Green algae in the middle of winter and a broken record… How can we do better in 2022?

His bungalow overlooks Grandville beach in Hillion. Before leaving to celebrate Christmas, the indefatigable André Ollivro snapped a photo of the immense expanse of sand where large brownish spots persisted. Green algae in December is almost unheard of in Brittany.

Just a stone’s throw away, the Hotel Beach has even set itself a new record: that of the beach closed the longest. Six months and a few days, a record to beat. Annoyed, the environmental activist says he is “worried” to see the phenomenon continue in winter. “There is a real bankruptcy of the collection so it goes and it comes according to the tides”. A real headache for communities, who have to make do with a few tractors and trailers to clean. A collection necessary to limit the proliferation but which seems very difficult to carry out.

The violent thunderstorms of early summer involved

While the new year has started eleven days ago, Brittany has still not managed to get rid of the green algae that pollutes some of its beaches in fine weather. An unprecedented phenomenon that reminds us that the year 2021 will have really been moldy, especially in the bay of Saint-Brieuc. “The strandings started very early last year because the temperature and the light were favorable to the development of algae,” explains Sylvain Ballu, responsible for monitoring the phenomenon at the Center for the Study and Valorization of Algae (CEVA).

But the major problem arose in June and July when violent thunderstorms washed away farmland, dumping nitrates from fertilizers and phytosanitary products into swollen rivers. “The concentrations have not changed but the flows have been very important,” adds Sylvain Ballu, citing figures “two to three times greater from July to October”.

Results ? A catastrophic summer for several Costa-Rican municipalities which have turned 2021 into a black year… and a green one. A new episode rather ill-timed for the State, which was severely tackled by the Court of Auditors for the ineffectiveness of its plans to fight. Forced to react, the administration appointed Etienne Guillet at the beginning of November to the post of high level expert “Water, green algae and agroecological transition”.

Nitrate concentrations that no longer decrease

“These late arrivals are very exceptional. They depend a lot on climatic conditions. We have little wind, little swell and high temperatures. These are factors that we do not control “, tempers the new” Mr. green algae “. On the shores of the bay of Saint-Brieuc, nitrate concentrations have halved compared to the 1990s. But for seven to eight years, they have stagnated.

Summoned to develop a new plan of struggle, the engineer knows that he is facing a thorny problem. In the region, agriculture is considered an asset and employs tens of thousands of people, but its intensive practice is singled out. Many voices are raised to demand the reduction of the herd in the region. “It’s not for me to say on that. There is a debate and I hear it, but my challenge is first of all to have a realistic plan, which is shared by as many players as possible, ”explains Etienne Guillet, referring to“ a reduction already at work in the regional territory ”.

At the negotiating table, he will have a lot to do to convince the powerful agricultural cooperatives, unions and departmental chambers of agriculture.

The reduction of the herd is carried by a certain number of actors but not by the agricultural profession. And without the farmers, we will not move this file forward. They are the ones who have part of the solution, particularly on the issue of nitrates, ”explains the Deputy Prefect.

“What is needed is to make the measures compulsory, not simply on a voluntary basis,” claims André Ollivro.

Even before the opening of discussions, another urgency emerges. With an abnormally high quantity of seaweed stocks at sea, Brittany could be confronted with very important strandings at the beginning of spring. To avoid this phenomenon, the region can only count on its capricious weather.

“We need more dispersive winters with wind and swell to push away the millions of tiny bits of algae before they proliferate. For the moment, this is not the case, ”regrets Sylvain Ballu. If the Breton winter promises to be still long, the storms will be closely scrutinized by the mayors of the coastal municipalities. “I met them in October. I told them clearly that if the situation did not develop favorably, we were in trouble ”. Verdict expected in March. At the same time as the decrees defining the areas under environmental constraints.


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