WEBVTT 00:00:08.630 --> 00:00:14.150 In the 1970s, our understanding of what's necessary for life itself was turned on its 00:00:14.150 --> 00:00:18.220 head with the discovery of hydrothermal vents. 00:00:18.220 --> 00:00:23.949 Deep on the sea floor among huge pillars, spilling super-heated, chemical-rich fluid 00:00:23.949 --> 00:00:30.689 scientists found lifeforms that don't require sunlight to exist, something previously thought 00:00:30.689 --> 00:00:33.040 to be impossible. 00:00:33.040 --> 00:00:38.059 Instead of sunlight and photosynthesis, the base of the food chain at these vent ecosystems 00:00:38.059 --> 00:00:44.140 was chemosynthesis or the production of food, using energy released by inorganic chemical 00:00:44.140 --> 00:00:45.140 reactions. 00:00:45.140 --> 00:00:50.860 But vents aren't the only ecosystems that can support chemosynthetic communities. 00:00:50.860 --> 00:00:55.399 Once scientists knew what to look for, they found them in hot springs on land, on the 00:00:55.399 --> 00:01:00.949 seafloor around whale carcasses and sunken chips, and in association with cold seas around 00:01:00.949 --> 00:01:04.110 the world. 00:01:04.110 --> 00:01:08.830 Cold seas are places where chemical rich fluids and gases escape from fissures in the ocean 00:01:08.830 --> 00:01:10.120 floor. 00:01:10.120 --> 00:01:14.900 Unlike hydrothermal vents, which are fueled by geothermal activity, the seepage of these 00:01:14.900 --> 00:01:17.530 sites is fueled by immense pressure. 00:01:17.530 --> 00:01:23.380 Also, in contrast vents, there isn't a strong increase in temperature relative to the surrounding 00:01:23.380 --> 00:01:24.490 waters. 00:01:24.490 --> 00:01:29.259 The chemicals that emerge from seas are toxic to most forms of life. 00:01:29.259 --> 00:01:34.939 However, these chemicals, most importantly, hydrogen sulfide, methane, and other hydrocarbons 00:01:34.939 --> 00:01:39.240 actually provide the building blocks for entire chemosynthetic ecosystems. 00:01:39.240 --> 00:01:45.860 At the base of the food web are chemosynthetic microbes, some that live freely and some of 00:01:45.860 --> 00:01:50.740 which live symbiotically within other organisms. 00:01:50.740 --> 00:01:56.250 Longer lasting and more stable in their vent counterparts, seeps can persist for decades, 00:01:56.250 --> 00:02:01.690 centuries, and likely even millennia before subsiding, but they don't last forever. 00:02:01.690 --> 00:02:09.379 Over time, the toxic flow lessons and stops entirely, and the ecosystem is settled by 00:02:09.379 --> 00:02:10.710 new species. 00:02:10.710 --> 00:02:17.590 From both a geological and ecological perspective cold seats are prime sites for new questions 00:02:17.590 --> 00:02:21.950 and answers, and then often more questions. 00:02:21.950 --> 00:02:25.420 To learn more, let's talk to an expert. 00:02:25.420 --> 00:02:31.880 Today we're joined by Melissa Betters, a PhD candidate from Temple University whose interests 00:02:31.880 --> 00:02:37.190 lie in the evolutionary origins of chemosynthetic organisms at cold seeps. 00:02:37.190 --> 00:02:38.190 Welcome Melissa. 00:02:38.190 --> 00:02:40.190 Thanks for being with us today. 00:02:40.190 --> 00:02:41.190 Hi, Liz. 00:02:41.190 --> 00:02:42.190 Thank you for having me. 00:02:42.190 --> 00:02:45.519 So cold seeps occurred globally, correct? 00:02:45.519 --> 00:02:48.739 Where exactly are they found and how do they form? 00:02:48.739 --> 00:02:52.459 Cold seeps are found all around the world in every ocean. 00:02:52.459 --> 00:02:55.260 They're found along continental margins. 00:02:55.260 --> 00:03:00.760 One place you can find them is at subduction zones where one plate is sliding underneath 00:03:00.760 --> 00:03:01.760 another plate. 00:03:01.760 --> 00:03:08.550 When that happens, that underlying plate is undergoing a massive amount of pressure, just 00:03:08.550 --> 00:03:09.690 like a sponge. 00:03:09.690 --> 00:03:15.710 All of the fluids and things contained in the sediment of that plate get expelled into 00:03:15.710 --> 00:03:18.830 the water column, and that's where we get seeps. 00:03:18.830 --> 00:03:23.640 I really like that sponge analogy, but what exactly does that look like on the sea floor? 00:03:23.640 --> 00:03:29.379 So the way the cold seeps, uh, look, when you're actually down there is pretty magnificent. 