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Restoring the Underwater Forests with Jon Dickson
213 Plays12 days ago
Before industrial dredging, clear-cutting, and destructive fishing practices, our rivers and oceans were full of wood. Fallen trees, driftwood, and branches created underwater forests where fish and countless other creatures could thrive. That wood provided shelter, food, and the foundation for entire aquatic ecosystems. Today, much of it is gone, and so are the fish.
Marine restoration expert Jon Dickson noticed this loss while working along Europe’s coasts and asked a deceptively simple question: if we remove the wood, do we also remove the fish? His answer is the “tree reef,” an artificial reef made from pear trees and other natural materials that replaces destroyed habitat. It is a low-tech, high-impact idea with the potential to revive aquatic life far beyond local waters, and it is deeply connected to the broader regenerative agriculture movement on land and at sea.
In this episode, we dive into:
- The forgotten role of wood in rivers, estuaries, and oceans and why it matters for fish
- How dredging and “cleaning” waterways destroyed essential aquatic habitats
- Why restoring fish populations is critical for global ecological balance, including land-based food systems
- The limitations of many well-meaning marine restoration efforts and how tree reefs succeed where others fail
- The design, construction, and surprising results of tree reefs
- How low-cost, replicable solutions could transform restoration at scale
- Why thinking like an ecosystem is the key to regeneration everywhere
If you have ever wondered how oceans and rivers fit into the future of regenerative food systems, Jon’s work might change the way you see both land and sea.
More about Jon and Marine Trees:
Jon grew up in British Columbia, Canada, where after university, he worked as a forest fire fighter. In the off season, he worked as a polar guide and boat driver in Antarctica, Greenland, and Northern Canada. These seasonal jobs and education were interspersed by backpacking trips; his favourite countries (so far) are Iceland, Mongolia, Uganda, Slovenia, and with a vote for the home team, Canada. Since moving to the Netherlands to work on a PhD, he noticed a distinct lack of driftwood in Europe and decided to see if fish were missing habitat due to lack of wood - and so invented tree-reefs, an artificial reef made of trees to replace destroyed habitat.
Agrarian Futures is produced by Alexandre Miller, who also wrote our theme song. This episode was edited by Drew O’Doherty.
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Transcript
Circular Economy & Waste Transformation
00:00:02
Speaker
Economics is driving restoration and wood is a waste product in a lot of scales in any case. And if we can turn a waste product into something beneficial, we're one step closer to a circular economy.
00:00:13
Speaker
And I really encourage your listeners to think about how waste products can be repurposed into something useful.
Season 2 Introduction: Agrarian Futures
00:00:20
Speaker
In season two of Agrarian Futures, we're starting with a simple question.
00:00:25
Speaker
How did we get here? Farms are disappearing. Land is getting harder to access. Rural economies are hollowing out. But there are people building better ways forward. Join us as we investigate what's broken in our food system and what it looks like to build something better.
Pear Trees in Ocean: Ecological Impact
00:00:46
Speaker
So John, thank you very much for joining here on Agrarian Futures. I've been looking forward to having this conversation for a while, ever since I learned about your work and we started to communicate back and forth a little bit because 70% of the planet is covered in water.
00:01:03
Speaker
These are just whole ecosystems that we don't hardly ever think about how they function and how we can improve the management of them because they're literally covered in water. You can't see hardly what's going on beneath the surface.
00:01:17
Speaker
So we're going to get into a whole bunch of this stuff. But let's start off with John, why do you put pear trees in the ocean?
00:01:28
Speaker
That's a very good question, and we'll get right to the point. And you know our whole initial rationale for doing this was we could make a really cute title on a SpongeBob reference, Who Lives in a Pear Tree Under the
Historic Logjams: Marine Life Benefits
00:01:38
Speaker
Sea?
00:01:38
Speaker
And the rest has just fallen in line alongside that. It's hard to believe now. There used to be heaps and heaps of driftwood moving from land out to sea. Just an example for North American listeners, the Red River, ah tributary of the Mississippi,
00:01:54
Speaker
had a 800-year log jam of 260 kilometers. I guess that's about 150 miles, give or take. And this would routinely spit out wood into the Mississippi, where it would sink.
00:02:05
Speaker
In the 1800s, humans, doing what humans do, decided to clear that log jam. I think the predecessor to the Army Corps of Engineers sent 25 soldiers with hand tools to go to try and clear 150 miles jam.
00:02:20
Speaker
Yeah, the soldiers just rocked up and looked at this and laughed. They wrote a report and went back to base because eventually they started coming in with steamboats and dynamites and all sorts of things like this.
00:02:31
Speaker
And even so, even with ah the high tech of the 1800s, it took them something like 30 years to clear this logjam. And then, of course, river traffic could proceed unmolested and trade could continue and But the ecological benefit of that driftwood, which is very important for fish and oysters, was gone.
