The fight to save the oceans

What is being done to combat the effects of human encroachment on our oceans and its inhabitants
04 July 2023
Presented by Will Tingle
Production by Will Tingle.


Looking out to sea, dark clouds on the horizon


This week, we’re diving into the fight to save the planet’s oceans. We’re looking at how humans are responsible for the effects on our planet’s oceans, but also perhaps lesser known strategies that are currently being employed to protect the sea and its inhabitants.

In this episode

An ocean wave

00:45 - How the oceans work, and how we affect them

What processes drive the global ocean system, and how are we changing those systems?

How the oceans work, and how we affect them
Helen Czerski, UCL

You’ve no doubt heard the news, and the projections, and the doom surrounding pretty much all aspects of the marine world as a result of climate change. This is nothing new and certainly isn’t going away any time soon. We’re in a mass extinction event, currently projected to lose 50-60% of species worldwide if we carry on at current level of consumption. It is a bleak prospect. But there are of course many people out there for whom protecting the oceans has become their life’s work. So this show hopes to highlight some of the perhaps lesser known strategies being deployed to alleviate the stress on our seas, and the life therein. And to have any hope of doing this, we must first understand how the ocean itself operates, and what humans are doing to that system. Helen Czerski is a physicist at University College London, and author of new book, ‘Blue Machine’.

Helen - Well, we have this cultural perception that the ocean is a void, that it's kind of big and empty, that it's just the space between the interesting bits. And the problem is that that's rubbish <laugh>. The ocean is doing things. We don't talk about it very much in society. When we talk about the ocean, we talk about the fish or the whales or the pollution. We talk about the things in the water, but not what the water itself is doing. The water itself is this engine. It's distinct, it's different in different places. It's got different components. They are moving over and around each other to form this engine. So it's not random, it's not that the ocean kind of just is a pool of water. And sometimes there's a current, on the surface there's this three dimensional engine where it's, it's turning over from the top to the bottom very, very slowly. And then it's kind of moving horizontally at the surface. And then there's these smaller little swirls at the surface. And then there's tiny, tiny things that happen at the ocean surface and further down. So like the breaking waves and bubbles that I study. And all of this forms an engine. It's a physical entity that is doing different things in different places and different parts of it are moving around.

Will - If the ocean is an engine, then it probably doesn't run on diesel. And please don't pour in any to check. So what powers it instead?

Helen - So the big drivers of the way the engine works on a larger scale are ultimately it's all solar energy and heating and surface currents are pushed by the wind, which is ultimately, that energy comes from the sun, but it's shaped by the Coriolis force and by the shape of the different ocean basins. And so there's a huge amount of energy in the ocean. They also get quite a lot of energy in there from the tides, so the moon is slowly drifting further and further away from the earth. And we are kind of capturing some of that energy, that tide energy that ends up in the ocean. So it's being driven by all these different things, but it's shaped by the land and the spin of the earth.

Will - But natural processes are not the sole drivers behind oceanic activity. Humans play their part too. The ocean weighs 1.5 million, million, million tonnes. The combined mass of humans on earth is 13 orders of magnitude less than that. So how much damage can we really do?

Helen - Well on the face of it, you'd think that just as for the atmosphere, you know, we puny little humans are too small to affect the ocean in any important way. And of course as we have discovered with the atmosphere, that's not true. So we're affecting the ocean in a few ways. The biggest one of course is global heating. So the extra carbon dioxide we put up into the atmosphere acts like a kind of block to energy flowing away into space. So what that means is the energy flowing in is more or less the same, but the energy flowing out is slowed down. And so we're kind of accumulating energy. 93% of that ends up in the ocean, mostly close to the surface. And the reason that matters is because, well, it matters for a few reasons, but one of them is the structure of the ocean. I said it's got different types of water in different places. And the thing that distinguishes those water masses is temperature and salinity. And it's the density of water that determines where it sits in the water column. So if you've got less dense water, it sits at the top. Now the reason that solar heating matters is that if you heat that surface water up even more, it's even more likely to stay at the top and less likely to mix downwards. And so you are creating a lid on the top of the ocean. I mean it's already there, but you're strengthening that lid. The energy, the sunlight is all at the top, but as time goes on and things live and die, the nutrients that you need for life tend to end up at the bottom. So you've got the nutrients at the bottom and the sunlight at the top. And so the places where you can mix cold water up to the surface, that's where you get loads of life. That's really important for biodiversity. But if you make that upper lid really, really strong because you've heated it up, you kind of shut down that system. You make it harder for nutrients to come up from underneath. And so you've got a physical thing which is caused by climate change, which is affecting how many nutrients there are for life in the places where life needs it.

