In 1984, a phytoplankton monitoring network was set up along the entire French coastline in order to detect and monitor the occurrence of any toxic species. Another type of toxic dinoflagellate, Gyrodinium cf. This species is therefore included in the list of monitored microalgal species.
Positive results lead to a ban of incriminated shellfish marketing.
Today, a significant portion of the French coastline is suffering from regular blooms of Dinophysis , most of them involving DSP shellfish contamination of variable duration. Maximum concentration periods, generally correlated to DSP toxicity occurrences, are primarily observed from July along the channel coastline and from May on the Atlantic and Mediterranean coast. Since 1988, intoxication cases have been reported very sporadically. The first development of Alexandrium minutum occurred in a small area of north-western Brittany in 1988. This species is now well established and cyst have been detected in muddy sediments throughout this zone.