Decades of industrialisation have polluted the waters of Italy's Mar Piccolo and brought mussel farming to its knees. Can harnessing the power of plants bring back a traditional way of life?

Adriano Lippo grips the tiller of his small boat, staring out over the dark blue waters of the Mar Piccolo. "I don't think it will happen this year," he says, shaking his head. "Everything is dead." The air carries a scent of salt, heat, and the bittersweet nostalgia of summer's end.

For the past decade, Lippo has made the same journey at the end of every summer, steering his boat between the port and the looming smokestacks of Taranto, southern Italy. His task: to transfer mussels from one inlet to the other across the Mar Piccolo, a semi-enclosed bay located between the city and the open sea. The narrow strait connecting the Mar Piccolo's two inlets has always been a lifeline for mussel farmers – a vital passage to shield their harvests from the contamination that has plagued the first inlet after years of relentless industrial growth.

The first inlet has historically been the best site for collecting larvae, and mussel farmers have passed down this knowledge over the generations, explains Giovanni Fanelli, a researcher working with mussel farmers at the National Research Council in the Istituto di Ricerca Sulle Acque (CNR-IRSA). "The first inlet is closer to the open sea, allowing cooler water to stream in. But for years, it has not been possible to complete mussel growth in that area," says Fanelli, as he bends from his boat to collect a submarine data logger, a device used to record and store environmental data underwater.

When mussels reach a certain size, farmers must transfer them to the second inlet, which lies further from the sources of pollution, to complete their growth. This allows the mussels to purge any toxins they may have absorbed during their early growth phase in the first inlet. But last year, rising temperatures killed the mussels before they could even make the trip. Ninety per cent of mussels were lost in the final weeks of September, devastating current yields and jeopardising future harvests.

Once the lifeblood of a centuries-old tradition, the Mar Piccolo supported generations of mussel farmers, producing an impressive 60,000 tonnes of mussels annually at the sector's peak in the early 2000s. Since then, mussel farming has been in decline, with pollution and heatwaves exerting ever greater pressure on an already precarious sector.

Now, researchers and mussel farmers are pinning their hopes on a plan to restore the contaminated Mar Piccolo through phytoremediation, a process where plants are used to absorb harmful toxins. While the approach holds promise for both the environment and the livelihoods of mussel farmers, its implementation faces significant hurdles, including logistical challenges, funding constraints and the ongoing impact of heavy industry in the region.

Known as "the city of the two seas" because of its location between the Mar Grande – the open sea – and the Mar Piccolo, Taranto has long wrestled with the impacts of industrial development. Since 1889, it has hosted Italy's largest naval base and military shipyard, and a major oil refinery and cement plant have been operating since the second half of the 20th Century. More recently, the city has been home to one of the biggest steel factories in Europe, Acciaierie d'Italia – still referred to locally by the name of its former owners, the state-owned Ilva Group.

Operational since 1965, at its peak, the factory produced more than 11 million tonnes of steel every year. Over the years, various scientific studies have identified alarmingly high levels of heavy metals and organic pollutants in marine sediments, alongside elevated cancer rates in the areas closest to the factory.

A trial in 2021 convicted 37 people and three companies for allowing the steelworks plant to emit deadly pollution, which the trial found had caused a surge in cancer in Taranto. However the verdicts were overturned by an appeals court in 2024. New legal proceedings are now underway.

A vibrant ecosystem home to seahorses, rare seaweeds and endangered fan mussels, the Mar Piccolo's low salinity levels create an ideal environment for mussel cultivation. "What should be, according to human logic, practically a putrid pond is instead a sea rich in biodiversity," says Giovanni De Vincentis, President of the Taranto branch of the World Wildlife Fund. The vitality of this ecosystem is largely attributed to the

© BBC