00:02:49
Speaker
And the Red River is one of the most known huge log jams that used to exist, but this would have occurred on almost every river in the world. And ever since humans have domesticated the landscape here in Europe, that was about 3,000 years ago when we shifted into widescale agriculture,
00:03:06
Speaker
The forests were clear cut for farms. Cities started coming in, mining. There hasn't been a supply of wood into the rivers. And what little wood does get in the rivers is cleaned out. it's a navigation hazard.
00:03:18
Speaker
So I looked at all this and thought, oh, this is probably an issue for the ocean that we've deprived millions upon millions of tons of wood going out to sea every year.
00:03:29
Speaker
so I'm going to look into that a bit more. So explain to me first, why is wood in a marine environment? Why is that valuable? Why is that
Ecological Importance of Reefs
00:03:39
Speaker
important? What is that wood providing that is otherwise not there?
00:03:44
Speaker
Well, I've got a question for you. When someone brings up the word reef, what comes to mind? I think of a tropical barrier reef with corals. Yeah, that's exactly it. So most people think of coral reefs, understandably, because they're very sexy, very pretty, great visuals, very clear water, very fun to swim on.
00:04:04
Speaker
You don't get hypothermia when you're diving. you know There's a lot of benefits to diving around coral reefs, but there's a whole bunch of other types of reefs. For example, oyster reefs in the Gulf of Mexico, or what used to be oyster reefs anyway, shall we say? And what used to be the Gulf of Mexico...
00:04:22
Speaker
Yeah, let's read up on the history. and There's a reason it's called the Gulf of Mexico there. But coming back to the actual reef point of view there, those reefs provided structure where coral could not or would not.
00:04:33
Speaker
But oysters need something hard to grow on They can't grow on sand. They can try, but the first time a storm comes along, the waves are going to pick up these baby oysters, disperse them, and your reef is gone.
00:04:45
Speaker
You've also got things like sponges, which are very important for filtering water in the marine sphere. They can create their own reefs. You've got a whole bunch of worms that build tubes out of sand to make stable or reefs.
00:04:57
Speaker
You have cold water corals, deep water corals. You get a lot off the Pacific Northwest and up to Alaska there. There are organisms, not like corals, but providing the same function as corals throughout the world's oceans.
00:05:11
Speaker
But generally they need stability because like corals, they're very slow growing. And if there's one thing humans know how to do very well is change things very quickly in the natural world.
Shifting Baseline Syndrome in Marine Ecosystems
00:05:21
Speaker
One thing that has come up in our conversations previously is what seems to be this this shifting baseline syndrome.
00:05:30
Speaker
And for those who are not familiar with it, shifting baseline syndrome is this thing where what we have today might look really, really good, but pales in comparison to what we had at a certain time previously, but we're just not aware of how good it was or sometimes how bad it was. So like, i think for example, a positive shifting baseline syndrome is 100 years ago or 200 years ago. For most of human history, people had to heat their water over it over a fire.
00:06:02
Speaker
They had to get water from a creek or from a well. They couldn't just turn on a hot water tap. A lot of people died in youth from diseases that now are completely curable.
00:06:13
Speaker
And today we expect to be able to turn on our hot water and we get we get hot water instantly. So that's a positive example. But negative examples have been people going fishing 100 years ago might pull in 10 fish that are three feet long.
00:06:28
Speaker
And that was that was a standard day. Whereas now in that same place, maybe you pull in two fish that are, two feet long. And that's a really good day.
00:06:38
Speaker
There's many, many examples of this where these baseline expectations of what you think is a good day or what you think is a good environment have shifted over the course
Decline of Fish Populations
00:06:49
Speaker
of generations. And we're not necessarily aware that those have shifted So can you paint us a picture of what are cold water in particular marine environments used to look like? you So you're talking about the log jam. Can you tell us a little bit more about the extent of oyster reefs in particular when they had their heyday whenever that was?
00:07:09
Speaker
Yeah, absolutely. I'll go back to that shifted baseline question first or the statement. There's a really pertinent example off the East Coast of North America. And of course, you've got the Gulf Stream heading north up from Florida, and it meanders its way over to Europe. It keeps Europe pretty warm, considering the latitude we're at.
00:07:26
Speaker
Then you have Arctic currents coming down off Greenland, mixing with the Gulf Stream and creating really nutrient-rich water, which animals love to live in. And when the first explorers, quote-unquote, discovered Newfoundland, just a bit north of Maine there, they were able to dip baskets in the water and come out with baskets overtopping with fish.
00:07:46
Speaker
There was no hook, there was no line, there was no net. You could just drop a bucket and you'd have fish to eat for days and days. wow Wow. The Basques from northern Spain were some of the first to come over from Europe to exploit these fisheries off the Grand Banks.
00:08:00
Speaker
and Maine and Newfoundland have been built on the story of these fisheries. The cod were so plentiful that you you literally couldn't see through them. It was just a wall of fish. And the Europeans and later on the North Americans exploited these up to a about the 1900s without much concern because, the like you say, the high tech wasn't there to take as much as you can as fast as you can.
