1 00:00:00,633 --> 00:00:07,100 ♪♪ 2 00:00:07,100 --> 00:00:09,800 NARRATOR: In 2013, the Caribbean Sea 3 00:00:09,800 --> 00:00:12,600 gave up an extraordinary secret. 4 00:00:12,600 --> 00:00:16,300 It was a vast, pristine coral reef 5 00:00:16,300 --> 00:00:20,066 rising up from the Caribbean's deepest waters. 6 00:00:20,066 --> 00:00:24,133 It was the discovery of a whole new world. 7 00:00:24,133 --> 00:00:26,533 PETERSEN: It's just humongous. 8 00:00:26,533 --> 00:00:31,433 It's like a medieval fortress, like big and robust. 9 00:00:31,433 --> 00:00:33,666 HEYMAN: I have never seen any place 10 00:00:33,666 --> 00:00:36,133 with the kind of live coral cover, 11 00:00:36,133 --> 00:00:41,500 the density of fish. It was so magic. 12 00:00:41,500 --> 00:00:43,600 NARRATOR: But once discovered, 13 00:00:43,600 --> 00:00:48,000 the challenge was how to keep this underwater Eden safe 14 00:00:48,000 --> 00:00:50,066 and how to learn from it. 15 00:00:50,066 --> 00:00:52,466 HEYMAN: I realized we needed to research it, 16 00:00:52,466 --> 00:00:54,500 learn more about it, understand it better. 17 00:00:54,500 --> 00:00:56,800 But we needed to keep it quiet. 18 00:00:56,800 --> 00:01:01,233 NARRATOR: And so began an undercover scientific adventure, 19 00:01:01,233 --> 00:01:06,433 a dive into a living treasure whose secrets may hold the keys 20 00:01:06,433 --> 00:01:10,000 to saving many other reefs in trouble. 21 00:01:10,000 --> 00:01:29,300 ♪♪ 22 00:01:46,733 --> 00:02:04,766 ♪♪ 23 00:02:04,766 --> 00:02:08,033 NARRATOR: Fishermen are known for tall tales, 24 00:02:08,033 --> 00:02:10,500 but this one is true. 25 00:02:10,500 --> 00:02:21,800 ♪♪ 26 00:02:21,800 --> 00:02:26,800 It begins in May 2013, when a fisher from Guatemala 27 00:02:26,800 --> 00:02:29,900 is pushed into an act of desperation. 28 00:02:29,900 --> 00:02:35,066 ♪♪ 29 00:02:35,066 --> 00:02:37,100 The big fish he depends on -- 30 00:02:37,100 --> 00:02:39,733 the groupers, snappers, and jacks -- 31 00:02:39,733 --> 00:02:41,366 have virtually vanished 32 00:02:41,366 --> 00:02:44,200 from waters that once teemed with life. 33 00:02:44,200 --> 00:02:58,033 ♪♪ 34 00:02:58,033 --> 00:03:00,500 He takes a dangerous gambit 35 00:03:00,500 --> 00:03:03,966 and pushes farther and farther into the open ocean. 36 00:03:03,966 --> 00:03:14,300 ♪♪ 37 00:03:14,300 --> 00:03:19,266 As the sun rises, his engine struggles under the strain. 38 00:03:19,266 --> 00:03:25,300 [ Motor sputters ] 39 00:03:25,300 --> 00:03:38,300 ♪♪ 40 00:03:38,300 --> 00:03:44,066 Miles from land, the water is unexpectedly shallow. 41 00:03:44,066 --> 00:03:51,566 ♪♪ 42 00:03:51,566 --> 00:03:53,900 Just beneath the swell, 43 00:03:53,900 --> 00:03:58,200 a massive crown of rock and coral rises up -- 44 00:03:58,200 --> 00:04:02,100 an uncharted, undiscovered reef. 45 00:04:02,100 --> 00:04:06,733 ♪♪ 46 00:04:06,733 --> 00:04:09,800 It's a tantalizing treasure, 47 00:04:09,800 --> 00:04:12,633 a Caribbean secret that will raise hopes 48 00:04:12,633 --> 00:04:16,233 for the survival of coral reefs everywhere. 49 00:04:16,233 --> 00:04:24,733 ♪♪ 50 00:04:24,733 --> 00:04:28,233 The fisher tells only a handful of people. 51 00:04:31,933 --> 00:04:36,666 Ana Giró, Kenny Martin, and Dr. Melanie McField 52 00:04:36,666 --> 00:04:40,366 have spent years studying Caribbean corals. 53 00:04:40,366 --> 00:04:42,733 Ana is among the first to hear. 54 00:04:42,733 --> 00:04:44,500 PETERSEN: So, this fisherman comes up to me, 55 00:04:44,500 --> 00:04:47,366 and he told me about some rocks. 56 00:04:47,366 --> 00:04:50,200 And so I told him, "Well, take me there. 57 00:04:50,200 --> 00:04:51,966 You know, I want to see the rocks 58 00:04:51,966 --> 00:04:53,766 that you -- that you're telling me." 59 00:04:53,766 --> 00:05:10,966 ♪♪ 60 00:05:10,966 --> 00:05:13,133 It's just humongous. 61 00:05:13,133 --> 00:05:16,033 ♪♪ 62 00:05:16,033 --> 00:05:20,400 It's like a medieval fortress, like, just big and robust. 63 00:05:20,400 --> 00:05:22,933 ♪♪ 64 00:05:22,933 --> 00:05:25,200 We have pinnacles that come out. 65 00:05:25,200 --> 00:05:27,633 ♪♪ 66 00:05:27,633 --> 00:05:32,166 Deep walls. 67 00:05:32,166 --> 00:05:35,633 And then, incredible barrel sponges. 68 00:05:35,633 --> 00:05:39,166 ♪♪ 69 00:05:39,166 --> 00:05:41,533 It's just mesmerizing. 70 00:05:41,533 --> 00:06:04,866 ♪♪ 71 00:05:51,533 --> 00:06:04,866 ♪♪ 72 00:06:04,866 --> 00:06:08,566 NARRATOR: This newfound reef is a stunning contrast 73 00:06:08,566 --> 00:06:11,666 to many other Caribbean reefs that are in peril. 74 00:06:11,666 --> 00:06:20,633 ♪♪ 75 00:06:20,633 --> 00:06:25,366 It's like stepping back in time to when all reefs were thriving. 76 00:06:25,366 --> 00:06:32,166 ♪♪ 77 00:06:32,166 --> 00:06:34,133 PETERSEN: There are shallow reefs, 78 00:06:34,133 --> 00:06:39,700 vibrant and beautiful and different kinds of fish. 79 00:06:39,700 --> 00:06:42,166 The ecosystem is just so diverse, 80 00:06:42,166 --> 00:06:44,100 many types of different communities 81 00:06:44,100 --> 00:06:46,100 that compose this incredible system. 82 00:06:46,100 --> 00:06:50,966 ♪♪ 83 00:06:50,966 --> 00:06:53,100 That was just an incredible experience 84 00:06:53,100 --> 00:06:55,466 for me, you know, personally. 85 00:06:55,466 --> 00:06:59,000 ♪♪ 86 00:06:59,000 --> 00:07:01,766 McFIELD: When Ana told me she found this new reef, 87 00:07:01,766 --> 00:07:03,566 that it's just totally amazing, 88 00:07:03,566 --> 00:07:06,366 I believed it, but I wanted to see it. 89 00:07:06,366 --> 00:07:09,766 We have benthic habitat maps. It's not there. 90 00:07:09,766 --> 00:07:11,966 It's not there, you know, when you look on Google Earth, 91 00:07:11,966 --> 00:07:14,000 You know, we saw nothing on our maps. 92 00:07:14,000 --> 00:07:16,933 ♪♪ 93 00:07:16,933 --> 00:07:19,566 NARRATOR: By 2017, 94 00:07:19,566 --> 00:07:24,633 the reef's significance is starting to emerge. 95 00:07:24,633 --> 00:07:29,133 It's an underwater mountaintop bigger than Manhattan, 96 00:07:29,133 --> 00:07:34,733 crowned with coral and set on the edge of the Cayman Trench, 97 00:07:34,733 --> 00:07:39,400 the deepest part of the Caribbean. 98 00:07:39,400 --> 00:07:45,066 It became known as the Cayman Crown. 99 00:07:45,066 --> 00:07:48,300 It's part of a Mesoamerican Reef system 100 00:07:48,300 --> 00:07:51,300 straddling the waters of Belize and Guatemala. 101 00:07:51,300 --> 00:07:59,800 ♪♪ 102 00:08:02,366 --> 00:08:03,833 News of the coral wonder 103 00:08:03,833 --> 00:08:08,700 is quietly shared with fisheries expert Dr. Will HEYMAN. 104 00:08:08,700 --> 00:08:10,966 HEYMAN: I was at a meeting and somebody came up to me 105 00:08:10,966 --> 00:08:13,866 and told me this incredible story 106 00:08:13,866 --> 00:08:18,000 of a place that nobody knew about. 107 00:08:18,000 --> 00:08:22,433 There's giant, giant fleets of ships that go through here 108 00:08:22,433 --> 00:08:24,733 supplying the country of Guatemala, 109 00:08:24,733 --> 00:08:26,133 the country of Honduras. 