- Hi there, I'm Frank Graff.

How floodplain restoration builds resiliency during storms and prevents flood damage.

A unique plan to save an endangered salamander.

And how a bacterium could help solve the world's plastic pollution problems.

We're splashing in water resources, next on Sci NC.

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- Sci NC is supported by a generous bequest gift from Dan Carrigan and the Gaia Earth Balance Endowment through the Gaston Community Foundation.

(upbeat music) ♪ - Hi again and welcome to Sci NC.

Weather data shows our changing climate is changing weather patterns, especially rainfall.

Long periods of dry weather are broken up by short torrential rains.

The runoff creates erosion problems, the flooding damages property.

Producer Michelle Lotker explains how floodplain restoration is helping nature and property owners deal with the new rainfall reality.

- During the flood that we experienced in Helene, the water was 12 to 15 feet above our heads right here, which was much higher than we had ever observed before or would have expected.

Conserving Carolina, the land conservancy in this region owns three projects and those three properties together held an estimated 1.25 billion gallons of water during the peak of the Helene floods.

While the rest of the water in the river moved down valley, that water was retained here.

That type of feature along this valley is really important as we look to the future and the potential for more floods like that to protect property, prevent downstream flooding, protect infrastructure and human lives.

- Conserving Carolina is a regional land trust based in Henderson County, which is in the mountains of Western North Carolina.

- We're at Pleasant Grove, which is a restoration site along the French Broad River in Etowah in Henderson County.

And it is one of a chain of restoration sites that Conserving Carolina has been working on throughout the French Broad River corridor.

Places like this can give us a more resilient landscape that is better able to handle the blows of a changing climate.

They protect our communities during flood events by giving the water a place to go that isn't destructive.

A place where it can spill over and it's meant to spill over and these floodplains hold really huge amounts of water.

- And then we also do a lot of creation of wetlands and excavating floodplain pools in order to store water in those drier dries that we expect to see.

- If you're not sending all of the water straight into the river channel and just like telling it goodbye, you know, down river, then it stays here.

It stays here for a while.

Historically in the last couple of hundred years, we really changed the way the river works.

- The history of the French Broad River is similar to many rivers in the Eastern United States in that they were dredged out and straightened to some extent to allow for boat traffic.

- People moved water off of the land with ditches.

They built berms along the side of the river.

The whole idea was to have like the land be the land and the water be the water.

And the river is just gonna run in this channel.

And if that's all you're used to, then maybe that's what you think like a river is.

It's like, it's just a line, a line of water that moves through the landscape.

But really it would be like a broader corridor of wet land.

- Our ultimate goal is to restore that hydrology and keep as much water on the floodplain as possible.

- The type of engineering that we do here is focused on the natural environment.

This entire property was a golf course until 10 years ago.

- This beautiful creek used to be a deep ditch.

You know, it wasn't picturesque and it wasn't that great for wildlife and it also caused a lot of erosion.

So there was a restoration to bring the creek back to a healthy natural state.

- We have a whole series of wetland cells that are throughout the property.

This whole eight acres of wetland developed by plugging a ditch up.

- There were already on this site two ponds.

So one of those ponds is still there as a pond.

And the other pond, we dug a channel connecting the pond to the river and that creates a backwater slough.

Sloughs would have once been common along the French Broad and were largely eliminated from the upper French Broad River corridor.

To the extent that it's not really even a word that people are that familiar with.

So slough is a word that we have to kind of introduce people to S-L-O-U-G-H.

So if you see the word written out, now you know how to say it.

- We have seven acres of water that is still water but it's connected to the river so the fish can easily come in and out and they have lots of room up here.

And the muskie in particular being such a large fish.

- Muskie are a big toothy fish.

They're an apex predator that is native to the French Broad River.

They get well over 35 inches and we've caught them up close to 50 inches.

- The population declined to the point that in 1970, the Wildlife Commission started stocking muskie.

- Muskie have really specific spawning requirements.

Their eggs aren't sticky like some other species.

So when they spawn, they kind of just lay on the bottom.

So these slack water areas are important.

- It allows them to get off of the conveyor belt to a less stressful environment to spawn and go through the egg development in early life stages.

- All of the muskie that we've stocked from 2018 through 2022 all were implanted with a little pit tag, which is very similar to what you would put in like your pet.

The tag is like their social security number.

When the fish swims across the antenna, the antenna talks to a little copper coil that's inside this glass tag.

So we know who they are, when we tagged them, where they came from.

- Just in this slough at Pleasant Grove, we've detected 29 muskie.

The detection equipment's been active since May, 2023.

And so that's a little less than a year and a half.

That's actually quite a lot.

So we're pretty excited about that.

- We're all part of nature.

