WEBVTT 00:03.670 --> 00:06.206 >>NARRATOR: The Florida Everglades. 00:06.206 --> 00:07.774 Beautiful. 00:07.774 --> 00:09.843 Vast. 00:09.843 --> 00:12.346 Harsh. 00:12.346 --> 00:14.114 Remote. 00:14.114 --> 00:15.849 >>It is a huge wetland 00:15.849 --> 00:19.319 that flows across most of southern Florida, 00:19.319 --> 00:21.922 and then it runs into the ocean. 00:21.922 --> 00:23.857 >>NARRATOR: Some of North America's 00:23.857 --> 00:26.393 fiercest predators live here, 00:26.393 --> 00:31.031 including the American alligator and the bull shark. 00:31.031 --> 00:34.134 >>They're top predators. 00:34.134 --> 00:36.537 They eat a lot of different types of prey, 00:36.537 --> 00:38.572 which means they could have a big impact 00:38.572 --> 00:40.374 on a lot of different prey populations, 00:40.374 --> 00:42.142 which then could have cascading effects 00:42.142 --> 00:44.745 down to lower levels of the food chain. 00:44.745 --> 00:48.248 >>NARRATOR: Despite its wild nature, 00:48.248 --> 00:52.920 the Everglades is an ecosystem in trouble. 00:52.920 --> 00:57.324 For nearly a century, man drained the swamp. 00:57.324 --> 01:00.661 Now, a large-scale restoration project 01:00.661 --> 01:05.232 aims to return the wetland to its former glory. 01:05.232 --> 01:07.768 >>More and more fresh water is going to come in, 01:07.768 --> 01:09.703 so it's really important we get the water right 01:09.703 --> 01:11.939 and we know how animals like sharks and alligators respond 01:11.939 --> 01:17.344 so we're managing the ecosystem right for them. 01:17.344 --> 01:19.846 That's why we're doing these studies-- 01:19.846 --> 01:21.715 to get an idea and make predictions 01:21.715 --> 01:24.451 about how this change will affect the ecosystem, 01:24.451 --> 01:26.453 so we can protect those animals 01:26.453 --> 01:29.556 and make sure they fill that critical ecological role. 01:31.758 --> 01:34.361 ♪♪ 01:54.948 --> 01:56.817 >>Major funding for this program 01:56.817 --> 01:59.586 was provided by the Batchelor Foundation, 01:59.586 --> 02:02.823 encouraging people to preserve and protect 02:02.823 --> 02:05.492 America's underwater resources. 02:08.261 --> 02:12.065 And by Divers Direct, inspiring the pursuit 02:12.065 --> 02:14.501 of tropical adventure scuba diving. 02:22.376 --> 02:25.345 >>NARRATOR: On the southern tip of the Florida peninsula, 02:25.345 --> 02:30.350 the Everglades meet the Gulf of Mexico. 02:30.350 --> 02:34.454 Here, the river of grass gives way to a maze 02:34.454 --> 02:40.961 of mangrove-lined rivers that eventually flow into the sea. 02:40.961 --> 02:42.295 >>The Shark River estuar 02:42.295 --> 02:45.499 is the terminus of the Shark River Slough, 02:45.499 --> 02:48.468 which is a major part of the central and southern Everglades. 02:48.468 --> 02:50.937 That is the main conduit of fresh water 02:50.937 --> 02:53.340 out of the Everglades and into the Gulf of Mexico. 02:53.340 --> 02:56.309 So the Shark River is a really important place 02:56.309 --> 02:58.512 where fresh water from the north 02:58.512 --> 03:01.381 and salt water from the Gulf of Mexico mix together, 03:01.381 --> 03:03.817 and we get this really interesting mix of organisms. 03:03.817 --> 03:06.386 >>NARRATOR: Recognized as a wetland 03:06.386 --> 03:09.523 of international importance, 03:09.523 --> 03:12.392 the Everglades ecosystem is a unique place. 03:12.392 --> 03:15.328 >>There's a huge abundance of life here. 03:15.328 --> 03:17.297 It's one of those wilderness places 03:17.297 --> 03:19.833 that are few and far between on the planet now, 03:19.833 --> 03:22.402 but it's also a place that's affected a lot by humans. 03:22.402 --> 03:25.839 >>NARRATOR: Over the course of the 20th century, 03:25.839 --> 03:28.975 humans have greatly changed the way water flows 03:28.975 --> 03:31.812 across the Everglades. 03:31.812 --> 03:34.147 Canals and dikes were built to provide flood control 03:34.147 --> 03:38.585 and deliver fresh water to agricultural operations 03:38.585 --> 03:42.289 and South Florida's ever-growing human population. 03:42.289 --> 03:46.760 This greatly decreased the amount of fresh water 03:46.760 --> 03:49.663 flowing across the Everglades. 03:49.663 --> 03:51.631 >>That fresh water that's the source of life 03:51.631 --> 03:53.500 for this part of the Everglades, 03:53.500 --> 03:56.103 the tap's kind of been turned off. 03:56.103 --> 03:59.406 >>NARRATOR: The impacts on the natural system were severe, 03:59.406 --> 04:03.443 and now a multibillion-dollar restoration project is underwa 04:03.443 --> 04:09.716 to return some of that water back to the Everglades. 