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New technologies are refortifying our coastlines against anthropogenic climate change, drawing our water edgelands near and making them tangible and perhaps valuable.

Edgelands, those ignored yet symptomatic hinterland spaces of our increasingly dysfunctional cities, are perhaps as characteristic of the Anthropocene as contaminated rivers and engineered clouds. They are the by-products of a capitalist growth that progressively urbanizes nature. Condemned to a peripheral, liminal, and silent existence on the edges of urban centres, edgelands proliferate and grow: self-storage units mushrooming on the outskirts of cities, suburban landfills where layers of garbage produced by surging urban populations lead a toxic afterlife… While often inspiring disgust and indignation, edgelands are also celebrated in the creative arts as bizarre hybrids and untapped sources of inspiration.

In this piece, I think about the near ocean—shores, beaches, and shallows—as an edgelands of our urban world. These aqueous margins often extend terrestrial modes of existence into the ocean: port infrastructure is situated in and inhabits marine ecologies; concrete breakwaters interact with currents and undermine sand deposits. What are these watery spaces that urbanization and industrialization produced on the edge of the sea? How do we create them and how do we deal with their decay?

Credit: Photograph of concrete and minerals sitting on a table
Photograph of concrete and minerals sitting on a table
A scientific employee of Géocorail shows samples from the company’s test site in Marseille. The three samples of underwater-grown concrete have different colors and textures and contain various types of maritime sediment.

In early 2020, I made an exploratory journey along the southern coast of France and Italy with my partner to conduct preliminary interviews with engineers and residents, and to photograph coastal development projects. It was interrupted by the COVID-19 pandemic, which led to an early shutdown of Genoa’s port facilities and forced us to quarantine in Germany.


When he hands me the specimen, I am strangely mesmerized by it. This eerie skeleton has grown underwater, I think; particle by particle, shell by shell. I turn it around in my hands, feel its heavy weight and coarse surface. The man, a young chemistry PhD student, points out that this sample stems from a test site. Under water, a subtle alchemy transformed a slim piece of rebar within hours into a thick, durable matter with a limestone-like texture. The process would have taken the polyps that build corals in the shallows near coasts years, if not centuries—a blink of an eye compared to the time that it took the sea and tectonic forces to form cliffs from compacted sediment.

On a sunny day in March, I visited the offices of Géocorail, a small start-up located in Marseille-Fos Port, France’s leading seaport. The company was founded in 2012, and its staff of eight work to reinforce sand beds and prevent abrasion to counteract the destruction of port structures, such as breakwaters, docks, or embankments. Géocorail is also the brand name of the patented electrochemical process that the company applies to prevent erosion, originally designed by former employees of Gaz de France. It allows sediment found in seawater to aggregate and form a stone-like, solid mass, or, in more technical terms, a “calcareous mineral agglomerate.” This agglomerate has properties similar to limestone or concrete. Géocorail can thus patch up cracked or fissured underwater foundations of docks or piers.

The in situ “germinative” process uses available nonorganic material, such as sand or shells, and also binds anthropogenic wastes like glass shards. They too are transformed into a durable support compound for rock, harbor, and offshore infrastructure. To kick off this germinative process, engineers submerge metallic cathodes in seawater and send a low current through it. Reverse electrolysis then leads particles to gravitate to the grid and accrete. The company has tried to generate whole breakwaters from scratch using this procedure. Distinguishing themselves from the concrete industry, it calls the product “natural concrete.”

What we witnessed in Nice suggests that migrants have to endure, perhaps hide, in coastal edgelands that, ironically, are a product of the city’s efforts to fortify itself against the sea.

I read Géocorail’s efforts to extend the lifespans of humanmade coastal infrastructures as an expression of what anthropologist Stephanie Wakefield and geographer Bruce Braun (2019, 213) in their work on oystertecture called the practice of “inhabit[ing] capitalist ruins in a more-than-human world.” As they argue, it may not be we humans who stand at the center of these ruins, but rather other species and nonhuman actors. “Natural concrete” is the result of ascribing new meanings to and valorizing nonhumans, such as sediment and seawater. It signals a new imaginary and politics of infrastructure and repairing the coast, moving on from sand. Sand is worldwide the most extracted raw material and is used in the concrete made to fortify coastal structures (see Beiser 2018). The construction industry is widely recognized as an anti-environment industry, one that leaves a massive human footprint on both fertile topsoil and the atmosphere. As Eli Elinoff (2018) noted, cement production now comprises anywhere from 5–10 percent of global carbon emissions. Géocorail questions the long-established human practice of injecting concrete into the ocean to safeguard coastal and land-based infrastructures.

Géocorail is still in an experimental stage, as the material shows different results in different marine settings. It tested Géocorail in the Wallis and Futuna Islands, a small French overseas territory in the South Pacific located close to Tuvalu, the infamously sinking island state. But Géocorail has also found paying clients. On an isolated island in the Pacific Ocean, it helped build an access road for a land reclamation project. These initial insights suggest that new economic ascriptions of nonhuman life travel and connect coasts along long-standing colonial and capitalist routes.

Extraterrestrial domestication

In 2013, in the Italian port city Genoa, Sergio Gamberini, president of a company that designs diving equipment, started exploring the possibility of growing plants underwater. The company has since built subaqueous arks: containers tied to the ocean floor, in which humidity and light conditions can be kept stable. These “water installations” also have a life of their own: in a YouTube video posted by the company they blink like floating airships ascending from the abyss. This is not “an alien base ready to invade us,” the project coordinator Gianni Fontanesi assures the audience, but a garden. In these biospheres, the divers have successfully grown various edible plants. That is why Gamberini cheekily calls the project Nemo’s Garden. The team constantly monitors the quality of air and water inside the tanks, temperature, and humidity. They also remotely watch the development of the underwater crops via a video feed.

