:56,200 --> 00:06:58,960 simple organisms will eventually evolve 97 00:06:58,960 --> 00:07:01,680 that can build limestone homes to protect themselves 98 00:07:01,680 --> 00:07:03,600 from the waves and their enemies. 99 00:07:05,800 --> 00:07:10,280 But most of these events started long before human beings appeared on Earth 100 00:07:10,280 --> 00:07:13,000 and took many thousands of years to complete. 101 00:07:16,160 --> 00:07:20,040 We now know the reef has dwindled and recovered 102 00:07:20,040 --> 00:07:23,000 many times in its long history, 103 00:07:23,000 --> 00:07:27,920 but it also has to withstand a major change every 24 hours, 104 00:07:27,920 --> 00:07:30,960 as the tide retreats and comes back. 105 00:07:35,480 --> 00:07:38,800 At low tide, the water drains away very quickly, 106 00:07:38,800 --> 00:07:42,520 leaving the topmost community of creatures dangerously exposed. 107 00:07:48,240 --> 00:07:50,600 Some are washed out with the tide. 108 00:07:56,880 --> 00:07:58,640 Others swim to safety. 109 00:08:01,160 --> 00:08:03,600 But the coral polyps can't move. 110 00:08:08,160 --> 00:08:10,560 Temperatures on the surface of the reef 111 00:08:10,560 --> 00:08:13,560 can now reach a scorching 30 degrees centigrade. 112 00:08:16,520 --> 00:08:19,160 The exposed corals could easily dry out 113 00:08:19,160 --> 00:08:22,160 and be damaged by intense ultraviolet rays. 114 00:08:24,440 --> 00:08:27,320 But corals have ways of protecting themselves. 115 00:08:29,520 --> 00:08:33,360 When exposed to air, they produce huge amounts of mucus, 116 00:08:33,360 --> 00:08:36,360 which keeps them wet and acts like a sunscreen. 117 00:08:38,400 --> 00:08:43,080 This remarkable slime actually increases its UV resistance, 118 00:08:43,080 --> 00:08:45,800 becoming stronger if the temperatures soar. 119 00:08:47,680 --> 00:08:52,440 So, the coral manages to survive for the few hours that it's out of water. 120 00:08:55,880 --> 00:09:00,480 But there's one fish that manages to turn this exposure to its advantage. 121 00:09:13,080 --> 00:09:18,160 The epaulette shark remains on the reef even when the tide goes out. 122 00:09:18,160 --> 00:09:20,480 Of course, with so little water, 123 00:09:20,480 --> 00:09:23,360 it doesn't get as much oxygen as it requires normally, 124 00:09:23,360 --> 00:09:27,920 but it deals with that possibility by shutting off a part of its brain 125 00:09:27,920 --> 00:09:30,280 and so, reducing its oxygen demands. 126 00:09:31,800 --> 00:09:35,760 As the retreating tide exposes the topmost branches of the corals, 127 00:09:35,760 --> 00:09:39,960 the shark remains in the little pools between them for as long as it can. 128 00:09:42,480 --> 00:09:46,640 And then, it sets off to try and find food - 129 00:09:46,640 --> 00:09:51,560 shrimps, crabs and small worms that live on the reef. 130 00:09:51,560 --> 00:09:55,720 And it does that by exploiting another talent it has. 131 00:09:55,720 --> 00:09:57,760 It can, in effect, walk. 132 00:10:10,640 --> 00:10:14,560 It may be slow-going, but the little shark manages to make its way 133 00:10:14,560 --> 00:10:18,800 between the rocky pools to look for prey that may be imprisoned in them. 134 00:10:26,760 --> 00:10:28,480 It has the run of the place, 135 00:10:28,480 --> 00:10:31,920 until the tide returns once more to flood the reeftop. 136 00:10:46,440 --> 00:10:50,200 So, the inhabitants of the reef, each in its own way, 137 00:10:50,200 --> 00:10:53,560 deal with the daily hazards brought by exposure. 138 00:11:00,160 --> 00:11:03,600 But there is one catastrophe that can strike each year 139 00:11:03,600 --> 00:11:05,800 against which there is no defence. 140 00:11:14,040 --> 00:11:15,840 From November onwards, 141 00:11:15,840 --> 00:11:18,760 warm, moisture-laden winds from the northwest 142 00:11:18,760 --> 00:11:22,000 sweep down across these tropic seas 143 00:11:22,000 --> 00:11:24,560 and it's then that cyclones form. 144 00:11:27,840 --> 00:11:32,520 They are, in fact, the biggest killers of the reef's corals. 145 00:11:34,000 --> 00:11:38,680 But that doesn't mean that the corals are permanently destroyed. 146 00:11:38,680 --> 00:11:41,720 Their resilience once more comes apparent. 147 00:11:45,920 --> 00:11:49,000 And there's an extraordinary example of that 148 00:11:49,000 --> 00:11:51,080 in the most unlikely of places. 149 00:12:07,560 --> 00:12:11,040 This is the wreck of the SS Yongala. 150 00:12:14,440 --> 00:12:17,440 It was sunk by a cyclone in 1911. 151 00:12:23,040 --> 00:12:27,840 It lies 30 metres below the surface on a barren, sandy plain... 152 00:12:31,520 --> 00:12:34,920 ..miles away from any natural coral reefs. 153 00:12:39,520 --> 00:12:42,360 By the time it was discovered, decades later, 154 00:12:42,360 --> 00:12:44,720 it had become an artificial reef... 155 00:12:47,200 --> 00:12:51,240 ..and had been colonised by an extraordinary variety of life. 156 00:12:57,320 --> 00:13:00,200 It was an oasis in the featureless ocean. 157 00:13:16,520 --> 00:13:18,800 But in the century since it sank, 158 00:13:18,800 --> 00:13:22,560 the wreck has been hit repeatedly by more cyclones. 159 00:13:27,040 --> 00:13:29,560 The waters here are not deep 160 00:13:29,560 --> 00:13:34,400 so the turbulence created by a cyclone can reach the sea floor. 161 00:13:43,600 --> 00:13:46,160 THUNDERCLAP 162 00:13:52,360 --> 00:13:55,000 Cyclones travelling towards the coast 163 00:13:55,000 --> 00:13:57,840 can rip up hundreds of miles of coral. 164 00:14:02,680 --> 00:14:06,440 Captain Trevor Jackson, who has been diving on this wreck for decades, 165 00:14:06,440 --> 00:14:13,000 saw the devastating effects caused in 2011 by a category five cyclone. 166 00:14:14,480 --> 00:14:16,720 Cyclone Yahtzee, a massive system, 167 00:14:16,720 --> 00:14:19,040 crossed the coast just north of here. 168 00:14:19,040 --> 00:14:20,480 The cyclone was so large, 169 00:14:20,480 --> 00:14:23,560 it generated waves that exposed the top of the Yongala. 