Will - So what is the upshot of our mistreatment of the sea? What will happen to both the marine and atmospheric processes if some don't change their carbon heavy lifestyles?

Helen - A lot of studies are trying to work out the extent of this. And you know that film the day after tomorrow where they said the Gulf Stream was going to shut down, that is probably not going to happen. But you can have a lot of things that sound less serious, that will have enormous consequences. So because the ocean moves around heat and nutrients, so for example, if you weaken the overturning circulation, which is what takes water from the surface down into the deeps for a few hundred years and and brings it back up somewhere else, if you weaken that, you weaken the exchange between the surface water and the deepen. So you kind of change the structure of what can live where. And then in terms of physical currents and things like that, it's unlikely I think that currents are really going to disappear because the wind is still going to blow. It's still going to push things around. But if you move those currents, so the temperature of the water in the current is not the same as it used to be and perhaps the warmer water is further north than it used to be, then animals that depended on the current and depended on the temperature can't find them both in the same place. So the problem is not so much that the engine is just going to shut down, it's that it's going to change shape and life in the ocean and us. We all depend on that ocean engine kind of having the shape that it does because it brings rain to the land in certain places. It brings fish to the surface, provides a place for them to live in a good environment in certain places and that's going to move and those species are going to have to adapt. But our whole system, we just take for granted that the weather we have in every country is, well that's the weather in that country, right? We take it for granted that Britain is a bit warmer than it should be because of the Gulf stream and that it rains quite a bit and all that kind of thing. And it's not, the weather is going to stop, it's just the patterns are going to change and our infrastructure is going to be a bit left behind. And it's the same for the animals in the ocean. Animals are going to have to move perhaps to cooler water, but then the other things that they need won't be in those places. And so they will need to adapt. The engine is going to keep turning, but it's just going to change shape and that's going to change things that we take for granted.

A floating iceberg.

07:51 - Net zero marine science: BAS' 10 year plan

The British Antarctic Survey has launched a strategy to monitor the poles, whilst aiming for net zero

Net zero marine science: BAS' 10 year plan
Geraint Tarling, BAS

The challenges facing the ocean are global, and therefore require a global response. And that’s why the most important thing we can gather is data. You cannot make informed choices without proper data. The British Antarctic Survey has just launched their 10 year plan, ‘polar science for a sustainable planet’, and Geraint Tarling spoke about what they’re hoping to achieve.

Geraint - BAS has been working in the polar regions for over 60 years. And what we have is a strategy that we call 'polar science for a sustainable planet.' And it's all about trying to make those measurements but also in a way that is relevant to society, to actually show that the measurements that we are making really do make a difference in terms of how we understand and can get evidence for the changing of the planet and the way that we're going to get that done. And also put it into evidence that policymakers need.

Will - Which measurements exactly are you talking about when you put something into the ocean, what are you hoping to find out?

Geraint - So we measure all the physical things that an ocean has in terms of the way that we would describe it, the temperature, the salinity, also its biology, what colour it is, which is an indication of the amount of chlorophyll, the amount of phytoplankton in there. But also using really unique instruments to look at the biology beyond that, the things that feed on phytoplankton like zooplankton and fish. And we even have listening devices out there that can listen for the populations of whales as they travel by and they make acoustic sounds that we can then record and even identify which species are going in which areas.

Will - Are you looking at the physical geography as well, perhaps where areas peak and trough and how that might affect the planet's currents?

