[lively bright music] - Our conservation effort is all about building sustainable and growing fisheries.

And that starts with healthy, sustainable habitat.

What you're designing is an area where small fish, juvenile fish, can hide from predator fish, and have an opportunity to grow up and spawn.

- [Narrator] It's a muggy, humid summer morning over the Pamlico River.

We're near Bath Creek.

And loaded onto that barge anchored near the middle of the river, are 100 examples of what could be the future of artificial reef construction.

- We will monitor this and see.

We've used a ton of recycled materials.

This is a new product that we have not used in North Carolina yet.

But we are eager to to see how it performs as reef material.

[bright pensive music] - [Narrator] Those cubes are made of concrete, roughly three feet by three feet wide.

They weigh about 2000 pounds.

The rectangular holes are for fish to swim through.

The cubes will be spaced roughly 10 feet apart to create the artificial reef.

But what's really unique about the cubes is how they were made.

The artificial reef cubes were 3D-printed by Raleigh-based Natrx.

This will be the first 3D-printed artificial reef ever built in North Carolina's waters.

[mildly tense music] - Each of these box here is about a two-by-two inch voxl.

Essentially every single box is where we'll have one needle injecting a finite amount of water which will diffuse out and create a ball.

And so every single one of these will create its own little diffused ball of concrete, which will merge together and form a shape.

So you can see the preview of that shape here and all the voids there, which will have fish swimming in or oysters growing.

- A couple main differences from a traditional 3D printer where they're using a wet mix going through a single head.

We use hundreds of injection needles and we're actually printing the water.

So we've got an aqueous solution here and these are running through a series of pumps with controller boards.

And just like an IV pump at the hospital, right, that gives you medicine, we know exactly how much liquid we're injecting at every single position in the printer here.

So as we move along, we'll continue to print layer by layer.

Right now, it's printing the bottom layer.

After that, the head will come up, and it'll look at the instructions from the digital file, and print the next layer.

- [Narrator] Once injected into the dry concrete mix, the water flows and diffuses where it wills.

It forms into a shape about the size of a baseball.

And all those individual shapes combine, and form a three dimensional structure.

- We have control on where to put the hardened structure, and where do we wanna have void space?

So unlike a lot of processes that we've been doing since Roman times, if you mix something, it's gonna fill up the size of the container.

We have the capability to create something more like Swiss cheese, right?

So we can use less material.

We can create all kinds of niches and voids and crannies for fish, or crabs, or other organisms.

- With our technology, we can develop something that looks like it belongs in the water.

And so, it works through reactive diffusion.

So it makes these rounded edges just like nature would.

So it looks very naturalistic.

And the crevices, the bumpiness, all of this makes it more amenable to the aquatic organisms, for them to attach, for them to hide in, for them to forage In.

- [Narrator] The engineers at Natrx say all those uneven surfaces are key.

The reefs mimic nature.

- Nature is irregular, and you have lots of variation in that.

And so, all of that complexity creates biodiversity.

So different types of animals, and they all work symbiotically together in this beautiful way to create the natural systems that we see out there.

- [Narrator] The technology also allows for structures to be customized to where they will be used.

The smaller reefs are designed for shoreline protection to break up waves and stabilize a coastline.

Larger structures are used for artificial reefs.

- We're matching both like the energy environment, what's causing some of the erosion, if we're protecting the shorelines, and then also the ecological environment.

[somber music] - [Narrator] Research clearly shows that if built correctly and in good locations, artificial reefs boost fish and shellfish populations.

The North Carolina Division of Marine Fisheries maintains 43 ocean artificial reefs and 25 estuary reefs.

They're all built using what are called materials of convenience.

- We use a variety of materials really depending on the habitat.

At this reef site, we have some other precast concrete products, things called reef balls, that are basically concrete domes.

We have some recycled culvert pipe, concrete pipe.

At other places, we use aggregate rock like limestone and granite, primarily for oyster habitat, for oysters to grow on and settle on.

And out in the ocean, we use the concrete pipe, as well as cleaned ships and vessels.

- [Narrator] The 3D-printed reefs offer new possibilities.

- So now we've gone from materials of convenience to actually designing structure that creates real habitat for the fish populations that we're trying to conserve and grow.

So we wanna make sure we've got a good, firm base that's gonna stay in place wherever we build the system.

And then, as you said, it's gonna grow.

There's different layers on top of that that are gonna attract the fish and the shellfish that are gonna grow in that area.

- And we can do that 24/7 with a high degree of automation.

The scale of what we do is really important and the speed because of the global challenge with reef systems.

So unfortunately we've lost 50 billion tons of oyster reefs and over a hundred billion tons of coral reefs.

So to sort of restore all that, we need high throughput and highly-tailored structure and substrate that can restore those ecosystems.