110 00:08:26,133 --> 00:08:29,533 But when you check it out, you zoom in, you look at it, 111 00:08:29,533 --> 00:08:32,666 all the ships are going this way or they're going this way. 112 00:08:32,666 --> 00:08:33,966 There's a shallow area 113 00:08:33,966 --> 00:08:36,966 right between these two massive shipping routes, 114 00:08:36,966 --> 00:08:40,433 and that's the Cayman Crown. It's hiding in plain sight. 115 00:08:43,466 --> 00:08:45,200 What I heard was these were 116 00:08:45,200 --> 00:08:47,800 some of the healthiest coral reefs in the world. 117 00:08:52,033 --> 00:08:58,000 I have never seen any place with the kind of live coral cover, 118 00:08:58,000 --> 00:09:03,966 the density of fish. It was so magic. 119 00:09:03,966 --> 00:09:06,100 I realized we needed to research it, 120 00:09:06,100 --> 00:09:08,400 learn more about it, understand it better, 121 00:09:08,400 --> 00:09:10,700 but we needed to keep it quiet. 122 00:09:13,200 --> 00:09:15,166 NARRATOR: To build the scientific case 123 00:09:15,166 --> 00:09:19,566 for protecting the Crown, the team works quietly. 124 00:09:19,566 --> 00:09:25,166 If news got out, fishers might be tempted to target the reef. 125 00:09:25,166 --> 00:09:27,033 PETERSEN: So, we kept it a secret. 126 00:09:27,033 --> 00:09:30,633 So research, the explorations, and everything, 127 00:09:30,633 --> 00:09:34,166 kind of just between a selected group of people. 128 00:09:34,166 --> 00:09:36,533 Before we have it, like, protected, 129 00:09:36,533 --> 00:09:39,566 that was, you know, our main -- our main goal. 130 00:09:39,566 --> 00:09:42,000 NARRATOR: But protection will only be possible 131 00:09:42,000 --> 00:09:46,166 with the support of local fishers. 132 00:09:46,166 --> 00:09:51,700 The team invites Kenny Martin into the circle of trust. 133 00:09:51,700 --> 00:09:53,466 MARTIN: We grew up from a fishing family 134 00:09:53,466 --> 00:09:54,900 in a coastal community 135 00:09:54,900 --> 00:09:59,900 catching fish on hand lines, and we used to use gillnets. 136 00:09:59,900 --> 00:10:01,966 It has caused a negative impact, 137 00:10:01,966 --> 00:10:07,366 and I've seen it now that I go out scuba diving. 138 00:10:07,366 --> 00:10:09,166 NARRATOR: Kenny wants to protect the fish 139 00:10:09,166 --> 00:10:12,033 that many people depend on. 140 00:10:12,033 --> 00:10:13,800 That means protecting the reef. 141 00:10:13,800 --> 00:10:15,733 MARTIN: ...1, go. 142 00:10:15,733 --> 00:10:18,133 NARRATOR: Without a healthy reef, 143 00:10:18,133 --> 00:10:20,100 there will be no fish to catch. 144 00:10:20,100 --> 00:10:24,200 ♪♪ 145 00:10:24,200 --> 00:10:28,066 A coral reef is a complex web of life, 146 00:10:28,066 --> 00:10:31,700 and different animal and plant species have different roles. 147 00:10:31,700 --> 00:10:36,266 ♪♪ 148 00:10:36,266 --> 00:10:40,466 Deep gullies lead to an extraordinary coral city. 149 00:10:40,466 --> 00:10:44,566 ♪♪ 150 00:10:44,566 --> 00:10:48,433 The inhabitants are strange and beautiful 151 00:10:48,433 --> 00:10:50,700 and dependent on one another. 152 00:10:50,700 --> 00:10:56,866 ♪♪ 153 00:10:56,866 --> 00:11:01,600 Parts of the reefscape can feel almost industrial. 154 00:11:01,600 --> 00:11:03,700 The chimney of a single sponge 155 00:11:03,700 --> 00:11:07,533 can filter 2,500 gallons of water a day. 156 00:11:09,700 --> 00:11:13,766 There are nurseries for raising young. 157 00:11:13,766 --> 00:11:16,300 And dormitories for the night shift. 158 00:11:16,300 --> 00:11:20,133 ♪♪ 159 00:11:20,133 --> 00:11:23,133 Everything is interconnected. 160 00:11:23,133 --> 00:11:24,700 At fish grooming stations, 161 00:11:24,700 --> 00:11:30,933 spritely cleaners pick off parasites like sea lice. 162 00:11:30,933 --> 00:11:35,100 The reef is also home to giant predators, 163 00:11:35,100 --> 00:11:38,566 like this 400-pound goliath grouper. 164 00:11:41,200 --> 00:11:45,266 The gutsy little cleaner is not intimidated. 165 00:11:48,433 --> 00:11:50,333 There are visitors. 166 00:11:50,333 --> 00:11:53,300 A pod of dolphins feeds around the reef. 167 00:11:53,300 --> 00:11:57,000 [ Dolphins squeaking ] 168 00:11:58,600 --> 00:12:02,433 Whale sharks, the biggest fish on the planet, 169 00:12:02,433 --> 00:12:06,966 gorge on an abundance of tiny zooplankton and fish eggs. 170 00:12:06,966 --> 00:12:15,733 ♪♪ 171 00:12:15,733 --> 00:12:17,966 Nurse sharks thrive here, too. 172 00:12:17,966 --> 00:12:23,266 ♪♪ 173 00:12:23,266 --> 00:12:25,066 In a healthy system, 174 00:12:25,066 --> 00:12:29,366 predators only take a proportion of their prey. 175 00:12:29,366 --> 00:12:31,266 If the balance is right, 176 00:12:31,266 --> 00:12:34,833 the number of predators and prey can be impressive. 177 00:12:34,833 --> 00:12:40,200 ♪♪ 178 00:12:40,200 --> 00:12:43,933 Predators, like jacks, snappers, and groupers, 179 00:12:43,933 --> 00:12:46,400 are vital to the health of the reef 180 00:12:46,400 --> 00:12:48,733 and a key food for local people. 181 00:12:48,733 --> 00:12:52,733 ♪♪ 182 00:12:52,733 --> 00:12:58,200 Most prized by fishers is the Nassau grouper. 183 00:12:58,200 --> 00:13:01,966 Nassau groupers were once the backbone of the local economy, 184 00:13:01,966 --> 00:13:04,366 but now they are critically endangered. 185 00:13:04,366 --> 00:13:07,466 ♪♪ 186 00:13:07,466 --> 00:13:10,533 Groupers hunt at dawn and dusk. 187 00:13:10,533 --> 00:13:13,800 They lie in ambush for small fishes in the reef's 188 00:13:13,800 --> 00:13:15,633 darker recesses. 189 00:13:18,033 --> 00:13:20,833 The Nassau grouper, like everything here, 190 00:13:20,833 --> 00:13:23,433 depends on a healthy, balanced system. 191 00:13:23,433 --> 00:13:27,166 ♪♪ 192 00:13:27,166 --> 00:13:29,500 The food web that feeds the groupers 193 00:13:29,500 --> 00:13:33,733 starts with sunlight and nutrients. 194 00:13:33,733 --> 00:13:36,633 Currents sweep in microscopic life 195 00:13:36,633 --> 00:13:40,766 that's harvested by fan corals and soft corals. 196 00:13:40,766 --> 00:13:43,500 ♪♪ 197 00:13:43,500 --> 00:13:48,233 Feather duster worms unfurl to collect the invisible morsels. 198 00:13:48,233 --> 00:13:57,566 ♪♪ 199 00:13:57,566 --> 00:13:59,833 The next level up are grazers, 200 00:13:59,833 --> 00:14:02,900 nibbling algae off coral and sponges. 201 00:14:02,900 --> 00:14:07,266 ♪♪ 202 00:14:07,266 --> 00:14:11,400 French angelfish enjoy a side of sponge with their algae. 203 00:14:11,400 --> 00:14:14,800 ♪♪ 204 00:14:14,800 --> 00:14:17,733 Parrotfish tend the coral garden. 205 00:14:17,733 --> 00:14:26,900 ♪♪ 206 00:14:26,900 --> 00:14:30,466 Porkfish forage for mollusks and worms. 207 00:14:30,466 --> 00:14:34,733 ♪♪ 208 00:14:34,733 --> 00:14:38,633 Everything from microscopic plant to predator 209 00:14:38,633 --> 00:14:40,800 is bound together. 210 00:14:45,933 --> 00:14:49,833 Spurred on by the riches, the team has been painstakingly 211 00:14:49,833 --> 00:14:55,433 creating an inventory of what lives on the reef and where. 212 00:14:55,433 --> 00:14:57,933 PETERSEN: It took us a long time to explore all the reefs 213 00:14:57,933 --> 00:14:59,066 that we surveyed, 214 00:14:59,066 --> 00:15:02,000 like 90 kilometers square of the reef. 215 00:15:02,000 --> 00:15:04,500 Doing monitoring of coral-reef health 216 00:15:04,500 --> 00:15:07,866 and the geomorphology, and the coral cover was incredible, 217 00:15:07,866 --> 00:15:11,700 like nothing that I've ever seen before. 