Geraint - Yeah, there's an extreme amount of topography in the Southern ocean. The area that we work in is the southwest Atlantic region of the Southern Ocean going into the Antarctic and the topography there really channels the amazingly large currents that circumnavigate the Antarctic, it's called the Antarctic circumpolar current. And that's guided by the topography there. But the other thing that's really important that happens in the Antarctic as well as in the Arctic, is that there is a descent of water from the surface right to the ocean depths. So what's amazing about the Southern Ocean is that 70% of atmospheric heat is taken up by the Southern Ocean as well as 40% of the carbon. And that's taken into the deep ocean and stored there away from the atmospheres that potentially would be warming even faster than they already are.

Will - And I couldn't help but notice, but in your name is the word Antarctic. So I'd assume most of the study is going to be heavily based on the South Pole, but presumably not all of it?

Geraint - That's exactly true. We are the British Antarctic Survey, but we are a polar organisation and we are actually really focusing quite a lot of our research on the Arctic as well. Now, for instance, in Greenland there are melting glaciers that are melting now six times faster than they were in the 1990s. We really want to know what's actually causing that, what the rates of change are so we can make better models to predict what's going to go on in the future. Also the Arctic is really important in terms of the amount of ice that's been retreating there. It's been predicted actually even by 2030 that you may have no summer sea ice in the Arctic. It was quite a frightening prospect. But that's gonna have huge implications on both the physics and the biology of that ocean.

Will - Once you've worked out what's going on at the poles, that affects the rest of the planet as well, doesn't it?

Geraint - Absolutely. So when I was talking about those waters descending into the deep parts of both the Arctic and the southern ocean, what they do then is they travel back in the deep parts of the ocean to the rest of the global ocean. And that actually this sort of conveyor belt of the currents as they go through the oceans is a really important process that drives a lot of the features that we see of the world's oceans. Also, what the Southern Ocean and Arctic do is that they provide most of the nutrients that the rest of the world's oceans rely on for their productivity. So they have a number of rolls in carbon, in nutrients and in ocean heat and currents. Once

Will - You've taken all this data, this salinity data, this chlorophyll data, the depths and the surveying of all the animals and plants and what have you, what do you then do with that data? Where does that go to hopefully make a meaningful change?

Geraint - Well, the first thing that we need to do with our data is to make sure that it's quality control, because lots of people are making measurements. We need to be absolutely certain that when we've made those measurements there to international standards that people can rely on them. And then the second part of that is to make sure that they're logged in a polar data centre that we have here or other data centres in the uk that they are both available to ourselves but then also available to the international science community so they can be analysed and put together with other data sets. And then the third thing, of course, is that we need to analyse it ourselves. We need to do peer peer review research. We need to actually get the analysis out in the scientific literature so that everybody else can scrutinise them and also that we can actually identify the patterns that really matter and also put them into models because models are really important to predict. Using these observations, constraining what they're predicting to make sure that they're as accurate as they possibly can be in their predictions.

Will - Is the final step of this to show this to some kind of policymaker and hopefully enact, hopefully global but potentially local ratifying change?

Geraint - Well, we think our role is to provide the evidence for policymakers the best available evidence so that when they are making decisions or they have to make choices between what decisions to make, but they have the evidence they need to make the choice that is the correct choice. But we try to engage as much as we possibly can. We regularly contribute to parliamentary inquiries about either the state of the climate or the state of the polls. We regularly talk to politicians or contributors to the IPCC and also the IPBS, which is about biodiversity and ecosystem structure in the oceans. And we try our best to be as outward looking as we possibly can to give as many lectures, to go to schools as well as to to to public forums, to actually talk about the things that we are seeing, the dramatic changes that we have witnessed in the the Southern Ocean and the Arctic. And to actually put that into a context of how rapid those changes are in relation to, you know, how things might look in the very near future.

Will - 10 years from now, where do you hope to be? What do you hope to know?

