Aurelia sp. in Saint Malo harbor (France)

Several Aurelia sp. between 5 and 10 cm in bell diameter seen in Saint Malo harbor (france, English Channel). When concentrated (in angles where currents brought them together) densities up to 5-10 individuals per m². None were seen outside the harbor or stranded in nearby beaches. The harbor is quite enclosed so i would say it's likely that they have strobilated and grew inside the harbor.