Can Spain keep the rising sea from washing away a critical delta?

EBRO DELTA, Spain — Perched on an oyster and mussel farming platform in the middle of Fangar Bay, Vacile Cotirlet works with the assured movements that come with two decades of experience. Cotirlet secures small cylinders covered with oyster spat onto a long rope. He’ll drop several such ropes off the wooden lattices that make up the farm so the spat can grow to marketable size in the bay’s shallow waters.

“There used to be everything here: eels, crabs, sea snails,” he tells Mongabay. “But now there’s none of that.”

The reason for this biodiversity loss in Spain’s Ebro Delta, the third largest in the Mediterranean? Scientists point the finger primarily at climate change and upstream management of the Ebro River.

Last year, water temperatures in the delta reached 87 degrees Fahrenheit, high even for a tropical sea, let alone a temperate one like the Mediterranean. The result was 100% mortality of mussel spat and a loss of 385,000 pounds of ready-for-market mussels, Gerardo Bonet, director of the Federation of Mollusc Producers of the Ebro Delta, tells Mongabay. Mussel growers in the delta had to replace their losses worth hundreds of thousands of euros by buying from growers in Italy and Greece so they had something to sell to their own customers, Bonet says.

Climate change is also affecting another of the delta’s main industries. Rice farms, which produce the area’s most important crop, are being pinched between storms that break the sand barrier protecting low-lying fields from the open sea and a rising saltwater table. “There is a fight between fresh water and saltwater in the rice fields,” Albert Pons, head of the rice sector for the Union of Farmers, tells Mongabay. And the saltwater is winning, putting at risk 22,000 hectares (54,400 acres) of rice cultivation in the area.

The threats facing the rice fields are consequential for the large variety of wildlife, particularly birds, that thrive in the wetlands. The Ebro Delta is an essential breeding, wintering and migration habitat for hundreds of bird species. Approximately 27,000 pairs of waterbirds breed in the area during summer and some 180,000 winter there, according to the nonprofit SEO/BirdLife.

With climate change causing sea levels to rise and an increased frequency and severity of storms, the delta needs sediment to replenish its landmass and maintain wildlife habitat. However, more than 180 dams, built primarily in the 1960s and ’70s, prevent most of the natural flow of sediment from reaching the delta.

“There’s no compensation for the erosion force of the sea,” Antoni Espanya, head of coasts in Tarragona province for Spain’s Ministry of Ecological Transition and the Demographic Challenge, tells Mongabay. The result is a loss of up to 5 meters (16 feet) of shoreline per year in some areas, according to Agustín Sánchez-Arcilla, project coordinator of REST-COAST, an EU-funded project piloting solutions for the restoration of Europe’s coastlines.

While scientists, farmers and conservationists have been raising the alarm about the delta for years, the issue reached the mainstream public consciousness in Spain during Storm Gloria in January 2020. The storm, which brought record wave heights and rainfall to the northeastern coast of Spain, devastated the delta. Flooding reached up to 4 kilometers (2.5 miles) inland, ruining rice crops, and it broke the Trabucador sand band, a critical barrier that required urgent reconstruction afterward. “We’ve never had anything like this before,” Lluís Soler, mayor of the town Deltebre, told the BBC.

The (multi-) million-dollar question now is what to do. The official government plan, launched in 2021 to the tune of 20-30 million euros ($22-33 million), relies heavily on trucking sediment from the lower part of the delta to its exposed outer banks. But moving sand is a “Band-Aid solution,” says Pons, the rice farmer. And, as the government is the first to admit, trucks are a highly carbon-intensive method of transport. It may be publicly acceptable to protect the Delta, a relatively small stretch of coastline, this way, but how do you protect the rest of Spain’s coasts and beyond? The solution then becomes a part of the problem, Sánchez-Arcilla, of REST-COAST, tells Mongabay.

Sediment transport by trucks can only be a temporary measure until more sustainable methods are proven. The REST-COAST team, for example, is trying to reestablish the river as the main transporter of sediment. Removing dams is politically difficult (the river stretches across eight of Spain’s 17 separate autonomous regions), so the researchers are experimenting with ways to move the sediment over the dams and then allow the river to take it the rest of the way. However, in-river tests have been on hold since 2022 due to droughts.

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  Agustin Sánchez-Arcilla, professor at the Polytechnical University of Catalunya and project coordinator of REST-COAST, an EU-funded project piloting solutions for the restoration of Europe’s coastlines in Barcelona, Spain. Image by Nathan Siegel for Mongabay.
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  Albert Pons, a fourth generation rice farmer and head of the rice sector of the Union of Farmers in the Ebro Delta, Spain, poses in his rice fields in the delta. Image by Nathan Siegel for Mongabay.
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  The town of San Carles de la Rapita, on the edge of the Ebro Delta, Spain's largest and most important delta. Image by Nathan Siegel for Mongabay.
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  Juan Ramón Morelló, president of a mollusc producers association in Fangar Bay in the Ebro Delta, motors his boat out to the mollusc farms. Image by Nathan Siegel for Mongabay.
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  Mollusc scaffolding in Fangar Bay in Spain's Ebro Delta, the third largest delta in the Mediterranean. Image by Nathan Siegel for Mongabay.

And there is a boisterous debate on the best way forward. Other potential solutions include removing dams to allow natural river function (despite the obstacles), building sediment bypasses in the dams, growing seagrass meadows to serve as natural breakwaters and reduce the need for sediment replenishment, and buying out land on the coast for surrender to the sea.

The effects of climate change, which not long ago felt distant to people in Europe, have become hard to ignore, with scorching heat waves, fires, floods and droughts peppering the continent. In the Ebro Delta, residents understand things have changed permanently.

“Young people who are inheriting family farms or starting businesses are afraid,” Espanya says. “They don’t know if they will be able to continue doing that job or, more dramatically, continue living in the houses of their ancestors.”

Banner image: Flamingos in Ebro Delta. Image by candi via Flickr (CC BY 2.0).

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