It has been blamed for a number of deaths in France.
Staff take away inexperienced algae from the Ris seashore in Douarnenez, Brittany (Picture: AFP/Getty Photos)
A poisonous “killer seaweed” blamed for a number of deaths in France has now been detected on British coastlines, sparking warnings over the hazards posed by rotting algal blooms on UK seashores. The seaweed, linked to the discharge of deadly hydrogen sulphide fuel, has devastated elements of Brittany for many years, the place courts not too long ago dominated that poisonous fumes from decomposing algae killed a marathon runner in a landmark case in opposition to the French state.
Now, environmental specialists worry related circumstances are rising in Britain amid worsening sewage air pollution and agricultural runoff. Brittany’s so-called “inexperienced tides” are brought on by enormous concentrations of nitrates washing into shallow coastal waters from intensive farming. The vitamins gasoline explosive blooms of Ulva armoricana—a vibrant inexperienced sea lettuce—which later rots on seashores and mudflats.
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Ulva armoricana (Picture: Getty)
Because the algae decomposes with out oxygen, it releases hydrogen sulphide (H₂S), a poisonous fuel that smells of rotten eggs and might set off respiratory failure, unconsciousness, and loss of life in excessive concentrations.
French authorities have linked the fuel to a number of incidents over the previous three a long time, together with the deaths of untamed boar, horses, and beach-cleaning staff, reported The Guardian.
In 2025, an enchantment courtroom in Nantes dominated that hydrogen sulphide emitted from rotting seaweed killed ultra-marathon runner Jean-Rene Auffray in Brittany in 2016, after he collapsed whereas working close to a seaweed-covered estuary.
The French state was discovered responsible for failing to maintain waters clear sufficient to stop the blooms. Consultants warn Britain faces rising dangers from related algal outbreaks.
Sea lettuce blooms have already been recorded alongside elements of the Welsh coast, southwest England, and estuaries affected by nutrient air pollution. Campaigners have repeatedly raised issues about untreated sewage discharges and fertilizer runoff pouring into rivers and coastal waters.
The hazard comes when thick mats of seaweed pile up and kind an hermetic crust. If disturbed by walkers, horses, equipment, or collapsing floor, trapped hydrogen sulphide can out of the blue burst out.
At decrease ranges, the fuel causes nausea, complications, and respiration difficulties. At excessive concentrations, it may well quickly overwhelm the nervous system, paralyzing the lungs inside seconds.
Pierre Philippe, a retired French emergency physician who has spent a long time investigating the Brittany deaths, warned that the fuel turns into particularly harmful as a result of it numbs the sense of odor.
He stated: “By 50 elements per million it anaesthetises your sense of odor — and that’s when issues get harmful.”
The Brittany disaster has grow to be a political flashpoint in France, with environmental teams accusing authorities of downplaying the well being dangers to guard farming and tourism industries.
The area accommodates greater than half of France’s pig inhabitants regardless of masking solely 5% of the nation’s landmass, producing huge portions of nitrogen-rich waste that feeds the algae.
French governments have launched a number of “seaweed plans” aimed toward decreasing air pollution, however critics say they’ve didn’t sort out the basis trigger: intensive livestock farming.
British environmental campaigners say the state of affairs ought to function a stark warning for the UK, the place rivers and coastal waters are already underneath mounting stress from sewage spills and agricultural air pollution.
Final 12 months, campaigners warned that worsening nutrient contamination was fueling bigger algal blooms round Britain’s shoreline, elevating fears that poisonous “inexperienced tides” may grow to be more and more frequent throughout hotter summers.
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