1 00:00:03,670 --> 00:00:06,206 >>NARRATOR: The Florida Everglades. 2 00:00:06,206 --> 00:00:07,774 Beautiful. 3 00:00:07,774 --> 00:00:09,843 Vast. 4 00:00:09,843 --> 00:00:12,346 Harsh. 5 00:00:12,346 --> 00:00:14,114 Remote. 6 00:00:14,114 --> 00:00:15,849 >>It is a huge wetland 7 00:00:15,849 --> 00:00:19,319 that flows across most of southern Florida, 8 00:00:19,319 --> 00:00:21,922 and then it runs into the ocean. 9 00:00:21,922 --> 00:00:23,857 >>NARRATOR: Some of North America's 10 00:00:23,857 --> 00:00:26,393 fiercest predators live here, 11 00:00:26,393 --> 00:00:31,031 including the American alligator and the bull shark. 12 00:00:31,031 --> 00:00:34,134 >>They're top predators. 13 00:00:34,134 --> 00:00:36,537 They eat a lot of different types of prey, 14 00:00:36,537 --> 00:00:38,572 which means they could have a big impact 15 00:00:38,572 --> 00:00:40,374 on a lot of different prey populations, 16 00:00:40,374 --> 00:00:42,142 which then could have cascading effects 17 00:00:42,142 --> 00:00:44,745 down to lower levels of the food chain. 18 00:00:44,745 --> 00:00:48,248 >>NARRATOR: Despite its wild nature, 19 00:00:48,248 --> 00:00:52,920 the Everglades is an ecosystem in trouble. 20 00:00:52,920 --> 00:00:57,324 For nearly a century, man drained the swamp. 21 00:00:57,324 --> 00:01:00,661 Now, a large-scale restoration project 22 00:01:00,661 --> 00:01:05,232 aims to return the wetland to its former glory. 23 00:01:05,232 --> 00:01:07,768 >>More and more fresh water is going to come in, 24 00:01:07,768 --> 00:01:09,703 so it's really important we get the water right 25 00:01:09,703 --> 00:01:11,939 and we know how animals like sharks and alligators respond 26 00:01:11,939 --> 00:01:17,344 so we're managing the ecosystem right for them. 27 00:01:17,344 --> 00:01:19,846 That's why we're doing these studies-- 28 00:01:19,846 --> 00:01:21,715 to get an idea and make predictions 29 00:01:21,715 --> 00:01:24,451 about how this change will affect the ecosystem, 30 00:01:24,451 --> 00:01:26,453 so we can protect those animals 31 00:01:26,453 --> 00:01:29,556 and make sure they fill that critical ecological role. 32 00:01:31,758 --> 00:01:34,361 ♪♪ 33 00:01:54,948 --> 00:01:56,817 >>Major funding for this program 34 00:01:56,817 --> 00:01:59,586 was provided by the Batchelor Foundation, 35 00:01:59,586 --> 00:02:02,823 encouraging people to preserve and protect 36 00:02:02,823 --> 00:02:05,492 America's underwater resources. 37 00:02:08,261 --> 00:02:12,065 And by Divers Direct, inspiring the pursuit 38 00:02:12,065 --> 00:02:14,501 of tropical adventure scuba diving. 39 00:02:22,376 --> 00:02:25,345 >>NARRATOR: On the southern tip of the Florida peninsula, 40 00:02:25,345 --> 00:02:30,350 the Everglades meet the Gulf of Mexico. 41 00:02:30,350 --> 00:02:34,454 Here, the river of grass gives way to a maze 42 00:02:34,454 --> 00:02:40,961 of mangrove-lined rivers that eventually flow into the sea. 43 00:02:40,961 --> 00:02:42,295 >>The Shark River estuar 44 00:02:42,295 --> 00:02:45,499 is the terminus of the Shark River Slough, 45 00:02:45,499 --> 00:02:48,468 which is a major part of the central and southern Everglades. 46 00:02:48,468 --> 00:02:50,937 That is the main conduit of fresh water 47 00:02:50,937 --> 00:02:53,340 out of the Everglades and into the Gulf of Mexico. 48 00:02:53,340 --> 00:02:56,309 So the Shark River is a really important place 49 00:02:56,309 --> 00:02:58,512 where fresh water from the north 50 00:02:58,512 --> 00:03:01,381 and salt water from the Gulf of Mexico mix together, 51 00:03:01,381 --> 00:03:03,817 and we get this really interesting mix of organisms. 52 00:03:03,817 --> 00:03:06,386 >>NARRATOR: Recognized as a wetland 53 00:03:06,386 --> 00:03:09,523 of international importance, 54 00:03:09,523 --> 00:03:12,392 the Everglades ecosystem is a unique place. 55 00:03:12,392 --> 00:03:15,328 >>There's a huge abundance of life here. 56 00:03:15,328 --> 00:03:17,297 It's one of those wilderness places 57 00:03:17,297 --> 00:03:19,833 that are few and far between on the planet now, 58 00:03:19,833 --> 00:03:22,402 but it's also a place that's affected a lot by humans. 59 00:03:22,402 --> 00:03:25,839 >>NARRATOR: Over the course of the 20th century, 60 00:03:25,839 --> 00:03:28,975 humans have greatly changed the way water flows 61 00:03:28,975 --> 00:03:31,812 across the Everglades. 62 00:03:31,812 --> 00:03:34,147 Canals and dikes were built to provide flood control 63 00:03:34,147 --> 00:03:38,585 and deliver fresh water to agricultural operations 64 00:03:38,585 --> 00:03:42,289 and South Florida's ever-growing human population. 65 00:03:42,289 --> 00:03:46,760 This greatly decreased the amount of fresh water 66 00:03:46,760 --> 00:03:49,663 flowing across the Everglades. 67 00:03:49,663 --> 00:03:51,631 >>That fresh water that's the source of life 68 00:03:51,631 --> 00:03:53,500 for this part of the Everglades, 69 00:03:53,500 --> 00:03:56,103 the tap's kind of been turned off. 70 00:03:56,103 --> 00:03:59,406 >>NARRATOR: The impacts on the natural system were severe, 71 00:03:59,406 --> 00:04:03,443 and now a multibillion-dollar restoration project is underwa 72 00:04:03,443 --> 00:04:09,716 to return some of that water back to the Everglades. 