218 00:15:11,700 --> 00:15:14,700 NARRATOR: Ana photographs the coral in strips, 219 00:15:14,700 --> 00:15:17,966 building a mosaic of the richer parts of the reef. 220 00:15:17,966 --> 00:15:21,900 ♪♪ 221 00:15:21,900 --> 00:15:24,400 The photo maps reveal that the Crown 222 00:15:24,400 --> 00:15:30,866 has the highest live coral cover in the Mesoamerican Reef. 223 00:15:30,866 --> 00:15:32,633 McFIELD: So we can zoom in right here. 224 00:15:32,633 --> 00:15:34,366 PETERSEN: Yeah, if you zoom in right here, 225 00:15:34,366 --> 00:15:36,300 you know the coral composition. 226 00:15:36,300 --> 00:15:37,566 Coral cover, as well. 227 00:15:37,566 --> 00:15:40,466 McFIELD: This is the site with 77% live coral cover? 228 00:15:40,466 --> 00:15:42,000 PETERSEN: Yes, this is the site that we have. 229 00:15:42,000 --> 00:15:43,166 McFIELD: And you see it. 230 00:15:43,166 --> 00:15:44,600 PETERSEN: A huge amount of coral cover. 231 00:15:44,600 --> 00:15:46,833 I mean, compared to the rest of the Mesoamerican Reef, 232 00:15:46,833 --> 00:15:50,966 when we're talking about a 19% coral cover... 233 00:15:50,966 --> 00:15:52,233 McFIELD: This is the highest now. 234 00:15:52,233 --> 00:15:55,133 PETERSEN: This is -- yeah, this is the highest. 235 00:15:55,133 --> 00:15:57,333 NARRATOR: What is revealed is a coral reef 236 00:15:57,333 --> 00:15:59,866 of global importance. 237 00:15:59,866 --> 00:16:04,266 But the team fears that time may be running out. 238 00:16:04,266 --> 00:16:07,100 Caribbean waters are warming alarmingly, 239 00:16:07,100 --> 00:16:11,033 posing a grave threat to the corals. 240 00:16:11,033 --> 00:16:14,600 They place temperature sensors on the Crown. 241 00:16:14,600 --> 00:16:17,866 McFIELD: We do have bleaching events in the whole Caribbean, 242 00:16:17,866 --> 00:16:19,500 the whole world, obviously. 243 00:16:19,500 --> 00:16:22,300 That is probably one of the greatest threats in this area. 244 00:16:22,300 --> 00:16:24,800 PETERSEN: In October, the water is just so hot, 245 00:16:24,800 --> 00:16:27,700 you can feel the heat when diving. 246 00:16:27,700 --> 00:16:31,866 McFIELD: 1998 was the first global mass bleaching event, 247 00:16:31,866 --> 00:16:34,833 and it has gotten worse in the last few years. 248 00:16:34,833 --> 00:16:37,566 ♪♪ 249 00:16:37,566 --> 00:16:39,500 NARRATOR: Tucked within the stony reef 250 00:16:39,500 --> 00:16:42,066 are tiny coral polyps. 251 00:16:42,066 --> 00:16:46,100 Inside them, algae make sugars. 252 00:16:46,100 --> 00:16:50,600 But if it gets too hot, the algae make toxins. 253 00:16:50,600 --> 00:16:54,033 ♪♪ 254 00:16:54,033 --> 00:17:00,166 Then the polyps eject the algae, and the coral bleaches white. 255 00:17:00,166 --> 00:17:03,966 The algae can return if the water cools soon. 256 00:17:03,966 --> 00:17:07,533 Otherwise, the coral often dies. 257 00:17:07,533 --> 00:17:12,600 ♪♪ 258 00:17:12,600 --> 00:17:17,433 From 2014 to 2017, a bleaching apocalypse 259 00:17:17,433 --> 00:17:20,433 killed up to a third of the world's corals. 260 00:17:20,433 --> 00:17:26,933 ♪♪ 261 00:17:26,933 --> 00:17:31,833 Amazingly, the Crown was unscathed. 262 00:17:31,833 --> 00:17:37,233 But in October 2019, tragedy strikes the region. 263 00:17:37,233 --> 00:17:45,333 ♪♪ 264 00:17:45,333 --> 00:17:47,833 The Crown takes a direct hit. 265 00:17:47,833 --> 00:17:53,966 ♪♪ 266 00:17:53,966 --> 00:17:55,733 PETERSEN: It was completely bleached. 267 00:17:55,733 --> 00:17:59,733 Like, all of it. It was just all white. 268 00:17:59,733 --> 00:18:02,300 HEYMAN: We saw a massive bleaching event. 269 00:18:02,300 --> 00:18:05,833 I mean, the corals that we came to know and love 270 00:18:05,833 --> 00:18:07,933 blanketed with snow, it looked like. 271 00:18:07,933 --> 00:18:15,100 ♪♪ 272 00:18:15,100 --> 00:18:17,500 NARRATOR: Then, four months later, 273 00:18:17,500 --> 00:18:21,166 the team notices something extraordinary. 274 00:18:21,166 --> 00:18:22,966 PETERSEN: When we go back in January, 275 00:18:22,966 --> 00:18:26,433 the corals get better. 276 00:18:26,433 --> 00:18:28,366 February, they get even better. 277 00:18:28,366 --> 00:18:32,233 ♪♪ 278 00:18:32,233 --> 00:18:34,800 May, the corals are looking fine. 279 00:18:34,800 --> 00:18:36,433 They're looking beautiful. 280 00:18:36,433 --> 00:18:40,466 ♪♪ 281 00:18:40,466 --> 00:18:43,233 McFIELD: We have this beautiful Cayman Crown Reef, 282 00:18:43,233 --> 00:18:44,966 and it has recovered. 283 00:18:44,966 --> 00:18:48,366 The corals in this region are resilient. 284 00:18:48,366 --> 00:18:53,033 ♪♪ 285 00:18:53,033 --> 00:18:56,966 NARRATOR: The news reaches coral expert Myles Phillips. 286 00:18:56,966 --> 00:19:02,900 He joins the team to investigate the Crown's remarkable recovery. 287 00:19:02,900 --> 00:19:06,233 Will Heyman shares his theory. 288 00:19:06,233 --> 00:19:08,033 HEYMAN: Let me give you the geographic context. 289 00:19:08,033 --> 00:19:09,633 So, this is the Gulf of Honduras. 290 00:19:09,633 --> 00:19:11,366 PHILLIPS: Yeah. HEYMAN: And in this channel, 291 00:19:11,366 --> 00:19:12,900 that's your Cayman Crown. 292 00:19:12,900 --> 00:19:17,300 What you got to remember is that this is the Cayman Trench. 293 00:19:17,300 --> 00:19:21,200 Here, it's already a thousand, 1,500 meters, 294 00:19:21,200 --> 00:19:22,900 and then drops, drops, drops, drop, drops -- 295 00:19:22,900 --> 00:19:25,266 7,600 meters, deepest point. 296 00:19:25,266 --> 00:19:33,066 ♪♪ 297 00:19:33,066 --> 00:19:34,466 NARRATOR: At its deepest, 298 00:19:34,466 --> 00:19:37,566 the trench is over 4 miles down. 299 00:19:37,566 --> 00:19:40,733 A 15-pound bowling ball dropped in 300 00:19:40,733 --> 00:19:44,033 would take over an hour and a half to hit bottom. 301 00:19:44,033 --> 00:19:52,733 ♪♪ 302 00:19:52,733 --> 00:19:55,566 Cold currents rising from those depths 303 00:19:55,566 --> 00:19:58,066 sweep nutrients up to the Crown. 304 00:19:58,066 --> 00:20:03,700 ♪♪ 305 00:20:03,700 --> 00:20:05,600 HEYMAN: This water comes slamming up 306 00:20:05,600 --> 00:20:07,733 onto this vertical shelf. 307 00:20:07,733 --> 00:20:10,266 So where we were, those jewel reefs -- 308 00:20:10,266 --> 00:20:12,600 PHILLIPS: Right at the top of it. 309 00:20:12,600 --> 00:20:13,833 So that's the source of your upwelling. 310 00:20:13,833 --> 00:20:15,100 HEYMAN: Exactly. 311 00:20:15,100 --> 00:20:18,566 ♪♪ 312 00:20:18,566 --> 00:20:22,633 NARRATOR: The upwelling flows along folds of rock and coral 313 00:20:22,633 --> 00:20:26,433 that act like pipes and channels in a cooling system, 314 00:20:26,433 --> 00:20:29,266 easing temperatures and providing nutrients. 315 00:20:29,266 --> 00:20:36,633 ♪♪ 316 00:20:42,800 --> 00:20:44,800 HEYMAN: The other factor that we haven't talked about, 317 00:20:44,800 --> 00:20:47,100 we get 4 meters, like 12 feet of rain, 318 00:20:47,100 --> 00:20:48,500 that falls all within a -- 319 00:20:48,500 --> 00:20:49,733 PHILLIPS: All in this region. 