Reddish water appeared in Brest harbor in October 2026, caused by decomposing red algae linked to heat and storms.
Red water reported in Brest harbor
On Sunday, October 25, and Monday, October 26, 2026, Ifremer received two reports of reddish to bright red water in the areas of Logonna-Daoulas and Landévennec, in the Brest harbor (Finistère). Samples confirm red algae presence
Samples collected from the affected areas showed fragments of decomposing red algae. This type of algae is common in coastal regions and can sometimes cause discoloration of the water when it breaks down. Natural causes identified
The phenomenon is attributed to the heat of the year and a recent storm that followed. These conditions can accelerate the growth and decay of algae, leading to changes in water color. No immediate danger reported
Authorities have not reported any immediate danger to human health or marine life from the red water. However, they are monitoring the situation closely to ensure there are no long-term environmental impacts.