170 00:14:28,920 --> 00:14:31,640 THUNDERCLAP 171 00:14:40,400 --> 00:14:42,120 There was a lifting action... 172 00:14:45,120 --> 00:14:46,720 ..and in the process, 173 00:14:46,720 --> 00:14:49,800 this scoured the top of the reef of all marine life. 174 00:15:01,320 --> 00:15:06,320 What was once a thriving ecosystem was now an almost bare skeleton. 175 00:15:10,920 --> 00:15:13,640 But amazingly, the reef on the Yongala 176 00:15:13,640 --> 00:15:16,400 began to repair itself within months. 177 00:15:21,720 --> 00:15:23,880 Green algae appeared on the wreck. 178 00:15:25,280 --> 00:15:28,800 Barnacles followed, allowing corals to get a grip. 179 00:15:36,040 --> 00:15:39,920 And soon, a new community had established itself. 180 00:16:05,160 --> 00:16:08,320 One of the things that makes the Yongala so unique 181 00:16:08,320 --> 00:16:12,920 is the way it rejuvenates itself after a major weather event. 182 00:16:12,920 --> 00:16:15,160 In the course of the last four or five years, 183 00:16:15,160 --> 00:16:17,600 about 80% of the reef has re-grown. 184 00:16:26,160 --> 00:16:30,440 The story of the Yongala shows that a coral reef can, remarkably, 185 00:16:30,440 --> 00:16:32,920 recover from natural disaster. 186 00:16:43,520 --> 00:16:46,560 And such recovery can be surprisingly quick 187 00:16:46,560 --> 00:16:49,040 when a reef is healthy and in balance. 188 00:16:52,040 --> 00:16:55,880 Most of the reef's inhabitants depend on one another for survival. 189 00:17:12,080 --> 00:17:15,480 But it is the coral that is the foundation of the reef 190 00:17:15,480 --> 00:17:19,600 and it plays a crucial role in many of the relationships. 191 00:17:28,880 --> 00:17:32,600 This is the crown-of-thorns starfish. 192 00:17:34,440 --> 00:17:37,080 For it, coral is food 193 00:17:37,080 --> 00:17:40,320 and it will eat relentlessly if not kept in check. 194 00:17:41,480 --> 00:17:43,920 But to other creatures, like the guard crab, 195 00:17:43,920 --> 00:17:45,640 coral is home. 196 00:17:50,920 --> 00:17:53,840 The crab is prepared to defend its patch 197 00:17:53,840 --> 00:17:57,040 from the carnivorous starfish at all costs. 198 00:18:02,000 --> 00:18:03,680 The crown-of-thorns, however, 199 00:18:03,680 --> 00:18:06,680 is much larger than most other starfish on the reef, 200 00:18:06,680 --> 00:18:11,080 so the tiny crab is forced to take a more stealthy approach. 201 00:18:15,600 --> 00:18:19,640 Hidden within the coral, it waits for its moment to attack. 202 00:18:34,200 --> 00:18:37,960 The starfish has left itself dangerously exposed, 203 00:18:37,960 --> 00:18:40,160 but the crab is cautious. 204 00:18:44,920 --> 00:18:47,760 When it can, the crab uses its powerful pincers 205 00:18:47,760 --> 00:18:51,960 to snip at the starfish's spines and tube-like feet... 206 00:19:04,960 --> 00:19:08,360 ..before retreating back into the safety of the coral. 207 00:19:10,200 --> 00:19:12,400 The crab has won this battle. 208 00:19:15,040 --> 00:19:17,600 But recently, something has changed 209 00:19:17,600 --> 00:19:19,600 and the balance has been upset. 210 00:19:23,560 --> 00:19:26,960 The number of crown-of-thorns has increased dramatically 211 00:19:26,960 --> 00:19:29,720 and they've become a big problem on the reef. 212 00:19:35,640 --> 00:19:37,280 To find out more, 213 00:19:37,280 --> 00:19:41,880 the Alucia is taking me to a research station in the far north of the reef. 214 00:19:50,800 --> 00:19:55,560 It's situated on Lizard Island, where we can observe this problem up close. 215 00:20:00,960 --> 00:20:04,360 Lizard is surrounded by some of the most spectacular reefs 216 00:20:04,360 --> 00:20:06,080 on the entire barrier. 217 00:20:07,840 --> 00:20:11,920 But they are under attack from the coral-eating starfish. 218 00:20:13,560 --> 00:20:16,000 And at the island's research station, 219 00:20:16,000 --> 00:20:20,120 they've been studying why we might be seeing more of them than we used to. 220 00:20:29,840 --> 00:20:32,040 They have an extraordinary ability 221 00:20:32,040 --> 00:20:37,600 to suddenly increase vastly in numbers, like a plague. 222 00:20:37,600 --> 00:20:41,800 There have been three such plagues since the 1960s 223 00:20:41,800 --> 00:20:43,200 and, unfortunately, 224 00:20:43,200 --> 00:20:46,640 it seems as though we're in the middle, now, of a fourth. 225 00:20:48,280 --> 00:20:52,240 You might think that these plagues are just another natural disaster 226 00:20:52,240 --> 00:20:55,360 that the reef has had to withstand, like cyclones. 227 00:20:55,360 --> 00:20:58,120 There are reasons to suppose that, in fact, 228 00:20:58,120 --> 00:21:01,720 the plagues have been affected by human activity - 229 00:21:01,720 --> 00:21:06,640 either through an accumulation of run-off of fertilisers from the land 230 00:21:06,640 --> 00:21:10,520 that creates more food for the young starfish, 231 00:21:10,520 --> 00:21:12,520 or because we have overfished 232 00:21:12,520 --> 00:21:15,440 and so destroyed the natural balance of the reef. 233 00:21:16,920 --> 00:21:20,040 The starfish outbreaks have been responsible 234 00:21:20,040 --> 00:21:23,760 for over 40% of the coral loss of the last 30 years. 235 00:21:24,880 --> 00:21:29,520 It's just one of the huge changes here witnessed by Dr Charlie Veron. 236 00:21:31,080 --> 00:21:33,560 In 1972, Charlie was appointed 237 00:21:33,560 --> 00:21:37,440 the reef's first full-time coral scientist. 238 00:21:37,440 --> 00:21:40,640 He's gone on to become a world authority on coral 239 00:21:40,640 --> 00:21:43,920 and has identified a third of the world's known species. 240 00:21:45,280 --> 00:21:49,680 He was one of the first scientists to spend time in this underwater world 241 00:21:49,680 --> 00:21:52,720 and that was due to a particular piece of technology. 242 00:21:54,400 --> 00:21:58,640 What we knew about corals at the beginning of the scuba era 243 00:21:58,640 --> 00:22:00,680 was just almost nothing. 