73 00:04:09,716 --> 00:04:12,185 >>As we re-engineer the water, we need to figure out 74 00:04:12,185 --> 00:04:14,187 how the plants and animals are going to respond 75 00:04:14,187 --> 00:04:17,023 so we don't muck up the ecosystem even worse. 76 00:04:17,023 --> 00:04:20,494 So really understanding how important different species are, 77 00:04:20,494 --> 00:04:22,863 how they respond to the water and other conditions 78 00:04:22,863 --> 00:04:25,966 is critical for getting the restoration right. 79 00:04:25,966 --> 00:04:28,802 >>NARRATOR: To better understand 80 00:04:28,802 --> 00:04:31,805 the various ecological roles species pla 81 00:04:31,805 --> 00:04:33,640 in the coastal Everglades, 82 00:04:33,640 --> 00:04:38,545 Mike Heithaus and his team study predator-prey interactions 83 00:04:38,545 --> 00:04:43,216 and how predators respond to changes in the environment. 84 00:04:43,216 --> 00:04:45,085 >>So a lot of the work we do 85 00:04:45,085 --> 00:04:48,488 is trying to figure out how humans affect this ecosystem, 86 00:04:48,488 --> 00:04:51,258 and as we try to restore it, how that's going to affect 87 00:04:51,258 --> 00:04:53,794 the big predators like alligators and sharks. 88 00:04:56,196 --> 00:04:59,065 >>NARRATOR: To do so, scientists want to know 89 00:04:59,065 --> 00:05:03,270 where the animals are found and why. 90 00:05:03,270 --> 00:05:06,807 During the daytime, they try to catch bull sharks 91 00:05:06,807 --> 00:05:10,076 in different parts of the Shark River. 92 00:05:10,076 --> 00:05:13,480 >>We have four different areas within the estuar 93 00:05:13,480 --> 00:05:17,584 that we set lines that typically have different conditions-- 94 00:05:17,584 --> 00:05:19,119 mainly differences in salinity. 95 00:05:19,119 --> 00:05:21,988 And so we set the lines at a salinity gradient, 96 00:05:21,988 --> 00:05:23,423 starting from the ocean 97 00:05:23,423 --> 00:05:26,960 all the way up to the freshwater marshes and in between. 98 00:05:26,960 --> 00:05:28,895 >>NARRATOR: Using the number of sharks 99 00:05:28,895 --> 00:05:30,263 caught in different locations 100 00:05:30,263 --> 00:05:33,500 and at different times of the year, 101 00:05:33,500 --> 00:05:35,268 the scientists can determine 102 00:05:35,268 --> 00:05:39,773 the types of areas and conditions the animals need. 103 00:05:39,773 --> 00:05:41,441 >>When we first came out here, 104 00:05:41,441 --> 00:05:43,677 we were told there's no way you're going to find sharks. 105 00:05:43,677 --> 00:05:48,148 We set our lines and had two sharks on our very first one. 106 00:05:48,148 --> 00:05:51,818 >>NARRATOR: Bull sharks are the only species of shark 107 00:05:51,818 --> 00:05:55,188 in North America that can live in fresh water, 108 00:05:55,188 --> 00:05:58,925 and the juvenile sharks usually live in rivers and estuaries 109 00:05:58,925 --> 00:06:02,128 until they are big enough to move to the ocean. 110 00:06:02,128 --> 00:06:04,297 >>To catch bull sharks, 111 00:06:04,297 --> 00:06:09,135 we use long lines with baited hooks with mullet, 112 00:06:09,135 --> 00:06:12,239 and those sit on the bottom for about an hour. 113 00:06:12,239 --> 00:06:15,876 So the long lines have about 50 hooks, and we allow them to soak 114 00:06:15,876 --> 00:06:18,545 to attract any sharks that are in the area. 115 00:06:18,545 --> 00:06:21,514 And we also use drum lines, 116 00:06:21,514 --> 00:06:23,884 which have larger hooks and larger bait 117 00:06:23,884 --> 00:06:25,585 to catch large predatory sharks 118 00:06:25,585 --> 00:06:28,255 that may feed on the juvenile bull sharks 119 00:06:28,255 --> 00:06:30,390 to quantify the risk of predation 120 00:06:30,390 --> 00:06:32,759 that they have in different areas. 121 00:06:41,067 --> 00:06:43,637 >>Oh, little shark! 122 00:06:43,637 --> 00:06:46,172 This is a little, little guy. 123 00:06:52,078 --> 00:06:55,515 >>After we catch a shark, we take length measurements... 124 00:06:55,515 --> 00:07:01,288 >>55, 62.5, and 78. 125 00:07:01,288 --> 00:07:02,722 >>...weight measurements. 126 00:07:02,722 --> 00:07:05,325 >>Four kilograms. 127 00:07:05,325 --> 00:07:08,161 >>We put an external identification tag in them 128 00:07:08,161 --> 00:07:09,663 so that if we recapture them, 129 00:07:09,663 --> 00:07:11,431 we can determine how much they've grown 130 00:07:11,431 --> 00:07:13,466 and if their body mass has changed. 131 00:07:13,466 --> 00:07:19,272 >>Identification tag j-1-0-6-4-1. 132 00:07:19,272 --> 00:07:21,107 >>That's the umbilical scar, 133 00:07:21,107 --> 00:07:23,410 and it takes a couple of months for that to heal, 134 00:07:23,410 --> 00:07:24,411 so when we see that, 135 00:07:24,411 --> 00:07:27,247 we know that this shark is relatively newborn, 136 00:07:27,247 --> 00:07:29,482 definitely less than one year old. 137 00:07:29,482 --> 00:07:32,953 >>NARRATOR: The scientists are also interested 138 00:07:32,953 --> 00:07:34,821 in studying the diets of the sharks 139 00:07:34,821 --> 00:07:38,825 using a method called stable isotope analysis. 140 00:07:38,825 --> 00:07:41,561 >>It's based on the idea that you are what you eat. 141 00:07:41,561 --> 00:07:45,732 And so carbon and nitrogen are common elements in our bodies, 142 00:07:45,732 --> 00:07:47,600 and we can look at different forms 143 00:07:47,600 --> 00:07:49,803 of those carbon and nitrogen isotopes 144 00:07:49,803 --> 00:07:51,738 and look at their ratios. 