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The region did not end with green algae, but it's better



Illustration of green algae on a Breton beach. – O SAL OF LIONEL / SIPA

  • About 20,000 tonnes of seaweed were harvested last year in Britain, the smallest since 2002.
  • Favorable weather has played for many, as has the decline in nitrate content in streams.
  • But Brittany is not finished with the phenomenon, as evidenced by the massive stranding of green algae in recent days in the bay of Saint-Brieuc.

Will there be green algae on the beaches of Brittany this summer? This is the question that comes back every year when the beautiful days are back. If it is too early to respond, because we are not climbers in terms of climate, it is clear that the situation has tended to improve in recent years in the region. Last year, 20,000 tonnes of green algae were collected off the coast of Brittany, the lowest since 2014 since the start of studies in 2002.

"This small year can be explained in particular by the low carry over of the previous year," explains Sylvain Ballu, a researcher at the Center for the Study and Evaluation of Algae (Ceva). The winter of 2018 was quite stormy in Brittany, this actually allowed to evacuate the stocks accumulated on the beaches in the previous months. The consequence was a subsequent beating of algae with 10 times less affected area at the beginning of the season compared to the period 2002-2017.

Nitrate content decreased in rivers

If climatic conditions play an important role in the proliferation of algae, the very complex phenomenon also depends on water quality. And at this point Brittany made efforts. "The nitrate content in rivers has dropped significantly, averaging 45 milligrams per liter in 2010 and now is around 30 milligrams, and even less in some red fruits," said Thierry Burlot, vice president of the region responsible for the environment environment.

"We can not do anything about the climate, so the only relevant action we can take is to reduce nitrogen leakage, especially from farms," ​​he continues. "We feel a sense of the agricultural world, but it takes time for the mentalities to change," said Mayor Michele Kirry.

The bay of Saint-Brieuc carpeted in green

To combat this scourge, the state and local authorities signed a second action plan in 2017, with 60 million dollars to be applied by 2021. But green algae only needs to make money. In recent days, they have made a huge comeback in the bay
of Saint-Brieuc (Côtes-d & Armor).

"This is a black spot because the situation has improved significantly in the Saint-Michel-en-Greve area, which has also been a problem," acknowledges Thierry Burlot, noting that the Bay of Saint-Brieuc concentrates 10% 1,200 farmers based in the catchment area.

Elsewhere in Brittany, the situation looks pretty good, with few recorded strandings. But from here, to imagine a complete eradication of the phenomenon, the goal set by this background, it is best to be cautious at that point. "Algae are a natural phenomenon anyway, they are part of the ecosystem.This is not a problem if there are green algae on the beaches," said Sylvain Ballu, "which is a massive disturbance.


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