The dynamics of Dinophysis acuta, D. acuminata, D. tripos and Gymnodinium catenatum was studied during the development of a weak to moderate upwelling event observed in a 9 days repeated coverage of a combined CTD/Phytoplankton section at 41º05\'N off the coast of Portugal. All the species were mainly distributed in the surface wind driven layer within the region of the equatorward coastal jet. Wind induced mixing, offshore transport and vertical motions were reflected in the distribution and concentration of cells, depending on the relative position of each species in the water column before the northerly wind event. It was generally observed that wind relaxation was associated with blooming conditions while active winds gave rise to dispersion of cells and reduction of their number.