WEBVTT 00:00:08.910 --> 00:00:13.950 Many of us are familiar with colorful images of tropical, shallow water coral reefs, and 00:00:13.950 --> 00:00:16.410 the abundant life they support. 00:00:16.410 --> 00:00:21.890 But did you know that deep in the dark, cold depths of the ocean, another type of coral 00:00:21.890 --> 00:00:24.410 has flourished for millions of years? 00:00:24.410 --> 00:00:30.519 Deep-sea corals, also known as cold-water corals, are found across the globe in waters 00:00:30.519 --> 00:00:35.440 deeper than 50 meters where little to no light penetrates. 00:00:35.440 --> 00:00:39.850 Like their shallow water counterparts, these corals are considered to be foundation species, 00:00:39.850 --> 00:00:47.969 providing habitat, shelter, and food for many other organisms. 00:00:47.969 --> 00:00:53.420 Some deep-sea corals form huge mounds over thousands, or even hundreds of thousands of 00:00:53.420 --> 00:00:57.950 years, growing upon the skeletons of their predecessors. 00:00:57.950 --> 00:01:05.539 Other types of corals form extensive groves and can resemble fans, columns, spirals, or 00:01:05.539 --> 00:01:07.960 branching trees. 00:01:07.960 --> 00:01:12.940 But these aren't plants. 00:01:12.940 --> 00:01:16.080 Corals are actually animals. 00:01:16.080 --> 00:01:22.429 The coral structures we see here consist of many individual polyps, a soft-bodied animal 00:01:22.429 --> 00:01:25.619 related to jellies and anemones. 00:01:25.619 --> 00:01:32.420 These polyps can live alone, but more often hundreds or thousands live together as a colony. 00:01:32.420 --> 00:01:36.830 Hi, I'm Liz with NOAA Ocean Exploration. 00:01:36.830 --> 00:01:41.040 Deep-sea corals are ancient and long lived organisms. 00:01:41.040 --> 00:01:45.990 Some of the oldest colonies date back to the time the last wooly mammoths roamed the earth. 00:01:45.990 --> 00:01:49.660 Yet, there's still so much we don't know about them. 00:01:49.660 --> 00:01:56.440 To take a deeper dive into the world of deep-sea corals let's talk to an expert. 00:01:56.440 --> 00:02:01.410 Today we're joined by Dr. Randi Rotjan, a professor of biology at Boston University 00:02:01.410 --> 00:02:06.209 and co-Chief Scientist of the Phoenix Islands Protected Area Conservation Trust. 00:02:06.209 --> 00:02:07.209 Welcome Randi. 00:02:07.209 --> 00:02:08.929 Hi, thanks so much for having me. 00:02:08.929 --> 00:02:10.700 I'm so glad to be here. 00:02:10.700 --> 00:02:15.330 I'm wondering if you can start us off by telling us a little bit about your work and how do 00:02:15.330 --> 00:02:16.650 deep sea corals fit in? 00:02:16.650 --> 00:02:22.480 You know, it's interesting, I've been working on corals for, you know, 20 years or so now 00:02:22.480 --> 00:02:27.000 and most of that time has been thinking about shallow water corals, you know, corals that 00:02:27.000 --> 00:02:28.520 you're probably more familiar with. 00:02:28.520 --> 00:02:31.940 And I really, um very recently started to work in the deep sea. 00:02:31.940 --> 00:02:36.530 You know, I really had to sort of think through and learn the language of the deep sea, um, 00:02:36.530 --> 00:02:41.220 in order to sort of connect with these coral animals. 00:02:41.220 --> 00:02:45.620 Why are deep sea corals so important, both in your line of research and in general? 00:02:45.620 --> 00:02:49.800 Corals are important because they, they're the trees that make the forest. 00:02:49.800 --> 00:02:51.630 Do you know what I mean? 00:02:51.630 --> 00:02:55.750 It’s like, these are the organisms that are the biodiversity multipliers. 00:02:55.750 --> 00:03:01.300 These are the creatures that so many other animals flock to and use and so they really 00:03:01.300 --> 00:03:04.050 augment and enhance the diversity of life on the deep seafloor. 00:03:04.050 --> 00:03:09.200 Deep-sea corals are also important because there may be implications for us, for humans. 00:03:09.200 --> 00:03:13.900 You know, we're just beginning to understand some of the ways that they do what they do. 00:03:13.900 --> 00:03:19.380 They defend themselves, or have really interesting or different immune systems may have implications, 00:03:19.380 --> 00:03:25.850 uh, for medicines or for other therapeutics here on the surface. 00:03:25.850 --> 00:03:30.510 It seems like there's a lot we still don't know about deep-sea corals. 