CASE

Understanding green algae in Brittany

Green algae on Ris beach, at the end of Douarnenez bay, in Finistère, summer 2019. © Olivier Favier

Text by: Olivier Favier Follow

9 mins

Green algae have invaded some beaches from late spring to late summer for half a century.

They are now picked up after being implicated in several deaths.

They are the most visible sign of overexploitation of the environment, linked to intensive agriculture and livestock farming.

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In Brittany, the history of green algae has its origins right in the middle of what the economist Jean Fourastié called the Glorious Thirties, this period which, from 1945 to 1975, associated strong economic growth and an increase in the standard of living, tipping a still largely traditional and rural France into a consumer society.

In 1960, the State launched its first agricultural orientation law.

Special rural action zones are set up in departments that do not benefit from sufficient economic development, are underdeveloped, underpopulated or overpopulated.

One of them is created in Morbihan.

It becomes the largest the following year when all or part of the four other departments of historic Brittany are added.

How Brittany became France's leading agricultural region

From the outset, the attention paid to Brittany is not linked to what, in a more traditional vision, could define a land devoted to peasant activities - fertile soils, relief, climatic conditions - but to the idea that industrialized agriculture and above all animal husbandry can develop according to human dynamics that are largely foreign to the environment.

This policy continues without interruption until these four departments are the leading agricultural region in France and the leading agri-food region in Europe.

Thus, Brittany today produces, in greenhouses, 40% of French tomatoes – with the only natural asset being a low annual thermal amplitude, guaranteeing, in the absence of taste properties, the regularity of very high yields.

Above all, it produces more than a third of farmed animals for meat in France – including more than 60% of pigs.

It is also the first slaughter region.

85% of Breton production is oriented towards breeding.

Half of the pigs and 80% of the poultry are raised without a substantial plant workshop.

This above-ground breeding, especially for pigs, produces considerable quantities of slurry – excrement – ​​and not manure – excrement mixed with straw.

This slurry, which is used for spreading, is extremely rich in nitrates, salts made up of nitrogen and dioxygen, particularly appreciated by plants.

What is the eutrophication of a natural environment?

When these nitrates are produced near the many coastal rivers of Brittany, the rain carries them to the coast, to the point that their rate has been multiplied by six since the beginning of the 1960s. The concentrations are even higher at the bottom of the bay. where the water is renewed less quickly – very indented, the Breton coast represents a third of the French mainland coasts.

This considerable nutrient supply is the cause of the proliferation of green algae.

The imbalance of an ecosystem caused by an excess of food for a given species is called eutrophication.

Green tides occur in spring with warmer waters and greater luminosity.

Algae grow on the surface until they form a curtain which, blocking the light from the sky towards the lower layer, puts a temporary brake on their proliferation.

Reproducing by cuttings, they are stimulated by tearing caused by marine fauna or human activities.

By washing up on the beaches, the

also called sea lettuce forms thick layers which, when they decompose, give off hydrogen sulphide with a strong smell of rotten eggs.

Collecting becomes necessary, even if the passage of mechanized machines constitutes a new aggression for the ecosystems.

The seaweed is then used for spreading on farms near the coast or ends up in composters mixed with other plants.

... © FMM Graphic Studio

G

reen algae

as a symptom of a degraded environment

In fact, green algae are a symptom of one of the imbalances generated by agriculture and intensive farming – in addition to nitrates, phosphates are experiencing record levels, like bacteria which require heavy treatment for drinking water. and drastically limit the harvesting of shellfish on the coast, especially in the bays.

They disfigure beaches, make them unsuitable for swimming and cause olfactory discomfort,

Above all, they represent a danger in themselves.

First of all, they threaten the underwater fauna and flora with asphyxiation.

Then, in places where the strandings are massive, they form a white crust on the surface which allows the creation of pockets of hydrogen sulphide, which is likely to be released suddenly when a human being or an animal (horse, dog, boar) crosses the premises.

In high doses, this gas causes olfactory amazement and becomes odorless.

Imperceptible, it can then cause a pulmonary embolism and a sudden death.

The first case to have aroused strong suspicions is that of a 26-year-old jogger found dead in 1989 on a beach in Saint-Michel-en-Grève, at the bottom of the bay of Lannion, in the Côtes-du-Nord. - today Côtes-d'Armor.