244 00:22:00,680 --> 00:22:03,680 So, scuba gear must have changed things radically. 245 00:22:03,680 --> 00:22:05,040 It changed everything. 246 00:22:05,040 --> 00:22:07,760 When you went down the face of a coral reef, 247 00:22:07,760 --> 00:22:11,680 you could see how corals fed, how they fought each other, 248 00:22:11,680 --> 00:22:13,400 how they reproduced and still, 249 00:22:13,400 --> 00:22:15,720 we're only just scratching the surface. 250 00:22:15,720 --> 00:22:18,040 Think of all the things that happen in a rainforest, 251 00:22:18,040 --> 00:22:19,440 how much we know about it. 252 00:22:19,440 --> 00:22:22,840 We haven't got a thousandth part of that information on the coral reef yet. 253 00:22:22,840 --> 00:22:25,160 'But since Charlie's first discoveries, 254 00:22:25,160 --> 00:22:27,760 'the reef has altered dramatically.' 255 00:22:27,760 --> 00:22:33,280 I've been going back to the same spots 10, 20, 30, 40 years ago 256 00:22:33,280 --> 00:22:36,000 and every time I go back, 257 00:22:36,000 --> 00:22:39,800 I'm sickened by some of the changes I've seen. 258 00:22:39,800 --> 00:22:42,240 Sometimes, I go back, I know it's the same spot 259 00:22:42,240 --> 00:22:43,960 and I can barely recognise it. 260 00:22:43,960 --> 00:22:46,240 Some species have been wiped out in the shallows now. 261 00:22:46,240 --> 00:22:48,480 It's already happened. 262 00:22:50,000 --> 00:22:54,320 What Charlie had witnessed were the effects of mankind upon the reef. 263 00:22:58,440 --> 00:23:03,520 When I myself first visited the Queensland coast almost 60 years ago, 264 00:23:03,520 --> 00:23:05,240 it was very different. 265 00:23:14,440 --> 00:23:17,600 Since then, like many coastlines around the world, 266 00:23:17,600 --> 00:23:20,480 there has been a massive increase in population 267 00:23:20,480 --> 00:23:22,880 and an explosion of industry. 268 00:23:37,560 --> 00:23:42,800 By 1975, the reef had been declared a National Marine Park. 269 00:23:42,800 --> 00:23:46,240 It was the biggest one of its kind in the world. 270 00:23:46,240 --> 00:23:49,760 But then, a new threat began to be recognised - 271 00:23:49,760 --> 00:23:53,480 not only to the reef, but to the world's oceans - 272 00:23:53,480 --> 00:23:54,960 climate change. 273 00:23:56,440 --> 00:24:00,000 THUNDERCLAPS 274 00:24:02,560 --> 00:24:06,400 There is more carbon dioxide in our atmosphere now 275 00:24:06,400 --> 00:24:09,600 than there has been in 800,000 years. 276 00:24:12,400 --> 00:24:15,560 Industrialised nations have been burning fossil fuels 277 00:24:15,560 --> 00:24:17,560 at an alarming rate. 278 00:24:19,320 --> 00:24:22,120 Global warming is slowly heating up our planet 279 00:24:22,120 --> 00:24:24,880 and threatens to cause huge problems for us all. 280 00:24:27,360 --> 00:24:32,800 Around 30% of the carbon dioxide we produce is absorbed by the ocean. 281 00:24:35,960 --> 00:24:39,200 As a result, we're seeing an increase in the temperature 282 00:24:39,200 --> 00:24:40,840 and acidity of our seas. 283 00:24:43,440 --> 00:24:46,720 Both are killing the inhabitants of the reef. 284 00:24:51,960 --> 00:24:54,160 But how quickly is it being damaged? 285 00:24:57,400 --> 00:25:02,320 To find out, I'm heading to meet Professor Ove Hoegh-Guldberg 286 00:25:02,320 --> 00:25:05,840 He's studying the effects of climate change on coral. 287 00:25:10,560 --> 00:25:12,720 Ove is based on Heron Island, 288 00:25:12,720 --> 00:25:16,080 near the southern end of the Great Barrier. 289 00:25:16,080 --> 00:25:20,360 Heron is a low, sandy island, 50 miles out from the mainland, 290 00:25:20,360 --> 00:25:22,000 right on the reef itself... 291 00:25:24,800 --> 00:25:28,040 ..so its research station is very well-placed. 292 00:25:29,640 --> 00:25:32,320 Here, Ove is carrying out an experiment 293 00:25:32,320 --> 00:25:34,320 to see how the reef is going to cope. 294 00:25:35,440 --> 00:25:37,240 At the research station here, 295 00:25:37,240 --> 00:25:41,320 the experiment we're running is really climate change sped up. 296 00:25:42,440 --> 00:25:46,320 Because it's often hard for people to really get their heads around 297 00:25:46,320 --> 00:25:48,760 when you talk about global change over decades 298 00:25:48,760 --> 00:25:51,080 and what might happen to coral reefs. 299 00:25:51,080 --> 00:25:54,080 We have, essentially, in these experiments, sped things up 300 00:25:54,080 --> 00:25:56,400 so that you can literally, over a year, 301 00:25:56,400 --> 00:26:00,240 see the impacts of what might be occurring over the next hundred. 302 00:26:03,960 --> 00:26:07,200 Each of these tanks contains a miniature coral reef 303 00:26:07,200 --> 00:26:09,680 with the same species of coral. 304 00:26:09,680 --> 00:26:11,920 But each is being subjected to 305 00:26:11,920 --> 00:26:15,960 slightly different conditions of temperature and acidity - 306 00:26:15,960 --> 00:26:19,880 the two factors that are most likely to alter with climate change. 307 00:26:24,760 --> 00:26:29,040 Using these tanks, scientists have shown that increasing acidity 308 00:26:29,040 --> 00:26:32,720 restricts hard corals from building their limestone skeletons. 309 00:26:35,920 --> 00:26:37,840 And a rise in temperature - 310 00:26:37,840 --> 00:26:40,400 a single degree centigrade warmer than normal - 311 00:26:40,400 --> 00:26:42,960 can cause corals to become so stressed 312 00:26:42,960 --> 00:26:45,920 that they eject the photosynthesising algae 313 00:26:45,920 --> 00:26:48,640 that enable them to grow and give some colour. 314 00:26:53,840 --> 00:26:57,040 So they bleach, turning ghostly white. 315 00:27:07,400 --> 00:27:09,160 If you go back in time, 316 00:27:09,160 --> 00:27:13,920 you can see the big swings between ice ages and the warm periods 317 00:27:13,920 --> 00:27:16,360 where the Great Barrier Reef disappears and regrows 318 00:27:16,360 --> 00:27:18,960 and that's happened numerous times. 