In Pictures: ‘Armageddon’ at Europe’s Swim Spots Linked to Climate Change and Factory Farm Pollution

A version of this article was published in Euronews and Climatica

Across Brittany, tractors can be seen trundling onto beaches to remove truckloads of foul-smelling algae ahead of the tourist rush. 

Situated below steep cliffs and ancient forests, these once pristine beaches have been devastated by algal blooms – the rapid growth of toxic seaweed which kills off fish and plant life. This sea lettuce algae can also release a toxic gas that can cause humans dizziness, chest pain, breathing problems, and even cardiac arrest.

The French peninsula is not alone. Fed by harmful pollution from agriculture, and fuelled by seas warmed by climate change, lurid green blooms are increasingly appearing on beaches and lakes across Europe – prompting hundreds of swimming bans across the continent this summer. 

Scientists are clear on the cause: for decades, chemicals including nitrogen and phosphorus have leached into waterways from human sewage, as well as fertilisers and excess manure fuelled by the rapid growth of Europe’s factory farms. 

These ‘nutrients’ are vital for plant growth – but in large quantities they destroy the delicate balance of ecosystems, allowing certain plants, including algae, to multiply at the expense of animals and other species.

DeSmog visited some of the worst impacted spots in Europe, speaking to fishers, swimmers, and business owners whose livelihoods and wellbeing depend on healthy waters.

On the shores of lakes and beaches across France, Spain, Germany and Northern Ireland, we heard accounts of plummeting fish and insect numbers, swimming bans, and beach closures. 

The risks of algal growth have been known for decades, but higher temperatures and longer summers mean these dangerous blooms are growing larger and lasting longer in many of the continent’s most iconic waterways. 

“I remember our beautiful beach before the pollution,” says Brittany resident Jean Hascoet, who leads local campaign group Baie de Douarnenez Environnement. “Now, with thousands of pigs near our town, everything is different.”

Brittany resident and environmental campaigner Jean Hascoet, pictured here in Douarnenez Bay, France, says the surge in intensive farming in the region has devastated local beaches. Credit: Selene Magnolia Gatti

‘Spain’s Sacrificial Zone’

“You’ll never see me swimming in that water again,” Fina says. 

The 84-year-old from Murcia in southeastern Spain lives with her husband Francisco on the beachfront at Los Urrutias, on the west coast of the Mar Menor, Europe’s largest saltwater lagoon. Rotting seaweed piles up on the shore, giving off a foul stench. 

“This used to be paradise. The sea was teeming with seahorses,” Fina says. 

The last decade has seen a sharp increase in algae growth in the Mar Menor – a hotspot for Spanish and international tourists. Cyanobacteria, also known as blue-green algae, is reliant on nutrients such as nitrogen and phosphorus to grow, and in this region, intensive farming has provided a ready supply. 

Spain is the EU’s largest producer of pork, accounting for a quarter of the bloc’s production. In the Mar Menor catchment area, according to latest government figures, 305 pig farms house nearly 700,000 animals – producing vast amounts of manure and slurry, a liquid mixture containing faeces and urine. When it rains, the nutrient-rich mixtures flow from fields into rivers feeding the lagoon.

“The land can’t accommodate it all,” says Pedro Luengo, a biologist and spokesperson for the campaign group Ecologistas en Acción in Murcia. “We’re a sacrificial zone.”

Tourists now steer clear of the area closest to the farmland – the western region where Fina lives, which was once an idyllic family holiday spot. 

Instead, on other beaches, such as La Manga in the east, bathers enjoy an artificial paradise thanks to local authorities who, as in France, remove the algae daily over the summer months. In the first three months of 2026, they collected more than 4,000 tonnes from Mar Menor’s shores and nearby water– roughly the weight of 1,000 elephants.

Authorities say these clean-ups help protect human health and allow essential sunlight to reach sea life, which would otherwise be blocked by the blooms. But it has not shielded those who rely on the lagoon for their livelihood.

“We used to catch far more gilthead seabream and prawns. Now the catch is much smaller,” says Rubén Albaladejo, a fisherman from Lo Pagán. “The Mar Menor is a drain into which everyone dumps their rubbish and waste.” 

Algal blooms endanger aquatic life by consuming vast amounts of oxygen, meaning fish, seahorses, and crustaceans can suffocate. They also produce toxins that attack the nervous and respiratory systems of sea life. 