In 1999, in the same town, an employee collecting green algae fell into a coma and narrowly escaped death.

In 2009, a carrier of green algae died in Binic, a little further east, in the bay of Saint-Brieuc.

Green algae kill

This time, an autopsy is performed.

It reveals a fatal level of hydrogen sulphide in the blood of the deceased, which, for the authorities, would be the consequence of poor conservation of the pocket in which it had been kept.

The same year, on the Gouessant estuary, still in the bay of Saint-Brieuc, during the summer, the remains of thirty-six wild boars, five coypus and a badger were found.

Autopsies, like others performed on animals in previous years, also reveal very high levels of hydrogen sulphide.

Finally, in 2016, a 50-year-old jogger was found dead on the Gouessant estuary.

The family refusing the autopsy – possibly under pressure – it is nevertheless ordered by the prosecutor two weeks later.

The results are given after two months, evoking “the toxicity (…) of the Gouessant mudflats”, but again the argument of a late analysis is put forward so as not to bring definitive conclusions on the reasons for the death.

It remains that these cases are those which have caught the attention, in particular that of an emergency doctor from Lannion, Pierre Philippe.

"I don't know how many people died during the green tides, he confides to Inès Léraud, author of the cartoon survey

, published in 2019. Probably more than the few on which I fell a little by chance, in the hospital.

(…) A blood test taken from any person found dead or fainted on the Brittany coast would make it possible to know if the H2S is in question.

»

Cover of the book-investigation by Inès Léraud © Delcourt

Two

women

journalists

break

the silence

The dangerousness of green algae is now recognized.

Since 2010, panels have informed of the risks associated with green tides at the entrance to the beaches, sticking for the rest to a series of natural explanations - low renewal of water at the bottom of the bay, rise in temperature and summer light – without mentioning the origin of the nitrates which ensure its proliferation.

Inès Léraud's book widely questions, with supporting documents, both the employers' organization FNSEA (National Federation of Farmers' Unions) and local, regional and national politicians, companies in the agri-food sector. or the Locarn Institute - think tank that the writer Françoise Morvan does not hesitate to call a lobby.

It earned the author half a dozen awards and two complaints.

These were withdrawn just before the trials.

In 2017, Morgan Large, journalist and opposition municipal councilor in Glomel (Côtes-d'Armor) testified at the microphone of Inès Léraud of collusion between industrialists, farmers and elected officials.

The municipal subsidy allocated to the media for which she works, Radio Kreiz Breizh, is immediately abolished.

She testifies again in a documentary broadcast on France 3,

.

The requirement of "clarity"

The regional branch of the employers' organization FNSEA broadcasts its portrait on twitter, the premises of the radio are vandalized.

She receives threats and her dog is poisoned.

In 2020, she founded with other journalists the online survey media

, a Breton word for daylight.

In 2021, she realizes that the bolts of a wheel of her car have been unscrewed, a judicial investigation is opened.

During the summer of 2022, director Pierre Jolivet is preparing to shoot a film called

, an adaptation of Inès Léraud's investigation.

The Brittany region refuses to finance the project.

As for the mayor of Saint-Michel-en-Grève, he expressed his dissatisfaction to the regional daily Le Télégramme.

"You will see that people are fed up" adds the president of the agglomeration of Lannion.

In the meantime, the book has sold over 100,000 copies in three years.

For Sylvain Ernault, founding member of

, it is the green algae, and not the bad publicity they give to the coasts concerned, that exasperate the inhabitants.

“When we conduct our investigations on the subject, people often say to us: - You should read the comic book!

And the anger threatens to spread.

From now on, green algae proliferate on large parts of the Atlantic coast and the English Channel, from the Gironde to Normandy.

Our selection on the subject:

•   

→ Splann, journalists and citizens, from Brittany and around the world

→ In Landunvez, the giant pigsty is approaching a dubious regularization (on Splann)

→ Brittany: breath of fresh air with ammonia (on Splann) 

•   

→ Nitrate pollution, Breton agriculture in question

→ Rachid Mrabet (Giec): "We must move towards ecologically intensive agriculture"

→ Can we do without intensive livestock farming?

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