145 00:07:51,738 --> 00:07:53,139 And so what happens is that 146 00:07:53,139 --> 00:07:56,142 plants have different values for their carbon 147 00:07:56,142 --> 00:07:59,946 whether they're plants in the ocean or plants in fresh water. 148 00:07:59,946 --> 00:08:03,516 >>NARRATOR: When animals eat plants or other animals, 149 00:08:03,516 --> 00:08:06,786 these carbon values stay roughly the same. 150 00:08:06,786 --> 00:08:10,190 So by analyzing the carbon isotopes in a shark, 151 00:08:10,190 --> 00:08:13,393 scientists can tell whether it has fed in food webs 152 00:08:13,393 --> 00:08:16,229 from the ocean or from fresh water. 153 00:08:16,229 --> 00:08:18,898 The nitrogen isotopes in its bod 154 00:08:18,898 --> 00:08:22,035 show how high in the food chain the animal eats. 155 00:08:22,035 --> 00:08:24,938 Different tissues in the animal's body reflect 156 00:08:24,938 --> 00:08:30,710 what and where an animal has eaten over various time periods. 157 00:08:30,710 --> 00:08:33,279 >>Fin tissue turns over the slowest, 158 00:08:33,279 --> 00:08:35,315 and it takes about a year-and-a-half to two years 159 00:08:35,315 --> 00:08:37,317 for that tissue to be replaced, 160 00:08:37,317 --> 00:08:40,854 so it's a very long-term estimate of their diet. 161 00:08:40,854 --> 00:08:41,988 The muscle tissue takes 162 00:08:41,988 --> 00:08:43,723 about a year-and-a-half to be replaced, 163 00:08:43,723 --> 00:08:45,925 so that's another long-term tissue that we use 164 00:08:45,925 --> 00:08:47,394 to look at their diet. 165 00:08:47,394 --> 00:08:49,662 And then blood, we look at whole blood, 166 00:08:49,662 --> 00:08:52,632 which is just the blood extracted from their veins, 167 00:08:52,632 --> 00:08:55,702 and that turns over in about a year, 168 00:08:55,702 --> 00:08:59,072 so that's kind of a mid-range estimate of their diet. 169 00:08:59,072 --> 00:09:00,306 And then we actually separate the blood 170 00:09:00,306 --> 00:09:02,342 and extract the plasma, 171 00:09:02,342 --> 00:09:04,477 which is replaced relatively quickly, and that provides us 172 00:09:04,477 --> 00:09:06,880 with a short-term estimate of their diet. 173 00:09:06,880 --> 00:09:09,149 And that actually allows us to look at seasonal changes 174 00:09:09,149 --> 00:09:13,353 or actually changes in their diet based on size. 175 00:09:15,155 --> 00:09:19,359 We have caught sharks all the way up at the top of the river 176 00:09:19,359 --> 00:09:21,027 about 20 miles from the ocean. 177 00:09:21,027 --> 00:09:24,130 So there are sharks everywhere within the estuary. 178 00:09:24,130 --> 00:09:26,800 When they're born, they're typically only eating 179 00:09:26,800 --> 00:09:29,669 estuarine and freshwater fish and other species, 180 00:09:29,669 --> 00:09:32,238 and as they grow, they're starting to eat more animals 181 00:09:32,238 --> 00:09:34,074 from marine food webs. 182 00:09:34,074 --> 00:09:36,209 >>NARRATOR: To expand their data, 183 00:09:36,209 --> 00:09:39,479 the scientists also outfit the juvenile sharks 184 00:09:39,479 --> 00:09:41,748 with acoustic transmitters. 185 00:09:44,217 --> 00:09:48,321 >>So the long-lining allows us to determine 186 00:09:48,321 --> 00:09:49,923 which areas have more sharks in them. 187 00:09:49,923 --> 00:09:53,426 However, it doesn't give us a fine-scale estimate 188 00:09:53,426 --> 00:09:55,562 of what the sharks are doing in between the time 189 00:09:55,562 --> 00:09:58,865 when we set these lines, and so we acoustically tag them 190 00:09:58,865 --> 00:10:00,733 and passively monitor their movements 191 00:10:00,733 --> 00:10:02,368 so we can know what they're doing 192 00:10:02,368 --> 00:10:04,604 while they're in the estuary until they leave. 193 00:10:04,604 --> 00:10:06,840 >>Come here, little cutie. 194 00:10:06,840 --> 00:10:09,275 There we go. 195 00:10:09,275 --> 00:10:11,044 >>For a lot of shark species, 196 00:10:11,044 --> 00:10:13,546 when they're turned on their backs, 197 00:10:13,546 --> 00:10:15,381 they go into a more relaxed state. 198 00:10:15,381 --> 00:10:18,017 This allows us to do the surgeries, 199 00:10:18,017 --> 00:10:19,819 to insert the acoustic transmitters into them 200 00:10:19,819 --> 00:10:23,156 without the sharks thrashing around too much. 201 00:10:23,156 --> 00:10:27,093 The transmitters emit a unique frequenc 202 00:10:27,093 --> 00:10:29,529 that's recorded by the receivers 203 00:10:29,529 --> 00:10:31,297 when they're within their listening range, 204 00:10:31,297 --> 00:10:33,867 and the battery life is up to three years. 205 00:10:33,867 --> 00:10:35,802 >>So these acoustic transmitters, 206 00:10:35,802 --> 00:10:38,071 they send out an ultrasonic ping randoml 207 00:10:38,071 --> 00:10:41,207 every 60 to 120 seconds, and the ping is a unique code. 208 00:10:41,207 --> 00:10:43,910 And then those pings are heard by monitors 209 00:10:43,910 --> 00:10:45,979 that we have stationed throughout the Everglades, 210 00:10:45,979 --> 00:10:48,815 and those monitors have ranges of up to 1,000 meters. 211 00:10:48,815 --> 00:10:50,984 The monitor will record the date and the time 212 00:10:50,984 --> 00:10:52,886 and the individual that was there. 