How Scientists Detect Ocean Life From a Single Bottle of Seawater and Why It Could Change Ocean Protection Forever

0:00 What if I told you that scientists can now detect hundreds of ocean species without ever seeing them, catching them, or even knowing where they are or where they were all from one bottle of seawater. Look, we know the oceans are huge and to monitor everything in the ocean is virtually impossible, especially as things are changing so quickly. And conservation decisions depend. They matter on what is in the ocean. That's how we look at things. That's how we get to connect ocean species to use so that you can fall in love with them and you can see how cool they are. But traditional surveys that we do often miss some of these species more than you actually realize. Some are shy. If there's a person in the water, some fish won't come out.

0:41 They'll hide because they're afraid of the person. You don't get a true sense of what was actually there or what lives there. But now we have this thing called environmental DNA, eDNA. And this is where it comes in. And in a recent study they show how powerful this method could be. We're gonna talk about that on today's episode of the How to Protect the ocean Podcast. Let's start the show. Hey everybody. Welcome back to another exciting episode of the How to Protect the ocean Podcast. I'm your host, Andrew Lewin, Marine biologist and science communicator here to tell you what's happening with the ocean, how you can speak up for the ocean, and what you can do to live for a better ocean by taking action. And today we're gonna be talking about actually a method to collect data on species, especially fish species the actually improving what we know what's actually in the ocean.

1:30 We don't often get to talk about this. I have talked about eDNA in the past. It was a number of years ago when it was first coming out and we were first catching on to the glimpse of, Hey, you know what, we can take a sample of water and we can detect what was there. How in the heck does that happen? That's gonna be talked about on today's episode, but first I want to say, 'cause I didn't get to say it last episode, ' cause I recorded last episodes with Peter Neill before the new year. I wanna wish you a happy New Year. I hope 2025 was great. I hope 2026 is even better. And if you had a crappy 2025, I hope 2026 is great ' cause it can only get better from here. On this year. Just a quick note, we are gonna be doing some crazy things, some fun things. We're gonna be putting out more podcasts on, not just episodes, but actual different shows on the Speak Up for Blue Podcast Network.

2:16 So if you want to find out more of where you can get that, just go to speak up for blue.com. That's speak up for blue.com. You'll be able to find all those shows as we put them out, I mentioned one before the new year ended in 2025, I mentioned that we're gonna be putting out polar bears in flip flops. That's with my buddy Angelo Villagomez and I, we're gonna be talking to a bunch of people, have guests. It's a live podcast. We'll talk about the day when we're gonna be recording, all that kind of stuff. It's gonna be once a week and it's gonna be a lot of fun. You can find it live on the YouTube channel, and then of course, pretty much soon after, you'll be able to hear it on audio, but it'll be a separate podcast in itself. We're gonna talk about conservation issues, we're gonna talk about all this kind of stuff. So that's coming. We got a Fisheries podcast in the works. I'm crowdfunding for a Seagrass podcast.

2:58 If you want to help with that, you can go speak up for blue.com/seagrass. Listen, this is amazing. I can't wait to bring this forward. I can't wait to say, Hey, you know what? This is gonna be an awesome year. This is gonna be so much fun. And the first thing we're gonna talk about is data collection. 'cause what is more fun than talking about data collection? Especially in this one recent study that came out. They talked about eDNA, environmental DNA. We kind of know what DNA is, right? It's like a helix. Everybody has its own separate DNA except for twins and triplets and so forth, but we have our own separate DNA. It's unique to ourselves. And then a lot of times when we think about it, I want you to think of times in terms of like when you leave DNA, like at a crime scene or somebody leaves DNA at a crime scene and they're able to identify that that person was there or that you see it in crime shows that their DNA was on the knife or the gun or whatever.

3:48 It's obviously a negative aspect of using DNA, but the fact is you can identify people based on their DNA. Well, imagine if you can do that for fish and understand that like in this piece of water, they actually swam through at some point, at some time and they left a piece of themselves back there. Whether it's a scale, whether it's mucus, whether it's bodily fluids, whether it's just poop or, or urine, it doesn't matter. They actually left something there that you can pick up that has DNA inside of that, and then that will detect that that fish or that species was there at that particular time. Now it won't identify individuals. We don't know that much, but it can identify fish species to species, a fish to species, but it can also do like the families and so forth.

