The Battle Of Coastal Restoration In Louisiana

5:15 minutes

Roseau cane sits in open water in the mouth of the Mississippi River. Credit: Travis Lux/WWNO

state of science iconThis segment is part of The State of Science, a series featuring science stories from public radio stations across the United States. A version of this story originally appeared on WWNO in New Orleans

Louisiana’s coast is disappearing for a few reasons: natural sinking of the land, saltwater intrusion, and sea level rise. Now there’s another threat: a little tiny bug from the other side of the ocean. It’s killing plants and destroying marshes at the mouth of the river, worrying the state and the shipping industry.

Down in the marsh near the mouth of the Mississippi River, Roseau cane is everywhere. It grows tall and bright green, as far as the eye can see. But suddenly, a lot of it is dying. That has state officials worried, so they’re sending biologists like Todd Baker, with Louisiana Department of Wildlife and Fisheries, to check it out.

From the front of a boat, Baker bends over and grabs a long, slender cane. It’s brown and half-dead. He peels it apart to reveal the killer—a tiny little insect.

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“So if you look at your say your fingernail on your pinky,” he says, “The adult version can get almost that big.”

It’s sometimes called a scale, sometimes called mealy bug. But no matter what you call it, Baker says it’s an invasive species—it comes from either China or Japan. He’s not sure how it got here, maybe by boat. Regardless, they’re hungry, and they love Roseau cane.

“It burrows, or puts a little nose, into the cane and withdraws the sap,” says Baker, “and that’s what kills it.”

And when the cane dies, so do its roots.

“It takes a lot to kill it,” he says, “The fact that it’s been dying off this quickly is alarming. I’ve never seen anything like this.”

And when the roots die, the soil loosens and can easily be washed away into the main river channel. Lots of land has been lost already.

“Thousands of acres over a short period of time,” Baker says.

The Army Corps —which dredges the river—and the state found out about the problem about a year ago. From the stern of his huge ship, a pilot looked down at the marsh as he made his way up the river. He noticed that the cane looked a little patchy and reported it.

Captain Michael Miller says it’s “a big big big big issue for Louisiana.” He’s the president of the Associated Branch Pilots —a group that pilots ships on the Mississippi. He worries the dying cane will make the job harder.

Roseau is what holds the river banks together. So if the banks start to disintegrate, that could require more maintenance for the Army Corps.

“It’ll have to be constant dredging to keep that channel open,” says Miller. “Because it’ll be—the sands from the Gulf of Mexico and mud and whatnot will be able to wash back and forth.”

So, what can be done to control it? That’s what Dr. Rodrigo Diaz is trying to figure that out. He’s an entomologist at LSU—he studies insects—and he’s leading the team looking for solutions. He says there are a couple initial ideas, but they all have drawbacks.

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In China, for example, they burn the cane to get rid of the bug. But that’s not an option here—burning a bunch of dead grass next to oil pipelines isn’t a good idea. They could use pesticides, but that might hurt fish and shrimp. Before they propose any kind of solution, Diaz says they just need to know more. They’re not sure, for example, if the insect is entirely to blame.

“Seems to be it’s a combination of stressors that’s actually resulted in the die offs,” says Diaz.

Stressors like saltwater intrusion and erosion. So Diaz and his research team are going to run some experiments to figure that out. He says it’ll be at least six months before they get their first results. If you’re thinking that sounds like a long time for such a fast-moving problem, Diaz says he gets it. But good science takes time.

“We want to do it properly,” he says, “rather than going in and spending millions of dollars to do something that may do more harm, you know?”

Which is why they don’t want to just spray pesticides or burn all the dead cane off right away. In the meantime, though, the bugs aren’t losing their appetite.

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Segment Guests

Travis Lux

Travis Lux is a coastal reporter for WWNO. He’s based in New Orleans, Louisiana.

Segment Transcript

IRA FLATOW: And now it’s time to play and check-in. No, we’re not going to play. We’re going to check in the state of science.

SPEAKER 2: This is KER–


SPEAKER 2: St. Louis public radio–

SPEAKER 3: Iowa public radio news.

IRA FLATOW: This is where we take a look at the science in the states, and this week we’re traveling to the bayou of Louisiana. And as you know, the area is susceptible to hurricanes and erosions, and that’s not good when all that stuff goes away. But the good news is that land loss has slowed in the area in the past few years. But the coastline, on the other hand, still loses about an acre every hour. This is due to climate change, oil drilling, rising sea levels.