00:03:29.379 --> 00:03:36.709 In a lot of cases ou get these really amazing bubble plumes, which is all of these hydrocarbons 00:03:36.709 --> 00:03:43.879 kind of bubbling up from the sediment, which create, uh, What looks like reverse waterfalls. 00:03:43.879 --> 00:03:48.390 Otherwise you get what we call shimmering water, which is where the water is slightly 00:03:48.390 --> 00:03:49.390 warmer than ambient. 00:03:49.390 --> 00:03:52.110 Um, and you get this really beautiful shimmering effect. 00:03:52.110 --> 00:03:57.069 But of course, there's a huge diversity of ways that cold seas can look. 00:03:57.069 --> 00:03:59.550 Can you tell us a little bit more about that diversity. 00:03:59.550 --> 00:04:01.890 What other forms of cold seeps are there? 00:04:01.890 --> 00:04:08.959 I work on hydrocarbon seeps specifically, but there are also seeps such as salt seeps 00:04:08.959 --> 00:04:16.880 that form, brine pools, which are essentially these pools of really salty water that comes 00:04:16.880 --> 00:04:19.060 up from the sediment. 00:04:19.060 --> 00:04:21.780 And this salty water is actually too salty. 00:04:21.780 --> 00:04:26.000 It can't mix with the overlying ocean water. 00:04:26.000 --> 00:04:28.800 And so it forms into these beautiful pools. 00:04:28.800 --> 00:04:34.610 Uh, you also get really dramatic formations, such as Tar Lilys, where you have these hard 00:04:34.610 --> 00:04:37.340 structures kind of solidifying once they seafloor. 00:04:37.340 --> 00:04:38.340 Wow. 00:04:38.340 --> 00:04:42.639 I didn't realize there were so many types of cult seeps out there. 00:04:42.639 --> 00:04:46.880 Can you tell us a little bit more about what exactly is being extruded at seep sites? 00:04:46.880 --> 00:04:53.510 Yeah, so there are a bunch of different chemicals that tend to be extruded at these seep sites. 00:04:53.510 --> 00:05:00.250 We tend to focus mainly as biologists on hydrogen sulfide and the hydrocarbons. 00:05:00.250 --> 00:05:03.080 So those are things like natural gas and methane. 00:05:03.080 --> 00:05:08.110 And the reason why is that hydrogen sulfide and methane can be used by the animals at 00:05:08.110 --> 00:05:13.030 these sites to actually fuel the ecosystems that we find there. 00:05:13.030 --> 00:05:17.930 So how exactly do these complex ecosystems form in the first place? 00:05:17.930 --> 00:05:24.699 Once methane and hydrogen sulfide start exuding from the sea floor, microbes tend to come 00:05:24.699 --> 00:05:30.840 in that are able to turn those chemicals coming up from the sea floor into energy. 00:05:30.840 --> 00:05:36.260 And once these microbes come and take hold, you have a lot of biological processes going 00:05:36.260 --> 00:05:40.310 on, one of which creates what we call carbonate rock. 00:05:40.310 --> 00:05:45.760 And that creates a hard surface on what would otherwise be bare sand. 00:05:45.760 --> 00:05:51.720 And once you have that hard surface, other animals can start coming in and colonizing 00:05:51.720 --> 00:05:53.310 that area. 00:05:53.310 --> 00:05:56.770 Oh, I'm so glad you mentioned the animals. 00:05:56.770 --> 00:06:02.170 I'm hoping you can tell us a little bit more about the diversity that cold seeps supports. 00:06:02.170 --> 00:06:07.539 Cold seeps support, a huge diversity of life, and you wouldn't necessarily expect that, 00:06:07.539 --> 00:06:08.539 right? 00:06:08.539 --> 00:06:11.389 These are sites way down on the ocean floor. 00:06:11.389 --> 00:06:18.360 They are at immense pressures, really cold temperatures, and to us what would be toxic 00:06:18.360 --> 00:06:19.449 conditions. 00:06:19.449 --> 00:06:22.310 But these cold seeps are highly diverse. 00:06:22.310 --> 00:06:28.150 They host what we call foundational species, which are the species that form kind of the 00:06:28.150 --> 00:06:31.521 three dimensional structure that other organisms can live in. 00:06:31.521 --> 00:06:37.680 So these are things like tubewom bushes, mussel beds, clam beds, that all of the other little 00:06:37.680 --> 00:06:43.960 critters at these sites can call their homes. 00:06:43.960 --> 00:06:49.760 These organisms are really unique because they have a symbiotic relationship with chemosynthetic 00:06:49.760 --> 00:06:50.760 microbes. 00:06:50.760 --> 00:06:55.949 That means that the foundational species and the microbes benefit one another. 