Clean Up City of St. Augustine, Florida: This lagoon is effectively a person, says Spanish law that’s attempting to save it. (SCIENCE Magazine)

Only a few years ago, the clear, shallow waters of Mar Menor, a saltwater lagoon off eastern Spain that is Europe’s largest, hosted a robust population of the highly endangered fan mussel, a meter-long bivalve. But in 2016, a massive algal bloom, fueled by fertilizer washing off farm fields, sucked up the lagoon’s oxygen and killed 98% of the bivalves, along with seahorses, crabs, and other marine life.

The suffocating blooms struck again and again, and millions of dead fish washed onto shore. By last year, local residents—some of whom benefit from tourism to the lagoon—had had enough. Led by a philosophy professor, activists launched a petition to adopt a new and radical legal strategy: granting the 135-square-kilometer lagoon the rights of personhood. Nearly 640,000 Spanish citizens signed it, and on 21 September, Spain’s Senate approved a bill enshrining the lagoon’s new rights.

The new law doesn’t regard the lagoon and its watershed as fully human. But the ecosystem now has a legal right to exist, evolve naturally, and be restored. And like a person, it has legal guardians, including a scientific committee, which will give its defenders a new voice.

“I am very excited,” says Ignacio Bachmann-Fuentes, a senior lecturer in constitutional law at Pablo de Olavide University. “This new law has very innovative and legally powerful elements.”

The lagoon is the first ecosystem in Europe to get such rights, but this approach to conservation has been gaining popularity around the world over the past decade. The Ganges and every river in Bangladesh have been granted personhood, for example; elsewhere, concepts in some Indigenous communities have helped drive the trend. “It’s taken off like wildfire,” says Catherine Iorns Magallanes, an environmental law expert at Victoria University of Wellington (VUW).

The clearest success story, scholars say, is the Whanganui River in New Zealand, which was given legal rights by an act of Parliament in 2017. Like a person, the river and its catchment can sue or be sued, enter contracts, and hold property. In that case, the aim was not to stop pollution but to incorporate the Māori connection between people and nature into Western law. “The river and the land and its people are inseparable,” Niko Tangaroa, a Māori elder of the Whanganui Iwi people and a prominent activist for the river, wrote in 1994.

The move appears to be paying off for the environment, catalyzing a shift in water management in New Zealand to emphasize the well-being of rivers over human needs, says Julia Talbot-Jones, an expert in environmental and natural resource issues at VUW. Granting rights to the Whanganui River has been “an integral steppingstone in this evolving transition,” she says.

In Mar Menor, where environmental concerns drove the personhood push, strong existing laws already protect species, habitats, and water quality. People and institutions are not allowed to harvest or harm the fan mussel for example, or pollute rivers and lakes that drain into the lagoon. But those laws have not been adequately enforced, says Francisca Giménez-Casalduero, a marine ecologist at the University of Alicante. “I am so disappointed, so sad,” about that failure and the state of the lagoon, she says.

Spain’s environmental ministry recently started to act, committing nearly €500 million over the next 5 years to address pollution in Mar Menor. This summer, workers removed large masses of algae from the lagoon to help prevent anoxia. Upstream, government agencies are destroying illegal irrigation canals to prevent some fertilizer from reaching the lagoon. But conservation advocates hope the new legal framework will bolster these efforts.

Now, any citizen can sue to protect Mar Menor, for example from too much fertilizer. The legal guardians, consisting of representatives from government and citizens who have yearslong appointments, can suggest legal and other actions on behalf of the lagoon. The scientific committee will gauge ecological health, for example by establishing healthy ranges of salinity, oxygen, and other variables. It will also identify new threats and advise on restoration measures. A monitoring commission will include representatives from environmental organizations, fishing and farming industries, and other stakeholders. Now, “We have another tool” for protection, Giménez-Casalduero says. “This opens a door for the control” of pollution and other problems afflicting Mar Menor.

The new law could spark a backlash. For example, farmers often resist cutting back on fertilizer, and the far-right Vox party called the initiative “legal nonsense,” and has said it will appeal to Spain’s Constitutional Court. Building broader support will be crucial. “Top-down declarations on their own can be empty,” says Elizabeth Macpherson, who researches environmental law at the University of Canterbury.

The new rights also need to be integrated into the current legal framework, which recognizes the property rights of farmers. That step is vital, Talbot-Jones says. “If there is ambiguity, they’ll end up embroiled in litigation.”

Other nations will be watching. In the United Kingdom, groups are campaigning for the rights of rivers, largely in response to pollution. “It’s genuinely exciting to see a rights of nature campaign succeed in Spain, because it really does show the other European nations what is possible,” says Erin O’Donnell, an expert in environmental law at the University of Melbourne Law School.