320 00:20:49,733 --> 00:20:51,766 HEYMAN: Through agricultural lands, through -- 321 00:20:51,766 --> 00:20:53,833 PHILLIPS: Into this one bay, through the same little channel. 322 00:20:53,833 --> 00:20:55,766 HEYMAN: Exactly. PHILLIPS: So this is forming, 323 00:20:55,766 --> 00:20:57,300 like a -- like, a roof, like a shade 324 00:20:57,300 --> 00:21:00,700 over this coral reef. HEYMAN: That's it. 325 00:21:00,700 --> 00:21:03,933 NARRATOR: Just as the Caribbean water temperature peaks, 326 00:21:03,933 --> 00:21:08,300 muddy water washes over the reef. 327 00:21:08,300 --> 00:21:11,266 Emerging research suggests that this runoff 328 00:21:11,266 --> 00:21:14,266 could shield corals from damaging sunlight. 329 00:21:14,266 --> 00:21:23,300 ♪♪ 330 00:21:23,300 --> 00:21:25,666 HEYMAN: They're getting shade, they're getting fed, 331 00:21:25,666 --> 00:21:27,233 and they're getting cooled. 332 00:21:27,233 --> 00:21:28,866 So where all the rest of the Caribbean 333 00:21:28,866 --> 00:21:31,500 took that bleaching and wrestled coming back, 334 00:21:31,500 --> 00:21:34,766 this area is resilient because of those factors. 335 00:21:36,900 --> 00:21:42,300 NARRATOR: Another factor may be the corals themselves. 336 00:21:42,300 --> 00:21:45,900 Myles finds an abundance of slow-growing corals 337 00:21:45,900 --> 00:21:49,000 that can withstand warming waters. 338 00:21:49,000 --> 00:21:53,266 He also sees a surprising amount of faster-growing corals 339 00:21:53,266 --> 00:21:57,400 that proliferate like weeds after bleaching events. 340 00:21:57,400 --> 00:21:59,900 PHILLIPS: Well, what I found was lettuce coral, 341 00:21:59,900 --> 00:22:04,700 considered the poster child for these weedy species 342 00:22:04,700 --> 00:22:07,166 that, honestly, reproduce so quickly 343 00:22:07,166 --> 00:22:13,000 or so effectively that they can quickly repopulate an area. 344 00:22:13,000 --> 00:22:15,333 You also had these stress-tolerant corals 345 00:22:15,333 --> 00:22:16,833 that invest a lot of metabolic energy 346 00:22:16,833 --> 00:22:19,200 in surviving things -- big brain corals. 347 00:22:19,200 --> 00:22:22,600 And they were massive at the Cayman Crown. 348 00:22:24,700 --> 00:22:26,466 NARRATOR: But what astounds Myles 349 00:22:26,466 --> 00:22:29,100 is something he doesn't find. 350 00:22:29,100 --> 00:22:32,700 A deadly disease has been sweeping the Caribbean. 351 00:22:32,700 --> 00:22:34,600 To Myles' relief, 352 00:22:34,600 --> 00:22:37,633 the normally susceptible pillar and brain corals 353 00:22:37,633 --> 00:22:41,866 seem untouched here. 354 00:22:41,866 --> 00:22:44,533 PHILLIPS: I saw no sign of stony coral tissue loss disease. 355 00:22:44,533 --> 00:22:48,266 Actually, no sign of any disease at all that I could see. 356 00:22:48,266 --> 00:22:51,200 These corals must be tens or hundreds of years old, 357 00:22:51,200 --> 00:22:52,666 and they look like they've never gone 358 00:22:52,666 --> 00:22:55,300 through anything in their lives. They're completely healthy. 359 00:22:58,800 --> 00:23:02,100 NARRATOR: The crown has been a sanctuary, 360 00:23:02,100 --> 00:23:06,266 except its isolation has not protected it 361 00:23:06,266 --> 00:23:08,066 from another invader. 362 00:23:08,066 --> 00:23:16,033 ♪♪ 363 00:23:16,033 --> 00:23:20,600 It's a creature that's become a global menace. 364 00:23:20,600 --> 00:23:23,900 Lionfish. 365 00:23:23,900 --> 00:23:27,733 They were first seen around Belize in 2008. 366 00:23:27,733 --> 00:23:30,800 ♪♪ 367 00:23:30,800 --> 00:23:33,433 These predators from the Indo-Pacific 368 00:23:33,433 --> 00:23:38,233 are among the most aggressive, invasive species on the planet. 369 00:23:38,233 --> 00:23:58,200 ♪♪ 370 00:23:58,200 --> 00:24:00,600 Even the regal Nassau grouper 371 00:24:00,600 --> 00:24:04,333 is wary of the lionfish's venomous spines. 372 00:24:04,333 --> 00:24:07,233 ♪♪ 373 00:24:07,233 --> 00:24:11,400 This disturbing discovery shows that the Cayman Crown 374 00:24:11,400 --> 00:24:16,566 is not totally disconnected from the outside world. 375 00:24:16,566 --> 00:24:19,233 The reef has trade routes. 376 00:24:19,233 --> 00:24:25,566 ♪♪ 377 00:24:25,566 --> 00:24:30,033 Fish use highways reaching out way beyond the reef. 378 00:24:30,033 --> 00:24:33,833 ♪♪ 379 00:24:33,833 --> 00:24:37,866 The Crown, the team realizes, could be part of a network 380 00:24:37,866 --> 00:24:42,200 stretching across the Caribbean with the kind of connections 381 00:24:42,200 --> 00:24:44,833 that we are just beginning to understand. 382 00:24:47,000 --> 00:24:51,833 But untangling these connections has to be put on hold. 383 00:24:51,833 --> 00:24:55,533 [ Thunder crashes ] 384 00:24:55,533 --> 00:25:00,333 [ Wind howling ] 385 00:25:00,333 --> 00:25:02,333 [ Thunder rumbles ] 386 00:25:05,533 --> 00:25:08,333 [ Thunder crashes ] 387 00:25:08,333 --> 00:25:11,400 Hurricanes and other storms in the Caribbean 388 00:25:11,400 --> 00:25:14,433 are becoming more frequent and powerful, 389 00:25:14,433 --> 00:25:18,300 most likely due to climate change. 390 00:25:18,300 --> 00:25:20,166 The researchers can only hope 391 00:25:20,166 --> 00:25:23,833 that the Crown's location will protect it 392 00:25:23,833 --> 00:25:27,466 as a storm lashes nearby shallow reefs. 393 00:25:31,466 --> 00:25:34,000 McFIELD: What we're seeing in areas that are being hit 394 00:25:34,000 --> 00:25:36,633 over and over with the intensity of hurricanes 395 00:25:36,633 --> 00:25:39,933 is that that is one of the main causes of reef decline. 396 00:25:39,933 --> 00:25:43,600 And we don't have that down here. It's very minimal. 397 00:25:43,600 --> 00:25:45,600 The Cayman Crown's perfectly situated 398 00:25:45,600 --> 00:25:48,233 below the main hurricane belt. 399 00:26:02,866 --> 00:26:04,766 NARRATOR: The Crown's exact position 400 00:26:04,766 --> 00:26:08,566 is yet another factor that may make it a kind of ark, 401 00:26:08,566 --> 00:26:11,566 able to seed other reefs with life. 402 00:26:11,566 --> 00:26:15,600 ♪♪ 403 00:26:15,600 --> 00:26:18,866 After the storm, the team is back at work 404 00:26:18,866 --> 00:26:21,300 documenting the Crown's inhabitants. 405 00:26:21,300 --> 00:26:25,300 ♪♪ 406 00:26:25,300 --> 00:26:28,533 Hamlets are easily overlooked fish, 407 00:26:28,533 --> 00:26:32,666 but seeing the start of their courtship brings renewed hope. 408 00:26:32,666 --> 00:26:45,533 ♪♪ 409 00:26:45,533 --> 00:26:48,600 They release hundreds of microscopic eggs 410 00:26:48,600 --> 00:26:50,500 into the current, 411 00:26:50,500 --> 00:26:54,066 which sweeps them away from the Crown's hungry mouths. 412 00:26:54,066 --> 00:27:00,666 ♪♪ 413 00:27:00,666 --> 00:27:05,000 A sea cucumber also adds eggs into the current. 414 00:27:05,000 --> 00:27:14,100 ♪♪ 415 00:27:14,100 --> 00:27:20,033 A school of blue tangs joins the party at a favorite parapet. 416 00:27:20,033 --> 00:27:24,133 The females release eggs, the males sperm, 417 00:27:24,133 --> 00:27:26,500 and the eggs are fertilized. 418 00:27:26,500 --> 00:27:33,466 ♪♪ 419 00:27:33,466 --> 00:27:37,400 Currents can carry eggs and larvae hundreds of miles, 420 00:27:37,400 --> 00:27:41,100 seeding reefs from Cuba to Honduras. 