04:09.716 --> 04:12.185 >>As we re-engineer the water, we need to figure out 04:12.185 --> 04:14.187 how the plants and animals are going to respond 04:14.187 --> 04:17.023 so we don't muck up the ecosystem even worse. 04:17.023 --> 04:20.494 So really understanding how important different species are, 04:20.494 --> 04:22.863 how they respond to the water and other conditions 04:22.863 --> 04:25.966 is critical for getting the restoration right. 04:25.966 --> 04:28.802 >>NARRATOR: To better understand 04:28.802 --> 04:31.805 the various ecological roles species pla 04:31.805 --> 04:33.640 in the coastal Everglades, 04:33.640 --> 04:38.545 Mike Heithaus and his team study predator-prey interactions 04:38.545 --> 04:43.216 and how predators respond to changes in the environment. 04:43.216 --> 04:45.085 >>So a lot of the work we do 04:45.085 --> 04:48.488 is trying to figure out how humans affect this ecosystem, 04:48.488 --> 04:51.258 and as we try to restore it, how that's going to affect 04:51.258 --> 04:53.794 the big predators like alligators and sharks. 04:56.196 --> 04:59.065 >>NARRATOR: To do so, scientists want to know 04:59.065 --> 05:03.270 where the animals are found and why. 05:03.270 --> 05:06.807 During the daytime, they try to catch bull sharks 05:06.807 --> 05:10.076 in different parts of the Shark River. 05:10.076 --> 05:13.480 >>We have four different areas within the estuar 05:13.480 --> 05:17.584 that we set lines that typically have different conditions-- 05:17.584 --> 05:19.119 mainly differences in salinity. 05:19.119 --> 05:21.988 And so we set the lines at a salinity gradient, 05:21.988 --> 05:23.423 starting from the ocean 05:23.423 --> 05:26.960 all the way up to the freshwater marshes and in between. 05:26.960 --> 05:28.895 >>NARRATOR: Using the number of sharks 05:28.895 --> 05:30.263 caught in different locations 05:30.263 --> 05:33.500 and at different times of the year, 05:33.500 --> 05:35.268 the scientists can determine 05:35.268 --> 05:39.773 the types of areas and conditions the animals need. 05:39.773 --> 05:41.441 >>When we first came out here, 05:41.441 --> 05:43.677 we were told there's no way you're going to find sharks. 05:43.677 --> 05:48.148 We set our lines and had two sharks on our very first one. 05:48.148 --> 05:51.818 >>NARRATOR: Bull sharks are the only species of shark 05:51.818 --> 05:55.188 in North America that can live in fresh water, 05:55.188 --> 05:58.925 and the juvenile sharks usually live in rivers and estuaries 05:58.925 --> 06:02.128 until they are big enough to move to the ocean. 06:02.128 --> 06:04.297 >>To catch bull sharks, 06:04.297 --> 06:09.135 we use long lines with baited hooks with mullet, 06:09.135 --> 06:12.239 and those sit on the bottom for about an hour. 06:12.239 --> 06:15.876 So the long lines have about 50 hooks, and we allow them to soak 06:15.876 --> 06:18.545 to attract any sharks that are in the area. 06:18.545 --> 06:21.514 And we also use drum lines, 06:21.514 --> 06:23.884 which have larger hooks and larger bait 06:23.884 --> 06:25.585 to catch large predatory sharks 06:25.585 --> 06:28.255 that may feed on the juvenile bull sharks 06:28.255 --> 06:30.390 to quantify the risk of predation 06:30.390 --> 06:32.759 that they have in different areas. 06:41.067 --> 06:43.637 >>Oh, little shark! 06:43.637 --> 06:46.172 This is a little, little guy. 06:52.078 --> 06:55.515 >>After we catch a shark, we take length measurements... 06:55.515 --> 07:01.288 >>55, 62.5, and 78. 07:01.288 --> 07:02.722 >>...weight measurements. 07:02.722 --> 07:05.325 >>Four kilograms. 07:05.325 --> 07:08.161 >>We put an external identification tag in them 07:08.161 --> 07:09.663 so that if we recapture them, 07:09.663 --> 07:11.431 we can determine how much they've grown 07:11.431 --> 07:13.466 and if their body mass has changed. 07:13.466 --> 07:19.272 >>Identification tag j-1-0-6-4-1. 07:19.272 --> 07:21.107 >>That's the umbilical scar, 07:21.107 --> 07:23.410 and it takes a couple of months for that to heal, 07:23.410 --> 07:24.411 so when we see that, 07:24.411 --> 07:27.247 we know that this shark is relatively newborn, 07:27.247 --> 07:29.482 definitely less than one year old. 07:29.482 --> 07:32.953 >>NARRATOR: The scientists are also interested 07:32.953 --> 07:34.821 in studying the diets of the sharks 07:34.821 --> 07:38.825 using a method called stable isotope analysis. 07:38.825 --> 07:41.561 >>It's based on the idea that you are what you eat. 07:41.561 --> 07:45.732 And so carbon and nitrogen are common elements in our bodies, 07:45.732 --> 07:47.600 and we can look at different forms 07:47.600 --> 07:49.803 of those carbon and nitrogen isotopes 07:49.803 --> 07:51.738 and look at their ratios. 