Alongside nutrient pollution, water temperatures rose sharply this year amid record-breaking heatwaves across the continent. “We’ve reached 30 degrees – something we’ve never seen before.” Albaladejo says that in these conditions, species such as gilthead seabream struggle to reproduce.

Scientists warned in August that human-caused climate change was driving record temperatures in the continent’s seas, with a 2C temperature rise registered in the Mediterranean, and around 1.4C in ​Western European seas.

‘The Lough Is Dead’

Albaladejo shares his worries with fishers across Europe. Around 2,000 kilometres away in Northern Ireland, Declan Coney has also seen Lough Neagh – the UK’s largest lake – devastated by blue-green algae every summer since 2023. 

“Fishing is instilled in me – generation after generation,” Coney says. “This year has been the worst ever for fishing. The Lough is dead.”

Coney has been working on the lake since 1975. He used to go out with his father and sometimes caught £1,000 worth of fish in a day, he says. But now the cost of the diesel required to boat to his nets can be greater than the value of the catch. 

Trout and eel numbers have fallen in recent years, in part thanks to the oxygen-hogging blue-green algae, whose weight also forces Coney’s fishing nets shut, so fish can’t swim inside. 

Since the 2000s, the lough has also been besieged by the invasive zebra mussel species. These consume large amounts of phytoplankton, depriving other species of these microscopic plant-like organisms, a vital food source, as well as attaching to fishing nets and ripping them. 

“There’s no money [in it],” Coney says. “It’s not a livelihood anymore.”

As in Spain, Lough Neagh’s algal blooms are the result of decades of nutrient pollution. Northern Ireland’s livestock sector has grown rapidly, supported by government expansion plans since 2013: poultry numbers have risen by a third, and pigs by 74 percent. 

Earlier this year, investigative outlet Watershed and The Guardian found evidence of cattle, pig and human faeces in samples of water from the lough, which spans nearly 400 square kilometres and provides 40 percent of Northern Ireland’s drinking water. 

Mary O’Hagan lives on the north-west of the lake. During the Covid-19 pandemic, she set up a wild swimming group, and found that the cold water had huge benefits – from improving mental health to relieving chronic pain.  

“In my 30s, I didn’t have much of a life, I wasn’t looking after myself. Swimming in Lough Neagh changed my life completely,” O’Hagan says. “We had a community.”

But after the second year of the blooms, she felt forced to shut the swimming group down. 

“I couldn’t in all good conscience organise swims where people would be exposed to bacteria, algae, or god knows what else.” 

“The first year… was awful. It was like Armageddon. To see the shores covered as far as the eye can see in pea green sludge, was horrendous,” she says.

O’Hagan’s concerns are shared by swimmers and local authorities elsewhere in Europe. In Germany, dozens of lakes are also routinely devastated by algal blooms, triggering a spate of temporary swimming bans this summer. 

“The water used to be clear, you could see your own feet,” says Oland Stephan, who has run a kiosk at Sander lake in northern Germany for 18 years. Once a popular bathing spot, the lake has been off-bounds for swimmers for the last few years because of the blue-green algae – which can cause vomiting, diarrhea, and skin irritation, among other issues. 

“I could make a living back then, but not anymore,” Stephan says. “I have bankruptcy papers at home.”

Peter Bünting, a lifeguard at the lake, says the cloudiness of the water from the algae makes search and rescue operations challenging. “You might have a casualty in front of you but you just can’t see.”

‘More Animals Than People’

Certain types of algae have been linked to fatalities. When sea lettuce and blue-green algaes break down, they can produce hydrogen sulfide, a lethal gas that smells like rotten eggs and causes  blocked airways and fluid to build up in the lungs if inhaled in large quantities. 

Since the 1980s, sea lettuce algae has been linked to as many as six deaths on Brittany’s beaches. 

Locals here are clear about the cause of the algae growth. Near the tourist town of Saint-Brieuc, “the pigs” has been scribbled across an official sign warning about the danger and symptoms of inhaling toxic gas from the algae. 

“We have many more animals than people,” environmental author Yves-Marie Le Lay told DeSmog. Although the peninsula covers just five percent of France’s surface, its 6.8 million pigs account for 58 percent of the country’s total population. “We have a manure problem, it all ends up in the rivers.”

For environmental activist Fabrice Hamon, who lives near the Penfoul beach in Western Brittany, bacteria such as E. coli and salmonella from manure run-off have also become a daily concern – washed by rain from farmland down to the sea. 

Since official tests in the summer of 2025 identified E. coli on Penfoul, the beach has been under a partial swimming ban, and is at risk of being closed permanently. 