421 00:27:41,100 --> 00:27:43,833 ♪♪ 422 00:27:43,833 --> 00:27:46,666 Others linger in gyres around the crown. 423 00:27:46,666 --> 00:27:54,100 ♪♪ 424 00:27:54,100 --> 00:27:58,000 From a few days old, larval fish can swim, 425 00:27:58,000 --> 00:28:04,366 guided by temperature, currents, or maybe even sound. 426 00:28:04,366 --> 00:28:09,266 They are heading for the mangroves on a nearby island. 427 00:28:09,266 --> 00:28:12,566 It's an in-between world of marine trees 428 00:28:12,566 --> 00:28:15,766 that will serve as their nursery. 429 00:28:15,766 --> 00:28:30,000 ♪♪ 430 00:28:30,000 --> 00:28:33,166 There are gangs of pint-sized predators, 431 00:28:33,166 --> 00:28:36,866 like snappers and jacks, learning the ropes. 432 00:28:36,866 --> 00:28:40,100 ♪♪ 433 00:28:40,100 --> 00:28:43,166 An inch-long barracuda lays low. 434 00:28:43,166 --> 00:28:46,033 ♪♪ 435 00:28:46,033 --> 00:28:49,666 Here's a baby cubera snapper, a miniature version 436 00:28:49,666 --> 00:28:54,900 of the voracious hunter it will become. 437 00:28:54,900 --> 00:28:57,466 Young wrasse go to school. 438 00:28:57,466 --> 00:29:01,333 And joining the class are baby butterfly fish. 439 00:29:01,333 --> 00:29:09,266 ♪♪ 440 00:29:09,266 --> 00:29:14,400 The next stop for many young fish is seagrass meadows. 441 00:29:14,400 --> 00:29:18,066 They find more food here but have less protection 442 00:29:18,066 --> 00:29:21,000 than when hiding in the mangrove roots. 443 00:29:21,000 --> 00:29:23,833 ♪♪ 444 00:29:23,833 --> 00:29:28,800 Young sardines try to avoid run-ins with Spanish mackerel. 445 00:29:28,800 --> 00:29:44,700 ♪♪ 446 00:29:44,700 --> 00:29:47,966 The abundance of life attracts nurse sharks 447 00:29:47,966 --> 00:29:52,400 and sting and eagle rays that scour the shallow beds. 448 00:29:52,400 --> 00:30:02,333 ♪♪ 449 00:30:08,966 --> 00:30:11,766 The juvenile fish will set out for new reefs 450 00:30:11,766 --> 00:30:13,500 when they're old enough. 451 00:30:13,500 --> 00:30:16,833 ♪♪ 452 00:30:16,833 --> 00:30:20,433 To the researchers, the reefs, the seagrass meadows, 453 00:30:20,433 --> 00:30:24,266 and the mangroves make up a trinity of life, 454 00:30:24,266 --> 00:30:28,800 each an essential part of a single system. 455 00:30:28,800 --> 00:30:30,766 PETERSEN: For snappers and groupers, 456 00:30:30,766 --> 00:30:32,133 we need to preserve all of it. 457 00:30:32,133 --> 00:30:33,500 We need to preserve the mangroves. 458 00:30:33,500 --> 00:30:37,400 We need to preserve the seagrass beds and the coral reefs. 459 00:30:37,400 --> 00:30:39,500 The connectivity is really important. 460 00:30:39,500 --> 00:30:43,533 ♪♪ 461 00:30:43,533 --> 00:30:45,933 NARRATOR: Young fish come back to the Crown, 462 00:30:45,933 --> 00:30:49,600 the hub of the system. 463 00:30:49,600 --> 00:30:53,400 Many fill the ranks of grazers or cleaners, 464 00:30:53,400 --> 00:30:57,200 ever vigilant for predators also coming of age, 465 00:30:57,200 --> 00:30:59,100 like these snappers. 466 00:30:59,100 --> 00:31:04,533 ♪♪ 467 00:31:04,533 --> 00:31:08,733 The journey to adulthood can last several years. 468 00:31:08,733 --> 00:31:11,633 But snappers can live to be 80. 469 00:31:11,633 --> 00:31:15,366 ♪♪ 470 00:31:15,366 --> 00:31:17,866 Each year, the predators aggregate 471 00:31:17,866 --> 00:31:20,133 at breeding grounds on the reef. 472 00:31:20,133 --> 00:31:37,400 ♪♪ 473 00:31:37,400 --> 00:31:41,000 Finding the location and timing of breeding big fish 474 00:31:41,000 --> 00:31:44,733 is like winning the lottery for a fisher. 475 00:31:44,733 --> 00:31:48,400 Spawning sites are targeted all across the Caribbean. 476 00:31:51,400 --> 00:31:53,700 MARTIN: We've been seeing a lot of fish being caught 477 00:31:53,700 --> 00:31:55,766 and most fish with eggs. 478 00:31:55,766 --> 00:31:58,266 We've noticed that, every time you go out, 479 00:31:58,266 --> 00:32:00,400 you'll find less fish. 480 00:32:09,133 --> 00:32:11,433 NARRATOR: Kenny and Will are searching the Crown 481 00:32:11,433 --> 00:32:13,900 for likely fish-breeding sites 482 00:32:13,900 --> 00:32:18,533 to protect the spawning when it happens. 483 00:32:18,533 --> 00:32:22,300 Both believe that the Crown must have major breeding grounds 484 00:32:22,300 --> 00:32:26,733 for Nassau groupers and other species based on the currents 485 00:32:26,733 --> 00:32:30,366 and ideal rocky outcrops and spurs. 486 00:32:30,366 --> 00:32:32,566 HEYMAN: These fish all come together to reproduce 487 00:32:32,566 --> 00:32:36,900 at these very specific places and times at elbows. 488 00:32:36,900 --> 00:32:39,200 This stage is promontory stage, 489 00:32:39,200 --> 00:32:41,166 so it's kind of like a table corner, right? 490 00:32:41,166 --> 00:32:44,333 Dropping off on two sides. 491 00:32:44,333 --> 00:32:48,233 NARRATOR: Multiple species can gather at a single site. 492 00:32:48,233 --> 00:32:50,966 HEYMAN: What blows me away about these multi-species aggregation 493 00:32:50,966 --> 00:32:54,266 is, they all come at slightly different times. 494 00:32:54,266 --> 00:32:56,066 They're all queued up with the lunar cycle, 495 00:32:56,066 --> 00:32:59,466 with the moon, and with the seasonal cycles. 496 00:32:59,466 --> 00:33:03,000 I want to understand and characterize these aggregations. 497 00:33:03,000 --> 00:33:04,433 We've got to know what's going on 498 00:33:04,433 --> 00:33:06,566 in order to really protect it. 499 00:33:08,666 --> 00:33:10,733 NARRATOR: Will and Kenny zero in 500 00:33:10,733 --> 00:33:14,200 on the most likely outcrops and edges. 501 00:33:14,200 --> 00:33:15,700 HEYMAN: I can't be there all the time, 502 00:33:15,700 --> 00:33:18,900 so we use remote sensing. 503 00:33:18,900 --> 00:33:22,233 NARRATOR: They place cameras and microphones to collect data 504 00:33:22,233 --> 00:33:24,533 during the breeding season. 505 00:33:24,533 --> 00:33:26,000 HEYMAN: That data's not easy to analyze. 506 00:33:26,000 --> 00:33:27,933 It takes time. 507 00:33:27,933 --> 00:33:30,766 And time is not on our side. 508 00:33:30,766 --> 00:33:35,333 ♪♪ 509 00:33:35,333 --> 00:33:37,133 NARRATOR: They also call in an expert 510 00:33:37,133 --> 00:33:41,633 on grouper spawning aggregations. 511 00:33:41,633 --> 00:33:45,833 Dr. Michelle Scharer studies fish acoustics. 512 00:33:45,833 --> 00:33:50,033 SCHARER: My main interest is in sound production of the fishes. 513 00:33:50,033 --> 00:33:52,566 They live in this environment that is full of sound, 514 00:33:52,566 --> 00:33:56,500 but very few people actually have studied that. 515 00:33:59,100 --> 00:34:01,400 There's an opportunity there to learn a lot 516 00:34:01,400 --> 00:34:03,966 about coral-reef ecology just by listening 517 00:34:03,966 --> 00:34:08,600 and not so much seeing what's going on. 518 00:34:08,600 --> 00:34:11,200 Took a little bit of training to hold your breath 519 00:34:11,200 --> 00:34:14,333 and actually listen when you're down there to the sounds 520 00:34:14,333 --> 00:34:16,966 and the different pitches 521 00:34:16,966 --> 00:34:20,266 and the different rumbles that are underwater. 