319 00:27:18,960 --> 00:27:21,120 So, we've always had changes, 320 00:27:21,120 --> 00:27:25,680 but we're talking about changes over 10,000 years, in those cases. 321 00:27:25,680 --> 00:27:29,840 But we're now seeing is the equivalent in a few decades. 322 00:27:29,840 --> 00:27:32,960 And that, of course, is stretching life's capacity to keep up. 323 00:27:39,480 --> 00:27:44,240 Organisms, ecosystems are falling behind as the world changes, 324 00:27:44,240 --> 00:27:47,800 faster than it has in this enormous amount of time. 325 00:27:53,040 --> 00:27:58,000 It's been shown here that a rise of just two degrees centigrade 326 00:27:58,000 --> 00:28:01,120 will turn a healthy reef into a decimated one. 327 00:28:02,440 --> 00:28:06,120 And such a rise will almost certainly happen in these seas 328 00:28:06,120 --> 00:28:09,040 if we continue to do what we are doing. 329 00:28:19,480 --> 00:28:21,800 As Ove's tests suggest, 330 00:28:21,800 --> 00:28:24,440 this man-made problem has reached the point 331 00:28:24,440 --> 00:28:26,880 where it needs a man-made solution. 332 00:28:31,000 --> 00:28:33,160 I'm returning to mainland Australia 333 00:28:33,160 --> 00:28:36,080 to meet the scientists who are approaching this problem 334 00:28:36,080 --> 00:28:37,920 in a radically new way. 335 00:28:39,960 --> 00:28:44,240 The Australian Institute of Marine Science, AIMS, 336 00:28:44,240 --> 00:28:47,760 is based in northeast Queensland, right on the coast. 337 00:28:51,000 --> 00:28:55,520 Here, pioneering research is pushing the boundaries of coral science. 338 00:29:00,800 --> 00:29:04,680 Over three million litres of filtered seawater 339 00:29:04,680 --> 00:29:07,360 are pumped through these tanks every day. 340 00:29:08,360 --> 00:29:11,800 So, it's possible for scientists to study the minute 341 00:29:11,800 --> 00:29:16,600 and often very complex changes that can affect coral's health. 342 00:29:20,280 --> 00:29:22,800 So, here, they're also conducting research 343 00:29:22,800 --> 00:29:25,200 to see whether it might not be possible 344 00:29:25,200 --> 00:29:29,480 to devise techniques of restoring damaged reefs back to health. 345 00:29:31,560 --> 00:29:35,800 In these tanks, they can simulate the exact conditions of the reef. 346 00:29:37,640 --> 00:29:40,560 They've been so successful that remarkably, 347 00:29:40,560 --> 00:29:44,320 the corals respond to the same astronomic and seasonal rhythms 348 00:29:44,320 --> 00:29:46,000 as those out in the ocean. 349 00:29:49,760 --> 00:29:53,800 And that is proving useful for one particular experiment. 350 00:29:56,280 --> 00:29:59,840 Corals are usually able to adapt to changing circumstances, 351 00:29:59,840 --> 00:30:01,160 given enough time. 352 00:30:05,920 --> 00:30:09,400 And that is partly due to the way they reproduce. 353 00:30:12,640 --> 00:30:14,800 After the first full moon in October, 354 00:30:14,800 --> 00:30:18,080 the great synchronised coral spawning event begins. 355 00:30:38,960 --> 00:30:42,480 It's a wonderful, annual rejuvenation. 356 00:30:48,920 --> 00:30:53,400 Hundreds of species release sperm and eggs into the ocean. 357 00:30:57,000 --> 00:31:01,080 Just as pollen from plants is blown far and wide by the wind, 358 00:31:01,080 --> 00:31:04,680 so coral spawn is swept away by the ocean currents. 359 00:31:07,560 --> 00:31:10,920 And at the same time, under the same moonlight, 360 00:31:10,920 --> 00:31:14,920 the corals will spawn here in the laboratory tanks. 361 00:31:19,160 --> 00:31:22,960 Using red light, so as not to disturb the process, 362 00:31:22,960 --> 00:31:25,480 scientists wait for the moment of release. 363 00:31:39,760 --> 00:31:41,360 And when it finally happens, 364 00:31:41,360 --> 00:31:44,600 they move fast to collect the sperm and the eggs. 365 00:31:49,280 --> 00:31:52,560 It's their one chance to get all the samples they need 366 00:31:52,560 --> 00:31:54,480 for a year's worth of research. 367 00:31:57,680 --> 00:32:00,560 But what exactly are they planning to do with them? 368 00:32:03,960 --> 00:32:08,560 Here, Dr Madeleine van Oppen has been selectively breeding them, 369 00:32:08,560 --> 00:32:13,120 using much the same techniques that we've used to produce crops on land 370 00:32:13,120 --> 00:32:16,320 that are resistant to drought and disease. 371 00:32:16,320 --> 00:32:18,840 It's the first time that selective breeding 372 00:32:18,840 --> 00:32:21,240 has been used in marine conservation. 373 00:32:25,280 --> 00:32:27,600 They release their sperm and eggs in bundles 374 00:32:27,600 --> 00:32:30,600 and those bundles float to the surface of the tank. 375 00:32:30,600 --> 00:32:34,360 We then agitate that to separate the eggs from the sperm. 376 00:32:37,360 --> 00:32:38,880 And we use that to set up 377 00:32:38,880 --> 00:32:41,960 our specific in vitro processes, basically. 378 00:32:45,840 --> 00:32:48,080 In the ocean, there is the potential 379 00:32:48,080 --> 00:32:51,280 for different species of coral to breed with each other. 380 00:32:52,480 --> 00:32:54,440 So, here, scientists wonder 381 00:32:54,440 --> 00:32:57,640 if you might be able to produce a new kind of coral 382 00:32:57,640 --> 00:33:01,320 that proves more successful in the changing waters of the reef. 383 00:33:03,000 --> 00:33:05,520 The problem that corals are facing now is that 384 00:33:05,520 --> 00:33:08,280 the change of the environment is extremely fast - 385 00:33:08,280 --> 00:33:10,080 much faster than ever recorded - 386 00:33:10,080 --> 00:33:12,360 so we need to help them a little bit in the lab. 387 00:33:12,360 --> 00:33:16,080 We need to speed up those natural processes of evolution. 388 00:33:18,400 --> 00:33:23,360 Van Oppen's aim is to use selective breeding to produce strains of coral 389 00:33:23,360 --> 00:33:27,240 that are able to withstand the worst effects of climate change... 