POMPANO BEACH, Fla. — At the back edge of a backyard, in a dead-end South Florida canal, Arthur Tiedeman is drilling holes into the face of a seawall his marine construction company recently installed.

The seawall is a newer design of reinforced concrete encased in vinyl. It’s a smooth, hardened ledge at the intersection of land and sea that’s designed to protect property and make the coastline more habitable for people.

The problem, Tiedeman says, is that it makes the coastline not very habitable to anything else. “It’s not a natural shoreline like mangroves and sand,” he says. “It’s just a straight giant wall.”

That’s why he and his crew are on a bobbing barge outfitted with a crane, installing two first-of-their-kind planters that, when hung, will house two living mangrove trees on the otherwise featureless wall.

The planters are pockmarked and rough-cut; etched and grooved to mimic oyster reefs and mangrove roots. They’re a wildlife-focused add-on — one of the latest products in a fast-growing commercial market that’s selling homeowners and municipalities on a more holistic approach to marine infrastructure.

“Even these tiny little pores you get, those are little pockets that tiny organisms will start to take up residence in,” says Keith Van de Riet, the designer of the new planters.

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“We’re in a time period — a golden era — where humanity has kind of realized what we’ve done here,” Tiedeman says, gesturing up the dredged canal. With the erasure of so much natural habitat, pollution, overfishing and climate change, populations of popular fish like grouper and snapper are declining. Water quality in many canals and bays is worsening.

There’s a growing recognition that municipalities and property owners need to “improve the shoreline and build infrastructure with the environment in mind,” Tiedeman says.

“That’s what makes all these properties worth what they’re worth,” he says, referencing the mansions lining the canal. “The water. And the enjoyment of the water.”

A “forgotten edge” 

The new mangrove planters were designed by Keith Van de Riet, a professor at the University of Kansas, who’s helping with their installation.

An architect by training and an avid angler, Van de Riet has long been interested in finding ways to improve the design of coastal infrastructure so that it benefits more than just people. For more than a decade, his primary focus has been on seawalls, what he calls “a forgotten edge.”

“I’ve always wanted to be near water,” says Keith Van de Riet. “And the idea of creating things that are beneficial for people and other species — I find that appealing.”

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And the reason, he says, is simple: In many places it’s the only shoreline left. “This all would have been meandering mangroves, maybe a mangrove creek here that [people] just blew out,” he says.

By dredging the waterway and barricading its edges, people have taken that soggy horizontal plane — a life-rich intertidal zone that supports oysters, crabs, fish and birds — and collapsed it, he says, “into a vertical wall with a single dimension to it.”

Marine organisms don’t like homogeneity. They like nooks and crannies — places to hide.

“The more texture the better,” Van de Riet says.

For water-filtering oysters, a keystone species in marine habitats, concrete seawalls — the standard in South Florida for more than a century — can provide some of that texture. Van de Riet points to clusters growing on a concrete ledge just below the scumline, just one property down from where his planters are being installed.

It’s a sliver of habitat compared to what they’d have in a natural environment, he says, but a critical one. And it’s now at risk of shrinking further, as many of South Florida’s concrete seawalls, built in the post-World War II boom, are hitting the end of their lifetime — what Tiedeman calls the “seawall pandemic.” Those seawalls, it turns out, are increasingly being replaced with steel or vinyl — smooth, featureless products that offer no welcoming texture for living things.

Arthur Tiedeman measures the distance between scumline and the seawall’s top to determine where to put the planters.

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“We’re taking that last 1% [of habitat] that they’re clinging to and changing the material,” Van de Riet says, “pulling the rug out from under these oysters.”

His hope is that his mangrove planters will help sustain populations of those oysters through the transition.

Mimicking nature

Globally, there’s a lot of innovation happening and new products like Van de Riet’s becoming available, says Rachel Gittman, a coastal ecologist at East Carolina University.

Property owners can now buy artificial reef balls or request vertical oyster gardens. Miami Beach recently installed its first “living seawall,” a wide mangrove root-etched panel, designed to provide habitat and protect against storm surge. In southwest Florida, a similar-style wall panel, created by Van de Riet, has been in the water since 2016.

“There’s a push towards: Can we mimic nature — and can we reproduce it in a way that’s going to support biodiversity or productive fisheries or erosion protection?” Gittman says.

She’s not convinced all of the new products will work. It’s hard to emulate nature.

“But in places where the habitat has already been lost or someone’s just going to put in a regular seawall, I think it’s a better option,” she says. “Even a small little oyster reef can support a lot of organisms.”

The real challenge will be creating enough of them. A study published in 2021 found that only about 15% of the world’s coastal regions remain ecologically intact. Restoring those coastlines, Gittman says, will require significant policy changes from national and local governments.

She adds that in places like South Florida, where coastal infrastructure is being updated to accommodate rising seas and the vast majority of coastline is privately owned, it will take buy-in from homeowners as well.

“We are in this critical period where we could make huge leaps in terms of how our infrastructure is designed in this country if we make thoughtful investments and we don’t just build exactly what we had 50 years ago,” she says. “I hope that’s not what we do. But we don’t always learn from our mistakes.”

When it comes to improving the built environment, Keith Van de Riet says, “We have to look at these hybrid models.” Incorporating parts of nature — like mangrove trees — into infrastructure.

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