213 00:10:52,886 --> 00:10:55,054 >>And they're arranged in a pattern 214 00:10:55,054 --> 00:10:57,023 such that they're paired, 215 00:10:57,023 --> 00:10:59,025 so we can determine not only the location of the sharks, 216 00:10:59,025 --> 00:11:00,927 but the direction that they're moving in. 217 00:11:00,927 --> 00:11:02,996 >>NARRATOR: Since 2006, 218 00:11:02,996 --> 00:11:06,466 the scientists have caught nearly 300 sharks 219 00:11:06,466 --> 00:11:09,769 and have acoustically tagged more than 60. 220 00:11:09,769 --> 00:11:14,174 >>This project is ongoing and a long-term project, 221 00:11:14,174 --> 00:11:16,843 and we are interested in how the change in abundance 222 00:11:16,843 --> 00:11:18,044 varies annually, 223 00:11:18,044 --> 00:11:20,013 and try to correlate that with changes in things 224 00:11:20,013 --> 00:11:25,185 like temperature, rainfall, and the dynamics of the seasons. 225 00:11:25,185 --> 00:11:28,188 So we pulled up our monitor over here from the water, 226 00:11:28,188 --> 00:11:31,424 and it has picked up more than 12,000 detections, 227 00:11:31,424 --> 00:11:32,592 so that's really good. 228 00:11:32,592 --> 00:11:35,528 >>NARRATOR: Over time, the research has revealed 229 00:11:35,528 --> 00:11:38,198 some astonishing information. 230 00:11:38,198 --> 00:11:42,035 The juvenile bull sharks live away from the ocean 231 00:11:42,035 --> 00:11:46,272 to be safe from larger sharks that could eat them. 232 00:11:46,272 --> 00:11:48,308 Some individuals, however, 233 00:11:48,308 --> 00:11:51,110 are willing to take risks for a meal. 234 00:11:51,110 --> 00:11:53,112 >>They might go from these freshwater areas 235 00:11:53,112 --> 00:11:55,081 down to the ocean and back again. 236 00:11:55,081 --> 00:11:57,150 There might be more food down at the ocean, 237 00:11:57,150 --> 00:12:00,753 but you have to run the gauntlet of big sharks to get there. 238 00:12:00,753 --> 00:12:02,488 So a lot of individuals are not willing to risk 239 00:12:02,488 --> 00:12:04,691 getting eaten by a bigger shark to go grab a meal. 240 00:12:04,691 --> 00:12:06,326 Others, for some reason, are. 241 00:12:06,326 --> 00:12:08,528 We're trying to find out why. 242 00:12:08,528 --> 00:12:10,630 If you don't understand the patterns of specialization 243 00:12:10,630 --> 00:12:11,864 within individuals, 244 00:12:11,864 --> 00:12:14,634 you can't develop particularly effective conservation 245 00:12:14,634 --> 00:12:17,837 and management plans. 246 00:12:26,746 --> 00:12:30,250 >>Gorgeous. 247 00:12:35,989 --> 00:12:37,890 >>NARRATOR: Another top predator 248 00:12:37,890 --> 00:12:42,228 at home in the Everglades is the alligator. 249 00:12:42,228 --> 00:12:45,898 Its behaviors could also provide clues to the scientists 250 00:12:45,898 --> 00:12:48,434 on how changes in freshwater levels 251 00:12:48,434 --> 00:12:51,504 might impact the ecosystem. 252 00:12:51,504 --> 00:12:55,908 Currently, freshwater levels in the Everglades 253 00:12:55,908 --> 00:13:00,213 can vary widely between seasons and from year to year, 254 00:13:00,213 --> 00:13:03,049 creating a "natural experiment" 255 00:13:03,049 --> 00:13:07,153 that helps experts make predictions about the future. 256 00:13:07,153 --> 00:13:09,422 >>We're trying to figure out how they're behaving now, 257 00:13:09,422 --> 00:13:11,424 under the current water management system, 258 00:13:11,424 --> 00:13:13,226 to predict how those behaviors 259 00:13:13,226 --> 00:13:14,627 are going to change in the future, 260 00:13:14,627 --> 00:13:15,995 and then predict how the Everglades as a whole 261 00:13:15,995 --> 00:13:18,131 might change in the future in response to that, as well. 262 00:13:21,200 --> 00:13:24,537 >>NARRATOR: As with sharks, the experts want to know 263 00:13:24,537 --> 00:13:28,941 where the alligators go and what they eat. 264 00:13:28,941 --> 00:13:31,878 But to track the animals' movements, 265 00:13:31,878 --> 00:13:35,315 scientists first need to catch the large reptiles. 266 00:13:37,884 --> 00:13:40,186 >>Tell me when we're on top of him. 267 00:13:40,186 --> 00:13:41,354 >>Okay. 268 00:13:41,354 --> 00:13:44,090 Slow, slow, slow, slow. 269 00:13:44,090 --> 00:13:47,260 >>We go out at night 270 00:13:47,260 --> 00:13:49,128 because it's easier to find them at night. 271 00:13:49,128 --> 00:13:50,697 And we use spotlights to find their eye shine, 272 00:13:50,697 --> 00:13:53,433 because their eye lights up a really bright red. 273 00:13:53,433 --> 00:13:55,168 >>Gator straight ahead. 274 00:13:55,168 --> 00:13:56,235 >>I see it. 275 00:13:58,438 --> 00:13:59,839 >>Oh, it went under. 276 00:14:04,877 --> 00:14:07,213 >>Persistence and patience. 277 00:14:09,716 --> 00:14:11,351 >>Okay, got one here, 278 00:14:14,087 --> 00:14:15,355 And there's another one up there, too. 279 00:14:15,355 --> 00:14:17,557 Got two of them right here. 280 00:14:17,557 --> 00:14:19,792 >>And then we approach them. 281 00:14:19,792 --> 00:14:21,961 We have these long poles with snares around the end of them 282 00:14:21,961 --> 00:14:24,630 so we can slip it around their neck and snare them. 283 00:14:28,134 --> 00:14:29,936 (loud splashing) 284 00:14:34,474 --> 00:14:35,875 >>So what do you say, 285 00:14:35,875 --> 00:14:37,477 the biggest we've caught by a good few pounds? 286 00:14:37,477 --> 00:14:38,878 >>Possibly. 