And now there is another culprit to add to the lists, something called the mealy bug. Here to tell us about that is Travis Lux, Coastal Reporter out of WWNO in New Orleans. Welcome to Science Friday.

TRAVIS LUX: Hey Ira, how’s it going?

IRA FLATOW: Is this same kind of bug we’re all familiar with, the mealy bug?

TRAVIS LUX: Yeah, we don’t know how it got here, really. We know that it came from China or Japan, probably on a boat. You know, there’s a lot of international shipping that comes up and down the Mississippi River. But it showed up here at the mouth of the river where it spits into the Gulf of Mexico, and it’s got a huge appetite for this plant called the Roseau cane which is basically everywhere in this part of the coast.

IRA FLATOW: Uh, huh, and you talked to state biologist, Todd Baker, I understand, and he described the importance of the Roseau cane plant, and we have a clip from your interview with him.

TODD BAKER: Roseau cane is the dominant vegetation of the Mississippi River Delta. It’s kind of the linchpin that holds these wetlands together. It fights erosion very well, it sustains the wetlands where they are very well. It takes a lot to kill it.

IRA FLATOW: Wow, well, what’s the difficulty in wiping out these bugs?

TRAVIS LUX: Well, it’s tough because it kind of just showed up. So people aren’t super familiar with what to do. And what they do in China is they just burn it and kind of start fresh. But here in South Louisiana, there’s a lot of oil and gas infrastructure in the coastal marshes. There’s a lot of pipelines and that kind of thing so burning it would not be very safe. They’ve thought about pesticides, but there’s also a lot of industrial fishing that happens in these marshes so that could be bad for the shrimp. So they just really don’t know what to do. They’re still trying to figure out what the best option is going to be, frankly.

IRA FLATOW: Now, I know there’s a group that’s looking at interesting ways to restore the coast by dropping mangrove seeds. Are they seeds? Or the little plants from airplanes?

TRAVIS LUX: Yeah, so they’re not technically seeds. They’re basically like little baby plants that are in a little pod. And so yeah, what they’re doing is they’re plucking them from these mangrove trees, and they’re loading them into crop duster airplanes and then flying low over the marsh and just basically carpet bombing the marsh hoping that these mangrove trees are going to take root and basically take the place of the marsh grasses where there’s currently marsh but which is rapidly going away. So they’re hoping these mangrove trees will help create that buffer zone that the marsh used to provide from storm surge and hurricanes, and that kind of thing.

IRA FLATOW: Well, sort of the idea makes sense, but the coast is not made up of mangroves right now. Why do they think it would grow?

TRAVIS LUX: Yeah, well actually this is kind of interesting. Mangroves– these black mangroves– that they’re using, they’re not invasive. They do grow here, but typically throughout history, they kind of wouldn’t last. They can’t really survive hard freezes. But because of climate change, because the environment is getting warmer, it’s getting a little bit more favorable for these mangroves to grow. So they’re thinking like maybe actually because of climate change, this could work.

IRA FLATOW: Yeah, so it has become more like southern Florida where you have the mangroves. They’re growing. Get a little bit warmer, and then they might grow. There is a state official restoration plan from the Coastal Restoration and Protection Agency. Are any of these issues included in that plan? How is the state looking to restore the coast?

TRAVIS LUX: Well, the mangrove seed bombing is not included in the state’s big plan. This is kind of a new one. But the state does have a plan. They have a big master plan for rebuilding the coast. It focuses on really big projects– things like building levees, and rebuilding marshes artificially, and using the muddy Mississippi River water to rebuild some land. But the trouble is that plan is not fully funded yet. It’s going to cost about $50 billion, but we don’t have all the money in the state. Only about $20 billion, rather, has been secured.

IRA FLATOW: Why am I not surprised? Yeah.


IRA FLATOW: All right, thank you, Travis. Travis Lux, Coastal Reporter at WWNO in New Orleans. We’re going to take a break, and when we come back it’s our annual best science books of the year show. We’ll have our favorites, and you can call in with yours. Our number, 844-724-8255. ‘Tis the season for giving, and so we will have science books. And we’re also including– in our upcoming segment– books for kids. 844-724-8255. or, of course, you can tweet us at scifri. We’ll be right back after this break.

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