00:08:23
Speaker
But when we started developing bottom trawlers and combustion driven ships rather than wind, refrigeration. You could stay out at sea for a long time, and the only reason you had to come in was because your ship is full, or you needed to get more beer or fuel or something important like that.
00:08:41
Speaker
Once we fished out those historic fishing grounds, we chased them to their spawning grounds because that was the last place that the the cod were still plentiful. And as you well know, when you wipe out a breeding population, you're not going to have a population much long after that.
00:08:56
Speaker
So that's a shifted baseline. The the early Europeans they could come over and just drop buckets and pick up fish. And this was extremely valuable for a fairly depleted Europe at the time.
00:09:07
Speaker
So the Basques and the Brits and the Norwegians, everyone else around, they'd more or less fished out the North Sea at that point. North Sea stocks had already declined, so they were looking for new places, new resources.
Cod Fishery Collapse & Species Shift
00:09:19
Speaker
And they came to Newfoundland, they're like, hey, we could build a lot of ships out of all this timber. Hey, look at all this fish. No, we don't want the land. We just want the resources. So here we are. About 500 years later, give or take, there's no cod.
00:09:32
Speaker
Or what little cod remains is just not catchable. The Canadian government has had a moratorium on cod catching since the 90s, with the hopes that the species would recover. It hasn't.
00:09:43
Speaker
Because as as any farmer will know, something is going to use those resources that the cod were feeding on. And now we have a huge amount of crab and lobster off the coast there.
00:09:54
Speaker
There is a fishery on it for sure, but it's not nearly as productive as reeling in cod by the bucket load. And so the cod are slowly recovering, but not so well. So there's a shift to baseline. If you brought ah Basque 500 years forward in time who last fished on the Grand Banks in the 1600s, he wouldn't recognize the area now.
00:10:12
Speaker
He would cry. I cry. Yeah.
00:10:17
Speaker
And can you explain for for me and others who are not initiated, what are the different ways? so you mentioned bottom trawling. Are there other techniques that have come into use over the last several hundred years that were not available prior that do damage to these ecosystems?
00:10:36
Speaker
We only have about an hour, I reckon. So I won't go too far into this. Maybe the main ones. Yeah, sure. So let's look at a ah small scale example on corals. We'll go back to corals here.
00:10:46
Speaker
The aquarium trade for people that want colorful fish in their aquarium is worth a lot of money every year, multiple billions. But fish come out pretty mangled from trawl nets, so you can't really use damaging nets to catch fish that are going to be aesthetics, more or less aesthetics.
00:11:05
Speaker
So what a lot of places in the developing world around the tropics have done is resorted to dynamite fishing or cyanide fishing. And when you throw an explosive in the water, set it off, it will create a pressure wave, which will more or less kill everything within its radius.
00:11:19
Speaker
And then within, i don't know, 100 yards, whatever, depending on the size of the explosive, ah it'll stun everything else and it'll come to the surface. wow And this is very effective for catching live fish because some of them aren't dead.
00:11:33
Speaker
Some of them are just stunned. So you can just come along and scoop up your stunned fish, put it in a bag, get it to a saltwater tank, and send it to Europe or North America, whatever. And now someone's the very happy owner of an exotic, very colorful fish.
00:11:47
Speaker
That's crazy. But what's this dynamite doing to the habitat that these fish are relying on? I've dove on a few dynamited reefs, and it's just it's just coral rubble. There is no coral left. It's just the bottom strewn with calcium chunks, essentially.
00:12:01
Speaker
it's ah It's quite sad. Similar way to do it, inject the water with cyanide. Yeah, you'll kill a lot of fish at the source, but you know there's still enough stunned fish that you can feed your family for another few months from what you can sell to aquarium dealers.
00:12:15
Speaker
So for better or worse, destructive methods of fishing like that, they're highly effective. They yield a lot, but they're no good in the long run because you are, again, destroying the habitat or the spawning population of the resource that you're relying on.
Marine Structures: Importance for Ecosystems
00:12:28
Speaker
That's insane. Going back here, it sounds like we've got two different things that are going on and that they're enforcing each other. So one, when you open up, we were talking about how there is a lot less woody debris in particular coming from terrestrial ecosystems into our aquatic ecosystems.
00:12:45
Speaker
And the material that was already there and the reefs that were there have been destroyed in many ways because of shipping, dredging, and then destructive fishing methods.
00:12:57
Speaker
Can you tell me a little bit more, why is so structure so valuable in marine ecosystems? To put it in simple terms, a shield against the environment.
00:13:08
Speaker
Let's take this back to terrestrial. Say you're in Arctic hair and it's a beautiful spring day, nice icy flat tundra as far as the eye can see, and suddenly a hawk appears or a wolf. Where are you going to run? Where are you going to hide?