00:03:30.510 --> 00:03:32.200 Can you explain why that is? 00:03:32.200 --> 00:03:34.810 What are some of the challenges of doing your work? 00:03:34.810 --> 00:03:37.700 It's really hard to get down that deep. 00:03:37.700 --> 00:03:43.930 You know, the deep sea starts at around 200 meters and can go all the way down to 5,000 00:03:43.930 --> 00:03:45.490 or more meters deep. 00:03:45.490 --> 00:03:50.290 So I would say that, you know, the past 20-50 years have really been a renaissance of technology 00:03:50.290 --> 00:03:56.270 that have enabled deep-sea science and deep-sea technology and engineering to get us down 00:03:56.270 --> 00:04:00.840 there and explore this part of our planet, which has always been there, right? 00:04:00.840 --> 00:04:06.130 It completely precedes us, but we're just getting to learn about it now. 00:04:06.130 --> 00:04:08.740 So I love that you mentioned that deep-sea corals pre-date us. 00:04:08.740 --> 00:04:14.569 That's something that I find personally really fascinating, but also really hard to understand. 00:04:14.569 --> 00:04:17.630 Can you explain just how old are deep-sea corals? 00:04:17.630 --> 00:04:20.530 I am so glad you asked that. 00:04:20.530 --> 00:04:22.970 It's such a cool timeframe to think about. 00:04:22.970 --> 00:04:28.660 Scientists think that corals evolved in the deep sea, at least 400 million years ago. 00:04:28.660 --> 00:04:33.330 But the modern, tropical, shallow-water corals that you still see alive on the reef today, 00:04:33.330 --> 00:04:35.010 are a much more recent development. 00:04:35.010 --> 00:04:41.530 So that's, that's sort of the evolutionary timescale, but then there's the timescale 00:04:41.530 --> 00:04:47.930 of the corals themselves, I mean, some individual colonies can live for over a thousand years. 00:04:47.930 --> 00:04:53.060 You know, the oldest ones that we know are about 4,000 years old, which is a pretty incredible 00:04:53.060 --> 00:04:54.060 thing. 00:04:54.060 --> 00:04:58.900 Wait a second, what exactly allows a deep-sea coral, in such an inhospitable environment, 00:04:58.900 --> 00:05:00.000 to live for so long? 00:05:00.000 --> 00:05:06.100 I think it's kind of truly a marvel that deep-sea organisms are so long lived when they just 00:05:06.100 --> 00:05:07.870 don't have a whole lot of food. 00:05:07.870 --> 00:05:12.290 Corals and sponges, they're indeterminate growth animals, meaning that they can just 00:05:12.290 --> 00:05:13.290 grow and grow and grow. 00:05:13.290 --> 00:05:14.870 They don't have a set body size, right? 00:05:14.870 --> 00:05:20.970 Whereas humans, you know, we kind of have a range, but we have a set body size. 00:05:20.970 --> 00:05:24.770 Because they're so food limited, and they have such a slow metabolism, and because there's 00:05:24.770 --> 00:05:28.210 nothing really limiting their growth, and their colonial, right, they can just create 00:05:28.210 --> 00:05:31.380 new polyps and new polyps and grow and grow and grow. 00:05:31.380 --> 00:05:37.540 They grow slowly but steadily and they can just persist for really long periods of time. 00:05:37.540 --> 00:05:42.540 Is there anything else that does eventually limit their growth, or what causes them to 00:05:42.540 --> 00:05:43.540 die? 00:05:43.540 --> 00:05:46.460 A lot of things can cause them to die, but I think the game of life, right, is to try 00:05:46.460 --> 00:05:48.070 to eat and not be eaten. 00:05:48.070 --> 00:05:51.620 And I think with deep-sea corals and sponges on the seafloor, that's true too. 00:05:51.620 --> 00:05:56.750 You know, they, they can die from stress or change in conditions or, um, you know, a number 00:05:56.750 --> 00:05:59.280 of things, but they can also be eaten. 00:05:59.280 --> 00:06:04.290 They have to use some of the limited energy they have to defend themselves either physically 00:06:04.290 --> 00:06:06.330 or chemically. 00:06:06.330 --> 00:06:11.830 So that's not the first time that you've mentioned corals and sponges together. 00:06:11.830 --> 00:06:16.740 What exactly is the association between deep-sea corals and deep-sea sponges? 00:06:16.740 --> 00:06:17.790 Wouldn't we all like to know? 00:06:17.790 --> 00:06:22.680 I think, you know, the interactions between those two organisms, there's something that, 00:06:22.680 --> 00:06:24.520 you know, is an active area of study. 00:06:24.520 --> 00:06:29.570 But, one of the shared things they have in common, besides both living in this incredibly 00:06:29.570 --> 00:06:36.310 different, deep, dark habitat, is the fact that they are some of the earliest animals 00:06:36.310 --> 00:06:39.380 on our planet - sponges, even older than corals. 