287 00:14:38,878 --> 00:14:41,647 >>We have an easier time catching the alligators 288 00:14:41,647 --> 00:14:43,850 the bigger they are, because they are less wary. 289 00:14:43,850 --> 00:14:45,785 They are used to being king of the hill, 290 00:14:45,785 --> 00:14:48,154 whereas the smaller alligators are a bit little more jumpy. 291 00:14:48,154 --> 00:14:51,190 Alligators are cannibals, so the smaller juvenile alligators, 292 00:14:51,190 --> 00:14:53,726 they need to be scared of bigger things, 293 00:14:53,726 --> 00:14:55,294 whereas those big alligators, 294 00:14:55,294 --> 00:14:57,897 they've been large for so long, they don't care. 295 00:15:00,032 --> 00:15:02,368 >>NARRATOR: Before the alligator is brought on board... 296 00:15:02,368 --> 00:15:04,737 >>Yeah, you don't like me at all. 297 00:15:04,737 --> 00:15:07,106 Hiss, hiss, hiss. 298 00:15:07,106 --> 00:15:09,575 >>NARRATOR: ...its mouth is taped shut as a precaution. 299 00:15:09,575 --> 00:15:11,077 >>That's enough. 300 00:15:11,077 --> 00:15:13,646 >>NARRATOR: While an alligator can chomp down fiercel 301 00:15:13,646 --> 00:15:15,548 on its prey, 302 00:15:15,548 --> 00:15:18,584 the muscles that open its mouth are rather weak. 303 00:15:18,584 --> 00:15:21,220 >>So you can actually hold an alligator's mouth shut 304 00:15:21,220 --> 00:15:22,989 just with one finger just pressing down, 305 00:15:22,989 --> 00:15:24,424 and they don't have the power to open it. 306 00:15:24,424 --> 00:15:26,492 It's the closing power you've got to be afraid of. 307 00:15:26,492 --> 00:15:27,960 >>NARRATOR: To study their diet, 308 00:15:27,960 --> 00:15:30,897 scientists take blood and skin samples 309 00:15:30,897 --> 00:15:34,100 for stable isotope analysis. 310 00:15:34,100 --> 00:15:36,469 >>So we take the skin sample from what's called the scutes. 311 00:15:36,469 --> 00:15:37,837 It's kind of the ridges that you see 312 00:15:37,837 --> 00:15:39,205 as you look at an alligator's back. 313 00:15:39,205 --> 00:15:41,207 So I clip a small piece of the scute 314 00:15:41,207 --> 00:15:44,310 off of the back of the tail, and we do that because 315 00:15:44,310 --> 00:15:46,045 that's the easiest place to get a skin sample, 316 00:15:46,045 --> 00:15:47,380 and it also doesn't hurt them 317 00:15:47,380 --> 00:15:48,714 because they don't have any nerve endings 318 00:15:48,714 --> 00:15:50,716 in the tops of those scutes, so it doesn't bother them. 319 00:15:50,716 --> 00:15:52,819 >>Lift, lift, lift, lift. 320 00:15:52,819 --> 00:15:56,222 >>NARRATOR: Next, a gator is weighed and measured, 321 00:15:56,222 --> 00:15:59,659 and an external tag is attached to its toe. 322 00:15:59,659 --> 00:16:02,995 >>It's a little metal tag that has a five-digit number in it. 323 00:16:02,995 --> 00:16:05,097 And so if anybody anywhere in the state 324 00:16:05,097 --> 00:16:06,766 catches that alligator again, 325 00:16:06,766 --> 00:16:09,402 they can say, "Okay, where was it originally tagged?" 326 00:16:09,402 --> 00:16:11,003 And we can learn about their movements and behaviors 327 00:16:11,003 --> 00:16:12,772 in that way also. 328 00:16:12,772 --> 00:16:14,474 >>NARRATOR: To track the alligators' movements 329 00:16:14,474 --> 00:16:15,842 within the estuary, 330 00:16:15,842 --> 00:16:19,579 they too are outfitted with acoustic transmitters. 331 00:16:19,579 --> 00:16:21,113 >>What I do is I attach it 332 00:16:21,113 --> 00:16:22,448 to the external part of the tail. 333 00:16:22,448 --> 00:16:24,851 So I drill holes in the scutes, 334 00:16:24,851 --> 00:16:26,352 and again, they don't have any nerve endings 335 00:16:26,352 --> 00:16:28,054 in that part of their body, so it doesn't hurt them. 336 00:16:28,054 --> 00:16:30,790 Then we thread some stainless steel wire through the scutes 337 00:16:30,790 --> 00:16:32,291 and also through the transmitter. 338 00:16:32,291 --> 00:16:34,694 The wire keeps the transmitter in place on the tail, 339 00:16:34,694 --> 00:16:37,530 and then we cover it with a marine-grade epox 340 00:16:37,530 --> 00:16:39,065 that'll set underwater. 341 00:16:39,065 --> 00:16:41,434 And the other half. 342 00:16:41,434 --> 00:16:42,935 So it'll keep that whole thing in place 343 00:16:42,935 --> 00:16:44,370 and also streamline the attachment. 344 00:16:44,370 --> 00:16:46,239 Okay, that's looking good. 345 00:16:46,239 --> 00:16:47,874 For my study, I only track adults, 346 00:16:47,874 --> 00:16:50,076 and adults in the Everglades are considered 347 00:16:50,076 --> 00:16:52,211 basically six feet or bigger. 348 00:16:52,211 --> 00:16:54,180 The average size of animals we catch 349 00:16:54,180 --> 00:16:56,048 is between six and eight feet. 350 00:16:56,048 --> 00:16:58,251 The biggest we ever caught is nine feet. 351 00:16:58,251 --> 00:17:00,887 In other parts of the alligators' range, 352 00:17:00,887 --> 00:17:03,923 they will grow bigger-- they'll grow to 12, 13, 14 feet. 353 00:17:03,923 --> 00:17:05,591 That's because they have much better food to eat, 354 00:17:05,591 --> 00:17:08,728 so it enables them to grow faster and bigger. 355 00:17:08,728 --> 00:17:11,931 One of the first alligators I ever tagged 356 00:17:11,931 --> 00:17:14,634 I'm still getting data from today. 357 00:17:14,634 --> 00:17:16,402 So I've been tracking this alligator 358 00:17:16,402 --> 00:17:18,437 for four-and-a-half years, roughly. 