00:13:19
Speaker
You're dead. Same goes for marine ecosystems. Animals that rely on hidey holes are basically screwed without some sort of structure that they can go into. And the same goes for laying eggs.
00:13:30
Speaker
If you just lay eggs on the bottom of the ocean and a wave comes along bottom currents, your eggs are going to get silted in or taken away or destroyed. So these these reefs, wood reefs, oysters, coral, whatever, they provide refuge for spawning, hiding holes for prey fish,
00:13:46
Speaker
And because there's so many prey fish around, this also attracts bigger fish that are eating these little fish and bigger fish that eat those bigger fish until you have a multi-trophic level ecosystem within this very small patch of structure.
00:14:01
Speaker
Because it is an island, in the middle of the ocean, except, well, the island is beneath the wheat the waves, I suppose we could say. But that most of the bottom is a featureless desert, like you're saying before.
00:14:14
Speaker
Not much going on. There's no food for fish. There's no shelter for fish. And it's just blowing sand. have you If you're looking for people, the best place to look for them is not in the desert, but it's going to be at the bar.
00:14:26
Speaker
Yeah, or at the oasis, as it so happens to be. Yep. And so all these stability-loving species, the oysters in particular, they need, like we said, they need some sort of substrate to attach onto to grow themselves.
00:14:40
Speaker
Other fish will hang out, use the structure for shelter. And of course, wood degrades. Everyone right now is probably thinking, this guy's an idiot. Wood rots away. Of course, yeah, obviously it does. But the sheer scale of how much wood used to go out to sea, throw some quick numbers at you.
00:14:55
Speaker
Pre-industrial times, the world was 40% forested on land. We're down to 27%, dropping annually. And a lot of that deforestation is in places we can get to.
00:15:06
Speaker
In other words, rivers. And rivers are the highways that took that wood out to sea. On the low end, and I'm sorry I don't have this in Imperial. ah Maybe you can ah put a ah subtitle for your...
00:15:18
Speaker
for your viewers, 500 million cubic meters of large wood longer than 10 feet annually used to go out to sea, more than did now. 8,000 Olympic swimming pools off the top of my head of large wood annually, every year, year in, year out.
00:15:34
Speaker
And wood'll float, yeah, six months, 12 months, depending on the type of wood, ah different types of densities. And it would just sink at random, more so around River Mouse, but also just at random, including in the deep sea.
00:15:48
Speaker
and it would become the genesis of a new reef almost every time that it sank. I enjoy snorkeling. I also enjoy spearfishing. And if I go snorkeling in my pond right here, there's about three or four places that I'll go in that pond if I want to see fish. Because I know if I'm snorkeling over the the muddy bottom, chances that I see something are very slim. If anything, it's just going to be something that's passing by. But if I go to a certain spot where there is a couple logs or a rock pile that I put in or a tripod of logs, I know every time that I go there, I want to see fish.
00:16:24
Speaker
Another example is my wife and I, we were kayaking a couple of years ago. We went to Assateague Bay here on on the East Coast and we hit it on a beautiful crystal clear day where there was there wasn't a single wave out there. So we could see right down to the bottom and we were kayaking. We probably spent two hours kayaking and I was looking down through the water to see what fish I saw.
00:16:47
Speaker
I didn't see a single fish. In all of that kayaking, there wasn't any any bit of structure. it was all flat, uniform, sandy, silty bottom. I didn't see a single fish in the whole time that we were down there.
00:17:05
Speaker
Yeah, fish loves structure. What else to say about that really cheesy analogy that sprung to mind when you were talking here? I don't know if you remember that awful Star Wars movie, ah The Phantom Menace, that came out in the early two thousand I did not.
00:17:19
Speaker
I was just a kid when that came out, and I thought it was the coolest thing when they're going through the tunnels of Naboo and there's always a bigger fish popping out to eat the bigger fish that's chasing them. Yeah, super cheesy. I have regrets about my taste in movies, but the ecological principle holds true.
00:17:35
Speaker
There's always a bigger fish in the ocean. And if you're not able to swim fast enough or defend yourself, your only option left is to hide. And without places to hide, from your tiny, tiny half-inch minnows all the way up to almost all the way up to Great White Sharks, because orcas will eat Great White Sharks,
00:17:52
Speaker
Not that they like structure, but I digress. That's a little too complicated. Let's call it tuna in any case. There's always a bigger fish that wants to eat you. And if you don't have a place to hide and you're just roaming along the bottom out in your featureless bay on your nice kayak, you are easy prey for something that's bigger and faster than you.
00:18:10
Speaker
And so by necessity, fish associate with structure, like you say in your pond, because it's a survival strategy. You wouldn't want to be out in the northern winter with nothing but a tent, would you? You'd want a cabin with a wood stove and so on and so forth. It's a survival strategy against the elements.
00:18:25
Speaker
So the more marine structure that we have, the more everyone seems to benefit, whether whether they're commercial fishermen, and recreational fishermen, people that like to eat fish.