522 00:34:20,266 --> 00:34:25,866 [ Discordant scratching ] 523 00:34:25,866 --> 00:34:28,466 [ Low-pitched thrum ] 524 00:34:28,466 --> 00:34:31,300 NARRATOR: What sounds like a cacophony to us... 525 00:34:31,300 --> 00:34:32,600 [ Scraping ] 526 00:34:32,600 --> 00:34:35,733 ...is actually a chorus of communication. 527 00:34:38,100 --> 00:34:39,900 SCHARER: Fish can definitely hear. 528 00:34:39,900 --> 00:34:41,933 They have ear bones just like we do, 529 00:34:41,933 --> 00:34:46,233 where they can actually sense those vibrations in the water. 530 00:34:46,233 --> 00:34:49,166 [ Low-pitched thrumming ] 531 00:34:49,166 --> 00:34:51,200 Basically, fishes are communicating. 532 00:34:51,200 --> 00:34:54,633 They are emitting signals and receiving signals 533 00:34:54,633 --> 00:34:57,300 that let them know what's going on, 534 00:34:57,300 --> 00:34:59,300 if they're ready to spawn. 535 00:34:59,300 --> 00:35:04,700 [ Thrumming ] 536 00:35:04,700 --> 00:35:07,266 NARRATOR: The scientists collect an underwater recorder 537 00:35:07,266 --> 00:35:09,133 set up months ago. 538 00:35:15,566 --> 00:35:17,366 SCHARER: We're recording 24 hours, 539 00:35:17,366 --> 00:35:21,300 and there's sounds accompanying all those moments. 540 00:35:21,300 --> 00:35:22,300 [ Croaking ] 541 00:35:22,300 --> 00:35:23,566 It sounds spectacular. 542 00:35:23,566 --> 00:35:26,166 Just the amount and diversity 543 00:35:26,166 --> 00:35:28,266 and the frequencies that we're hearing. 544 00:35:28,266 --> 00:35:30,433 [ Croaking ] 545 00:35:30,433 --> 00:35:33,033 And there's other little grunts and beeps and boops 546 00:35:33,033 --> 00:35:36,566 that are different organisms that live on the reef. 547 00:35:36,566 --> 00:35:39,600 So I think it sounds pretty cool. 548 00:35:39,600 --> 00:35:42,866 Different species will have different frequency bands. 549 00:35:42,866 --> 00:35:44,900 [ High-pitched croaking ] 550 00:35:44,900 --> 00:35:47,233 -Toadfish. -Toadfish, oh! 551 00:35:47,233 --> 00:35:49,433 [ Laughs ] 552 00:35:49,433 --> 00:35:53,933 NARRATOR: Toadfish are the noisy neighbors. 553 00:35:53,933 --> 00:35:56,466 Squirrelfish communicate in clicks. 554 00:35:56,466 --> 00:35:59,500 [ Squirrelfish clicking ] 555 00:35:59,500 --> 00:36:01,266 [ Scraping ] 556 00:36:01,266 --> 00:36:05,000 Grunts make sound by grinding their teeth. 557 00:36:05,000 --> 00:36:10,833 [ Scraping continues ] 558 00:36:10,833 --> 00:36:12,800 A batfish bleats. 559 00:36:12,800 --> 00:36:14,933 [ Batfish bleating ] 560 00:36:18,166 --> 00:36:22,066 Michelle has identified fish calls used to court, 561 00:36:22,066 --> 00:36:25,766 defend territory, and warn of danger. 562 00:36:25,766 --> 00:36:27,400 [ Low-pitched thrumming ] 563 00:36:32,333 --> 00:36:35,833 Nassau groupers grumpily defend their home. 564 00:36:35,833 --> 00:36:40,366 [ Thrumming continues ] 565 00:36:40,366 --> 00:36:43,233 The calls travel long distances. 566 00:36:43,233 --> 00:36:44,433 [ Thrumming continues ] 567 00:36:44,433 --> 00:36:48,166 Listening is key to survival. 568 00:36:48,166 --> 00:36:50,933 SCHARER: Baby fish need to hear where they're going 569 00:36:50,933 --> 00:36:54,100 and they use the sound to guide their swimming. 570 00:36:54,100 --> 00:36:56,966 This helps them then grow up on these reefs. 571 00:36:59,466 --> 00:37:03,366 As they grow and they need to find where to go to spawn, 572 00:37:03,366 --> 00:37:06,966 they can rely on sound to find those pathways to meet up 573 00:37:06,966 --> 00:37:10,533 at the spawning aggregation site when it's time. 574 00:37:10,533 --> 00:37:11,833 I heard something there different. 575 00:37:11,833 --> 00:37:13,233 Did you hear it, too? 576 00:37:13,233 --> 00:37:14,800 Yeah? PETERSEN: Yeah, it's different. 577 00:37:14,800 --> 00:37:16,266 SCHARER: Okay. There's something in here. 578 00:37:16,266 --> 00:37:19,133 NARRATOR: This rich soundscape helps make the case 579 00:37:19,133 --> 00:37:22,833 that the Cayman Crown must be protected. 580 00:37:22,833 --> 00:37:27,833 And in 2020, science wins a big victory. 581 00:37:27,833 --> 00:37:29,700 The countries sharing the reef 582 00:37:29,700 --> 00:37:34,733 grant the Crown conservation status. 583 00:37:34,733 --> 00:37:36,566 McFIELD: We've protected this reef now. 584 00:37:36,566 --> 00:37:38,400 In Guatemala, it's fully protected. 585 00:37:38,400 --> 00:37:41,833 In Belize, it's highly protected. 586 00:37:41,833 --> 00:37:43,833 They've stepped up to the plate and protected it. 587 00:37:43,833 --> 00:37:47,966 So, you know, that was our ultimate goal, 588 00:37:47,966 --> 00:37:49,633 is, "Hey, we need to protect this," 589 00:37:49,633 --> 00:37:51,966 and now it's happened. 590 00:37:51,966 --> 00:37:59,400 ♪♪ 591 00:37:59,400 --> 00:38:02,766 This helps, but I think we need to now really work 592 00:38:02,766 --> 00:38:08,233 on management and enforcement and do all that we can to ensure 593 00:38:08,233 --> 00:38:11,433 that this reef does have all the elements 594 00:38:11,433 --> 00:38:13,433 that will help it be resilient 595 00:38:13,433 --> 00:38:17,066 and that fish are on the reef and not being taken. 596 00:38:17,066 --> 00:38:20,400 ♪♪ 597 00:38:20,400 --> 00:38:23,433 NARRATOR: And, indeed, the conservation win 598 00:38:23,433 --> 00:38:26,166 appears short-lived. 599 00:38:26,166 --> 00:38:28,366 ♪♪ 600 00:38:28,366 --> 00:38:30,833 Michelle is already finding evidence 601 00:38:30,833 --> 00:38:35,333 that the Crown's future is in jeopardy. 602 00:38:35,333 --> 00:38:37,166 It's spawning time, 603 00:38:37,166 --> 00:38:40,633 the same season Will heard groupers two years ago. 604 00:38:40,633 --> 00:38:43,700 ♪♪ 605 00:38:43,700 --> 00:38:48,000 Now, Michel detects a shift. 606 00:38:48,000 --> 00:38:50,600 ♪♪ 607 00:38:50,600 --> 00:38:53,366 SCHARER: We did not hear as many as we would expect. 608 00:38:53,366 --> 00:38:56,733 ♪♪ 609 00:38:56,733 --> 00:39:01,266 So I think there may be something going on. 610 00:39:01,266 --> 00:39:04,333 NARRATOR: In fact, the groupers seem to have 611 00:39:04,333 --> 00:39:07,100 almost disappeared from the Crown. 612 00:39:07,100 --> 00:39:21,733 ♪♪ 613 00:39:21,733 --> 00:39:25,200 The news stuns the team. 614 00:39:25,200 --> 00:39:28,600 HEYMAN: Fishers have realized that this is a gold mine. 615 00:39:28,600 --> 00:39:30,533 You know, I'm not an emotional guy, 616 00:39:30,533 --> 00:39:33,266 but how do you deal with this? 617 00:39:35,466 --> 00:39:39,466 McFIELD: How do we stop it? How do we stop the degradation? 618 00:39:42,433 --> 00:39:46,700 NARRATOR: Fishers must have been targeting the Crown. 619 00:39:46,700 --> 00:39:48,533 But it's not the locals. 620 00:39:48,533 --> 00:39:50,700 Kenny has been working with him. 621 00:39:50,700 --> 00:39:53,733 He's confident they are respecting a fishing ban 622 00:39:53,733 --> 00:39:55,666 the government's put in place. 623 00:39:58,433 --> 00:40:00,166 [ Indistinct conversations ] 624 00:40:00,166 --> 00:40:02,000 The team suspects the raiders 625 00:40:02,000 --> 00:40:05,300 are from outside Belize and Guatemala. 626 00:40:11,100 --> 00:40:14,733 MARTIN: We've been seeing nets, fishing line, even starting 627 00:40:14,733 --> 00:40:16,800 and batting into the reef. 628 00:40:16,800 --> 00:40:19,133 I've been seeing anchors that are used 629 00:40:19,133 --> 00:40:21,633 to moor their boats when they go fishing. 