00:06:55.949 --> 00:07:01.660 The microbes which live inside these foundational animals use the seep fluids to produce their 00:07:01.660 --> 00:07:02.760 energy. 00:07:02.760 --> 00:07:05.750 Which subsequently provides food for the animal. 00:07:05.750 --> 00:07:10.810 The animal meanwhile gives the microbes a really comfortable place to live, free from 00:07:10.810 --> 00:07:16.610 predators and grazers, like the snails that I study. 00:07:16.610 --> 00:07:19.800 So can any animal come in and live at a cold seep? 00:07:19.800 --> 00:07:26.729 So not every animal at the bottom of the ocean can live at a cold seep right away when seepage 00:07:26.729 --> 00:07:31.069 starts, to most things, those are relatively toxic chemicals. 00:07:31.069 --> 00:07:37.540 And so the only animals that can really start to live there are those animals that are specifically 00:07:37.540 --> 00:07:44.319 adapted to those conditions, primarily the foundational species that I was talking about. 00:07:44.319 --> 00:07:50.319 And then from there you have what we call ecological succession, which is where different 00:07:50.319 --> 00:07:54.770 animals live at these sites at different points in time. 00:07:54.770 --> 00:08:00.979 So over the lifespan of a cold seep, you have decrease in the amount of chemicals actually 00:08:00.979 --> 00:08:03.860 coming up to the water column. 00:08:03.860 --> 00:08:07.169 And so that changes the animals that can live there. 00:08:07.169 --> 00:08:12.229 Near the end of a cold seep's life, that's where you can have animals that are typically 00:08:12.229 --> 00:08:13.960 considered background species. 00:08:13.960 --> 00:08:20.440 So things like deep-sea corals, deep-sea sponges, a variety of fish species that don't rely 00:08:20.440 --> 00:08:22.970 on those chemicals for their source of energy. 00:08:22.970 --> 00:08:28.949 And they can come in and start living at and around those cold seep environments. 00:08:28.949 --> 00:08:33.729 It's both strange and wonderful to think about these complex ecosystems having their own 00:08:33.729 --> 00:08:36.640 life cycles so far away from us. 00:08:36.640 --> 00:08:39.219 Do they have any impact on our own lives? 00:08:39.219 --> 00:08:45.920 So despite cold seeps being located, you know, miles offshore, miles beneath the surface 00:08:45.920 --> 00:08:51.860 of the ocean, cold seeps are hugely important to our daily lives. 00:08:51.860 --> 00:08:57.490 Keep in mind that these hydrocarbons exude from the sea floor naturally. 00:08:57.490 --> 00:09:01.769 And these can also be known as greenhouse gases. 00:09:01.769 --> 00:09:08.180 So if these hydrocarbons, such as methane, are able to make their way to the surface 00:09:08.180 --> 00:09:15.070 of the ocean, they can make their way into our atmosphere and potentially exacerbate 00:09:15.070 --> 00:09:17.880 greenhouse gas effects in our atmosphere. 00:09:17.880 --> 00:09:24.860 And so the ecosystems at these sites essentially function to stop that from happening. 00:09:24.860 --> 00:09:32.930 They sequester that carbon in their own little ecosystems and keep the hydrocarbons from 00:09:32.930 --> 00:09:35.890 exiting into our greater atmosphere. 00:09:35.890 --> 00:09:42.260 And so these cold seep animals play a vital role in both the health of our oceans, as 00:09:42.260 --> 00:09:46.170 well as, the health of our atmosphere. 00:09:46.170 --> 00:09:49.329 What questions about cold peeps are still unanswered? 00:09:49.329 --> 00:09:52.190 There are so many unanswered questions out there. 00:09:52.190 --> 00:09:57.510 The questions that are the most kind of interesting to me and to the scientific community is, 00:09:57.510 --> 00:10:04.100 you know, understanding how these [00:10:00] cold seeps are resilient or fragile in the 00:10:04.100 --> 00:10:06.950 face of potential disturbance. 00:10:06.950 --> 00:10:12.540 Because as I said, these ecosystems have huge consequences for the state of our climate 00:10:12.540 --> 00:10:14.459 and for our ocean. 00:10:14.459 --> 00:10:20.240 And then also I'm interested in still understanding how they relate to other ecosystems that rely 00:10:20.240 --> 00:10:22.329 on that chemosynthesis. 00:10:22.329 --> 00:10:24.730 That's something that we are still trying to understand. 00:10:24.730 --> 00:10:28.490 Melissa, thank you so much for being here today. 00:10:28.490 --> 00:10:29.490 Thank you so much, Liz. 00:10:29.490 --> 00:10:30.660 This has been a lot of fun.