00:18:36
Speaker
I'm assuming that even just recreation is going to be better. I bet water clarity goes up when you have oysters because they're filter feeders. So all these things that benefit the public in general, someone's going to have to be the one to go out and establish that structure and it seems that the core challenge area is who is going to pay for that? Because this is, the ocean is is the ultimate example of a commons.
00:19:06
Speaker
There is a hell of a lot to unpack in that statement there.
Artificial Reef Failures
00:19:11
Speaker
So yes, structure is good, but not all structure, as a caveat. I don't want people going out and throwing junk in the water, more or less.
00:19:19
Speaker
There was a well-meaning attempt of the Carolinas in the 80s or 90s to make a huge artificial reef with 2 million used tires. who use tires And they thought, well, structure. Fish love structure. Lots of hidey holes in tires. This will be great.
00:19:34
Speaker
Yeah, those tires are still washing up. 40 years later, they were not secured properly. The chains broke. And there's now just rubber pollution throughout the Carolinas.
00:19:46
Speaker
I imagine that there's chemicals in those tires, too, that we don't necessarily want in the water. No, and chemicals will accumulate up the food chain as smaller fish are grazing on the rubber. Bigger fish will eat lots of small fish, accumulate the the toxins.
00:20:00
Speaker
Any material is not so good, but wood is largely natural at natural scales anyway. If you have a lot of decomposing wood, you start to get some weird chemical reactions that...
00:20:11
Speaker
do some funky stuff like off the west coast of Washington, for example, mills used to dispose of bark and sawdust and whatever into the sea just because it's convenient.
00:20:22
Speaker
But it basically turned the water anoxic because um so much sulfide was produced by the organism decomposing the wood that nothing else could live there. it smothered the bottom and it's a functional dead zone.
00:20:34
Speaker
And those were probably sawdust and bark. It was probably very fine material rather than really big material that's going to be slow to break down. It's going to have that effect very quickly in that case, I imagine.
00:20:45
Speaker
Exactly. Just so. Surface area to volume. the The golden rule everywhere we go.
Japan's Success with Artificial Reefs
00:20:50
Speaker
So who's going to pay for all the structure and who's going to benefit? Let's take a look at Japan. They are well known as a fishing nation, great sushi.
00:20:58
Speaker
They're also known for not so particularly modern environmental practices like whaling, but that's neither here nor there. Japan has known about the benefits of structure for fish and fish yield for at least 500 years.
00:21:13
Speaker
You've had fishermen building independent reefs or government-sponsored reefs all around the country, to the point where there's now 7,500 artificial reef installations around Japan.
00:21:24
Speaker
In the 1980s, global fish populations and yields dropped off a cliff. We hit critical mass of how intensively we were fishing, and yields dropped drastically everywhere, except Japan.
00:21:37
Speaker
And it is thought that the reason Japanese fish yields remained relatively stable is because there was so much habitat for fish to replenish on these reefs, that their local yields remained pretty much okay.
00:21:50
Speaker
But they've been doing this for 400 years. And yeah, it's all been more or less independently funded. But with your example, if you're producing fish 200 miles up coast, and they swim down, and I catch them down here,
00:22:01
Speaker
everyone is benefiting because maybe the reef that I built here is exporting fish to your area. And in a world such as ours, where everything is ah private and owned and taking responsibility for yourself, so to speak, it's very difficult to put out common benefits when it may not be you that's getting the benefit.
00:22:22
Speaker
So now we've established the the value of of woody structure, the the importance of of structure for for fisheries and all that. Can you tell us a little bit about the research that you have done specifically and the work that you have done to establish tree reefs, trees in marine
Wood's Role in Marine Environments
00:22:42
Speaker
environments?
00:22:42
Speaker
What have been some of your key takeaways from your work so far? Key takeaway, wood good, human bad, more wood and water. you want you want to expound on those a little bit?
00:22:55
Speaker
Yeah, of course. So the system I work in, the Dutch Wadden Sea, it is arguably the most degraded marine system in the world. We used to have fishery for cod and sturgeon and salmon here. We no longer have a single fish fishery at industrial scale.
00:23:10
Speaker
The only thing that remains is bottom trawling for shrimp. as well as a few little artisanal fisheries. Two thirds of the Wadden Sea has been turned into freshwater or farmland. As a result, the tidal currents are extremely strong. The water turbidity is very high. Imagine sticking your hand in the water and by the time your elbow is wet, you can't see your fingers.
00:23:30
Speaker
The tidal currents run at about five feet, six feet a second. It sucks. It really sucks. I've got 275 pound weights on my buoys and the buoys are routinely moved.
00:23:42
Speaker
Yeah. 300, 400 feet in a month, just picked up by the currents and moved. It is a very difficult system to work in. So just to set this the scene for you, it is functionally a marine river where nothing except shrimp and crabs is left alive due to centuries upon centuries of human alteration to the system.