359 00:17:18,437 --> 00:17:19,805 >>Right there, right there. 360 00:17:19,805 --> 00:17:21,407 >>We've caught over 100 alligators. 361 00:17:21,407 --> 00:17:24,744 We've attached tracking devices to 52 of them. 362 00:17:24,744 --> 00:17:27,747 I got him, I got him, I got him. 363 00:17:27,747 --> 00:17:30,516 I got him. 364 00:17:32,552 --> 00:17:34,086 >>NARRATOR: In addition to taking 365 00:17:34,086 --> 00:17:36,088 blood and skin samples, 366 00:17:36,088 --> 00:17:38,925 Adam has also analyzed the stomach contents 367 00:17:38,925 --> 00:17:42,695 of about 50 alligators to learn more about their diet. 368 00:17:42,695 --> 00:17:45,798 >>So right now, we are immobilizing his arms and legs 369 00:17:45,798 --> 00:17:47,833 so we can transport him 370 00:17:47,833 --> 00:17:50,937 without fear of him climbing out of the boat. 371 00:17:50,937 --> 00:17:53,339 The duct tape that we're putting on 372 00:17:53,339 --> 00:17:56,842 will protect them from hurting themselves and us. 373 00:18:00,513 --> 00:18:02,315 >>One, two, three. 374 00:18:02,315 --> 00:18:05,184 >>NARRATOR: Taking the stomach contents from an alligator 375 00:18:05,184 --> 00:18:08,087 is similar to a person having his or her stomach pumped 376 00:18:08,087 --> 00:18:09,488 at the hospital. 377 00:18:09,488 --> 00:18:11,958 It is the least invasive method 378 00:18:11,958 --> 00:18:15,962 for scientists to collect this critical information. 379 00:18:15,962 --> 00:18:17,363 >>So that's one of my favorite parts. 380 00:18:17,363 --> 00:18:20,099 We strap it to a long wooden plank 381 00:18:20,099 --> 00:18:22,034 with duct tape and with straps 382 00:18:22,034 --> 00:18:23,436 to make sure that it can't move too much, 383 00:18:23,436 --> 00:18:24,870 because it's really not for our safety, 384 00:18:24,870 --> 00:18:26,205 it's for its own safet 385 00:18:26,205 --> 00:18:27,840 because if it moves during this process, it can hurt itself. 386 00:18:27,840 --> 00:18:29,141 So we strap it to the board. 387 00:18:29,141 --> 00:18:31,978 Then we angle the board so that the head is pointing down, 388 00:18:31,978 --> 00:18:35,281 and then we take the tape off of the mouth 389 00:18:35,281 --> 00:18:37,350 and it instinctually opens its mouth up. 390 00:18:37,350 --> 00:18:39,552 Oh, hello! 391 00:18:39,552 --> 00:18:43,055 And then we take a PVC pipe and we place it in the mouth. 392 00:18:43,055 --> 00:18:44,357 Whew! 393 00:18:44,357 --> 00:18:45,791 Hello, sir. 394 00:18:45,791 --> 00:18:47,793 The pipe is strong enough that it doesn't break 395 00:18:47,793 --> 00:18:49,295 in the alligator's mouth. 396 00:18:49,295 --> 00:18:52,064 So the pipe is basically holding the alligator's mouth open. 397 00:18:52,064 --> 00:18:55,935 And then we tape the mouth around the PVC 398 00:18:55,935 --> 00:18:58,137 so that it can't also open its mouth any more. 399 00:18:58,137 --> 00:19:00,573 We take a hose that's been coated in mineral oil, 400 00:19:00,573 --> 00:19:02,508 and I stick the hose through the PVC pipe 401 00:19:02,508 --> 00:19:04,477 that's in the mouth 402 00:19:04,477 --> 00:19:08,147 and down through the esophagus and into the stomach. 403 00:19:08,147 --> 00:19:10,750 Ooh, that smells lovely. 404 00:19:10,750 --> 00:19:12,585 There we go. 405 00:19:12,585 --> 00:19:14,420 That's disgusting. 406 00:19:14,420 --> 00:19:15,888 And then once it's in the stomach, 407 00:19:15,888 --> 00:19:19,725 I turn on a pump that fills the stomach with water, 408 00:19:19,725 --> 00:19:22,328 and then we do sort of a gentle Heimlich maneuver motion 409 00:19:22,328 --> 00:19:25,898 to massage the water and the food out of the stomach 410 00:19:25,898 --> 00:19:29,435 and out of the mouth and into a waiting bucket. 411 00:19:29,435 --> 00:19:30,636 Definitely feathers. 412 00:19:30,636 --> 00:19:31,971 >>More? 413 00:19:31,971 --> 00:19:33,673 >>Yeah, keep going. 414 00:19:33,673 --> 00:19:37,343 Yeah, yeah, I feel some chunks. 415 00:19:37,343 --> 00:19:39,412 Oh, yeah. 416 00:19:39,412 --> 00:19:40,680 Uh-huh. 417 00:19:40,680 --> 00:19:42,882 Oh, that smells so bad. 418 00:19:42,882 --> 00:19:45,851 Oh my god, that's really bad. 419 00:19:45,851 --> 00:19:48,521 >>Well, we don't have a vegetarian alligator here! 420 00:19:48,521 --> 00:19:51,123 >>It's coming out gangbusters, now. 421 00:19:51,123 --> 00:19:52,425 Here we go. 422 00:19:52,425 --> 00:19:53,793 Oh, look at that, 423 00:19:53,793 --> 00:19:55,194 there are feathers all the way up in there. 424 00:19:55,194 --> 00:19:56,195 That is awesome. 425 00:19:56,195 --> 00:19:57,797 We find really exciting things. 426 00:19:57,797 --> 00:20:00,499 The most frequent thing we find is blue crab parts. 427 00:20:00,499 --> 00:20:02,501 We've also found crayfish, we've found shrimp, 428 00:20:02,501 --> 00:20:03,969 lots of tiny little fish, which was surprising. 429 00:20:03,969 --> 00:20:06,806 I was expecting to find them eating big fish, 430 00:20:06,806 --> 00:20:09,608 like a gar or a snook or something of that nature. 431 00:20:09,608 --> 00:20:12,411 We've also found turtle parts, other alligators, 432 00:20:12,411 --> 00:20:14,447 and one of the most interesting things we found 433 00:20:14,447 --> 00:20:16,782 was pond apple seeds. 