A human-made nature reserve. That may sound like an oxymoron, but in the Netherlands, the artificial island chain known as Marker Wadden has been touted as just that. But can people actually build effective—and lasting—solutions for Mother Nature? Journalist Elizabeth Claire Alberts investigates.
I am meandering around curving wetlands sprawled across a septet of islands. The wind blows hard, but a babel of birds dominates the soundscape: Screaming gulls, whistling plovers and deep-bass-thumping bitterns. A tern hovers over the water like an arabesque dancer before diving to snap up a small fish. Reedlings—tiny, egg-shaped birds—cling to the stalks of swaying marsh reeds. Blue-gray water ripples with avocets, long-tailed ducks, and even a couple of flamingos.
The islands thrum with life. It’s hard to believe that none of this was here seven years ago. There were no birds. No wetlands. No islands. Instead, there was only the open water of the Markermeer, a human-made lake in the center of the Netherlands, just west of Amsterdam.
But in 2016, dredgers started scooping mud and sand from the bottom of the lake to construct an entirely artificial 1,300-hectare archipelago. It was named the Marker Wadden.
The aim of the islands was to create a kind of paradise for nature and nature lovers alike. It was also meant to mitigate some of the ecological damage previously caused by the building of dikes that cut off the Markermeer from the North Sea, turning what was once an inland sea into a silty, nutrient-poor freshwater lake. Experts speculated that the islands would help clarify the water by trapping sediment on its shorelines, although this has yet to be proven.
Marker Wadden quickly attracted a notable amount of biodiversity—a feat that surprised many. They’ve also become a unique sailing destination on the Markermeer, giving visitors a sense of traveling to a strange, quasi-real place far removed from the minutiae of everyday life, only about an hour from the mainland.
But the islands have also raised questions about their longevity and upkeep. Some say that without intervention, Marker Wadden will disappear—slowly, or even swiftly—sinking back into the muddy lake.
The idea of manufactured islands may conjure images of Dubai’s palm-shaped archipelago or the chain of artificial islands in Miami’s Biscayne Bay. These two projects focused on real estate development and caused significant environmental damage. Other projects, such as the restoration of Poplar Island in the Chesapeake Bay in the United States, have tried to restore wetland habitat for wildlife while providing a site for dredged sediment.
The Marker Wadden project—which is one of the largest in history in Western Europe—bears the closest resemblance to Poplar Island since both used dredged material to create new bird habitat. At the same time, Marker Wadden is entirely different. It’s an artificial archipelago built with artificial means on an artificial lake—but meant to perform a natural function.
The term “restoration” is often applied to the Marker Wadden. But this term doesn’t entirely fit the situation, says Ben Abbott, an ecosystem ecologist at Brigham Young University in Utah, who was not involved with Marker Wadden. He thinks it’s better to call it a “mitigation project.”
“In five or six years, it’s in the water. I warned them in 2013… but they didn’t want to listen.”
- Bart Schultz, retired engineer
“A restoration project is where you’re trying to go back to something that nature was before human disturbance,” Abbott explains. “A mitigation process project is where you’ve recognized that that’s not possible for some reason, and so you’re trying to create something new that mitigates the damage from that loss of natural habitat. Those types of projects are fundamentally different in their objectives.”
Sacha de Rijk, a freshwater ecology and water quality expert at the research institute Deltares in the Netherlands, has been researching the Marker Wadden project since 2018. She refers to the islands as a “creation of nature.”
While the idea of creating nature might seem strange, De Rijk points out that most nature in the Netherlands is, in fact, “constructed.” She’s referring to the dikes, dams, canals, and large-scale beach replenishments the country has implemented to reshape waterways and reclaim land.
“We are a very artificial country in that respect,” De Rijk says.
It’s a clear but chilly spring morning when I meet Roel Posthoorn, the willowy, softly-spoken 63-year-old creator of Marker Wadden. For the past 20 years, he’s lived in Lelystad, a Dutch town built on land once at the bottom of the sea. Following construction, this land is called a “polder.” Lelystad, which is four meters below sea level, would be underwater without the dike that separates the Markermeer from its adjoining lake to the north, the IJsselmeer, as well as the dike that separates the IJsselmeer from the North Sea.
A ferry takes visitors across to the islands, but I’m traveling with Posthoorn on the island’s work boat, along with Posthoorn’s son and his son’s friend, who traveled from Utrecht to visit Marker Wadden for the day. Out on the water, we pass sailboats, gulls and geese. It’s easy to believe we’re on the ocean, except there’s no scent of the sea. And on the horizon, I see the Houtribdijk, the dike that separates the Markermeer from the IJsselmeer, and a line of wind turbines, reminding me of our proximity to land.