00:24:00
Speaker
Our first experiment involved more or less dropping a bunch of rocks and wood and small rocks and small wood into the Wadden Sea. And because it's so violent and so sandy, everything just got buried.
00:24:12
Speaker
just straight up. So our reefs were pointless. I really enjoy that I wasted two years of my life on that study, but whatever. But we came to the conclusion- You learned.
00:24:22
Speaker
You learned. We did learn a lot that height is life. And in these these mobile violence systems, you need to get away from the bottom stressors, the flood of crabs, the sand scour, the burial.
00:24:34
Speaker
And so i was looking at tank traps from World War II that the Germans put on the beaches to deter the Allies from landing in Normandy. And I thought, hey, that'll be a pretty good artificial reef.
00:24:45
Speaker
It doesn't matter which way it turns. It's pretty stable. Wood is pretty cheap. Maybe I'll play around with some junk wood. And I made some half-size models. And my initial tank trap reefs failed. But then, thinking back to my time in Egypt, I thought, oh, those pyramids have been sitting here for a real long time. I wonder if I made some some woody pyramids, see see what they'd do.
00:25:05
Speaker
Sure enough, that was winner. So these pyramids are about 9, 10 feet high and equally so wide. And because a pyramid, no matter which way it turns, it still remains a pyramid with the same amount of surface area away from the bottom stress.
00:25:18
Speaker
of those crabs and the scour. Also, because they're highly porous with a lot of branches in the middle, that's a lot of protected habitat where water can come through and filter feeders like oysters, mussels, bryozoans, whatever, can actually interact with the water flow and extract particles from it to eat, meaning that you don't get the seawall effect.
00:25:39
Speaker
I know if you've ever snorkeled along a seawall, but if you go down and look at the bottom where the sand and seawall meet, About the bottom two feet will be just bare concrete because that but edge effect of the concrete blocking the waves and sandblasting the bottom of the seawall basically kills everything that can establish.
00:25:59
Speaker
But if you let water through one of these complex woody tree structures, The water just becomes turbulent, but it doesn't create sand scouring. Thank you for coming to my TED Talk.
00:26:13
Speaker
So you've figured out some ways to reintegrate woody structure, tree reefs, let's call them. You've called them. into marine environments.
00:26:24
Speaker
I was wondering, as you were sharing there, it sounds like we're never going to get the same volume of wood into our marine systems ever again. Like thats that's probably just a thing of the past. But as you were talking, it dawned on me, maybe we can get more quality over quantity. We're not going to get the quantity, but can we through...
00:26:47
Speaker
engineering this, can we get better quality with a fraction of the the volume, get similar results as we had in in days gone by, and also do it in a much more, maybe much more strategic way as well?
00:27:03
Speaker
You've hit the nail on the head. We're never going to be able to mimic the same scale as used to occur with natural processes. There's just too many people, there's too much interest, wind farms, trawlers, dredgers, shipping in the North Sea alone.
00:27:16
Speaker
They don't want logs floating all over all over the place. You would not believe the amount of permitting hassle I've gone through to get these dinky, dinky structures in ah in an area close to ships in the water.
00:27:27
Speaker
If and when we do go wide scale, it's going to be real problematic. But scale is a really important concept in restoring marine ecosystems.
00:27:37
Speaker
Of course, it's a 3D environment, and it is a vast, vast 3D environment. The oyster reefs that used to exist in the North Sea alone covered an area the size of Nevada, give or take.
00:27:50
Speaker
not huge in the grand scheme of things, but when you consider you've got oyster banks 30 by 30 miles and 10 feet tall, how much structure is that for fish that rely on oyster banks?
00:28:03
Speaker
That's crazy. For reference, can you say, like how much do we have now? None. The European oyster is functionally extinct. Really?
00:28:14
Speaker
Wow. That's sobering. Globally, 85% of oyster reefs have been lost. Not to put a downer on things too much, there is quite a lot of effort being put into restoration.
00:28:25
Speaker
But these oyster banks took tens of thousands of years to establish to natural levels, and we wiped them out in about three or four centuries of concerted fishing. and disease as well. The 1950s was the last time we had functional oyster in the North Sea.
00:28:40
Speaker
We could move heaven and earth and move to a so-called wartime economy and still not even come close to 10% of what natural processes could do in terms of restoration. So yeah, we're never going to get back to that system. But what we can do is create functional spawning populations and hopefully over centuries,
00:29:01
Speaker
these oysters we will be able to move out and recolonize the areas that they used to be and provide the ecosystem services, the fish habitat, the actual fisheries that they used to provide. When we think about oyster banks now, we think about the kind of just a pile of shells on the bottom, maybe, what, six inches, maybe a foot tall.
00:29:18
Speaker
Like I said, these ones in the North Sea were 10 feet tall. In the Black Sea, in Southern Europe, they were... 24 feet tall. wow They were a two and a half story building of oyster reefs stretching two dozen miles, 10 miles wide.