630 00:40:21,633 --> 00:40:23,900 We've been seeing a lot of broken corals, 631 00:40:23,900 --> 00:40:26,266 ripped-out sponges, and stuff like that. 632 00:40:26,266 --> 00:40:29,433 So we know that fishermen are targeting it a lot 633 00:40:29,433 --> 00:40:33,100 for commercial species. 634 00:40:33,100 --> 00:40:36,866 NARRATOR: A sponge is sliced cleanly by a fishing line. 635 00:40:38,933 --> 00:40:42,033 Kenny and Melanie stitched the pieces together. 636 00:40:42,033 --> 00:40:49,000 ♪♪ 637 00:40:49,000 --> 00:40:52,233 But the team can only do so much. 638 00:40:52,233 --> 00:40:55,000 ♪♪ 639 00:40:55,000 --> 00:40:57,500 MARTIN: I would like to see more protection. 640 00:40:57,500 --> 00:41:00,500 I would like to see patrol boats out there. 641 00:41:00,500 --> 00:41:04,733 I would like to see Belize, Guatemala, and Honduras 642 00:41:04,733 --> 00:41:07,300 working together to protect these resources 643 00:41:07,300 --> 00:41:11,100 that is very vital to fishermen's livelihood 644 00:41:11,100 --> 00:41:14,900 and also for the local people. 645 00:41:14,900 --> 00:41:16,333 NARRATOR: The current protections, 646 00:41:16,333 --> 00:41:18,066 incomplete as they are, 647 00:41:18,066 --> 00:41:22,500 are placing the guardians of the reef at risk. 648 00:41:22,500 --> 00:41:24,800 HEYMAN: They're protecting globally important, 649 00:41:24,800 --> 00:41:28,933 valuable resources on the front line at night, 650 00:41:28,933 --> 00:41:31,433 you know, with people coming out there with guns. 651 00:41:31,433 --> 00:41:35,100 It's dangerous. This is protecting gold. 652 00:41:35,100 --> 00:41:41,533 ♪♪ 653 00:41:41,533 --> 00:41:44,933 [ Generator whirring ] 654 00:41:44,933 --> 00:41:46,433 PETERSEN: It's really alarming. 655 00:41:46,433 --> 00:41:50,100 You know, we need to think about what to -- what to do. 656 00:41:50,100 --> 00:41:52,233 ♪♪ 657 00:41:52,233 --> 00:41:54,366 We need to bring back our fish. 658 00:41:54,366 --> 00:42:00,033 ♪♪ 659 00:42:00,033 --> 00:42:03,100 NARRATOR: As the team calls for enforcement, 660 00:42:03,100 --> 00:42:05,100 Michelle ponders whether groupers 661 00:42:05,100 --> 00:42:08,666 can be lured back to the Crown. 662 00:42:08,666 --> 00:42:11,500 She takes inspiration from the marine sanctuary 663 00:42:11,500 --> 00:42:15,466 of Glover's Reef, five hours north by boat. 664 00:42:17,833 --> 00:42:19,900 SCHARER: For a few years, I've been collaborating 665 00:42:19,900 --> 00:42:22,600 with Myles Phillips, recording the sounds 666 00:42:22,600 --> 00:42:26,233 of the groupers at the northeast point of Glover's, 667 00:42:26,233 --> 00:42:28,700 specifically listening to the sounds produced 668 00:42:28,700 --> 00:42:30,566 by the Nassau grouper 669 00:42:30,566 --> 00:42:34,300 to be able to detect when they are supposed to spawn. 670 00:42:36,666 --> 00:42:38,400 NARRATOR: Those recordings suggest 671 00:42:38,400 --> 00:42:42,200 that the groupers are starting to gather. 672 00:42:42,200 --> 00:42:44,633 SCHARER: These fish have to migrate quite a way 673 00:42:44,633 --> 00:42:46,700 from different distances. 674 00:42:46,700 --> 00:42:48,433 They need to know they're on the right track. 675 00:42:48,433 --> 00:42:52,533 So communication between them as they form little groups 676 00:42:52,533 --> 00:42:54,866 and move towards the main aggregation site 677 00:42:54,866 --> 00:42:58,133 is really important for them. 678 00:42:58,133 --> 00:43:01,966 NARRATOR: Nassau groupers are solitary most of the year. 679 00:43:01,966 --> 00:43:06,300 Reproduction brings them together. 680 00:43:06,300 --> 00:43:09,033 Some will travel hundreds of miles. 681 00:43:09,033 --> 00:43:24,033 ♪♪ 682 00:43:24,033 --> 00:43:26,833 They arrive in December and January, 683 00:43:26,833 --> 00:43:30,966 when Caribbean waters are coolest. 684 00:43:30,966 --> 00:43:33,533 SCHARER: They start communicating to each other. 685 00:43:33,533 --> 00:43:35,166 They have different signals, 686 00:43:35,166 --> 00:43:39,000 different languages or different words or vowels 687 00:43:39,000 --> 00:43:42,066 for the different behaviors that they conduct only 688 00:43:42,066 --> 00:43:43,700 when they aggregate to spawn. 689 00:43:46,700 --> 00:43:49,733 NARRATOR: They also communicate with stylized movements 690 00:43:49,733 --> 00:43:52,966 and shifting patterns on their skin. 691 00:43:52,966 --> 00:43:54,066 HEYMAN: They look cool already. 692 00:43:54,066 --> 00:43:55,733 They got their stripes and everything. 693 00:43:55,733 --> 00:43:57,366 But when it's getting close to spawning, 694 00:43:57,366 --> 00:43:59,233 they're, like, trying on different outfits. 695 00:43:59,233 --> 00:44:03,166 Some turn white, some turn black. 696 00:44:03,166 --> 00:44:07,866 NARRATOR: More groupers arrive. The chorus swells in volume. 697 00:44:07,866 --> 00:44:15,400 [ Loud thrumming ] 698 00:44:15,400 --> 00:44:17,866 ♪♪ 699 00:44:17,866 --> 00:44:23,000 Some wait on the sea floor, conserving their energy. 700 00:44:23,000 --> 00:44:25,400 SCHARER: They need to synchronize to 1 or 2 nights. 701 00:44:25,400 --> 00:44:27,966 Everybody has to have their eggs and their sperm ready 702 00:44:27,966 --> 00:44:29,866 for that moment. 703 00:44:29,866 --> 00:44:31,966 They are communicating, "Are we ready to spawn? 704 00:44:31,966 --> 00:44:34,533 Do you think we can spawn now?" 705 00:44:34,533 --> 00:44:38,533 [ Thrumming continues ] 706 00:44:38,533 --> 00:44:40,300 NARRATOR: As their numbers grow, 707 00:44:40,300 --> 00:44:44,633 they rise from the sea floor each evening, as if rehearsing. 708 00:44:44,633 --> 00:44:52,366 [ Thrumming continues ] 709 00:44:52,366 --> 00:44:54,433 As the full moon approaches, 710 00:44:54,433 --> 00:44:58,100 the performance has become more sophisticated. 711 00:44:58,100 --> 00:44:59,366 HEYMAN: Where the real fun is, 712 00:44:59,366 --> 00:45:02,366 is in the courtship prior to spawning. 713 00:45:02,366 --> 00:45:07,033 Each has their own suite of behaviors and sounds 714 00:45:07,033 --> 00:45:11,933 that all come together into this courtship dance. 715 00:45:11,933 --> 00:45:14,733 [ Grouper thrums ] 716 00:45:14,733 --> 00:45:16,400 NARRATOR: If they are ready, 717 00:45:16,400 --> 00:45:19,900 they change into matching costumes. 718 00:45:19,900 --> 00:45:21,566 HEYMAN: But as you get closer to spawning, 719 00:45:21,566 --> 00:45:24,966 they all choose this tuxedo, it looks like to me -- 720 00:45:24,966 --> 00:45:27,500 black, black, black, with a bar over the eye, 721 00:45:27,500 --> 00:45:28,633 and a white belly. 722 00:45:28,633 --> 00:45:32,366 We call it bicolor phase. 723 00:45:32,366 --> 00:45:34,400 [ Grouper thrumming ] 724 00:45:34,400 --> 00:45:36,600 It's like a vaudeville act. 725 00:45:36,600 --> 00:45:40,933 Males fighting over females, making sounds at each other. 726 00:45:40,933 --> 00:45:45,266 [ Thrumming continues ] 727 00:45:45,266 --> 00:45:48,600 NARRATOR: Males wrestle around the females. 728 00:45:48,600 --> 00:45:50,066 The noise builds. 