390 00:33:29,560 --> 00:33:34,840 ..and to use them to bring life back to worst-affected part of the reef. 391 00:33:37,120 --> 00:33:39,120 Maybe in five years or so, 392 00:33:39,120 --> 00:33:42,200 we will be allowed to place those corals 393 00:33:42,200 --> 00:33:45,320 onto a real reef, a disturbed reef - 394 00:33:45,320 --> 00:33:48,000 and test it and these selectively-bred corals 395 00:33:48,000 --> 00:33:50,680 will be able to restore that reef faster. 396 00:33:51,880 --> 00:33:55,040 And you have to realise, this is really a last resort option. 397 00:33:55,040 --> 00:33:58,800 We wouldn't want to do that if the reef is able to restore itself. 398 00:34:04,160 --> 00:34:08,000 But is there a chance that the reef, damaged by our activities, 399 00:34:08,000 --> 00:34:10,720 could restore itself without our help? 400 00:34:13,240 --> 00:34:15,640 Well, we now think that there may be clues 401 00:34:15,640 --> 00:34:18,680 in the reef's most distant and mysterious regions. 402 00:34:25,920 --> 00:34:28,560 There are still parts of the Great Barrier Reef 403 00:34:28,560 --> 00:34:31,200 that are virtually unexplored. 404 00:34:31,200 --> 00:34:35,480 But today, we have got remarkable new underwater vessels, 405 00:34:35,480 --> 00:34:38,400 like this submersible, that can take us to places 406 00:34:38,400 --> 00:34:42,800 where no unprotected human being could possibly go. 407 00:34:42,800 --> 00:34:47,040 What they will find down there, nobody knows. 408 00:34:47,040 --> 00:34:49,320 But I'm lucky enough to be one of those 409 00:34:49,320 --> 00:34:51,800 who's about to go down to find out. 410 00:34:54,360 --> 00:34:56,160 At the outer edge of the reef, 411 00:34:56,160 --> 00:35:01,440 the continental shelf plunges down over 2,000 metres to the seafloor. 412 00:35:05,800 --> 00:35:09,280 The Alucia has brought us over the edge of the drop-off, 413 00:35:09,280 --> 00:35:12,000 90 miles out into the Coral Sea... 414 00:35:15,360 --> 00:35:17,600 ..out to Osprey Reef. 415 00:35:19,920 --> 00:35:23,960 Here at Osprey, this sheer vertical drop of the seafloor 416 00:35:23,960 --> 00:35:26,960 enables us to see corals at a variety of depths. 417 00:35:28,480 --> 00:35:31,440 Between 100 and 150 metres down, 418 00:35:31,440 --> 00:35:33,760 daylight is reduced to a glimmer. 419 00:35:33,760 --> 00:35:36,840 This is the mesophotic zone. 420 00:35:36,840 --> 00:35:40,280 Here, a mysterious community of corals is thriving, 421 00:35:40,280 --> 00:35:43,360 despite the damage being done to the reef above. 422 00:35:43,360 --> 00:35:46,240 The Great Barrier Reef, it's a marvel beyond marvels. 423 00:35:46,240 --> 00:35:51,480 It's a million species living in this symbiotic tangle, 424 00:35:51,480 --> 00:35:53,040 half of which we don't know. 425 00:35:53,040 --> 00:35:55,600 I mean, when you get to mesophotic depths, 426 00:35:55,600 --> 00:35:58,080 we know very few of the species down there. 427 00:35:58,080 --> 00:36:01,560 It literally is one of the last frontiers of biology, 428 00:36:01,560 --> 00:36:03,160 to understand this system. 429 00:36:06,520 --> 00:36:09,760 Scientists are now beginning to wonder if these corals 430 00:36:09,760 --> 00:36:14,000 might have the potential to restore the damaged parts of the reef. 431 00:36:15,280 --> 00:36:17,480 - RADIO: - '..Down about 100 metres...' 432 00:36:23,440 --> 00:36:25,400 Our state-of-the-art submersible 433 00:36:25,400 --> 00:36:29,280 is going to take me to see these deep corals for myself 434 00:36:29,280 --> 00:36:31,040 and even bring back a sample. 435 00:36:36,280 --> 00:36:38,320 Nadir in position. 436 00:36:38,320 --> 00:36:40,440 Are we clear to vent? 437 00:36:40,440 --> 00:36:43,360 You are clear to vent, clear to vent. 438 00:36:43,360 --> 00:36:45,000 Roger. Venting now. 439 00:36:57,360 --> 00:37:00,800 We are descending into the twilight zone. 440 00:37:07,840 --> 00:37:10,440 As we drop down the face of the reef, 441 00:37:10,440 --> 00:37:12,560 the light begins to dim. 442 00:37:21,040 --> 00:37:23,360 At about 100 metres, 443 00:37:23,360 --> 00:37:26,440 we enter the mesophotic zone. 444 00:37:26,440 --> 00:37:29,560 "Mesophotic" literally means "middle light". 445 00:37:32,040 --> 00:37:35,320 The corals here are beginning to look very different. 446 00:37:37,760 --> 00:37:40,360 Despite the apparent lack of light down here, 447 00:37:40,360 --> 00:37:44,000 there's still enough for some corals to photosynthesise, 448 00:37:44,000 --> 00:37:46,960 just like their relations closer to the surface. 449 00:37:46,960 --> 00:37:50,760 And to do that, they've formed these flat, broad plates 450 00:37:50,760 --> 00:37:53,200 to collect what little light there is. 451 00:37:57,800 --> 00:38:02,400 Mesophotic corals lie mostly out of reach of cyclones and bleaching. 452 00:38:04,800 --> 00:38:08,000 So, one of the big questions facing scientists is, 453 00:38:08,000 --> 00:38:13,200 could these deeper corals naturally repopulate the damaged reefs above? 454 00:38:24,440 --> 00:38:27,960 We've now passed beyond the mesophotic zone. 455 00:38:31,120 --> 00:38:33,640 The light begins to disappear completely 456 00:38:33,640 --> 00:38:36,240 and the reef changes again. 457 00:38:47,920 --> 00:38:50,960 Most of the light that filters down from above 458 00:38:50,960 --> 00:38:53,840 comes from the blue end of the spectrum, 459 00:38:53,840 --> 00:38:58,280 so the rock surface ahead of me looks very dull. 460 00:38:58,280 --> 00:39:01,560 But turn on the lights and it looks very different. 461 00:39:25,720 --> 00:39:27,720 Despite their remoteness, 462 00:39:27,720 --> 00:39:30,680 these strange relatives of reef-building corals 463 00:39:30,680 --> 00:39:33,080 are still part of the great reef system. 464 00:39:35,080 --> 00:39:38,960 To understand how they're connected, we need to study them closely. 465 00:39:41,080 --> 00:39:44,920 So, this seems an excellent place to collect a sample. 466 00:39:47,280 --> 00:39:51,800 But manoeuvring our eight-tonne submersible close to the rock face 467 00:39:51,800 --> 00:39:53,440 is a delicate operation. 468 00:40:12,400 --> 00:40:14,200 Oh, that's great. 