00:29:34
Speaker
It's almost unimaginable to think about that in our present day and what used to exist. So let's go back to Japan and a sense of scale. Japan's been building their artificial reefs for fishery yields, not environmental conservation or restoration for 400 years, like I said.
00:29:51
Speaker
And with 400 years of experience building these reefs, they've come to the conclusion that at minimum for positive fisheries yields, you need 300 meter reef. We'll never get to the same scale as natural, but if we can go big enough with, say, these 300 cubic yard installations in multiple places, we'll start to create meta populations, which is basically all populations in an area lumped into one.
00:30:17
Speaker
And so if one gets wiped out by fisheries or disease or whatever, there's other populations to fill in the gap and recolonize that reef that we've built. And of course, wood, it will degrade. That's the point.
00:30:30
Speaker
um It's a natural material, but it's got an advantage over concrete in that it actually provides nutrients to the system. Shipworm is a type of boring bivalve, a muscle basically, that eats wood up.
00:30:43
Speaker
poops out the leftovers, and then other animals like sea cucumbers, for example, will come along, eat shipworm poop, and then the sea cucumber becomes food for a fish, which becomes food for another fish and another fish.
00:30:55
Speaker
So it's not just the structure that was coming out of land that we've lost when we dammed the woodfalls, basically. We've also lost that terrestrial nutrient subsidy to the marine environment.
00:31:06
Speaker
Yeah, you're probably thinking, well, shipworm poop, whatever. That doesn't account for much, does it? One cubic meter of softwood will produce 25 kilos of protein directly via shipworm.
00:31:17
Speaker
That's 55 pounds, give or take. And when you consider that we've lost 5 million cubic yards of large wood annually, wow That's 125 million tons.
00:31:31
Speaker
I think I'd have to correct my math, perhaps. There's a lot of zeros in there. I'm not going i'm not going to try to There's a lot of zeros. it's it It is a hell of a lot of marine proteins that we've deprived from the system, which would have gone into economically useful fish like cod, for example.
00:31:50
Speaker
So long story short, wood good, human bad, put more wood in the sea. So let's let's try to reform some of those those humans into taking concerted, targeted, positive action.
00:32:05
Speaker
so are you public with wanting to start up a business in doing this? Are you willing to discuss that? We are starting our own business to put these tree reefs out. They've been remarkably successful, arguably more so than any other type of artificial reef.
00:32:19
Speaker
They're also unique in that they're the only reef that works with water rather than against it. So maybe you've heard of reef balls. I'm not sure. They're like these hollow spheres, more or less, with holes in them that are made of concrete.
00:32:35
Speaker
Like a half of a ball. Think of a ball cut in half, made out of concrete, with a bunch of holes in it. Yeah, and they can be anything from like a foot wide to 10 feet wide. They're made of concrete. They're extremely heavy, but the way they stay in place is through sheer mass by resisting the water.
00:32:50
Speaker
And like I said with the seawalls earlier, anytime you get a sand concrete interface, the bottom two feet more or less are useless for life because there's so much force of the sand being sandblasted at the concrete.
00:33:03
Speaker
My reefs are extremely light, so to speak. They're about 1,200 kilos because they don't resist water by mass. They resist water by design. They let water through and induce turbulence, so you get calmer water behind them.
00:33:16
Speaker
But because of that, we're able to create this cubic yardage that's required for fish at a much cheaper manner because it's not the structure itself
Creating Complex Structures for Reefs
00:33:27
Speaker
that's key. It's the space within the structure.
00:33:30
Speaker
Like if you had a concrete block, like a solid concrete block that was resting in the water, even if it was 10 feet on either side, a huge block that was dropped in the water, that's providing almost no habitat in it because it's just all of the the surfaces are flat and there's no there's no nooks and crannies. There's no small spots for things to get away.
00:33:51
Speaker
At the most, you have you have a barrier that you're working with that you can that a fish can like swim around. But otherwise... it It's not providing any habitat, whereas if you fill up that space with a whole bunch of trees and a whole bunch of small branches that are intertwined, now you have thousands, if not millions, of little tiny spaces that fish can go and hide, right?
00:34:12
Speaker
Yeah, that's exactly it. And within my field of marine ecology, it's called complexity. What we want is highly complex objects with lots and lots of surface area, but not a terrible amount of volume.
00:34:24
Speaker
Fish need to be able to get in and wrap eggs around branches or metal spindly bits or so on and so forth. If you could just imagine an apartment building with all the windows and doors taken off, all the toxic things taken out, and plop that into the ocean, that would be an incredible artificial reef.
00:34:42
Speaker
Much like it's an incredible habitat for people because there's so much space within it and the shell is just protection from the elements, from the big fish, but the little fish can inhabit the kitchen itself.
00:34:54
Speaker
toilet, the living room, and create their own ecosystem within this highly complex building. This is kind of what I'm aiming at with tree reefs, to create little apartments while still being actually manageable and natural.