4:31 And this is a really cool thing 'cause like, just imagine. You don't need nets, you don't need cameras, and you don't need divers to do everything or to see anything and everything. Like I want you to think about when you're out in the ocean and a net goes in, there are certain fish species and certain species that can actually avoid those nests pretty quickly. They can swim away. And so for the mammals can swim a, some of 'em get caught by accident, some of them die. But imagine not having to use a net if you don't need to use a net. Imagine not having to use a net to detect what those species are. You can use a different method like the eDNA method It's just a really cool thing. When you put a camera down there, you're actually disturbing when you put nets. You're disturbing the ocean. When you're putting a camera down there, you're actually disturbing the ocean. Probably not as much, but you're disturbing the ocean. The big thing now are BRUVs. It's like a video camera down underneath a baited underwater video.

5:13 It's a camera. It's got some bait on it. And then what it does, it tracks a bunch of fish, but nothing's there. There's no person there. It's just a video camera with a long pole that has bait at the end, and then every time a fish or something or invertebrate comes and grabs it, that video camera takes the video of the thing. It's constantly working. And then you go and you retrieve that, and then you go through hours and hours and hours and hours and hours and hours of video to see what species are there. So it requires somebody to do that. But now just imagine that you can take a sample of water. Just a little in a test tube, or if you want more sample, if you want more water, you can take like a Niskin bottle if you've ever seen what a Niskin bottle looks like. And you can actually take that sample. And then when you do the DNA analysis, you can determine whether that sample is there.

5:54 We're gonna talk about the intricacies of that and sort of like how great or how accurate those can be. So here in this study, what they did is they compared eDNA sampling to traditional visual surveys by people, right? Visual surveys. So they have a diver in the water. I think it's really cool, but first before we go into that, the authors titled this environmental DNA metabarcoding enriches the conventional survey of a high diverse fish community in the Dongsha Atoll. This is done in Taiwan. This is all from people at the Department of Oceanography, the National Sun Yat-sen University, Kaohsiung, Taiwan. That's where they're from. And it was accepted on December 3rd, so it just came out in 2025.

6:35 The lead author seems to be You-Chen Liu, is the name and Yi-Ching Yang. There's a number of different, I'll put the authors down there too, 'cause they deserve to be acknowledged, obviously, for their work and being able to provide this out openly so that I can talk to you about it, which is kind of cool. So essentially they compared eDNA sampling to visual surveys. So a person in the water or people in the water doing those visual surveys. The results essentially were the eDNA detected significantly more species. So essentially they had divers in the water looking for species. They run a transact, they run a number of transects. They identify all the fish And then they finish their transact. They do another one. They finish their, and they go through. That's expensive. That takes a lot of work. It's tiring, depending on the conditions, if they're visible or not You don't know really what's going on if it's not visible, so you can't see as much.

7:18 But if it is visible and you're in a reef area, you've got a lot of clarity. You can see pretty far if you're a very good diver And so forth, and you have good eyesight, better eyesight than I do, and you can identify all these species, but it takes time. It takes a lot of money and that's not always there, right? And so that could be a difficult thing to look at. However, when you look at eDNA, they take a little sample, right? Or they take a bunch of samples and they run the DNA for all this. They identify the different strands of DNA, and then they cross-reference it to a number of different databases, and they're able to identify the fish. That is pretty cool. Like I can't tell you how cool that is. The amount of money that it saves, the amount of effort that saves. Just to go in and be able to take water samples and then identify it through a DNA analysis is mind boggling to me.

8:02 The amount of work you can do, more than what you can do if you just have divers in the water is ridiculous. Now, it takes away the fun of diving, and we're not gonna take away diving at all, but that's what it does. This is pretty cool, right? It doesn't say that the divers are useless. It just means that the tools are doing better. We still need divers to ensure that the species that are there are there and see what species are there. Make sure that we can ground truth them. It's like using satellite imagery. When I started out, I was using satellite imagery. I was doing GIS, Geographical Information Systems. We learned remote sensing, right? And so remote sensing is using satellite imagery but to identify specific features using the wavelengths and doing a bunch of different analysis to look at the wavelengths, to be able to tell which features are which. But you still have to go out in the field and you have to ground truth, not only the geographic locations of these, of like, whether it's lidar or actual satellite imagery, but you also have to make sure that what you are identifying through like a bunch of different analysis, like doing a bunch of calculations and modeling.