434 00:20:16,782 --> 00:20:18,651 So there are these fruits called pond apples, 435 00:20:18,651 --> 00:20:20,786 and most people don't think that alligators would eat a fruit. 436 00:20:20,786 --> 00:20:22,955 They think that they're strict carnivores. 437 00:20:22,955 --> 00:20:26,025 In some alligators, we found up to four or five pond apples. 438 00:20:26,025 --> 00:20:28,494 And so that was a very exciting find. 439 00:20:28,494 --> 00:20:31,864 >>These big reptiles with huge mouths and big teeth, 440 00:20:31,864 --> 00:20:35,434 the fact that you find little fish, pond apples 441 00:20:35,434 --> 00:20:38,337 and crabs came as a very big surprise for us. 442 00:20:38,337 --> 00:20:41,474 It's hard to say exactly why they're doing it. 443 00:20:41,474 --> 00:20:44,376 One thing is that it's probably what's easy to catch. 444 00:20:44,376 --> 00:20:46,712 You might be really big, but it's hard 445 00:20:46,712 --> 00:20:49,081 to catch a gar or a snook or a big fish, 446 00:20:49,081 --> 00:20:50,783 but it's a lot easier to catch small fish. 447 00:20:50,783 --> 00:20:53,152 Pond apples don't run away very well, 448 00:20:53,152 --> 00:20:55,254 and the crabs are pretty abundant here 449 00:20:55,254 --> 00:20:57,456 and are also easy to catch. 450 00:20:57,456 --> 00:20:58,858 Yummy raccoon? 451 00:20:58,858 --> 00:20:59,992 >>May be yummy raccoon. 452 00:20:59,992 --> 00:21:02,595 That's what my money is on. 453 00:21:02,595 --> 00:21:04,363 >>But we also know that when they get a chance, 454 00:21:04,363 --> 00:21:06,232 they will go after big things, 455 00:21:06,232 --> 00:21:08,067 so you find mammals and birds in them, 456 00:21:08,067 --> 00:21:10,336 just not as many as we thought. 457 00:21:10,336 --> 00:21:12,972 Ready? 458 00:21:12,972 --> 00:21:14,507 >>I'm going to drop my end in first. 459 00:21:14,507 --> 00:21:16,075 One, two... 460 00:21:16,075 --> 00:21:17,543 >>The thing about the alligators is that 461 00:21:17,543 --> 00:21:19,145 they have very limited food sources here. 462 00:21:19,145 --> 00:21:21,147 It's a very nutrient-poor environment. 463 00:21:21,147 --> 00:21:22,414 >>There's the tape. 464 00:21:22,414 --> 00:21:24,950 Most estuaries are just teeming with life 465 00:21:24,950 --> 00:21:26,719 because the nutrients from the fresh water 466 00:21:26,719 --> 00:21:29,922 hit the nutrients from the ocean and things go crazy. 467 00:21:29,922 --> 00:21:31,957 But here, as that fresh water moves slowl 468 00:21:31,957 --> 00:21:35,161 through the Everglades, most of the nutrients get sucked out. 469 00:21:35,161 --> 00:21:37,329 >>There's just not a lot of food for them. 470 00:21:37,329 --> 00:21:39,832 >>NARRATOR: The scientists weren't just surprised 471 00:21:39,832 --> 00:21:42,067 by what the gators were eating, 472 00:21:42,067 --> 00:21:44,503 but where some of them went to feed. 473 00:21:44,503 --> 00:21:46,639 >>They travel between the freshwater 474 00:21:46,639 --> 00:21:48,240 and the saltwater environments. 475 00:21:48,240 --> 00:21:50,042 Some individuals will do it very frequently. 476 00:21:50,042 --> 00:21:52,211 These alligators would make upwards 477 00:21:52,211 --> 00:21:54,246 of a 30-kilometer roundtrip. 478 00:21:54,246 --> 00:21:55,981 So they would travel 15 kilometers 479 00:21:55,981 --> 00:21:57,716 from fresh water to salt water, 480 00:21:57,716 --> 00:21:59,985 and they would stay in the salt water for about a day or so, 481 00:21:59,985 --> 00:22:03,022 and then they would turn around and come back after a day, 482 00:22:03,022 --> 00:22:04,590 so they would be making these roundtrips 483 00:22:04,590 --> 00:22:07,059 every three or four days, and they would do it repeatedly. 484 00:22:07,059 --> 00:22:08,894 In one wet season, which lasts about six months, 485 00:22:08,894 --> 00:22:11,430 there was one alligator that made about 50 trips. 486 00:22:11,430 --> 00:22:15,668 >>When Adam tracked that first alligator down to the ocean, 487 00:22:15,668 --> 00:22:16,836 we had some people sa 488 00:22:16,836 --> 00:22:19,071 our equipment must be malfunctioning. 489 00:22:19,071 --> 00:22:21,707 But by studying these animals with different technologies 490 00:22:21,707 --> 00:22:23,442 and across many years, 491 00:22:23,442 --> 00:22:25,878 Adam has found that probably a third of those alligators 492 00:22:25,878 --> 00:22:27,479 are commuters. 493 00:22:27,479 --> 00:22:30,482 >>NARRATOR: This was a very unusual discovery. 494 00:22:30,482 --> 00:22:33,352 >>Alligators are thought to be strictly freshwater species 495 00:22:33,352 --> 00:22:35,454 and that they can't survive in salt water 496 00:22:35,454 --> 00:22:36,989 for very long periods of time. 497 00:22:36,989 --> 00:22:39,158 And we have found that similar thing, 498 00:22:39,158 --> 00:22:42,061 but we found that they will choose to go into salt water, 499 00:22:42,061 --> 00:22:43,529 and that was a very interesting finding. 500 00:22:43,529 --> 00:22:46,699 So why would they choose to go into a salty environment? 501 00:22:46,699 --> 00:22:48,434 And we think that the answer is that 502 00:22:48,434 --> 00:22:49,935 there must be more food there. 503 00:22:49,935 --> 00:22:53,305 So they're trading off food for a little bit of stress, 504 00:22:53,305 --> 00:22:54,907 but then they come back into fresh water 505 00:22:54,907 --> 00:22:57,243 to sort of even out their salt load again. 