00:35:08
Speaker
And over time, tree reefs that you're creating will degrade, right? because Because the wood is going to be eaten, it's going to be consumed, that is going to have beneficial impacts on the environment.
00:35:20
Speaker
Oh, are you ready to get in some real nerdy stuff here? Oh, I got some good stuff for you here. ahll try to keep it at a layman's approach. But so the shipworm, i was mentioning, they eat wood from the inside out.
00:35:34
Speaker
So they'll burrow in as larvae and then they'll consume the inside of the tree. But because they're very fleshy, they excrete a calcium lining in their tunnels to protect their body from splinters.
00:35:45
Speaker
Somehow, shipworm are able to determine where another shipworm tunnel is within the wood, and they will not cross over into the next shipworm tunnel. meaning that you've got tunnels winding every which way within the wood, but if there's not enough wood left to create a new tunnel, they don't go there.
00:36:01
Speaker
So you get these very thin walls within the wood that's consumed, and it turns out shipworm will eat ah about 60% of the wood and stop, because they simply run out of room.
00:36:11
Speaker
And the wood will remain stable until the bark comes off, in which case you get a whole host of other organisms that will start to eat from the outside, ah marine microbes, fungi, bacteria, whatever.
00:36:22
Speaker
They'll soften up the wood, much like in terrestrial systems. And then your boring isopods, many of whom are quite interesting, as a matter of fact. will come in and eat from the outside, expose the shipworm tunnels.
00:36:34
Speaker
The shipworm, who are just chilling, are then able to be eaten by fish so that biomass enters the marine food web until more or less the wood shrinks and disappears.
00:36:45
Speaker
But it depends on species, of course. If you put out a Christmas tree, it's probably gone in two years. It's a very, very soft wood. If you put out something like ah orange osage or pear or some sort of hardwood, it's going to last quite a while. I'm expecting my tree reefs to last, yeah, maybe 15 or 20 years.
00:37:04
Speaker
this This is just an estimate, mind you. But it's it's like a critical mass. If you roll a tiny snowball downhill, it's probably not gonna go anywhere in deep powder. But if you get a big enough snowball, like the size of a head or a torso or something and push that one downhill, it's gonna keep building and going and going.
00:37:20
Speaker
Similar concept applies to reef sizes. I'm looking at my guitar here. If you threw out a guitar, it would make a nice reef for a little while till it degraded. And then there's not enough shellfish to really continue to expand.
00:37:31
Speaker
But if you threw out ah car or a hundred tree reefs or something like that, there's enough of a critical mass of a population that it continued to grow itself. And the the beauty of shellfish is that they produce their own hard substrate with their shells, of course.
00:37:45
Speaker
And so if you have enough shellfish in an area producing enough shells, they are quite literally creating their own hard substrate, which remains at the reef site, which new generations of shellfish can grow on.
00:37:58
Speaker
And so long as it's not disturbed, the reef can expand and maintain itself with zero human cost or effort. That's the goal. We want one or two pushes and then leave it alone.
Protecting Tree Reefs from Damage
00:38:09
Speaker
What's to prevent that tree reef that we worked so hard to establish from then getting trawled or ah for from losing that?
00:38:20
Speaker
Trawlers tend to avoid shipwrecks because it screws up their nets, more or less. ah So out of economic interest, it doesn't pay to trawl over hard substrates in sufficient quantity that it destroys your nets.
00:38:34
Speaker
John, I want to be thoughtful of your time. You are quite a few hours ahead of me, so I know it's getting to be fairly late for you. Is there anything else that you would like to share with listeners as we get towards wrapping up this conversation? Yeah, how long do you have again? i could i could talk for hours and hours here. You really got me going with the the marine windborers.
00:38:55
Speaker
I'd like to throw some some food out for thought. There is an opportunistic species in the deep sea, a type of shipworm, that is able to bore through bark. And if we have multiple different species that evolved to only eat wood in the deep sea, how prevalent do you think this wood has been through millennia?
00:39:17
Speaker
What have we done to the wood cycle to disrupt it? And have we killed off species that we never knew existed? because we've deprived them of habitat? I don't know. We'll never know. But it is possible.
00:39:29
Speaker
Put wood in the water. Wood good, human bad. Cheers. Thanks for leaving us with a positive note there. Well, John, thank you so much for for your time.
00:39:41
Speaker
Yeah, absolutely. My pleasure to come on. And much like with your work with ah Trees for Grazers, economics is driving restoration. It has to. We're capitalistic creatures at heart.
00:39:53
Speaker
And wood is a waste product in a lot of scales in any case. And if we can turn a waste product into something beneficial, we're one step closer to a circular economy. And I really encourage your listeners to think about how waste products can be repurposed into something useful and really recreate the create that circular economy for the betterment of humans and earth.
00:40:14
Speaker
Absolutely. Thank you very much. Cheers. Thank you.
00:40:20
Speaker
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00:40:30
Speaker
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