469 00:40:22,800 --> 00:40:26,000 The chances are that this could well be a species 470 00:40:26,000 --> 00:40:28,000 that no-one has ever seen before. 471 00:40:31,440 --> 00:40:34,240 But things don't go quite to plan. 472 00:40:36,960 --> 00:40:39,720 - Oh, no! - We're going to have to go and fetch that. 473 00:40:52,680 --> 00:40:54,120 There it is. 474 00:41:08,120 --> 00:41:09,560 Oh, terrific! 475 00:41:14,160 --> 00:41:15,720 Success! 476 00:41:25,360 --> 00:41:28,560 As we descend past the 200 metre mark, 477 00:41:28,560 --> 00:41:32,200 the coral finally begins to disappear altogether. 478 00:41:37,640 --> 00:41:39,760 Surface, surface, Nadir. 479 00:41:39,760 --> 00:41:44,200 My depth now, 300 metres. Over. 480 00:41:45,480 --> 00:41:50,160 At this depth, the pressure bearing down on the submersible's sphere 481 00:41:50,160 --> 00:41:53,000 is more than 30 times that at the surface. 482 00:41:55,040 --> 00:41:59,240 That's an incredible 450 pounds per square inch. 483 00:42:03,480 --> 00:42:06,680 Here, there's a sediment that is drifting down from above, 484 00:42:06,680 --> 00:42:09,240 cloaking the surface of the reef. 485 00:42:09,240 --> 00:42:11,920 That means it's very difficult for any organism 486 00:42:11,920 --> 00:42:16,280 to get a hold of the rock, because it's continually being swept down. 487 00:42:16,280 --> 00:42:21,920 The sediment itself is the result of the erosion of the coral skeletons from high above, 488 00:42:21,920 --> 00:42:25,240 but also from the remains of coral 489 00:42:25,240 --> 00:42:28,360 that parrot fish have munched and excreted 490 00:42:28,360 --> 00:42:30,880 and it's slowly drifting down here. 491 00:42:30,880 --> 00:42:34,280 So, this is so deep, it's almost barren. 492 00:42:44,480 --> 00:42:46,200 But not quite. 493 00:42:48,760 --> 00:42:51,480 At almost the deepest point of our dive, 494 00:42:51,480 --> 00:42:53,440 something pays us a visit. 495 00:42:56,760 --> 00:42:59,840 There's a fish to your right, David. On your shoulder. 496 00:42:59,840 --> 00:43:01,360 Look at this! 497 00:43:07,000 --> 00:43:09,520 It's a deep-water grouper. 498 00:43:09,520 --> 00:43:13,720 No-one has ever seen them up close like this, at this depth. 499 00:43:21,200 --> 00:43:24,840 'It appears to find the sub and its occupants fascinating.' 500 00:43:27,040 --> 00:43:30,360 And he's big, this boy. He must be... 501 00:43:32,600 --> 00:43:35,720 ..four, five feet long - a couple of metres, almost. 502 00:43:38,520 --> 00:43:39,680 Hello. 503 00:43:39,680 --> 00:43:41,040 Oh, gosh! 504 00:43:45,800 --> 00:43:49,200 And why he is down here, what he's looking for - who knows? 505 00:43:56,960 --> 00:43:58,160 He's going up. 506 00:44:00,000 --> 00:44:01,320 So are we. 507 00:44:11,600 --> 00:44:16,320 As we ascend, light and colour returns to the reef around us. 508 00:44:58,400 --> 00:45:02,240 'Our on-board reef scientist, Professor Justin Marshall, 509 00:45:02,240 --> 00:45:05,840 'is on hand to retrieve the sample we gathered in the darkness.' 510 00:45:05,840 --> 00:45:08,440 - What do you reckon? - Well, it's fantastic. 511 00:45:08,440 --> 00:45:12,320 This is one of the deepest samples ever from Osprey Reef. 512 00:45:12,320 --> 00:45:14,840 - It's wonderful. - Will it survive? Will it still live? 513 00:45:14,840 --> 00:45:17,280 It will still live and we'll take samples back 514 00:45:17,280 --> 00:45:20,720 - to the University of Queensland and work on it there. - Great. 515 00:45:22,600 --> 00:45:25,800 In fact, they think this coral has never been reported 516 00:45:25,800 --> 00:45:29,120 in this part of the world before and may be new to science. 517 00:45:33,720 --> 00:45:36,520 We are a long way off from having a solution 518 00:45:36,520 --> 00:45:39,680 to the threats which now face the Great Barrier Reef. 519 00:45:41,720 --> 00:45:43,600 But in these deep water samples 520 00:45:43,600 --> 00:45:46,680 and in the scientists' experimental tanks, 521 00:45:46,680 --> 00:45:48,600 there is a small glimmer of hope. 522 00:45:51,200 --> 00:45:53,520 But time is not on our side -... 523 00:45:57,520 --> 00:46:01,280 ..an opinion shared by many of the scientists I've met along the way. 524 00:46:05,880 --> 00:46:08,360 Are you fearful for the future of the reef? 525 00:46:08,360 --> 00:46:10,000 There will be change, for sure. 526 00:46:10,000 --> 00:46:14,800 I mean, we're seeing change within our own human lives' timescales now. 527 00:46:14,800 --> 00:46:16,600 And what's your prediction about 528 00:46:16,600 --> 00:46:19,800 what it's going to look like in another hundred years? 529 00:46:19,800 --> 00:46:21,720 The sea levels will be higher. 530 00:46:21,720 --> 00:46:24,520 We want to know - as a scientist, we want to know 531 00:46:24,520 --> 00:46:26,920 how the Great Barrier Reef will respond. 532 00:46:26,920 --> 00:46:30,640 Whether it has the resilience to bounce back 533 00:46:30,640 --> 00:46:35,240 with the future changes to the climate remains to be seen. 534 00:46:39,880 --> 00:46:41,480 Here on the Great Barrier Reef, 535 00:46:41,480 --> 00:46:45,160 we've lost about 50% of the coral since the early 1980s. 536 00:46:47,280 --> 00:46:51,480 Coral provides a habitat for over a million species. 537 00:46:51,480 --> 00:46:54,720 This is such a fundamental part of our oceans 538 00:46:54,720 --> 00:46:57,640 and the fact that it's going to disappear on our watch, 539 00:46:57,640 --> 00:46:58,840 it's incredible. 540 00:47:16,440 --> 00:47:20,160 When the Great Barrier Reef starts to go seriously backwards, 541 00:47:20,160 --> 00:47:21,960 the next generation is going to say, 542 00:47:21,960 --> 00:47:25,760 "Why didn't you guys do something about it when you had a chance?" 543 00:47:25,760 --> 00:47:27,720 And well may they ask that 544 00:47:27,720 --> 00:47:30,840 because we're not doing what we should be doing 545 00:47:30,840 --> 00:47:32,880 and we're going to pay the price. 