00:06:39.380 --> 00:06:45.540 So I know these deep-sea coral and sponge communities are found on seamounts or canyon 00:06:45.540 --> 00:06:46.540 walls. 00:06:46.540 --> 00:06:48.390 How did they get there in the first place? 00:06:48.390 --> 00:06:52.600 You know, corals and sponges move through their next generation. 00:06:52.600 --> 00:06:54.480 They move through their gametes. 00:06:54.480 --> 00:07:01.270 They produce these larvae, that then are carried by the currents and what's amazing is that 00:07:01.270 --> 00:07:04.290 they can get pretty far away from the parent colony. 00:07:04.290 --> 00:07:07.070 And they are really at the whim of the current. 00:07:07.070 --> 00:07:10.960 And in fact, a lot of these coral gametes get lost in the process. 00:07:10.960 --> 00:07:15.229 You know, they just get swept out and never find an appropriate place to settle. 00:07:15.229 --> 00:07:20.220 But some of these coral larvae and sponge larvae are transported to a place that's got 00:07:20.220 --> 00:07:22.229 the optimal conditions, it's got the right flow. 00:07:22.229 --> 00:07:27.760 You know, it has enough food, it's good enough protection and they can settle and start to 00:07:27.760 --> 00:07:32.320 grow and that's how they move from place to place, it’s, they send their next generation 00:07:32.320 --> 00:07:33.320 off into the world. 00:07:33.320 --> 00:07:35.950 That is a brutal way to start your life. 00:07:35.950 --> 00:07:40.500 It is a brutal way to start your life, but once you're there, once you're settled, you 00:07:40.500 --> 00:07:43.550 can live for a really long time. 00:07:43.550 --> 00:07:46.919 So you bring up the idea of food, right? 00:07:46.919 --> 00:07:51.419 So they live in these deep, dark locations, they stay in one spot for life. 00:07:51.419 --> 00:07:54.030 So what exactly are they eating? 00:07:54.030 --> 00:07:59.150 You know, they are eating food from the surface, believe it or not. 00:07:59.150 --> 00:08:04.520 We have all of this surface productivity fueled by nutrients and sunlight that fuels the growth 00:08:04.520 --> 00:08:08.860 of phytoplankton and it, it you know, there's a whole food chain that cascades from this 00:08:08.860 --> 00:08:10.490 growth at the surface. 00:08:10.490 --> 00:08:16.500 And as these organisms either excrete, or die and decompose and decay, they start to 00:08:16.500 --> 00:08:17.789 fall through the water column. 00:08:17.789 --> 00:08:22.419 But as it falls slowly down, it's trapped and caught by sponges, which are filtering 00:08:22.419 --> 00:08:27.890 the water or by corals, which have their polyps extended and can capture those tiny particles 00:08:27.890 --> 00:08:29.450 and, um, eat them. 00:08:29.450 --> 00:08:34.089 So even though they live so far away from the surface, they are surface dependent on 00:08:34.089 --> 00:08:36.949 the food that falls gently down. 00:08:36.949 --> 00:08:42.639 What we see is this wide diversity of corals and I was wondering if you could describe 00:08:42.639 --> 00:08:43.639 that a little more? 00:08:43.639 --> 00:08:48.889 You know, even though they're not plants, I often think about flowers and different 00:08:48.889 --> 00:08:50.569 botanical strategies, right? 00:08:50.569 --> 00:08:55.009 How plants try to capture sunlight because they're trying to maximize their surface area 00:08:55.009 --> 00:08:56.420 to get as much sun as they can. 00:08:56.420 --> 00:09:00.350 Of course, there's no sun in the deep sea, but corals and sponges are doing the same 00:09:00.350 --> 00:09:01.350 thing. 00:09:01.350 --> 00:09:05.660 They're trying to maximize their surface area to capture as many food particles as they 00:09:05.660 --> 00:09:07.769 can in the position of flow. 00:09:07.769 --> 00:09:12.399 So sometimes that's straight up and down as things just filter down and sometimes it's 00:09:12.399 --> 00:09:17.589 actually, you know, turned sideways as they're trying to capture particles that are moving 00:09:17.589 --> 00:09:18.839 past them. 00:09:18.839 --> 00:09:22.569 So I think a lot of the shapes that we're seeing have a lot to do with where these corals 00:09:22.569 --> 00:09:27.790 like to position themselves and it's all about trying to capture as much food as they can. 00:09:27.790 --> 00:09:29.410 What gives corals their shape? 00:09:29.410 --> 00:09:31.550 What helps them stand upright? 00:09:31.550 --> 00:09:34.059 There are different kinds of corals. 00:09:34.059 --> 00:09:39.009 There are hard corals, scleractinians, that actually produce an aragonite skeleton. 