Nemo’s Garden is translating known forms of cultivation to a new medium—water—and has produced astonishing findings: the increased pressure of the artificial environment apparently benefits plant growth. Moreover, naturally occurring condensation due to a difference in water and spheric temperatures makes watering the plants virtually unnecessary. While Nemo’s Garden suggests a beautiful new balance between human and nature—akin to the fish farms described by Chang Rae Lee in his dystopian novel On Such A Full Sea—they require intensive and technologically sophisticated design. Tending to plants on the ocean floor demands technologies that inoculate the human against pressure and anaerobic conditions. Extending terrestrial modes of production to the ocean is a risky and expensive undertaking.

Nemo’s Garden emerged from a vast edgelands—the polluted shores of the Mediterranean Sea. Unprecedented amounts of trash are entering the waters of this most polluted ocean in the world, turning up on beaches, and endangering the health of fish. The United Nations Environment Programme estimates that about 0.5 billion litter items are covering the Mediterranean seafloor. Researchers recently “spotted a floating ‘island’ of plastic waste, measuring several dozen miles long in between the French island of Corsica and the Italian island of Elba.”G Nemo’s Garden revalorizes the coastal edge by showing that new and useful life can emerge from it. The project shows us how the coast is imagined as a new type of infrastructure, an undiscovered frontier space in which experiments may unveil mysteries that could revolutionize food production.

What are these watery spaces that urbanization and industrialization produced on the edge of the sea? How do we create them and how do we deal with their decay?

Let me return to the peculiar ontological and infrastructural work of oysters described by Wakefield and Braun (2019). As the mollusk is celebrating a return to New York in environmentalist efforts to protect the bay from future storms and erosion, the organism is enrolled in infrastructural processes and interspecies sociality. It is the peculiar life of oysters, the authors argue, that appears as the perfect antidote to our toxic relationship with the earth. After birth, they show, the oyster is “little more than a tiny mobile blob of larva, nourished only by the nutrients from the egg. Within a few days, it begins to extract calcium carbonate from lime-rich waters and develops organs able to process food, and it begins to grow a thick, hard shell” (ibid., 199). It then attaches to older or dead oysters to form the durable structures that we call reefs, a natural breakwater that shelters countless other maritime species.

In New York, people are intensively gardening these oysters, helping them to thrive. But Wakefield and Braun warn against romanticizing the oyster project: oysters are put to work by humans to safeguard human life on densely urbanized shores. They are the subjects of a kind of offshore biopolitics. Building relationships with mollusks will therefore not disrupt ecological and economic practices that perpetuate suffering and environmental risk elsewhere. Still, they claim, the project significantly changes our relation to life, politics, and time: “Oystertecture is not significant because it enrolls nature as infrastructure, but also because with projects like oystertecture infrastructure gains a new political ontology.” As we extend urban space into the sea, we not only leave traces, but we remodel ecosystems according to these new political ontologies.

Edgelands of a hard coast

As our last stop, my partner and I visited the French city of Nice. The city’s seaside promenade was vibrant with people sitting by the water, sipping cocktails on patios, and strolling by the beach. As we approached the small harbour, I was struck by the sight of tetrapods lying idly outside the harbour. Dumped in front of a line of massive concrete blocks, the tetrapods were supposed to fortify the shoreline––a sort of last line of defense dispersing peak waves and diminishing the erosive force of the ocean. We realized that one could walk on the blocks near the tetrapods, from one end of the improvised seawall to the other. But none of the other pedestrians were using this waterfront trail, probably because it was almost on a level with the choppy and breaking sea. As we leaped from block to block, we suddenly noticed that we were not jumping across voids but peopled shelters—tents tucked into the niches between the hard tetrapods, their fractal shape slightly reminiscent of a choral forest.

Credit: Lukas Ley
Photograph of concrete structures.
Concrete coastal fortification provides unlikely shelter to homeless migrants outside Nice’s harbor.

Millions of African migrants have tried to traverse the Mediterranean since 2014. Almost daily, they come up against the symbolic and material walls of Europe in their efforts to transcend dire economic and social conditions in their home countries. Their exceptional plight doesn’t end with their arrival in Europe. What we witnessed in Nice suggests that migrants have to endure, perhaps hide, in coastal edgelands that, ironically, are a product of the city’s efforts to fortify itself against the sea.

The anthropocenic coastline

Edgelands exist on our cities’ coasts. These watery spaces are often off-limits to humans but not to our technical and ethical imagination. The examples of Géocorail and Nemo’s Garden show how cutting-edge technology is able to repair and revalorize ruins in the near ocean, drawing this environment near and making it tangible and perhaps valuable. Short-term solutions to coastal fortification against anthropogenic climate change, however, also produce hazardous niches—spaces of refuge on the edge of the very ontological order that is responsible for the environmental and social disasters of the Anthropocene. Because coasts can turn into deadly borders; because coasts often display the ecological degradation caused by unregulated urban expansion; and because new coastal infrastructures show the important work of nonhumans in maintaining shores, coastal edgelands require urgent scientific attention. What might we discover as we further investigate such watery fringes between land and sea to shine a light on the social orders and ecological processes that are at their origin?


Lukas Ley

Lukas Ley is a social anthropologist at the Institute of Anthropology, Heidelberg University. His current research is broadly concerned with urban marginalization, temporality, and the material environment within postcolonial urban landscapes. His first monograph, “Building on Borrowed Time,” considers the temporalities of tidal flooding in Semarang, Indonesia, and will appear in fall 2021.

Cite as

Ley, Lukas. 2021. “The Coastal Edge.” Anthropology News website, January 12, 2021.