506 00:22:57,243 --> 00:22:58,944 If it drinks the fresh water, 507 00:22:58,944 --> 00:23:02,815 then it can expel the extra salt from its body. 508 00:23:02,815 --> 00:23:05,017 The stable isotope analysis of their tissues showed that 509 00:23:05,017 --> 00:23:07,086 the alligators that were traveling down to the salt water 510 00:23:07,086 --> 00:23:09,054 were traveling there to feed. 511 00:23:09,054 --> 00:23:11,223 The individuals that did not move down to the salt water, 512 00:23:11,223 --> 00:23:12,591 they had isotope values 513 00:23:12,591 --> 00:23:15,361 indicative of the freshwater food web. 514 00:23:18,631 --> 00:23:21,033 >>NARRATOR: Now, scientists are trying to determine 515 00:23:21,033 --> 00:23:24,503 if the sharks and alligators which feed in the ocean 516 00:23:24,503 --> 00:23:28,140 are excreting those nutrients upriver. 517 00:23:28,140 --> 00:23:29,742 >>In a system like this, 518 00:23:29,742 --> 00:23:31,710 where you have generally low nutrients, 519 00:23:31,710 --> 00:23:34,947 a little bit of nutrient coming in can have a big impact. 520 00:23:34,947 --> 00:23:36,715 The question for us now is, 521 00:23:36,715 --> 00:23:39,485 is it enough nutrient coming upstream 522 00:23:39,485 --> 00:23:42,021 from alligators and sharks to have a big impact? 523 00:23:42,021 --> 00:23:43,923 And that's a tough question to answer, 524 00:23:43,923 --> 00:23:45,991 but it's one that we're trying to work on. 525 00:23:49,895 --> 00:23:52,898 >>NARRATOR: During their research, Mike, Adam and Phil 526 00:23:52,898 --> 00:23:56,068 have made some really surprising observations. 527 00:23:56,068 --> 00:23:57,403 >>One of the neatest is that 528 00:23:57,403 --> 00:24:00,105 we find out that these predators are really individuals. 529 00:24:00,105 --> 00:24:01,840 You can't just see an alligator and say, 530 00:24:01,840 --> 00:24:03,108 "Oh, it's an alligator, 531 00:24:03,108 --> 00:24:04,543 it does what all the other alligators do." 532 00:24:04,543 --> 00:24:08,247 They kind of have their own behaviors, almost personalities. 533 00:24:08,247 --> 00:24:10,149 This is one of the things that's really exciting to me is 534 00:24:10,149 --> 00:24:13,552 learning more about why are animals doing what they do, 535 00:24:13,552 --> 00:24:16,722 and then how does that affect their role in the ecosystem? 536 00:24:16,722 --> 00:24:18,991 So it's really important that we learn more 537 00:24:18,991 --> 00:24:20,492 about the behaviors individuals displa 538 00:24:20,492 --> 00:24:23,462 to really understand their ecological roles. 539 00:24:23,462 --> 00:24:24,964 So here in the Everglades, 540 00:24:24,964 --> 00:24:27,700 some of these more stay-at-home animals 541 00:24:27,700 --> 00:24:30,269 probably have a very different role in the ecosystem 542 00:24:30,269 --> 00:24:32,171 than the ones that commute down to the ocean. 543 00:24:37,676 --> 00:24:40,012 >>NARRATOR: Figuring out how to properly redirect 544 00:24:40,012 --> 00:24:42,614 the fresh water back into the Everglades 545 00:24:42,614 --> 00:24:45,284 is not an easy task. 546 00:24:45,284 --> 00:24:47,987 >>If we put the water in in too big of a burst, 547 00:24:47,987 --> 00:24:50,556 we might see animals get pushed out of the system 548 00:24:50,556 --> 00:24:52,758 to areas where they don't survive very well. 549 00:24:52,758 --> 00:24:54,860 So we have to be sure that we're mimicking 550 00:24:54,860 --> 00:24:57,763 the natural pulses of fresh water. 551 00:24:57,763 --> 00:25:00,966 One thing about the Everglades is that 552 00:25:00,966 --> 00:25:02,935 things are changing almost constantly. 553 00:25:02,935 --> 00:25:05,270 We have wet seasons, we have dry seasons, 554 00:25:05,270 --> 00:25:08,040 so the amount of fresh water coming in varies that way. 555 00:25:08,040 --> 00:25:11,243 But we have wet wet seasons, we have dry dry seasons. 556 00:25:11,243 --> 00:25:12,578 We have wet dry seasons. 557 00:25:12,578 --> 00:25:15,114 So by looking across many years and many seasons, 558 00:25:15,114 --> 00:25:17,416 we can get an idea of how fresh water 559 00:25:17,416 --> 00:25:19,585 affects sharks and alligators. 560 00:25:19,585 --> 00:25:23,989 So it requires long-term studies to really figure it out, 561 00:25:23,989 --> 00:25:26,825 and that's one of the exciting things about this project is 562 00:25:26,825 --> 00:25:28,494 we've been at it long enough 563 00:25:28,494 --> 00:25:30,162 that we're starting to get an idea 564 00:25:30,162 --> 00:25:32,965 of how these animals respond to changes in their environment. 565 00:25:32,965 --> 00:25:35,834 The challenge for managers isn't just getting the water right 566 00:25:35,834 --> 00:25:37,936 for alligators and sharks; 567 00:25:37,936 --> 00:25:39,972 it's for all of the other organisms here, as well. 568 00:25:44,176 --> 00:25:47,413 ♪♪ 569 00:26:08,867 --> 00:26:10,969 >>Major funding for this program 570 00:26:10,969 --> 00:26:13,639 was provided by the Batchelor Foundation, 571 00:26:13,639 --> 00:26:16,742 encouraging people to preserve and protect 572 00:26:16,742 --> 00:26:21,880 America's underwater resources. 573 00:26:21,880 --> 00:26:26,051 And by Divers Direct, inspiring the pursuit 574 00:26:26,051 --> 00:26:30,051 of tropical adventure scuba diving.