Watermass stratification is classically considered the essential habitat condition needed for dinoflagellates and other flagellate species to bloom. This requirement is thought to reflect their relative inability, unlike diatoms, to tolerate the elevated shear-stress associated with water-column mixing or developing during horizontal transport of local and coastal currents. Populations entrained in such currents are subjected to shear-stress forces considerably greater than those in smaller-scale Langmuir circulation patterns which flagellates exploit to their ecological advantage. This paper analyzes the swimming speeds of 71 dinoflagellate, raphidophyte and other flagellate taxa, and compares these to the turbulence fields developing during representative wind conditions, and to the current velocities reported from frontal zones. The results suggest that the classical stratification-bloom paradigm needs revision. Tolerance of, and exposure to well-mixed watermasses, and/or entrainment within fast-moving current systems appear to be important, even essential, aspects of the bloom ecology of many flagellate species. Dinoflagellate species array along a mixing-stratification gradient, rather than exhibit a uniform response (= association) to the degree of stratification. The cell size of many bloom species falls within the diameters of the physical cells developing during the turbulence cascade which dissipates the energy introduced by wind-induced mixing. This diminishes the potentially damaging impact of associated shear-stress forces. The motility of many species exceeds in situ vertical current velocities allowing diel migrational patterns to persist. The ability of dinoflagellate species to tolerate the vertical mixing of offshore, frontal zones, where abundant populations often develope, suggests that "pelagic seeding zones" occur, from which seed stock is recruited and dispersed, and may be as important as sediment "seed banks" of dinoflagellate resting cysts in providing seed stock, particularly for holoplanktonic species. I suggest that watermass stratification frequently noted to accompany flagellate blooms is often a secondary, parallel event less essential then than some other factor in triggering the observed bloom. Dinoflagellates and other flagellates generally may have evolved a biophysical tolerance to frequent, growth-promoting, water column disturbances, rather than depend exclusively upon the quiescent conditions of a stratified water column whose characteristic nutrient-poor conditions would promote stasis of the population, rather than growth-promotion.