The sandy curves of Marker Wadden loom into view. Posthoorn smiles. “That’s one of the nice things,” he says. “You can’t see it from the mainland. It’s a bit of a secret.”
He drives the boat past the two newest islands in the archipelago, one of which still needs to be finished. Already, there are signs of life. A colony of sand martins has poked holes in a mound of leftover sand. Freshly formed mudflats are dotted with the bright yellow flowers of marsh ragwort, a pioneer plant that takes root in new habitats.
Before the Marker Wadden project, there’d been much discussion about what to do with the Markermeer. The original plan had been to reclaim it to make another polder, but this idea was scrapped in the 1980s.
Posthoorn, who has worked on restoration projects as a project director at Natuurmonumenten, the Netherlands’ largest private nature conservation and management organization, created a proposal for the Marker Wadden. The first funding he received was 15 million euros from the National Postcode Lottery in the Netherlands. An additional 75 million euros came from Natuurmonumenten, Rijkswaterstaat (a government agency in the Netherlands responsible for water and infrastructure management, where Posthoorn previously worked for 10 years), and other partners.
The original plan was to build 6,000 to 10,000 hectares of manufactured islands across the Markermeer. However, this was pared down to a single archipelago of seven islands, only one open to the public. However, Posthoorn tells me his long-term vision is to build three more groups of islands if he can raise funds.
In 2016, dredging and infrastructure company Boskalis began building the islands. Constructors formed sand walls, then filled them with a muddy mixture. Some parts of the islands also used stone to protect the archipelago from wind and waves. By 2018, Marker Wadden started welcoming visitors, even though the first island wasn’t fully completed until 2020.
There were many challenges along the way. During the construction process, the land started sinking due to silt consolidation, a process called subsidence. Nearly two meters of subsidence occurred within two years, although it slowed down after two and a half years, according to a Deltares report.
“If I were to make a prediction about where this may go, I think there is a high likelihood that through time the project is not self-sustaining and that it requires perpetual, large-scale human intervention.”
- Ben Abbott, ecosystem ecologist
Bart Schultz, a now-retired civil engineer who worked on land reclamation projects near Lelystad for over 20 years, but is not connected to Marker Wadden, says he believes subsidence will continue—and fast—raising a question about the archipelago’s efficacy. “In five or six years, it’s in the water,” he says. “I warned them in 2013… but they didn’t want to listen.”
Thomas Vijverberg of Boskalis, the engineering manager for the Marker Wadden project, counters this view. He says the islands were carefully designed to account for settling and consolidating sediment. He insists that the islands will not, in fact, disappear.
Another issue is erosion. Anne Ton, a coastal engineer from the Delft University of Technology, says that some of the islands’ beaches are eroding faster than expected due to a combination of waves and currents, and will likely need replenishment. On other parts of the islands, sand is gathering to form spits.
“These beaches are behaving completely different than what we would have expected beforehand,” says Ton. “That keeps surprising me.”
After Posthoorn docks the boat, I step onto a sandy land blooming in yellow, gold, green, umber maroon and white. Posthoorn tells me that the team only did a little planting: Some marram grass on the dunes near the marina and some reeds along the mudflats. Everything else came on its own. There are now over 127 known plant species on the Marker Wadden, including watermilfoil and red goosefoot.
Mennobart van Eerden, who worked as an ecological advisor for Rijswaterstaat for more than 40 years, says that birds, fish, and the wind would have carried seeds to the islands from nearby locations, allowing a diversity of plants to sprout. For example, he says seeds for some of the marsh reeds likely came from Oostvaardersplassen, a 7,500-hectare nature reserve and wetland across the water from Marker Wadden. Both Marker Wadden and Oostvaardersplassen are part of the Nieuw Land National Park, which, as its name suggests, are human-made nature preserves.
The birds came as quickly as the plants. Jan van der Winden, a freelance ornithologist affiliated with the Lowland Ecology Network, says birds started habituating the island even during construction. For instance, he says 1,700 breeding pairs of common terns, classified as an endangered bird in the Netherlands, started nesting on the islands in 2017.
Other birds rarely seen in the Netherlands, including the long-tailed duck, gull-billed tern, little gull, and bearded reedlings, have also come to the islands. There’s an array of insects to accompany them. Spiders, beetles, midges, cicadas, butterflies. A rare moss bumblebee mysteriously appeared, perhaps after a strong, westerly wind carried it over, says bee expert Arjan van der Veen.
