Is it the sudden and prolonged rise in temperatures that is causing this proliferation? In Brittany, an alert was triggered after the discovery of a high concentration of Alexandrium-type phytoplankton in the water of the Rance estuary. Fishing for shellfish such as cockles, clams, oysters or scallops is therefore prohibited for several kilometers between the Châtelier lock and the tidal power plant.
This algal bloom was detected as part of the phytoplankton monitoring networks for the health quality of shellfish. Algae toxins, likely to accumulate in shellfish, can cause poisoning and pose a risk to human health, according to the prefectures of Côtes-d’Armor and Ille-et-Vilaine.
For now, these measures are preventive, pending the results of shellfish analyses. Professional and recreational sea fishing is therefore temporarily prohibited.