8:57 You have to make sure that you have the actual information right in front of you. And that is, the thing that you're identifying, you have to go in the field and you'll be like, okay, this is actually a feature. It's like a stone or it's a reef, it's a coral, or whatever that might be. You still have to do that. You still have to go out and do that. But this kind of tells you like, Hey, the DNA's there. You still have to use divers to make sure that all that's there, but the DNA is there. You're pretty good once you know it. So it fills out those blind spots that divers can't see, because of their presence, which disturbs and disrupts the regular ongoings of a reef system or any kind of system when you're sampling it. So that's pretty cool. Now, here's the thing. The methods are cool but how does this really work with conservation? This is a podcast we call How to Protect the ocean. So, Andrew, how does this actually happen?

9:39 Why does this matter for ocean conservation? Well, the thing is, is better data leads to better management. So the more data you have, the better reasoning you have for marine protected areas. Managers can actually monitor changes faster and cheaper. It takes a lot to take divers out in the ocean. It takes a lot to take a boat for that length of time to go out. But if you just have to go out and take samples of water and then come back and just do DNA analysis, it's so much faster. It's so much cheaper. You don't need the same amount of people, all that kind of stuff. And so you just get a lot more data for cheaper. That's pretty cool. It also tells, like, you can tell the trends, right? If you have a lot of DNA at one point And then the next year you don't have as many DNA, you're like, hold on a second, what's going on?

10:20 Are these species not in this area for a particular reason? Now that we're getting a lot more species, now, I'm sure that'll be the reference data. And I don't know if that's the actual reference, like the best data we can get ' cause it could have changed from before, but we're gonna know from now on how these things are changing. We'll be able to detect trends faster. We'll be able to detect trends just in a better way, more accurately, which will be really great. It gives early warning signs of any kind of ecosystem decline. Basically they become more visible because we have so many more species. And I think that's really good. If we don't know a species is there, we can't protect it. But eDNA changes that. That was a quote in the thing that I read. So it was pretty cool. Just think about how we have to react and how we have to manage. I always think this is interesting.

11:01 I worked as an environmental consultant one time, private environmental consultant. We worked with a lot of industries. We didn't have enough data to detect, like how bats were gonna react in a specific alleyway. Kinda like a wind tunnel of like a specific part in Ontario. And the company's like, well, if you don't know, that's not up to us to find out. It's up to the government to find out, or academics or researchers to find out. And the government's like, no, no, no, no, no. You have to pay for it to find out. It's a costly study and they did it, but they had to do it and all that kinda stuff. That happens in the ocean as well. When you don't know what a system is like, we're seeing this with deep sea mining. People are like, well, if we don't know what's there, we're probably not disturbing anything. Well, no, that's not true. There's still out there. We just don't know what's there and how it's gonna affect it. We still have to know. But the fact is now with all these things going on, like climate change, overfishing, habitat loss, like I said, deep sea remote ecosystem monitoring, all that kinda stuff can be done now through eDNA.

11:51 When I was a Marine technician in the Gulf of Mexico, we used to cast these CTDs, Conductivity Temperature Depth meters, conductivity, detected salinity. And we used to have this basically a data logger. And it used to be around this, ring, this like sort of outfit that goes around it, like a carousel. On the carousel it would have these Niskin bottles. These are water sampling bottles that would be open. We keep them open and we would be able to lower the CTD down through the water column, keep those water bottles open so water can go through it and it doesn't float and it goes all the way down to wherever you want, whatever depth you want. We went from like 10 meters all the way down to 3000 meters if we were able to. And then I was able to press a button on the keyboard and it would close a Niskin bottle, and it would take a sample at that depth. So as long as you knew which Niskin bottle was closed, at which depth, you can go back and you can take eDNA from all those depths.

12:39 Think about that. Think about all the species that we can determine from there. If there's new DNA, oh, great new DNA, we don't know what it is, but we have this map of DNA of a fish that's down there, or some kind of species that's down there that we don't know what it is. It's pretty damn cool, I think. Now, of course there are limitations, like I just mentioned. The fact that we don't have the DNA of all the species. These are cross-reference, like once you get the DNA out of the water, like once you analyze it for the D, have all these DNA makeups. And then you're like, okay, cool. Now let's cross reference them into these databases. There's a number of different databases. Some are regional and more local specific. Some are massive and people just continue to grab DNA and be able to contribute to this data. So we're having more and more species available.