So like what's good for nature is also good for human beings to flourish.

- At our Dodd Meadows restoration site, we restored about 1500 linear feet of stream.

And we had the opportunity to also install a multi-use walking path adjacent to that stream.

That's really important because right next to the site is a pretty large Habitat for Humanity community with a lot of residents.

- Before Conserving Carolinas came in, that was not somewhere you wanted to go.

It was a straight line.

It was deep.

Debris would go down in there.

It was full of lots of trees and trash.

It was just not a place to go.

Not a place to go walk, not a place for children.

It was really beyond our expectation, what we wound up with.

We have families that go down and walk on the trail.

Children play in the creek.

The mental health of children when they have green spaces is 55 to 60% better as adults.

So it's really a great surrounding of the community.

- Seeing that the power of nature just doing what it does best is really inspiring to me to know that we can go in and make some of these minor changes to the land and then see it become its fullest is just super exciting.

- In the last five years, we've had a really strong focus on restoration projects.

So within that period of time, we completed the Mouth of Mud Creek restoration, which was the first large scale natural flood plain restoration in the mountains in North Carolina.

It was kind of a new thing that we tried and we've seen like really good results on all kinds of levels.

And what we've seen too is just so much interest.

As soon as people could see, oh, Riverside property could be like this.

There were a lot of people that were like, my property also has this potential.

- I think part of the reason that that's true is because there are so many benefits to these projects.

- Once you start to have like this growing network of natural floodplain areas along the river corridor, you can really imagine the river being, you know, quite different in the future and in a way that is better.

And I think that's really valuable because I think a lot of times when we look to the future, we have so many things to worry about.

We have so many things that are not going well, right?

But you can also look toward things that are going well, that are getting better, that are hopeful.

And the more we do of that, the better world we will live in and the better world that we'll pass on to our children and grandchildren.

I think you really can imagine a French Broad River corridor where restoration is widespread and these kind of habitat areas are common along the river.

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The Eastern Hellbender Salamander is iconic to North Carolina, but pollution, sedimentation, and a shrinking habitat threaten the species, which is why the program in this next story offers hope for saving the Hellbender.

Hurricane Helene hit the area a few months after we shot this story, and scientists are struggling now to find out just how many Hellbenders survive the storm.

But they hope to resume this program with the Hellbenders that remain.

It's all about the water, above it and below it.

- So removing this dam allows this pristine water from the headwaters to keep flushing the needed nutrients and cold, clean, oxygenated water downstream.

- Dams are kind of like clogs in your artery.

You don't want that kind of blockage.

And so when you can let the river be a river again and be free flowing, have room to move, that's really helpful.

- Removing abandoned dams like the Scholl's Mill Dam just outside of Boone brings new life to rivers.

This is the Watauga River.

Once the dam is gone, water and nutrients will be free flowing, habitats opened up.

But there's a challenge.

You're looking at the Eastern Hellbender Salamander.

It's the largest aquatic salamander species found in North America.

About 29 inches long, four to five pounds.

- We care about Hellbenders because we care about the health of the river.

Everything is interconnected.

- Eastern Hellbender Salamanders live in the underwater caves created by boulders just below the dam.

Taking down the dam will send a mountain of sediment into the pool.

That will bury prey, fertilized eggs, and hiding places for juveniles.

It will essentially wipe out the salamanders.

Which is why, days before the dam deconstruction started, scientists were searching the pool at the base of the dam for salamanders.

This Salamander rescue operation will move the Hellbenders a few miles downstream.

- We relocated the Hellbenders to suitable habitat downstream to avoid any impacts from the dam removal.

So the process is monitoring and relocation of the Hellbenders to fresh habitat.

Then comes the dam removal.

Hey, sweet thing.

- Eight Hellbender Salamanders were caught, weighed, measured, tagged.

- So I'm gonna go in, back out, insert, pull it out.

So we go right here.

Sorry, buddy.

Sorry, buddy.

In, out, insert.

That's it.

- And then relocated.

The move also allowed researchers to test a new relocation plan.

- To my knowledge, Hellbender relocation has never been done in this way before.

We collected eight adult individuals and moved them to another site.

And they actually were able to hang out and habituate into crayfish traps for a little while.

And when we released them, they were wriggling and raring to go.

- That small adjustment dramatically increases the survival rates for relocation.

- When Hellbender populations are doing well, we know that the river is doing well.

So we're really excited to be able to keep an eye on these Hellbender species for years to come to just really see how the Watauga River comes back to life after these two dam removal projects.

- Now for the dam.

Think deconstructing Lego blocks.

The Shulls Mill Dam was built in the late 1800s.

It's an obstruction, but it's not watertight.

Flooding in the 1940s punched a hole in the dam and it was abandoned.