00:09:39.009 --> 00:09:46.130 And then there are soft corals, um, octocorals, hexacorals, gorgonians actually have calcite 00:09:46.130 --> 00:09:51.300 skeleton, which is not quite the same as, you know, when some of these hard corals, 00:09:51.300 --> 00:09:54.839 but it's still strong enough and rigid enough to give them structure. 00:09:54.839 --> 00:10:01.069 You know, you want to be strong enough to stand up, um, in the current, but you also 00:10:01.069 --> 00:10:04.709 need to be flexible enough to kind of go with the flow so that you don't just break. 00:10:04.709 --> 00:10:09.269 I would love if you could elaborate - what are some current areas of research in the 00:10:09.269 --> 00:10:12.390 field or unanswered questions about deep-sea corals? 00:10:12.390 --> 00:10:17.170 I think the great thing about this field is that there is no shortage of questions. 00:10:17.170 --> 00:10:22.459 We are finally at the point where we understand a little bit about these ecosystems, and who 00:10:22.459 --> 00:10:26.119 the species are, and sort of how they fit together evolutionarily. 00:10:26.119 --> 00:10:30.089 And now I think it's time for some behavior, for us to understand the interactions between 00:10:30.089 --> 00:10:33.550 organisms and how they do what they do on the seafloor. 00:10:33.550 --> 00:10:38.239 So for me, I think there's many, many, many more lifetimes of study in trying to understand 00:10:38.239 --> 00:10:45.009 not just who these corals are, or what they do, but how they do what they do. 00:10:45.009 --> 00:10:50.019 One of the most popular questions we often get is - what are the implications of climate 00:10:50.019 --> 00:10:52.470 change on the deep-sea corals? 00:10:52.470 --> 00:10:57.779 Deep-sea corals and deep-sea ecosystems are definitely going to be impacted by climate 00:10:57.779 --> 00:10:58.779 change. 00:10:58.779 --> 00:11:03.399 Um, the easiest way to think about this is from the surface productivity that feeds them, 00:11:03.399 --> 00:11:04.399 right? 00:11:04.399 --> 00:11:08.579 Changes in food production at the surface are going to change the food availability 00:11:08.579 --> 00:11:10.420 for corals that live deeper down. 00:11:10.420 --> 00:11:14.290 When food falls down, that's also how we sequester carbon. 00:11:14.290 --> 00:11:19.269 So our carbon sequestration equation on a planetary scale might change and, um, the 00:11:19.269 --> 00:11:21.100 deep sea has a lot to do with that. 00:11:21.100 --> 00:11:26.379 You know, in addition, the deep sea is not immune to changes in temperature or ocean 00:11:26.379 --> 00:11:27.379 pH. 00:11:27.379 --> 00:11:32.629 We might see up to a one degree in the next 80-100 years, and to have an increase of a 00:11:32.629 --> 00:11:34.569 degree is a really big deal. 00:11:34.569 --> 00:11:40.300 Well, Randi, you've told us a lot about deep-sea corals today, but what I want to know now, 00:11:40.300 --> 00:11:43.720 is what do you think is the most interesting thing about them? 00:11:43.720 --> 00:11:45.689 That they exist. 00:11:45.689 --> 00:11:47.699 I mean, come on! 00:11:47.699 --> 00:11:53.999 These are like the most incredibly cool creatures and they just defy imagination in so many 00:11:53.999 --> 00:11:55.119 different ways. 00:11:55.119 --> 00:11:59.480 And to me, it just feels really important to know that they're here. 00:11:59.480 --> 00:12:05.239 They are on the one hand, incredibly resilient, and on the other hand, incredibly dependent, 00:12:05.239 --> 00:12:08.420 fragile and reliant on the decisions that we make here on the surface. 00:12:08.420 --> 00:12:13.110 I think that's a really powerful message too, to leave us on. 00:12:13.110 --> 00:12:15.209 Thank you so much for joining us Randi. 00:12:15.209 --> 00:12:19.530 Thank you so much for having me and I hope to learn lessons from these students in the 00:12:19.530 --> 00:12:20.530 future, right? 00:12:20.530 --> 00:12:25.720 It is all about the next generation. 00:12:25.720 --> 00:12:29.410 The world of deep-sea corals is full of contradictions. 00:12:29.410 --> 00:12:37.569 They're remote yet reliant on the waters above; important, yet poorly understood; ancient, 00:12:37.569 --> 00:12:44.369 but far less studied than most organisms living closer to the inquisitive minds of humans. 00:12:44.369 --> 00:12:49.459 What questions do you still have about deep-sea corals and how would you go about answering 00:12:49.459 --> 00:12:54.009 them?