Question 16954 — sea and coastline

Summary

Mr. Damien Girard draws the attention of the Minister Delegate to the Minister for Ecological Transition, Biodiversity and International Negotiations on Climate and Nature, responsible for the sea and fisheries, to the inadequacies of the seventh regional nitrate action program (PAR7) in the fight against the proliferation of green algae on the Breton coast, in particular concerning mudflats and activities economics that depend on it. Following the conviction of the State by the administrative court, on March 13, 2025, for its shortcomings in the application of European and national regulations intended to protect waters against pollution of agricultural origin, the prefecture of Brittany initiated the revision of PAR7. This new version of PAR7 defines “challenged areas”, representing approximately 20% of the Breton surface area. These areas finally include some of the mudflat watersheds, until now excluded from plans to combat green algae, even though they account for nearly 84% of the ulva stranding areas. In these problem areas, a cap on total nitrogen inputs must be established. In its opinion of June 26, 2026, the environmental authority, however, underlines the limited scope of this measure, the planned ceilings being considered too high, only applying for a period of two years and being restricted to certain territories. Furthermore, the classification of mudflat watersheds as problematic areas is based on a threshold of 29 mg/l of nitrates present in watercourses. This threshold is in no way justified and the proliferation of green algae in the mudflats also depends on other particular factors, still little studied, such as their intense exposure to light or their low exposure to winter storms, which encourages the accumulation of algae from one year to the next. This single criterion also leads to inconsistent situations, such as in the harbor of Lorient where part of the Blavet watershed is classified as a high-stakes area, unlike the Scorff, even though both supply the same mudflat area. The environmental authority highlights the need to define specific objectives for each environment, taking into account not only nitrate concentrations, but also nitrogen flows, phosphorus inputs and stocks and other parameters influencing the development of green algae. These mudflats constitute essential reservoirs of biodiversity, serving as nurseries for numerous species of fish, molluscs and birds. Their degradation weakens the trophic chain and all economic activities that depend on it, notably fishing and oyster farming. Green tides on mudflats therefore require particular attention, based on in-depth studies carried out on a case-by-case basis on each of the sites concerned. Thus, although PAR7 presents significant developments in the fight against green algae, it still appears largely insufficient to protect coastal ecosystems, particularly mudflats, as well as all the activities that depend on it, in particular fishing and aquaculture. He therefore asks what measures the Government intends to implement to respond to the injunction to take “all necessary measures” in order to protect coastal waters and the economic activities that develop there, in addition to the only regulatory system announced. He also asks him how the Government understands better integrate mudflats into the plan to combat green algae and whether it plans to conduct studies to define, for each bay and each mudflat, objectives adapted to their ecological specificities.

Machine translation from French. The official text remains authoritative.

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