07:51.738 --> 07:53.139 And so what happens is that 07:53.139 --> 07:56.142 plants have different values for their carbon 07:56.142 --> 07:59.946 whether they're plants in the ocean or plants in fresh water. 07:59.946 --> 08:03.516 >>NARRATOR: When animals eat plants or other animals, 08:03.516 --> 08:06.786 these carbon values stay roughly the same. 08:06.786 --> 08:10.190 So by analyzing the carbon isotopes in a shark, 08:10.190 --> 08:13.393 scientists can tell whether it has fed in food webs 08:13.393 --> 08:16.229 from the ocean or from fresh water. 08:16.229 --> 08:18.898 The nitrogen isotopes in its bod 08:18.898 --> 08:22.035 show how high in the food chain the animal eats. 08:22.035 --> 08:24.938 Different tissues in the animal's body reflect 08:24.938 --> 08:30.710 what and where an animal has eaten over various time periods. 08:30.710 --> 08:33.279 >>Fin tissue turns over the slowest, 08:33.279 --> 08:35.315 and it takes about a year-and-a-half to two years 08:35.315 --> 08:37.317 for that tissue to be replaced, 08:37.317 --> 08:40.854 so it's a very long-term estimate of their diet. 08:40.854 --> 08:41.988 The muscle tissue takes 08:41.988 --> 08:43.723 about a year-and-a-half to be replaced, 08:43.723 --> 08:45.925 so that's another long-term tissue that we use 08:45.925 --> 08:47.394 to look at their diet. 08:47.394 --> 08:49.662 And then blood, we look at whole blood, 08:49.662 --> 08:52.632 which is just the blood extracted from their veins, 08:52.632 --> 08:55.702 and that turns over in about a year, 08:55.702 --> 08:59.072 so that's kind of a mid-range estimate of their diet. 08:59.072 --> 09:00.306 And then we actually separate the blood 09:00.306 --> 09:02.342 and extract the plasma, 09:02.342 --> 09:04.477 which is replaced relatively quickly, and that provides us 09:04.477 --> 09:06.880 with a short-term estimate of their diet. 09:06.880 --> 09:09.149 And that actually allows us to look at seasonal changes 09:09.149 --> 09:13.353 or actually changes in their diet based on size. 09:15.155 --> 09:19.359 We have caught sharks all the way up at the top of the river 09:19.359 --> 09:21.027 about 20 miles from the ocean. 09:21.027 --> 09:24.130 So there are sharks everywhere within the estuary. 09:24.130 --> 09:26.800 When they're born, they're typically only eating 09:26.800 --> 09:29.669 estuarine and freshwater fish and other species, 09:29.669 --> 09:32.238 and as they grow, they're starting to eat more animals 09:32.238 --> 09:34.074 from marine food webs. 09:34.074 --> 09:36.209 >>NARRATOR: To expand their data, 09:36.209 --> 09:39.479 the scientists also outfit the juvenile sharks 09:39.479 --> 09:41.748 with acoustic transmitters. 09:44.217 --> 09:48.321 >>So the long-lining allows us to determine 09:48.321 --> 09:49.923 which areas have more sharks in them. 09:49.923 --> 09:53.426 However, it doesn't give us a fine-scale estimate 09:53.426 --> 09:55.562 of what the sharks are doing in between the time 09:55.562 --> 09:58.865 when we set these lines, and so we acoustically tag them 09:58.865 --> 10:00.733 and passively monitor their movements 10:00.733 --> 10:02.368 so we can know what they're doing 10:02.368 --> 10:04.604 while they're in the estuary until they leave. 10:04.604 --> 10:06.840 >>Come here, little cutie. 10:06.840 --> 10:09.275 There we go. 10:09.275 --> 10:11.044 >>For a lot of shark species, 10:11.044 --> 10:13.546 when they're turned on their backs, 10:13.546 --> 10:15.381 they go into a more relaxed state. 10:15.381 --> 10:18.017 This allows us to do the surgeries, 10:18.017 --> 10:19.819 to insert the acoustic transmitters into them 10:19.819 --> 10:23.156 without the sharks thrashing around too much. 10:23.156 --> 10:27.093 The transmitters emit a unique frequenc 10:27.093 --> 10:29.529 that's recorded by the receivers 10:29.529 --> 10:31.297 when they're within their listening range, 10:31.297 --> 10:33.867 and the battery life is up to three years. 10:33.867 --> 10:35.802 >>So these acoustic transmitters, 10:35.802 --> 10:38.071 they send out an ultrasonic ping randoml 10:38.071 --> 10:41.207 every 60 to 120 seconds, and the ping is a unique code. 10:41.207 --> 10:43.910 And then those pings are heard by monitors 10:43.910 --> 10:45.979 that we have stationed throughout the Everglades, 10:45.979 --> 10:48.815 and those monitors have ranges of up to 1,000 meters. 10:48.815 --> 10:50.984 The monitor will record the date and the time 10:50.984 --> 10:52.886 and the individual that was there. 