729 00:45:50,066 --> 00:45:51,900 [ Grouper thrumming ] 730 00:45:51,900 --> 00:45:56,033 But night after night, they hold back. 731 00:45:56,033 --> 00:46:02,466 [ Grouper thrumming ] 732 00:46:02,466 --> 00:46:06,100 Then, one night, the temperature is right. 733 00:46:06,100 --> 00:46:08,300 The moonlight is right. 734 00:46:08,300 --> 00:46:12,566 Most importantly, there's a critical mass of fish. 735 00:46:12,566 --> 00:46:15,766 The chorus reaches a crescendo. 736 00:46:15,766 --> 00:46:23,300 [ Grouper thrumming loudly ] 737 00:46:23,300 --> 00:46:27,733 Then, silence. 738 00:46:27,733 --> 00:46:30,733 Spawning has begun. 739 00:46:46,200 --> 00:46:57,866 ♪♪ 740 00:46:57,866 --> 00:46:59,966 HEYMAN: These are the volcanoes of reproduction 741 00:46:59,966 --> 00:47:03,700 for the entire region. 742 00:47:03,700 --> 00:47:05,800 All of these fish coming all together 743 00:47:05,800 --> 00:47:08,500 at these promontories, currents that are upwelling 744 00:47:08,500 --> 00:47:10,200 and shooting by there and creating 745 00:47:10,200 --> 00:47:11,966 and captured in gyres, 746 00:47:11,966 --> 00:47:17,033 some shooting way long distances to seed other places. 747 00:47:17,033 --> 00:47:19,400 That is the large-scale connectivity 748 00:47:19,400 --> 00:47:22,100 throughout this entire wider Caribbean basin. 749 00:47:22,100 --> 00:47:33,433 ♪♪ 750 00:47:35,066 --> 00:47:38,033 NARRATOR: The mating spectacle at Glover's most likely 751 00:47:38,033 --> 00:47:40,400 used to take place at the Crown. 752 00:47:43,100 --> 00:47:47,300 Could it happen here again with a helping hand? 753 00:47:47,300 --> 00:47:52,000 Michelle hatches a plan to use sound recordings from Glover's 754 00:47:52,000 --> 00:47:55,433 to attract groupers to the Crown. 755 00:47:55,433 --> 00:47:58,600 SCHARER: If there are fish nearby, whatever's left, 756 00:47:58,600 --> 00:48:01,366 can we actually make them recover 757 00:48:01,366 --> 00:48:04,266 that spawning aggregation that once was at the jewel? 758 00:48:04,266 --> 00:48:05,966 HEYMAN: I'm curious. SCHARER: How about 759 00:48:05,966 --> 00:48:08,400 we put out loudspeakers and play these sounds 760 00:48:08,400 --> 00:48:11,100 and see if we can attract whatever's left 761 00:48:11,100 --> 00:48:13,533 of what used to be the aggregation at the jewel? 762 00:48:13,533 --> 00:48:14,766 HEYMAN: Okay. SCHARER: This would be 763 00:48:14,766 --> 00:48:17,133 the first try to attract fish 764 00:48:17,133 --> 00:48:19,966 that maybe are still there, but they've lost their cues 765 00:48:19,966 --> 00:48:22,166 because there's only a few fish left. 766 00:48:22,166 --> 00:48:26,333 So if we play back these sounds and they recognize them, 767 00:48:26,333 --> 00:48:29,066 maybe they'll come back to the aggregation site. 768 00:48:31,500 --> 00:48:35,733 NARRATOR: It's not such a wild idea. 769 00:48:35,733 --> 00:48:40,200 In Australia, sound recordings were used to lure baby fish 770 00:48:40,200 --> 00:48:42,633 to settle on a recovering reef. 771 00:48:47,666 --> 00:48:52,533 Michelle and Kenny test an underwater speaker at the Crown. 772 00:48:52,533 --> 00:48:56,033 The first step is to gauge how far the sound travels. 773 00:48:56,033 --> 00:49:01,466 [ Grouper thrumming plays ] 774 00:49:01,466 --> 00:49:03,733 If the experiment works, 775 00:49:03,733 --> 00:49:09,133 it could jumpstart the recovery of fisheries at the Crown. 776 00:49:09,133 --> 00:49:12,466 [ Grouper thrumming plays ] 777 00:49:12,466 --> 00:49:14,733 But recovery will also depend 778 00:49:14,733 --> 00:49:18,933 on staunch enforcement of the fishing ban. 779 00:49:18,933 --> 00:49:24,600 [ Grouper thrumming plays ] 780 00:49:24,600 --> 00:49:27,133 Groupers can recover. 781 00:49:27,133 --> 00:49:29,600 Strict protection of two aggregations 782 00:49:29,600 --> 00:49:30,900 in the Cayman Islands 783 00:49:30,900 --> 00:49:36,100 tripled their numbers in under a decade. 784 00:49:36,100 --> 00:49:38,233 The team listens to the grouper calls 785 00:49:38,233 --> 00:49:41,000 coming from the speakers below. 786 00:49:41,000 --> 00:49:43,666 They anticipate what might happen. 787 00:49:49,533 --> 00:49:53,133 [ Thrumming  ] 788 00:49:53,133 --> 00:49:55,833 MARTIN: Imagine hundreds of them coming up and "Kkkkkk," 789 00:49:55,833 --> 00:49:58,766 just making that thing happen. 790 00:49:58,766 --> 00:50:00,766 HEYMAN: Oh, listen to that. 791 00:50:00,766 --> 00:50:03,100 SCHARER: I guess it takes one first one to go off, 792 00:50:03,100 --> 00:50:04,833 and then everybody follows in queue. 793 00:50:04,833 --> 00:50:06,066 PHILLIPS: They see one person go to the dance, 794 00:50:06,066 --> 00:50:08,033 where they're like, [snaps] "That's it." 795 00:50:08,033 --> 00:50:10,333 SCHARER: Mm-hmm. HEYMAN: Yeah. 796 00:50:10,333 --> 00:50:12,833 [ Thrumming continues  ] 797 00:50:12,833 --> 00:50:18,266 ♪♪ 798 00:50:18,266 --> 00:50:20,166 NARRATOR: When the Crown was discovered, 799 00:50:20,166 --> 00:50:22,466 it sparked a sense of hope 800 00:50:22,466 --> 00:50:27,533 that the Caribbean's embattled coral reefs may not be doomed. 801 00:50:27,533 --> 00:50:34,033 And it has brought once unlikely allies together. 802 00:50:34,033 --> 00:50:37,933 MARTIN: It's gonna be a huge change to have fishermen 803 00:50:37,933 --> 00:50:41,433 thinking on a positive note to protect these resources 804 00:50:41,433 --> 00:50:44,066 so they could replenish the areas. 805 00:50:44,066 --> 00:50:49,066 ♪♪ 806 00:50:49,066 --> 00:50:51,266 NARRATOR: The team's success in exploring 807 00:50:51,266 --> 00:50:53,933 and protecting this natural wonder 808 00:50:53,933 --> 00:50:58,633 has given them encouragement to carry on. 809 00:50:58,633 --> 00:51:01,933 McFIELD: We all get refreshed, and our enthusiasm 810 00:51:01,933 --> 00:51:04,566 and our hope for what we're doing, that it -- 811 00:51:04,566 --> 00:51:05,900 we can succeed 812 00:51:05,900 --> 00:51:08,100 and we will succeed if we keep pushing. 813 00:51:08,100 --> 00:51:12,533 So that's what we do. 814 00:51:12,533 --> 00:51:15,100 NARRATOR: The Crown itself has also demonstrated 815 00:51:15,100 --> 00:51:17,366 a remarkable resilience. 816 00:51:21,333 --> 00:51:26,133 And the fight for its future has only just begun. 817 00:51:28,066 --> 00:51:31,133 HEYMAN: I've seen places recover. 818 00:51:31,133 --> 00:51:33,300 If we're -- If we're gentle, if we're good, 819 00:51:33,300 --> 00:51:37,066 if we realize the value, 820 00:51:37,066 --> 00:51:38,500 these places are resilient. 821 00:51:38,500 --> 00:51:41,966 These places can come back. 822 00:51:41,966 --> 00:51:44,466 And that's why I maintain hope. 823 00:51:44,466 --> 00:51:58,000 ♪♪ 824 00:51:58,000 --> 00:52:00,966 PHILLIPS: It's not even a little ray of hope. 825 00:52:00,966 --> 00:52:03,933 This place is huge. It's like -- 826 00:52:03,933 --> 00:52:06,766 It's like seeing the sun spilling out of the clouds. 827 00:52:06,766 --> 00:52:23,400 ♪♪ 828 00:52:25,466 --> 00:53:03,200 ♪♪ 829 00:53:03,200 --> 00:53:06,600 To learn more about what you've seen on this "Nature" program, 830 00:53:06,600 --> 00:53:08,533 visit pbs.org. 831 00:53:08,533 --> 00:53:17,433 ♪♪