Murcia residents hope to protect the polluted Mar Menor, Europe’s largest saltwater lagoon, with a change in legal status

At least we know it is alive,” says a fisherman, walking back down the pier to the muddy beach at Los Urrutias, in the south-east Spanish province of Murcia, where he’s been fishing all day. He doesn’t mean his catch, but rather the water in the Mar Menor, one of the largest seawater lagoons in Europe.

Los Urrutias may look idyllic, with flamingos, great cormorants and grey herons flocking to the waters around the volcanic islands off the coast, separated from the Mediterranean by a 22km (13-mile) stretch of sand.

But the wind tells a different story. It has a putrid smell that reveals what the Murcia government has described as a “grave ecological unbalance”, and what activists are calling “ecocide”: a crime against an ecosystem and the species – including humans – that live within it.