10:52.886 --> 10:55.054 >>And they're arranged in a pattern 10:55.054 --> 10:57.023 such that they're paired, 10:57.023 --> 10:59.025 so we can determine not only the location of the sharks, 10:59.025 --> 11:00.927 but the direction that they're moving in. 11:00.927 --> 11:02.996 >>NARRATOR: Since 2006, 11:02.996 --> 11:06.466 the scientists have caught nearly 300 sharks 11:06.466 --> 11:09.769 and have acoustically tagged more than 60. 11:09.769 --> 11:14.174 >>This project is ongoing and a long-term project, 11:14.174 --> 11:16.843 and we are interested in how the change in abundance 11:16.843 --> 11:18.044 varies annually, 11:18.044 --> 11:20.013 and try to correlate that with changes in things 11:20.013 --> 11:25.185 like temperature, rainfall, and the dynamics of the seasons. 11:25.185 --> 11:28.188 So we pulled up our monitor over here from the water, 11:28.188 --> 11:31.424 and it has picked up more than 12,000 detections, 11:31.424 --> 11:32.592 so that's really good. 11:32.592 --> 11:35.528 >>NARRATOR: Over time, the research has revealed 11:35.528 --> 11:38.198 some astonishing information. 11:38.198 --> 11:42.035 The juvenile bull sharks live away from the ocean 11:42.035 --> 11:46.272 to be safe from larger sharks that could eat them. 11:46.272 --> 11:48.308 Some individuals, however, 11:48.308 --> 11:51.110 are willing to take risks for a meal. 11:51.110 --> 11:53.112 >>They might go from these freshwater areas 11:53.112 --> 11:55.081 down to the ocean and back again. 11:55.081 --> 11:57.150 There might be more food down at the ocean, 11:57.150 --> 12:00.753 but you have to run the gauntlet of big sharks to get there. 12:00.753 --> 12:02.488 So a lot of individuals are not willing to risk 12:02.488 --> 12:04.691 getting eaten by a bigger shark to go grab a meal. 12:04.691 --> 12:06.326 Others, for some reason, are. 12:06.326 --> 12:08.528 We're trying to find out why. 12:08.528 --> 12:10.630 If you don't understand the patterns of specialization 12:10.630 --> 12:11.864 within individuals, 12:11.864 --> 12:14.634 you can't develop particularly effective conservation 12:14.634 --> 12:17.837 and management plans. 12:26.746 --> 12:30.250 >>Gorgeous. 12:35.989 --> 12:37.890 >>NARRATOR: Another top predator 12:37.890 --> 12:42.228 at home in the Everglades is the alligator. 12:42.228 --> 12:45.898 Its behaviors could also provide clues to the scientists 12:45.898 --> 12:48.434 on how changes in freshwater levels 12:48.434 --> 12:51.504 might impact the ecosystem. 12:51.504 --> 12:55.908 Currently, freshwater levels in the Everglades 12:55.908 --> 13:00.213 can vary widely between seasons and from year to year, 13:00.213 --> 13:03.049 creating a "natural experiment" 13:03.049 --> 13:07.153 that helps experts make predictions about the future. 13:07.153 --> 13:09.422 >>We're trying to figure out how they're behaving now, 13:09.422 --> 13:11.424 under the current water management system, 13:11.424 --> 13:13.226 to predict how those behaviors 13:13.226 --> 13:14.627 are going to change in the future, 13:14.627 --> 13:15.995 and then predict how the Everglades as a whole 13:15.995 --> 13:18.131 might change in the future in response to that, as well. 13:21.200 --> 13:24.537 >>NARRATOR: As with sharks, the experts want to know 13:24.537 --> 13:28.941 where the alligators go and what they eat. 13:28.941 --> 13:31.878 But to track the animals' movements, 13:31.878 --> 13:35.315 scientists first need to catch the large reptiles. 13:37.884 --> 13:40.186 >>Tell me when we're on top of him. 13:40.186 --> 13:41.354 >>Okay. 13:41.354 --> 13:44.090 Slow, slow, slow, slow. 13:44.090 --> 13:47.260 >>We go out at night 13:47.260 --> 13:49.128 because it's easier to find them at night. 13:49.128 --> 13:50.697 And we use spotlights to find their eye shine, 13:50.697 --> 13:53.433 because their eye lights up a really bright red. 13:53.433 --> 13:55.168 >>Gator straight ahead. 13:55.168 --> 13:56.235 >>I see it. 13:58.438 --> 13:59.839 >>Oh, it went under. 14:04.877 --> 14:07.213 >>Persistence and patience. 14:09.716 --> 14:11.351 >>Okay, got one here, 14:14.087 --> 14:15.355 And there's another one up there, too. 14:15.355 --> 14:17.557 Got two of them right here. 14:17.557 --> 14:19.792 >>And then we approach them. 14:19.792 --> 14:21.961 We have these long poles with snares around the end of them 14:21.961 --> 14:24.630 so we can slip it around their neck and snare them. 14:28.134 --> 14:29.936 (loud splashing) 14:34.474 --> 14:35.875 >>So what do you say, 14:35.875 --> 14:37.477 the biggest we've caught by a good few pounds? 