Environmental groups orchestrated its removal.

- Vital to remove the Shulls Mill Dam to reconnect the aquatic habitat, right?

So the headwaters, kind of the cradle of stream health, right?

Clean, clear water coming down from the source, flows down through the forested protected slopes of Grandfather Mountain.

While this barrier was here, limited connectivity upstream, right?

So fish passage, passage for the Hellbender Salamander mussels, and also provides an impairment for stream health.

Things like collecting sediment, slowing down the water, warming it up, lowering dissolved oxygen.

- And one of the main things that we're trying to do is recreate the passage that existed before the dam was in place.

And so by removing that, the concrete and that barrier, that lets things move back and forth up the stream channel.

- And so the best thing when you have these kinds of structures that are serving no purpose is to get them off the landscape.

It helps to support biodiversity, in this case, Hellbenders.

It helps public safety to get rid of an attractive nuisance.

And then it's also just really good for climate change adaptation and mitigation.

So what we're seeing in climate change is that we know that we're having more extreme droughts.

We're also seeing more extreme floods.

Rivers need room to move.

We're also seeing temperatures rising.

So we have species like Hellbenders here that need clean, cool water.

And so when you remove a dam, you allow them to move in the river system.

- Hellbenders used to be found in rivers across 15 states in the Eastern part of the US, but almost 80% of the population has been lost because many rivers are filled with sediment from farms and development.

Hydropower dams stopped free-flowing rivers and cut off Hellbender populations.

But Western North Carolina is one of the few places in the country with relatively stable Hellbender populations.

In addition to removing the dam, the river's banks will be restored and replanted with native species.

78 miles of the Watauga River will be free-flowing once again.

- And so when we have Hellbender populations doing really well, that tells us a lot of things about the river.

It means it's clean and it's cold.

We're really excited to be able to keep an eye on these Hellbender species for years to come to just really see how the Watauga River comes back to life.

- You can watch more Sci NC episodes anytime on our website or through the PBS streaming app.

- Plastic pollution has become one of the most pressing environmental problems.

Plastic just doesn't truly go away.

It breaks down into microplastics, which pollute the environment and harms animals, marine life, and people.

But as producer Evan Howell shows us, microscopic bacteria might be a solution to the massive plastic problem.

- The Pacific garbage patch, the collective name of a swirl of floating plastic trash that drifts in the middle of the Pacific Ocean.

The floating island of junk is now twice the size of Texas.

And it's mostly a mass of plastic, plastic bottles, wrappers, containers, and fishing nets.

And even tiny pieces of plastic called microplastics.

You name it, if it's made of plastic, it's probably in there.

Nature can't break any of it down, but only make it smaller.

That's where microplastics are created.

And all of it, large and small, is lethal to fish, wildlife, and people.

Most materials that you find in nature, nature's had millions of years to figure out how to break down.

Plastic's only been around for 100 years at most.

- Much of this garbage is made up by a type of plastic called PET, or polyethylene terephthalate, that you might find in things like water bottles and other packaging.

But what if we found something in nature that could actually eat some of it?

- And in our lab, we've taught this microbe that couldn't eat plastic how to eat plastic.

(upbeat music) - Mark and colleagues at NC State are using an enzyme found in Japan where in 2016, researchers announced they had found some bacteria years before that was slowly eating away at plastic bottles in Osaka at a recycling facility.

And they've been trying to make the process go faster.

Experiments around the world had worked somewhat in the lab, but one challenge was getting it to work well in salt water.

Well, these scientists think they may have come up with a way to do that.

Well, what is this new way?

It might help to look at the bacteria that produces this special enzyme microscopically.

- What you're seeing are actual images of Adenylla sacchiensis.

This is the microbe that was discovered by researchers in Japan.

This is the cell body of the microbe, and it's actually adhering to the surface of a plastic.

The plastic's on the bottom there.

And what's interesting about this plastic is that if you take the bacteria away, it looks pitted.

There's holes in that plastic where that microbe has eaten it away.

(upbeat music) - Crook and Tianyu Li are hacking this Japanese plastic-eating enzyme, putting it into a bacteria called Vibrio natrogens, which is a super fast-growing bacteria that thrives in salty environments like the ocean.

- This strain is actually the fastest-growing microbe that we know of.

- When they inject their hacked enzyme into the super bacteria, flagella at its tail helps it swim toward the plastic molecules using enzymes they say are displayed on top, which are ready for eating.

They call what's going on here hitchhiking.

For the experiment, they first grow their bacteria in some nutrients.

And once that's done, they add a sample of their PET plastic and it ends up looking a bit like, well, cooking broth.

So you're starting, you've prepped everything.

What are the next steps at this point?