Geraint - What we want to do is to have Earth system models that are really accurate in predicting what the earth is going to be like in 10 years time. And that will take a lot of observation and a lot of modelling. We want to actually also be an organisation that, by 2040 and we hope to be sooner than that, we are net zero. Now doing oceanographic science means that you do have to take ships to sea and we want to make those as carbon neutral as they possibly can. And the way we are actually gonna combat that as well is to use lots of autonomous instruments that have very low carbon footprints that we can set out. As well as having a low carbon footprint, it measures oceans in unique ways that we haven't been able to do before. So we're gonna both become more carbon neutral, but also be amazing at observing the oceans in ways that have never been even considered even 10 years ago.

CGI images of DNA double helix

14:23 - eDNA: how to find hidden species

The best way to discover animals is to study what they leave behind

eDNA: how to find hidden species
Dean Pentcheff, Natural History Museum of Los Angeles County

Whilst it cannot be stated how important the ocean itself is to us and the planet, it is also the home of hundreds of thousands of animal and plant species. And they need all the help they can get. Now, we’ll never be able to monitor and conserve the entire ocean. That would just be a complete waste of our limited time and resources. It makes far more sense to focus our operations on areas that contain the most vulnerable groups of species. But first, we need to know where these biodiversity hotspots are and one of the problems… is that the ocean does not lend itself to being observed. Surveys are expensive and time consuming, and require specialist boats and observers. And realistically they will only be able to observe what happens at the surface, perhaps a bit below it. Yes, you can use sound to try and ID organisms, as long as the stuff you’re trying to find actually makes sound, which plants do not. You could try and fish out what you want to see, but you might just end up killing the stuff you’re trying to preserve. So how could you possibly hope to know what’s there, if you can’t see or hear anything? Well, what if all of our problems could be solved by one bucket of water? Dean Pentcheff is from the Natural History Museum in Los Angeles County, and he is part of a blossoming field of surveying known as eDNA.

Dean - eDNA or environmental DNA is pretty much exactly what it sounds like. It is DNA in the environment. It is reminiscent of all the bad TV shows you've seen where scientists come in and find a trace of someone in a room. We are all leaving a little trail of DNA behind us, and that includes people, that includes mammals, it includes all ocean life, it includes plants. Everybody is leaving a trail of DNA in the environment, and it is now possible to study that DNA from the environment.

Will - So it's sort of our skin cells and, dare I say, it's excreted substances that give us away almost.

Dean - Exactly that. In a lot of cases, it is skin cells that are being sloughed off, but all organisms have a variety of things that, as you imply, come off them and leave a trail in the environment.

Will - What gives it away as to how we can identify a species using it?

Dean - The most popular and most practical way that we use right now, has been sort of put under the umbrella term DNA barcoding. And that term was invented directly analogous to the idea of barcodes for products in stores where you scan a product and there's a numerical code that gets read, and then the store knows what the product is. What we can do with organisms is carefully pick a gene or a couple of genes, a very short segment of DNA through the whole genome that has enough variability that it's different between species, but not so much variability that we can't pick it out of the soup. And so we've identified a few of those genes across organisms across the natural world. And what we can do is from known specimens, we can take tissue samples, isolate those particular genes in those known organisms of known species, and create a library of reference codes more like an old fashioned phone book where you can look up a sequence by its genetic sequence, the sequence of A's and G's and T's and C's in the sequence and get a species name out. So that's how we go about identifying species in the ocean or anywhere using DNA.

Will - On all the marine surveys I've ever been on, it's always been something as indelicate as throwing a bucket into the ocean and analysing what comes out of the bucket. Is that what's going on here?

Dean - It really is. We can make it as high tech as we wish, depending on the question we want to ask, but honestly, yes, you can literally throw a bucket over the side, pull up some seawater and analyse the DNA in it, and that's definitely doable. Obviously, if you want to know things about particular depths or particular areas or particular microenvironments, the sampling can get as intricate as you can imagine. You can put tubes into the water and pump water out to a sampling station, or you can put bottles into the ocean that you release at a known depth, take a sample and then bring back up. So there's pretty much anything you can imagine is somebody's trying with varying degrees of success depending on the question they want to answer.

Will - It's always drilled into me that spooling up an array of equipment to run DNA tests was complicated and expensive. If that is the case, what advantages does eDNA have over your more traditional methods?