14:37.477 --> 14:38.878 >>Possibly. 14:38.878 --> 14:41.647 >>We have an easier time catching the alligators 14:41.647 --> 14:43.850 the bigger they are, because they are less wary. 14:43.850 --> 14:45.785 They are used to being king of the hill, 14:45.785 --> 14:48.154 whereas the smaller alligators are a bit little more jumpy. 14:48.154 --> 14:51.190 Alligators are cannibals, so the smaller juvenile alligators, 14:51.190 --> 14:53.726 they need to be scared of bigger things, 14:53.726 --> 14:55.294 whereas those big alligators, 14:55.294 --> 14:57.897 they've been large for so long, they don't care. 15:00.032 --> 15:02.368 >>NARRATOR: Before the alligator is brought on board... 15:02.368 --> 15:04.737 >>Yeah, you don't like me at all. 15:04.737 --> 15:07.106 Hiss, hiss, hiss. 15:07.106 --> 15:09.575 >>NARRATOR: ...its mouth is taped shut as a precaution. 15:09.575 --> 15:11.077 >>That's enough. 15:11.077 --> 15:13.646 >>NARRATOR: While an alligator can chomp down fiercel 15:13.646 --> 15:15.548 on its prey, 15:15.548 --> 15:18.584 the muscles that open its mouth are rather weak. 15:18.584 --> 15:21.220 >>So you can actually hold an alligator's mouth shut 15:21.220 --> 15:22.989 just with one finger just pressing down, 15:22.989 --> 15:24.424 and they don't have the power to open it. 15:24.424 --> 15:26.492 It's the closing power you've got to be afraid of. 15:26.492 --> 15:27.960 >>NARRATOR: To study their diet, 15:27.960 --> 15:30.897 scientists take blood and skin samples 15:30.897 --> 15:34.100 for stable isotope analysis. 15:34.100 --> 15:36.469 >>So we take the skin sample from what's called the scutes. 15:36.469 --> 15:37.837 It's kind of the ridges that you see 15:37.837 --> 15:39.205 as you look at an alligator's back. 15:39.205 --> 15:41.207 So I clip a small piece of the scute 15:41.207 --> 15:44.310 off of the back of the tail, and we do that because 15:44.310 --> 15:46.045 that's the easiest place to get a skin sample, 15:46.045 --> 15:47.380 and it also doesn't hurt them 15:47.380 --> 15:48.714 because they don't have any nerve endings 15:48.714 --> 15:50.716 in the tops of those scutes, so it doesn't bother them. 15:50.716 --> 15:52.819 >>Lift, lift, lift, lift. 15:52.819 --> 15:56.222 >>NARRATOR: Next, a gator is weighed and measured, 15:56.222 --> 15:59.659 and an external tag is attached to its toe. 15:59.659 --> 16:02.995 >>It's a little metal tag that has a five-digit number in it. 16:02.995 --> 16:05.097 And so if anybody anywhere in the state 16:05.097 --> 16:06.766 catches that alligator again, 16:06.766 --> 16:09.402 they can say, "Okay, where was it originally tagged?" 16:09.402 --> 16:11.003 And we can learn about their movements and behaviors 16:11.003 --> 16:12.772 in that way also. 16:12.772 --> 16:14.474 >>NARRATOR: To track the alligators' movements 16:14.474 --> 16:15.842 within the estuary, 16:15.842 --> 16:19.579 they too are outfitted with acoustic transmitters. 16:19.579 --> 16:21.113 >>What I do is I attach it 16:21.113 --> 16:22.448 to the external part of the tail. 16:22.448 --> 16:24.851 So I drill holes in the scutes, 16:24.851 --> 16:26.352 and again, they don't have any nerve endings 16:26.352 --> 16:28.054 in that part of their body, so it doesn't hurt them. 16:28.054 --> 16:30.790 Then we thread some stainless steel wire through the scutes 16:30.790 --> 16:32.291 and also through the transmitter. 16:32.291 --> 16:34.694 The wire keeps the transmitter in place on the tail, 16:34.694 --> 16:37.530 and then we cover it with a marine-grade epox 16:37.530 --> 16:39.065 that'll set underwater. 16:39.065 --> 16:41.434 And the other half. 16:41.434 --> 16:42.935 So it'll keep that whole thing in place 16:42.935 --> 16:44.370 and also streamline the attachment. 16:44.370 --> 16:46.239 Okay, that's looking good. 16:46.239 --> 16:47.874 For my study, I only track adults, 16:47.874 --> 16:50.076 and adults in the Everglades are considered 16:50.076 --> 16:52.211 basically six feet or bigger. 16:52.211 --> 16:54.180 The average size of animals we catch 16:54.180 --> 16:56.048 is between six and eight feet. 16:56.048 --> 16:58.251 The biggest we ever caught is nine feet. 16:58.251 --> 17:00.887 In other parts of the alligators' range, 17:00.887 --> 17:03.923 they will grow bigger-- they'll grow to 12, 13, 14 feet. 17:03.923 --> 17:05.591 That's because they have much better food to eat, 17:05.591 --> 17:08.728 so it enables them to grow faster and bigger. 17:08.728 --> 17:11.931 One of the first alligators I ever tagged 17:11.931 --> 17:14.634 I'm still getting data from today. 