- So next step, we'll mix in the PET microplastics into the cell culture.

- So wait, hold that up a little bit.

Looks kind of like goo.

What actually is ultimately in there now?

- That's a really great question.

So inside of the shake flask, it is a vibrio-natriegen bacteria cell, which has been engineered to displaying relevant enzyme can depolymerize.

- So an enzyme that can depolymerize or break down that plastic.

So PET like water bottles and whatnot.

- Polyester clothes, fibers.

- Okay, so we've got our goo.

Where are we taking it now?

- So what are we gonna do next?

We'll be putting the shaking flask, holding the reaction into the shaking incubator to make the reaction happening at a stable temperature and a shaking speed.

- Okay, let's go ahead.

- So what are we gonna do is open the shaking incubator door and put it into the rack.

- Li says it'll take several days for the shaking incubator to drive the reaction before the modified bacteria degrades the PET.

Once it's finished, it only takes about 20 minutes to verify the reactions have worked.

The sample is typically around 10 microliters, which is certainly not a huge amount, but that's why the research is so important since it may have big potential in getting rid of PET, which makes up about 12% of all plastic around the world.

But this all begs the question of, after the enzyme has degraded the plastic, what's left?

- It's broken down into two particular molecules.

One's called ethylene glycol and one is terephthalic acid.

Luckily, both of those molecules, nature knows how to break down.

So we can then take those molecules and use them to feed microbes, potentially using those as feedstocks, either for new plastics or for producing fertilizer, for example, or biofuels or biodegradable plastics.

- So the result is the bacteria keeps growing as long as the plastic foodstock lasts.

It's almost a closed loop process.

Brooks says that one day he hopes one could throw a simple packet of the solution into a vat with unwanted PET plastic and get rid of it.

But he cautions they're still well in the research phase.

And while their process breaks down PET, there are lots of different types of plastic.

And each one of those will need a different biological strategy to get the job done.

- All of these plastics are chemically different.

And so they require different enzymes to break them down.

That's why there's actually a large global community of researchers trying to make enzymes and microbes that can break down all the different types of plastic that are an issue in the environment.

- Follow us on Instagram for beautiful images of North Carolina and cool science facts.

- Well, you could think of it as kind of a robot dog, but this next story blends software development, hardware engineering, and a reimagining of assistive technology.

It's also a sign of what happens when you have a chance encounter with a robot in a lab at UNC Chapel Hill.

(upbeat music) - Like anything, you have a learning curve.

With welding, you can learn the basics that you practice to actually get even better at it.

For some of my welds, some of them are pretty good.

There's others where it's completely burnt and the aluminum is melted.

And you're like, yeah, that's a really bad weld.

I'm Lilly Nekervis, and I am a fourth year student at the School of Information and Library Sciences.

Spot is a software controlled robot, and it has dog-like traits or animalistic traits.

So it is a zoomorphic robot.

It has four motors on it, and using software, we're able to individually control all of these different motors.

I came up with the idea to modify Spot to be a seeing eye dog when I was watching it move around.

We were all kind of joking and being like, oh, come here, Spot.

And I was like, oh, well, it is very dog-like.

What if we use it for some sort of guiding capacity?

And then it clicked.

And I was like, well, why can't we do this for people who have visual impairments, where they can be led by Spot?

The current modifications that we have on it is a digital camera system to detect environment.

We also have a Nvidia Jetson, which is like a supercomputer.

Also a speaker and microphone system for users to take and receive commands.

And then on top of that, we also have a lot of software development.

The first steps were mainly coding and understanding of the obstructions.

It took a lot of detection and understanding for the robot to make sure that when it's maneuvering, it has a person next to it.

So how do we move with a person?

We built this harness in the machine shop and we use the lathe, drill press, and we also welded most of the pieces together.

When running the experiment, the person would have a QR code marker on the side of the leg, so that the robot can keep track of the person's position.

Once that straps the leg and once the person has the harness, the robot is ready to go.

The speaker microphone system would allow the user to talk to Spot and also for Spot to interpret the surrounding environments.

It recognizes there are obstacles or people.

It would be like, "Hey, there are people."

In turn, the user can talk to Spot and be like, "Hey Spot, can you do this?"

This research is important because it allows for the moving forward of accessible technologies.

I love working with the robots.

I've had to learn so much for this project.

Everything from software to hardware to working in the machine shop, it's most exciting just to learn and see and do things.

- And just a bit of advice, do not try to feed treats to Spot the robot dog.

That's it for Sci NC for this week.

If you want more Sci NC, be sure to follow us online.

I'm Frank Graff.

Thank you for watching.

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- Quality public television is made possible through the financial contributions of viewers like you who invite you to join them in supporting PBSNC.