Along with the plants and wildlife, the islands attract a steady stream of visitors who come to enjoy the 12 kilometers of walking trails and sandy beaches. Some take the ferry to visit for the day; others sail here on private boats and stay for a few days. There are three off-grid holiday cabins for rent, a cafe, a gift shop, an information center and a research lab. Most facilities, including the cafe, are run by a network of about 250 volunteers.
My visit falls on a holiday weekend in the Netherlands, and the island is packed. Every berth in the marina is full, but boats keep sailing in to look for a spot. As Posthoorn gives me a tour of the island, there are times when it feels like we are entirely alone in some far-off wilderness. Other times, there are mini-traffic jams as bird watchers jostle for right-of-way across the wooden boardwalks and vie for the best positions on one of the island’s bird hides.
I look across the trail and see a closed sign where the path is now blocked off after black-headed gulls and common terns started nesting there. “We had some conversation with the birds, and at the end of the day, we decided that we lost,” Posthoorn says with a grin. “So we closed the footpath.”
Later, when the day tourists depart the island, the beach is still busy with children building sandcastles, tossing balls and flying kites. A man swims in the shallows, braving the chilly water. There’s a yoga class taking place in the shade of a dune.
Posthoorn says visitors would likely have some impact on the islands’ nature, which is why only one of the seven islands are accessible to the public. However, he says visitors also help pay for about 60-70 percent of the maintenance of Marker Wadden. It currently costs EUR25.50 to take the ferry over to Marker Wadden for the day, or EUR9.95 to visit on your own boat. Renting one of the island’s cabins for a few days costs anywhere from about EUR450-1,500.
It’s easy to fall under the spell of Marker Wadden’s charms, but protecting the islands against subsidence and erosion will be expensive. Posthoorn explains that it will be Boskalis’ responsibility to take care of any maintenance until the end of 2030. But the project currently lacks funding for further maintenance in the future.
Lorie Staver, a plant ecologist at the University of Maryland, points out that the Poplar Island project in the Chesapeake Bay was allocated $1.4 billion over a 45-year-period to fund dredged material placement, habitat restoration, monitoring, and maintenance, such as invasive species control—and that the project may accrue further expenses after the mid-2040s. “That’s a big investment,” she says. “You’re going to great effort to create these marshes [but] are they going to be there in 50 years?”
Abbott, who was highly critical of a proposal to build artificial islands on Utah Lake in the US, calls the Marker Wadden project “valuable and interesting” in its attempts to restore ecological value to the Markermeer. However, he points out that most mitigation projects have been largely experimental, and many are unsuccessful. “Let’s hope that this project is different,” he says of the Marker Wadden. “But if I were to make a prediction about where this may go, I think there is a high likelihood that through time the project is not self-sustaining and that it requires perpetual, large-scale human intervention to maintain what is ultimately relatively limited ecological benefit.”
There is also an unanswered question of whether the Marker Wadden is fulfilling its original aim to improve the lake’s water quality. De Rijk of Deltares says researchers currently lack evidence that islands have helped improve the water but that it “doesn’t mean the goal is not met.”
Wil Lases, a hydraulic engineer and water management expert who was not connected to the project, has a different view of Marker Wadden: he argues that it actually disturbed the natural development of the Markermeer, which he says was “very alive” with bacterial activity, generating a different type of biodiversity. “They claim repair of nature, but they don’t,” Lases says. “It is a misleading sales argument.”
Yet Van Eerden says he believes the islands “provided safety” to nature and placed “natural values at the right level,” particularly when it comes to bird life, which has been ailing not only in the Netherlands but across Europe. “It’s fascinating that if you add a certain function to an area by making this archipelago, you facilitate a whole world,” he says. “The combination of breeding habitat and food makes it all happen.”
Posthoorn says the Marker Wadden project should never be an excuse to “mess things up because you can improve it afterward,” and that conservation is “always preferable.” However, he says a concept like Marker Wadden can help when damage has already been done to a natural environment. “For a long time, I thought this [damage] was only a Dutch issue because a large part of the Netherlands is manmade,” says Posthoorn. “But if you travel a little bit around the world, you see that every coastal area is heavily developed.”
“As human beings, we have a lot of creativity in destroying things,” he adds, “but we can use the same creativity to improve it.”
Elizabeth Claire Alberts is an American-born journalist who lived in Australia for more than a decade before landing in Belgium. She is a senior staff writer at Mongabay, where she writes about all things related to the ocean. Her words have also appeared in The Guardian, Earth Island Journal, Sierra, Alternatives Journal, The Dodo, and many other publications.