17:14.634 --> 17:16.402 So I've been tracking this alligator 17:16.402 --> 17:18.437 for four-and-a-half years, roughly. 17:18.437 --> 17:19.805 >>Right there, right there. 17:19.805 --> 17:21.407 >>We've caught over 100 alligators. 17:21.407 --> 17:24.744 We've attached tracking devices to 52 of them. 17:24.744 --> 17:27.747 I got him, I got him, I got him. 17:27.747 --> 17:30.516 I got him. 17:32.552 --> 17:34.086 >>NARRATOR: In addition to taking 17:34.086 --> 17:36.088 blood and skin samples, 17:36.088 --> 17:38.925 Adam has also analyzed the stomach contents 17:38.925 --> 17:42.695 of about 50 alligators to learn more about their diet. 17:42.695 --> 17:45.798 >>So right now, we are immobilizing his arms and legs 17:45.798 --> 17:47.833 so we can transport him 17:47.833 --> 17:50.937 without fear of him climbing out of the boat. 17:50.937 --> 17:53.339 The duct tape that we're putting on 17:53.339 --> 17:56.842 will protect them from hurting themselves and us. 18:00.513 --> 18:02.315 >>One, two, three. 18:02.315 --> 18:05.184 >>NARRATOR: Taking the stomach contents from an alligator 18:05.184 --> 18:08.087 is similar to a person having his or her stomach pumped 18:08.087 --> 18:09.488 at the hospital. 18:09.488 --> 18:11.958 It is the least invasive method 18:11.958 --> 18:15.962 for scientists to collect this critical information. 18:15.962 --> 18:17.363 >>So that's one of my favorite parts. 18:17.363 --> 18:20.099 We strap it to a long wooden plank 18:20.099 --> 18:22.034 with duct tape and with straps 18:22.034 --> 18:23.436 to make sure that it can't move too much, 18:23.436 --> 18:24.870 because it's really not for our safety, 18:24.870 --> 18:26.205 it's for its own safet 18:26.205 --> 18:27.840 because if it moves during this process, it can hurt itself. 18:27.840 --> 18:29.141 So we strap it to the board. 18:29.141 --> 18:31.978 Then we angle the board so that the head is pointing down, 18:31.978 --> 18:35.281 and then we take the tape off of the mouth 18:35.281 --> 18:37.350 and it instinctually opens its mouth up. 18:37.350 --> 18:39.552 Oh, hello! 18:39.552 --> 18:43.055 And then we take a PVC pipe and we place it in the mouth. 18:43.055 --> 18:44.357 Whew! 18:44.357 --> 18:45.791 Hello, sir. 18:45.791 --> 18:47.793 The pipe is strong enough that it doesn't break 18:47.793 --> 18:49.295 in the alligator's mouth. 18:49.295 --> 18:52.064 So the pipe is basically holding the alligator's mouth open. 18:52.064 --> 18:55.935 And then we tape the mouth around the PVC 18:55.935 --> 18:58.137 so that it can't also open its mouth any more. 18:58.137 --> 19:00.573 We take a hose that's been coated in mineral oil, 19:00.573 --> 19:02.508 and I stick the hose through the PVC pipe 19:02.508 --> 19:04.477 that's in the mouth 19:04.477 --> 19:08.147 and down through the esophagus and into the stomach. 19:08.147 --> 19:10.750 Ooh, that smells lovely. 19:10.750 --> 19:12.585 There we go. 19:12.585 --> 19:14.420 That's disgusting. 19:14.420 --> 19:15.888 And then once it's in the stomach, 19:15.888 --> 19:19.725 I turn on a pump that fills the stomach with water, 19:19.725 --> 19:22.328 and then we do sort of a gentle Heimlich maneuver motion 19:22.328 --> 19:25.898 to massage the water and the food out of the stomach 19:25.898 --> 19:29.435 and out of the mouth and into a waiting bucket. 19:29.435 --> 19:30.636 Definitely feathers. 19:30.636 --> 19:31.971 >>More? 19:31.971 --> 19:33.673 >>Yeah, keep going. 19:33.673 --> 19:37.343 Yeah, yeah, I feel some chunks. 19:37.343 --> 19:39.412 Oh, yeah. 19:39.412 --> 19:40.680 Uh-huh. 19:40.680 --> 19:42.882 Oh, that smells so bad. 19:42.882 --> 19:45.851 Oh my god, that's really bad. 19:45.851 --> 19:48.521 >>Well, we don't have a vegetarian alligator here! 19:48.521 --> 19:51.123 >>It's coming out gangbusters, now. 19:51.123 --> 19:52.425 Here we go. 19:52.425 --> 19:53.793 Oh, look at that, 19:53.793 --> 19:55.194 there are feathers all the way up in there. 19:55.194 --> 19:56.195 That is awesome. 19:56.195 --> 19:57.797 We find really exciting things. 19:57.797 --> 20:00.499 The most frequent thing we find is blue crab parts. 20:00.499 --> 20:02.501 We've also found crayfish, we've found shrimp, 20:02.501 --> 20:03.969 lots of tiny little fish, which was surprising. 20:03.969 --> 20:06.806 I was expecting to find them eating big fish, 20:06.806 --> 20:09.608 like a gar or a snook or something of that nature. 20:09.608 --> 20:12.411 We've also found turtle parts, other alligators, 20:12.411 --> 20:14.447 and one of the most interesting things we found 20:14.447 --> 20:16.782 was pond apple seeds. 