Hamon says these bacteria are “super dangerous” if they are swallowed or come into contact with areas like the eyes and nose – and can cause infections, such as conjunctivitis, urinary tract infections, and gastro-intestinal infections that lead to diarrhea and vomiting.

Hamon is uneasy about the coming months. This summer’s droughts meant that fewer harmful excess nutrients were washed into the waterways from fields treated with manure, but instead are stored in the soil until it rains. Europe, the fastest-warming continent in the world, is seeing more intense and unpredictable bouts of extreme weather, including increased downpours and flooding.

“Right now there’s a build-up of bacteria in the fields,” Hamon says. “All it takes is a heavy downpour and bingo. It’s a slow-acting poison: little by little, ecosystems are being degraded by the build-up of pollution linked to intensive farming.”

Warming Seas

As climate change accelerates, warming temperatures are also exacerbating the algal blooms. Algae grows quicker and lasts longer in warm waters, as higher temperatures allow it to digest and reproduce at a faster rate. 

Jürgen Leicher, deputy chairman for the German environmental group BUND in the state of Schleswig-Holstein, has been sailing on the Baltic Sea for 40 years, and says this year’s algal blooms were the worst he’s ever seen. 

Temperatures in Germany broke records for three consecutive days in June, reaching almost 42C. Satellite images of the Baltic in August show vast algal blooms swirling towards the coast.“You feel really afraid when you sail for hundreds of miles through a yellow-brown dirty sea,” says Leicher. “All the way through this algae, the sea was dead. You see no birds, no mammals, no fish. It’s so empty.”

Agriculture is the biggest source of the problem: the intergovernmental body HELCOM estimates it accounts for up to 90 per cent of nitrogen and up to 80 per cent of phosphorus in diffuse nutrient run-off into the Baltic. 

Despite decades of intergovernmental efforts to reduce nutrient pollution, the Baltic is struggling to recover from the environmental damage combined with rising temperatures. Each year, when algae dies it sinks to the seabed, taking large amounts of phosphorus with it. That phosphorus is released back into the ocean in future years — a dangerous feedback loop that picks up speed as the sea warms.

Seeking Solutions

In the face of these huge challenges, residents, campaigners and scientists are united in their determination to find solutions. 

Leicher thinks that better monitoring could help track the profound environmental disruption taking place in the Baltic Sea. His colleagues at BUND Schleswig-Holstein have launched a citizen science project, which will see volunteers collect water samples twice a month from local rivers. By analysing the samples in a laboratory, the organisation hopes to pinpoint sources of pollution and help efforts to cut nutrients.

In Brittany, Fabrice Hamon has designed an app – La Météo Bacterio – which helps monitor for bacteria in the 20 odd rivers that flow onto local beaches, meaning tourists and residents can check for warnings before they swim.

Others are focusing their efforts on political and legal action. In recent years, campaigners and residents have won a raft of legal victories – including persuading the Spanish government in 2022 to bestow ‘legal personhood’ on Mar Menor, providing the lagoon with rights to protection and restoration.

Ultimately, though, scientists say that nutrient pollution must be slashed to limit the recurrent harmful algae growth – and that means transforming agricultural practices. 

“The science is clear on what needs to be done,” says Professor Friedhelm Taube from Kiel University (CAU), who spent 12 years advising Germany’s Ministry of Agriculture. Governments should support farmers to use less nitrates-heavy fertiliser, plant catch crops like grass clover that absorb some of the excess nutrients from soils before they run into rivers, lakes and sea, and reduce the number of animals farmed on limited land, he says.

“Farming animals can be fine,” Taube says, but to keep nutrient run-off within safe limits, numbers should be reduced to just one ‘livestock unit’ per hectare – a technical term that translates to just one dairy cow or around three pigs. That means far fewer animals in regions where they are intensively farmed, he adds. 

Campaigners in Spain also face a stark choice. “Either we wreck the Mar Menor,” says Pedro Luengo from Ecologistas en Accion, “or we transform the agricultural model”.

In Northern Ireland, Mary O’Hagan is determined to continue to fight for change. “I credit getting into Lough Neagh for the lovely active life I lead,” she says. “It’s one of the reasons I fight back in the way I do.” 

It’s a long fight, but Mary is hopeful. “I’d like to see improvements in my children’s lifetimes – to see it restored to how it was.”

Additional research by Joey Grostern and Louis Bontemps

Editing by Phoebe Cooke and Clare Carlile