546 00:47:51,000 --> 00:47:54,400 The Great Barrier Reef is in grave danger. 547 00:47:54,400 --> 00:47:57,560 The twin perils brought by climate change 548 00:47:57,560 --> 00:48:02,120 and increase in the temperature of the ocean and in its acidity 549 00:48:02,120 --> 00:48:05,080 threaten its very existence. 550 00:48:05,080 --> 00:48:08,400 If they continue to rise at the present rate, 551 00:48:08,400 --> 00:48:11,960 the reefs will be gone within decades. 552 00:48:11,960 --> 00:48:15,720 And that would be a global catastrophe. 553 00:48:18,480 --> 00:48:22,440 About one quarter of the species of fish in the world 554 00:48:22,440 --> 00:48:25,960 spend some part of their lives in the reefs. 555 00:48:25,960 --> 00:48:29,560 If the reefs go, the fish will also disappear. 556 00:48:30,800 --> 00:48:33,400 And that could affect the livelihood 557 00:48:33,400 --> 00:48:36,960 and diet of human communities worldwide. 558 00:48:38,440 --> 00:48:42,440 But there's surely another reason why we should protect the reefs. 559 00:48:42,440 --> 00:48:46,680 They are among this planet's richest, most complex 560 00:48:46,680 --> 00:48:49,200 and most beautiful ecosystems. 561 00:49:05,880 --> 00:49:10,600 Do we really care so little about the Earth on which we live 562 00:49:10,600 --> 00:49:14,560 that we don't wish to protect one of its greatest wonders 563 00:49:14,560 --> 00:49:17,640 from the consequences of our behaviour? 564 00:49:42,440 --> 00:49:45,160 For this series, the production team were determined 565 00:49:45,160 --> 00:49:47,960 to show the Barrier Reef in a new way, 566 00:49:47,960 --> 00:49:50,800 by filming in some of its most remote areas... 567 00:49:53,280 --> 00:49:54,920 ..and allowing me to meet 568 00:49:54,920 --> 00:49:58,080 some of its more unusual and surprising inhabitants. 569 00:50:00,440 --> 00:50:03,800 'This took us out onto the top of Heron Island's reef, 570 00:50:03,800 --> 00:50:05,960 'which is only exposed at low tide. 571 00:50:09,520 --> 00:50:12,360 'But we had to tread carefully, accompanied by guides, 572 00:50:12,360 --> 00:50:15,560 'to ensure that we didn't damage any of the coral.' 573 00:50:16,840 --> 00:50:19,040 Anybody who's coming on here, it's weird at first, 574 00:50:19,040 --> 00:50:22,400 but just try and walk on the dead coral - the concrete stuff. 575 00:50:22,400 --> 00:50:24,880 'We were there to film an elusive creature 576 00:50:24,880 --> 00:50:28,640 'that feeds in this special habitat when the tide is out - 577 00:50:28,640 --> 00:50:30,160 'the epaulette shark.' 578 00:50:31,360 --> 00:50:34,920 There's one with a tail - the first one is there. 579 00:50:34,920 --> 00:50:37,520 - Just gone. - It's gone under there. 580 00:50:39,640 --> 00:50:44,680 'Professor Gillian Renshaw has been studying these sharks for 20 years.' 581 00:50:44,680 --> 00:50:46,800 It's very hard to see the epaulettes 582 00:50:46,800 --> 00:50:50,040 because they're cryptically coloured and blend in very well 583 00:50:50,040 --> 00:50:53,800 with the fingers of coral that are rising out of the reef platform. 584 00:50:55,240 --> 00:50:58,040 'It's a challenging location, not least because 585 00:50:58,040 --> 00:51:00,920 'it's only accessible for short periods of time.' 586 00:51:03,080 --> 00:51:05,360 We've got probably about 40 minutes 587 00:51:05,360 --> 00:51:07,440 to get all of the shots that we need, 588 00:51:07,440 --> 00:51:10,840 so I shouldn't really be talking to you, we should be getting this. 589 00:51:10,840 --> 00:51:15,000 - OK, quiet please! - Camera's rolling. And action, David. 590 00:51:15,000 --> 00:51:18,240 The epaulette shark remains on the reef, 591 00:51:18,240 --> 00:51:20,640 even when the tide goes out. 592 00:51:21,880 --> 00:51:23,880 Of course, with so little water, 593 00:51:23,880 --> 00:51:27,080 it doesn't get as much oxygen as it requires normally, but... 594 00:51:29,040 --> 00:51:30,760 'Although my piece is done, 595 00:51:30,760 --> 00:51:34,160 'the team must now film the shark's unique walking behaviour.' 596 00:51:34,160 --> 00:51:36,880 The water is literally pouring in around the equipment 597 00:51:36,880 --> 00:51:38,560 and over our feet. 598 00:51:38,560 --> 00:51:41,200 We've got about 10 to 15 minutes to get this sequence finished 599 00:51:41,200 --> 00:51:43,680 and get back in the boats before we're literally cut off 600 00:51:43,680 --> 00:51:45,760 and we can't get back to the boats. 601 00:51:47,840 --> 00:51:50,320 'The tide creeps in around us.' 602 00:51:55,880 --> 00:51:58,200 He's walking beautifully, now. Look at that. 603 00:52:00,280 --> 00:52:03,640 Let's try and get it in the water a bit. 604 00:52:03,640 --> 00:52:06,600 Really nice performance from the epaulette shark. 605 00:52:08,480 --> 00:52:11,240 'Now, it's a race against time to get off the reef.' 606 00:52:12,320 --> 00:52:13,800 Are we ready for the boat, now? 607 00:52:13,800 --> 00:52:16,280 Geraldine, can we get David on, please? 608 00:52:21,360 --> 00:52:23,800 Yeah, looked stunning. Worth the stress. 609 00:52:25,560 --> 00:52:28,720 'This trip took us from the very top of the reef 610 00:52:28,720 --> 00:52:30,800 'down almost to its bottom... 611 00:52:31,920 --> 00:52:34,720 '..for our most ambitious sequence of the series -... 612 00:52:36,040 --> 00:52:38,560 '..to attempt the deepest dive in this area 613 00:52:38,560 --> 00:52:42,320 'and collect a sample of the mysterious coral that survives there. 614 00:52:43,720 --> 00:52:46,160 'And it's down to cameraman Paul Williams 615 00:52:46,160 --> 00:52:48,480 'to film our mission single-handedly.' 616 00:52:50,400 --> 00:52:52,200 I'm on my own down there. 617 00:52:52,200 --> 00:52:54,240 I've gone over it and over it again in my mind, 618 00:52:54,240 --> 00:52:57,040 about what we're trying to do and how we're going to do it, 619 00:52:57,040 --> 00:52:59,040 so I think I've got it locked in. 620 00:52:59,040 --> 00:53:01,120 I hope haven't forgotten anything. 