20:16.782 --> 20:18.651 So there are these fruits called pond apples, 20:18.651 --> 20:20.786 and most people don't think that alligators would eat a fruit. 20:20.786 --> 20:22.955 They think that they're strict carnivores. 20:22.955 --> 20:26.025 In some alligators, we found up to four or five pond apples. 20:26.025 --> 20:28.494 And so that was a very exciting find. 20:28.494 --> 20:31.864 >>These big reptiles with huge mouths and big teeth, 20:31.864 --> 20:35.434 the fact that you find little fish, pond apples 20:35.434 --> 20:38.337 and crabs came as a very big surprise for us. 20:38.337 --> 20:41.474 It's hard to say exactly why they're doing it. 20:41.474 --> 20:44.376 One thing is that it's probably what's easy to catch. 20:44.376 --> 20:46.712 You might be really big, but it's hard 20:46.712 --> 20:49.081 to catch a gar or a snook or a big fish, 20:49.081 --> 20:50.783 but it's a lot easier to catch small fish. 20:50.783 --> 20:53.152 Pond apples don't run away very well, 20:53.152 --> 20:55.254 and the crabs are pretty abundant here 20:55.254 --> 20:57.456 and are also easy to catch. 20:57.456 --> 20:58.858 Yummy raccoon? 20:58.858 --> 20:59.992 >>May be yummy raccoon. 20:59.992 --> 21:02.595 That's what my money is on. 21:02.595 --> 21:04.363 >>But we also know that when they get a chance, 21:04.363 --> 21:06.232 they will go after big things, 21:06.232 --> 21:08.067 so you find mammals and birds in them, 21:08.067 --> 21:10.336 just not as many as we thought. 21:10.336 --> 21:12.972 Ready? 21:12.972 --> 21:14.507 >>I'm going to drop my end in first. 21:14.507 --> 21:16.075 One, two... 21:16.075 --> 21:17.543 >>The thing about the alligators is that 21:17.543 --> 21:19.145 they have very limited food sources here. 21:19.145 --> 21:21.147 It's a very nutrient-poor environment. 21:21.147 --> 21:22.414 >>There's the tape. 21:22.414 --> 21:24.950 Most estuaries are just teeming with life 21:24.950 --> 21:26.719 because the nutrients from the fresh water 21:26.719 --> 21:29.922 hit the nutrients from the ocean and things go crazy. 21:29.922 --> 21:31.957 But here, as that fresh water moves slowl 21:31.957 --> 21:35.161 through the Everglades, most of the nutrients get sucked out. 21:35.161 --> 21:37.329 >>There's just not a lot of food for them. 21:37.329 --> 21:39.832 >>NARRATOR: The scientists weren't just surprised 21:39.832 --> 21:42.067 by what the gators were eating, 21:42.067 --> 21:44.503 but where some of them went to feed. 21:44.503 --> 21:46.639 >>They travel between the freshwater 21:46.639 --> 21:48.240 and the saltwater environments. 21:48.240 --> 21:50.042 Some individuals will do it very frequently. 21:50.042 --> 21:52.211 These alligators would make upwards 21:52.211 --> 21:54.246 of a 30-kilometer roundtrip. 21:54.246 --> 21:55.981 So they would travel 15 kilometers 21:55.981 --> 21:57.716 from fresh water to salt water, 21:57.716 --> 21:59.985 and they would stay in the salt water for about a day or so, 21:59.985 --> 22:03.022 and then they would turn around and come back after a day, 22:03.022 --> 22:04.590 so they would be making these roundtrips 22:04.590 --> 22:07.059 every three or four days, and they would do it repeatedly. 22:07.059 --> 22:08.894 In one wet season, which lasts about six months, 22:08.894 --> 22:11.430 there was one alligator that made about 50 trips. 22:11.430 --> 22:15.668 >>When Adam tracked that first alligator down to the ocean, 22:15.668 --> 22:16.836 we had some people sa 22:16.836 --> 22:19.071 our equipment must be malfunctioning. 22:19.071 --> 22:21.707 But by studying these animals with different technologies 22:21.707 --> 22:23.442 and across many years, 22:23.442 --> 22:25.878 Adam has found that probably a third of those alligators 22:25.878 --> 22:27.479 are commuters. 22:27.479 --> 22:30.482 >>NARRATOR: This was a very unusual discovery. 22:30.482 --> 22:33.352 >>Alligators are thought to be strictly freshwater species 22:33.352 --> 22:35.454 and that they can't survive in salt water 22:35.454 --> 22:36.989 for very long periods of time. 22:36.989 --> 22:39.158 And we have found that similar thing, 22:39.158 --> 22:42.061 but we found that they will choose to go into salt water, 22:42.061 --> 22:43.529 and that was a very interesting finding. 22:43.529 --> 22:46.699 So why would they choose to go into a salty environment? 22:46.699 --> 22:48.434 And we think that the answer is that 22:48.434 --> 22:49.935 there must be more food there. 22:49.935 --> 22:53.305 So they're trading off food for a little bit of stress, 22:53.305 --> 22:54.907 but then they come back into fresh water 22:54.907 --> 22:57.243 to sort of even out their salt load again. 