Dean - So I'm going to turn your question right around at you and tell you it's a whole lot cheaper. What we think of as the traditional way that you sample things in the ocean seems very straightforward, but is actually very expensive. What we do is we go out in boats, pick up a piece of ocean, whether it's fish in a net or invertebrates in a net or a grab from the ocean bottom. And that is actually really expensive to do. Boats cost a lot of money. Time on boats is very expensive. And then number two, once you've got that sample, if you want to know what's in it, let's say you want to know what the fish species are or what the invertebrate species are, or even more interesting what the microbial community might be, you've got to then get experts who can identify those things, line them up, in many cases literally line them up on the boat, have them do the identifications right there and move on. Again, that's a super expensive thing to do. By contrast, taking a water sample is about as cheap as it gets. You can go out there, grab the water sample, come back, and it's a very, very economical way of sampling the world that can be done much more quickly and in many ways, much more cheaply than the traditional standard ways that we have of sampling the ocean.

Will - Now you mentioned a little while ago about how this is a very useful tool for known species, but there are still unknown species. Is there anything we can do about identifying those?

Dean - Yes, there really is. When I talked about DNA earlier, I said it's, it's kind of like a telephone book and we have these known sequences from known species, but thanks to evolution and the way evolution works, the DNA sequences of closely related species are more similar than the sequences to more distantly related species. So if you are looking through your DNA that you've come up with from the ocean and you sequence all of the sequences that you got from your bucket of water, you will find a bunch that match your, your reference library and tick, tick, tick. Then you've got a list of species that you found almost inevitably you will find sequences that are similar, but not exactly like the sequences that you have in your reference library. Those sequences are very suggestive that there might be something new out there. It might be a new population of a species that you already have sequenced or might be a new species. And because the sequences are somewhat similar to sequences you know about, you can tell a little bit about it. You know, again, a little bit like a phone book, you know, if you find a name that isn't in the phone book, but you find a name that's similar, maybe they're in the same family in this case, maybe it's a species in the same genus, same family, closely related, and that gives you a target to look for. Then it gives you something that, that, you know, you can be looking for something that is similar to things you know, but a little bit different and go after that.

Will - One thing that I've always found a little bit crude about previous forms of marine monitoring was the fact that a lot of the time if we wanted to know what was out there, we'd have to go and fish them out and a lot of them would die in the process. This is presumably far less invasive a means of doing that.

Dean - You've put your finger on one of the beautiful aspects of using environmental DNA. It is non-destructive of the organisms. So we're really, really excited about the possibilities of using that kind of technology to be able to look at the presence or absence of organisms exactly as you said, without having to pull them out of the environment and kill them just to see if they're there.

Will - Okay. I'm really trying hard to catch you out here with some kind of drawback. So let's try this. You said earlier you can get a lovely qualitative list of species in that area, but what about the other side? Can it tell you anything about the number of individuals of that species?

Dean - If you had asked me that question two years ago, I'd have shaken my head and mumbled and said, 'no maybe future, future, we'll get there, we'll get there'. At this most vague obvious nature, you can imagine that the amount of DNA floating around in the ocean from a particular organism is going to have something to do with the amount or number of that organism that's out there. Making that connection quantitatively is really, really challenging, but is increasingly being shown to be practical and doable for particular species, one at a time. What I don't want to imply is that we could take that bucket of seawater and give you a count or a biomass for every species that's out there. That's way, way off. But if there's a particular species of interest, we could talk about fisheries, interested species or endangered species that we really want to know something about. By modelling how the DNA processing works, we can create a model to relate the amount of DNA that you find in the sample to the amount of the organism that's out there, whether that's mass or numbers in ways that are giving us some pretty good numbers.

Will - Putting all this together, then, we've got a non-destructive, non-invasive way of finding out what species are present in an area. How does this help us to help them?

Dean - One of the biggest challenges for any conservation initiative is just answering the question, 'what's there? How's that changing with time?' The only thing that you can serve is what you can see, and the only thing you can see is what you can detect. And so if it's very difficult or very expensive to detect the presence of something, it's very much more difficult to conserve it. So environmental DNA provides us what we think is an incredibly potent tool to let us see how the conservation efforts should be developed, and then once they're developed, how well they're working. And that I think is the biggest promise of environmental DNA for conservation biology.