13:20 Not just fish, but all these different species. But also, we don't know, we don't have the DNA of every species, 'cause we don't know every species. So eDNA tells us presence, but it also doesn't tell us population size. That's one thing, but also. We don't know the actual like DNA of everything, but it does allow us to identify what we don't know and say, Hey, you know what? Here's a new species. We don't know what it is. If we ever find out, we're gonna be able to match it to that and we can find out if there's more. So it allows us to kind of bank those DNA until larger. So I think that's really great and something that we need to continue to do. But eDNA doesn't tell us the number of that population, so it tells us the presence. So great for diversity. Like species diversity, but it doesn't tell you how much of one species it is or how much of individuals are in that population size.

14:01 And DNA moves with current. So it doesn't necessarily tell you that that species was there at that point. This a fish scale can go as far as a current will take it. It's not as if it can swim against, it's just a piece of skin or a piece of scale that they have. So, you know, you never know if it's gonna be there, but you know, it's around that area. And you can probably model it as we know more. And of course it works best with other methods, as I mentioned before. It's something that we look at and we have to ground truth it in the field. So that's something that's really good. But like, let's talk about what this means, right? This means we can do faster biodiversity assessments for cheaper, which is really great. We can better protect some of the overlooked ecosystems because some of those species, we don't know if they're there 'cause they hide whenever we do any other type of sampling, which is great to be able to identify those.

14:43 And of course it's more inclusive science, so it's more data, more information, especially in regions with fewer resources. Imagine like island communities who cannot pay for a dive team to go down and get this safely. I had a conversation with somebody on the Beyond Jaws podcast, which will come out soon, probably out just probably when you get this podcast. But it was kind of cool because she was talking about how she went out diving and there wasn't necessarily safety divers there. Because they didn't have the money to pay for all that. So when she just went through, she's like, I probably wouldn't be able to do that now because there's needs of safety divers and other divers to help you out in medics and so forth to make sure it's safe. That's all expensive. You can't do an expensive PhD sometimes if you don't have the funding. And so to be able to have this ability to sample this size is really, really great.

15:26 The science helps decision makers before it's too late. Not after an ecosystem collapses. So it's before that, which is great. So the thing is like if you want better ocean protection, it starts with the knowledge. It starts with the information. Science like eDNA helps us understand what's worth protecting, why we need to urgently and how we need to urgently react. I think that's something that's really great. And so that's the episode. This makes me excited because eDNA is fun. Collecting ocean information is fun. Just as I think about this as I end this episode, the other benefit is you don't have to actually have to sample fish. This is the stuff that just comes off fish, that comes outta fish or comes out of any kind of animal and that we can grab and they can get their DNA. It's not as if we're harming them. It's not as if the thing. It provides a great thing for diversity, which we don't act on enough because we don't think we know enough about biodiversity.

16:12 We don't know enough about the species and everything like that, or how many species. It's really hard to detect, as I mentioned in this podcast. So I'd love to hear your thoughts on this method of eDNA. If you're a scientist and you've used eDNA before, I would love to hear from you. Let me know in the comments below if you're watching this on YouTube. And of course, if you want to give me feedback or you want to just participate and get into a conversation, I'd love to hear from you. You can go to speak up for blue.com/feedback. Those of you're listening to audio and you can't comment. If you wanna comment on Spotify, you're more than welcome to. I'll answer those. But also speak up for blue.com/feedback. You can leave a voicemail or you can comment. I would love to be able to respond to those. This is a community, this is what we're building. 2026 is all about community. I've got some really cool things coming.

16:53 I've got a Patreon coming. I've got YouTube memberships coming. I'm gonna go live a lot more in 2026. It's gonna be a lot of fun. So stay tuned, subscribe, follow whatever you need to do. I love you guys. I hope you guys have a great 2026, 'cause I know I'm gonna have a great 2026 with this. It's gonna be a lot of fun. Thank you so much for listening. You have been listening to this episode of the How to Protect the ocean Podcast. I'm your host Andrew Lewin from the True North Strong and free. Have a great day. We'll talk to you next time and happy conservation.