621 00:53:01,120 --> 00:53:03,200 'It's something of a squeeze in the sub, 622 00:53:03,200 --> 00:53:06,160 'with all of Paul's filming equipment.' 623 00:53:06,160 --> 00:53:08,800 Do you mind if I just give you that for a moment? 624 00:53:09,880 --> 00:53:12,520 'But our third crew member is essential. 625 00:53:12,520 --> 00:53:14,920 'He's the pilot, Buck Taylor.' 626 00:53:19,120 --> 00:53:22,240 I'm sitting with a big camera on my shoulder 627 00:53:22,240 --> 00:53:25,280 and two other cameras, which were outside the sub, 628 00:53:25,280 --> 00:53:28,480 controlled by laptops which were both on my lap. 629 00:53:32,160 --> 00:53:35,200 The sound kit was under Buck's feet. 630 00:53:35,200 --> 00:53:36,440 It was tight in there. 631 00:53:44,720 --> 00:53:46,080 David, do you mind? 632 00:53:46,080 --> 00:53:49,120 - Would you get your towel and just give that a little wipe there? - Yup. 633 00:53:49,120 --> 00:53:50,920 Thank you, sir. 634 00:53:53,800 --> 00:53:55,920 'For the first part of the dive, 635 00:53:55,920 --> 00:53:58,720 'underwater cameramen filmed the sub's descent. 636 00:53:59,800 --> 00:54:02,960 'But at about 60 metres, they reached their limit. 637 00:54:05,040 --> 00:54:07,120 'It's only possible to venture further 638 00:54:07,120 --> 00:54:09,560 'within the protection of the submarine. 639 00:54:10,760 --> 00:54:14,240 'As we enter the mesophotic zone, around 100 metres down, 640 00:54:14,240 --> 00:54:15,840 'we're on our own. 641 00:54:20,120 --> 00:54:22,680 'To get the best shots of the reef beyond, 642 00:54:22,680 --> 00:54:25,640 'Paul requires all of Buck's skill as a pilot.' 643 00:54:26,800 --> 00:54:29,440 Do you want to try some other light options? 644 00:54:29,440 --> 00:54:32,000 - What have you got? - I can give you that. 645 00:54:32,000 --> 00:54:35,800 Yeah, put the higher ones on, take the lower ones off. 646 00:54:35,800 --> 00:54:39,960 - How's that? - Yes. Actually, that looks better. - Isn't it lovely? 647 00:54:39,960 --> 00:54:42,480 - Probably full of nooks and crannies. - Yeah. 648 00:54:42,480 --> 00:54:44,240 Buck, the sub driver, was brilliant. 649 00:54:44,240 --> 00:54:46,000 He'd find a drift in the currents 650 00:54:46,000 --> 00:54:48,040 and then we'd just drift across the coral. 651 00:54:48,040 --> 00:54:50,360 What's nice is, I can actually see the wall. 652 00:54:50,360 --> 00:54:53,360 - That's a very good angle for me. - Is it? - Yeah. 653 00:54:53,360 --> 00:54:56,800 So, just let us drift a tiny bit to starboard. 654 00:54:56,800 --> 00:54:58,640 And...action, David. 655 00:54:58,640 --> 00:55:04,320 This wall of rock ahead of me is actually the flank of Osprey Reef - 656 00:55:04,320 --> 00:55:07,080 an oasis for life. 657 00:55:07,080 --> 00:55:09,720 'But we weren't down here just to look. 658 00:55:09,720 --> 00:55:13,600 'We also wanted to collect samples for deep reef scientists... 659 00:55:15,480 --> 00:55:18,400 '..and that proved easier said than done.' 660 00:55:18,400 --> 00:55:21,480 - Oh, no! - We have to go and fetch that. 661 00:55:21,480 --> 00:55:22,880 We'll take that on film. 662 00:55:25,200 --> 00:55:28,000 'As we descended beyond 250 metres, 663 00:55:28,000 --> 00:55:31,600 'we entered a landscape rarely seen with the naked eye. 664 00:55:33,760 --> 00:55:37,280 'It was the perfect opportunity simply to explore.' 665 00:55:38,560 --> 00:55:40,920 This is the first time that manned submersibles 666 00:55:40,920 --> 00:55:42,600 have worked at this depth 667 00:55:42,600 --> 00:55:45,320 and it gives one the ability to look and observe 668 00:55:45,320 --> 00:55:48,280 and just do curiosity-driven research. 669 00:55:48,280 --> 00:55:50,120 It's fantastic. 670 00:55:50,120 --> 00:55:52,960 The visibility down here spectacular, isn't it? 671 00:55:52,960 --> 00:55:55,200 It's absolutely pure, yeah. 672 00:55:55,200 --> 00:55:58,400 There were many times when I had to take my eye away from the eyepiece 673 00:55:58,400 --> 00:56:01,320 because I just had to look with my own eyes, 674 00:56:01,320 --> 00:56:04,000 so it goes into the brain properly 675 00:56:04,000 --> 00:56:05,680 in the right perspective. 676 00:56:07,360 --> 00:56:09,640 'Soon, we reached our target depth.' 677 00:56:12,680 --> 00:56:14,200 There it is. 300. 678 00:56:15,760 --> 00:56:21,320 Nobody before has ever been as deep as this on the Great Barrier Reef. 679 00:56:21,320 --> 00:56:22,840 I like it. 680 00:56:22,840 --> 00:56:25,480 LAUGHTER 681 00:56:25,480 --> 00:56:28,240 So, it hasn't even come up on here - 290 metres, 682 00:56:28,240 --> 00:56:31,160 but we've heard that they've just reached 300 metres. 683 00:56:31,160 --> 00:56:34,800 Another thing to add to the things that David's done on this planet. 684 00:56:34,800 --> 00:56:37,080 'The purpose of our record-breaking trip 685 00:56:37,080 --> 00:56:40,880 'was to raise awareness of the reef's fragility. 686 00:56:40,880 --> 00:56:44,200 'Fortunately, while production continued on the series, 687 00:56:44,200 --> 00:56:47,080 'the dive caught the attention of a president.' 688 00:56:48,160 --> 00:56:52,600 - Mr President. - When I heard that you had gone down, 689 00:56:52,600 --> 00:56:55,400 you dove into the Great Barrier Reef again... 690 00:56:56,880 --> 00:56:58,800 ..60 years after the first time you did it? 691 00:56:58,800 --> 00:57:00,480 - Yes. - That impressed me. 692 00:57:00,480 --> 00:57:02,800 Ah, but I was in a sub. 693 00:57:02,800 --> 00:57:05,440 I mean, I was in a very, very remarkable research sub 694 00:57:05,440 --> 00:57:07,760 and we went down to over 300 metres. 695 00:57:07,760 --> 00:57:10,000 Oh, so you went really deep. 696 00:57:10,000 --> 00:57:11,920 And that was just mind-blowing. 697 00:57:13,120 --> 00:57:16,800 The deep dive proved a truly memorable moment for me 698 00:57:16,800 --> 00:57:19,880 and allowed us the unique opportunity of revealing 699 00:57:19,880 --> 00:57:23,520 a part of this great reef that has never before been seen.