22:57.243 --> 22:58.944 If it drinks the fresh water, 22:58.944 --> 23:02.815 then it can expel the extra salt from its body. 23:02.815 --> 23:05.017 The stable isotope analysis of their tissues showed that 23:05.017 --> 23:07.086 the alligators that were traveling down to the salt water 23:07.086 --> 23:09.054 were traveling there to feed. 23:09.054 --> 23:11.223 The individuals that did not move down to the salt water, 23:11.223 --> 23:12.591 they had isotope values 23:12.591 --> 23:15.361 indicative of the freshwater food web. 23:18.631 --> 23:21.033 >>NARRATOR: Now, scientists are trying to determine 23:21.033 --> 23:24.503 if the sharks and alligators which feed in the ocean 23:24.503 --> 23:28.140 are excreting those nutrients upriver. 23:28.140 --> 23:29.742 >>In a system like this, 23:29.742 --> 23:31.710 where you have generally low nutrients, 23:31.710 --> 23:34.947 a little bit of nutrient coming in can have a big impact. 23:34.947 --> 23:36.715 The question for us now is, 23:36.715 --> 23:39.485 is it enough nutrient coming upstream 23:39.485 --> 23:42.021 from alligators and sharks to have a big impact? 23:42.021 --> 23:43.923 And that's a tough question to answer, 23:43.923 --> 23:45.991 but it's one that we're trying to work on. 23:49.895 --> 23:52.898 >>NARRATOR: During their research, Mike, Adam and Phil 23:52.898 --> 23:56.068 have made some really surprising observations. 23:56.068 --> 23:57.403 >>One of the neatest is that 23:57.403 --> 24:00.105 we find out that these predators are really individuals. 24:00.105 --> 24:01.840 You can't just see an alligator and say, 24:01.840 --> 24:03.108 "Oh, it's an alligator, 24:03.108 --> 24:04.543 it does what all the other alligators do." 24:04.543 --> 24:08.247 They kind of have their own behaviors, almost personalities. 24:08.247 --> 24:10.149 This is one of the things that's really exciting to me is 24:10.149 --> 24:13.552 learning more about why are animals doing what they do, 24:13.552 --> 24:16.722 and then how does that affect their role in the ecosystem? 24:16.722 --> 24:18.991 So it's really important that we learn more 24:18.991 --> 24:20.492 about the behaviors individuals displa 24:20.492 --> 24:23.462 to really understand their ecological roles. 24:23.462 --> 24:24.964 So here in the Everglades, 24:24.964 --> 24:27.700 some of these more stay-at-home animals 24:27.700 --> 24:30.269 probably have a very different role in the ecosystem 24:30.269 --> 24:32.171 than the ones that commute down to the ocean. 24:37.676 --> 24:40.012 >>NARRATOR: Figuring out how to properly redirect 24:40.012 --> 24:42.614 the fresh water back into the Everglades 24:42.614 --> 24:45.284 is not an easy task. 24:45.284 --> 24:47.987 >>If we put the water in in too big of a burst, 24:47.987 --> 24:50.556 we might see animals get pushed out of the system 24:50.556 --> 24:52.758 to areas where they don't survive very well. 24:52.758 --> 24:54.860 So we have to be sure that we're mimicking 24:54.860 --> 24:57.763 the natural pulses of fresh water. 24:57.763 --> 25:00.966 One thing about the Everglades is that 25:00.966 --> 25:02.935 things are changing almost constantly. 25:02.935 --> 25:05.270 We have wet seasons, we have dry seasons, 25:05.270 --> 25:08.040 so the amount of fresh water coming in varies that way. 25:08.040 --> 25:11.243 But we havewetwet seasons, we havedrydry seasons. 25:11.243 --> 25:12.578 We havewetdry seasons. 25:12.578 --> 25:15.114 So by looking across many years and many seasons, 25:15.114 --> 25:17.416 we can get an idea of how fresh water 25:17.416 --> 25:19.585 affects sharks and alligators. 25:19.585 --> 25:23.989 So it requires long-term studies to really figure it out, 25:23.989 --> 25:26.825 and that's one of the exciting things about this project is 25:26.825 --> 25:28.494 we've been at it long enough 25:28.494 --> 25:30.162 that we're starting to get an idea 25:30.162 --> 25:32.965 of how these animals respond to changes in their environment. 25:32.965 --> 25:35.834 The challenge for managers isn't just getting the water right 25:35.834 --> 25:37.936 for alligators and sharks; 25:37.936 --> 25:39.972 it's for all of the other organisms here, as well. 25:44.176 --> 25:47.413 ♪♪ 26:08.867 --> 26:10.969 >>Major funding for this program 26:10.969 --> 26:13.639 was provided by the Batchelor Foundation, 26:13.639 --> 26:16.742 encouraging people to preserve and protect 26:16.742 --> 26:21.880 America's underwater resources. 26:21.880 --> 26:26.051 And by Divers Direct, inspiring the pursuit 26:26.051 --> 26:30.051 of tropical adventure scuba diving.