The tail of a humpback whale surfacing above the water.

23:51 - Slowing down to save the whales

Is the easiest way of protecting marine life just going slower?

Slowing down to save the whales
Charlotte Findlay, University of Aarhus

If we find a marine area full of life that needs protecting, how do we reconcile the need to protect vulnerable marine species against inevitable human presence? Because it is an inescapable fact that much of the ocean is encroached on by humans: cargo ships transport 80% of the world’s goods. Oil and gas rigs use huge drills to get into the Earth’s inner layers. All of this activity leads to a lot of marine noise, which is a big problem for a lot of marine species. What if you’re a whale who wants to chat to a mate, but can’t even hear yourself think? What can we do? The University of Aarhus’ Charlotte Findlay has a proposal which is perhaps the most simple of all: just slow down.

Charlotte - Yes, slowing down is a really effective way of reducing a lot of these impacts from shipping noise to animals. And what we found was that if you slow down even by a small percentage, you can substantially reduce the loudness of your boat. So that's what we call the source level of your boat. And you can also shrink the area around your boat that's being exposed to noise. And as such, that reduces the number of animals that are being exposed to noise. So we found that if you reduce your speed by 20% from the maximum, you can actually reduce the loudness of your boat by six decibels and six decibels doesn't sound like a lot, but that's actually a halving of the noise pressure, which in terms of acoustics underwater is a lot. And then you can reduce the area around the boat that's being exposed to noise by 75%. So it's a real win-win situation. In terms of reducing impacts to animals.

Will - I suppose what appears to be the big issue is that most of these boats will be carrying goods and by slowing them down, are you somewhat disrupting the supply chain?

Charlotte - So of course if you slow down your boats, it's going to take you longer to transport goods. But the really interesting thing is that a lot of these shipping companies that are transporting goods are already slowing down. So they do slow downs when they're trying to save fuel. They slow down when there's over capacity in the market, so there's too many of certain goods. And they also slow down if they know they're going to be sitting outside a port for an extended period of time. And that happens quite a lot actually. So by slowing down, you can actually in some ways save money because you can save money on fuel and you can save money on time that you're spending on the boat. And I think it's important for me just to say that I'm not asking shipping companies to slow down for the entire route between two ports, which you know, could be an entire ocean, but perhaps considering slowing down in areas which we know are important to animals like marine protected areas or coastal areas where we have high densities of animals could have really big impacts on reducing impacts to a number of different species. So the marine mammals that we studied, but also all the other wildlife that's living in those habitats.

Will - And you mentioned earlier about how slowing downwards improve your fuel efficiency, but would it help in the emissions side of things as well?

Charlotte - Yeah, so that's the great thing about slowing down boats. It doesn't just reduce noise, it doesn't just reduce fuel efficiency, but it also reduces greenhouse gas emissions. So it means less carbon dioxide, less sulphur dioxide, less particulate matter. And this is especially important given the climate crisis that's going on and the International Maritime Organization has actually just put into place a law that asks the shipping industry to reduce their greenhouse gas emissions by 70% by 2050 when we compare it to levels measured in 2008. To achieve that, we can potentially use this slowdown approach. And so we are getting a multitude of different benefits from slowing down our big commercial vessels.

Will -
Sounds like a win-win-win here for everyone involved. So it seems extraordinary that perhaps it hasn't been implemented as much as it should be up until this point.

Charlotte - So we're starting to see slowdowns being implemented. So for example, in the port of Vancouver, there is a project to slow vessels down voluntarily and they've actually seen quite good uptake from the shipping companies. They're very keen to be involved and to help to reduce impacts to southern resident killer whales that are living in that habitat, which are also endangered species. So I think it's just a matter of time and I think potentially this could be a really useful tool to the shipping industry if they now know that doing a slowdown could help marine mammals. And they might be able to think about, 'okay, well we could slow down on our transits in certain areas and we'll still save some money and get to port on time, but we can also help the environment.'


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