This study investigates the effects of small-scale turbulence on the dynamics of ecdysal cysts and toxins in two Alexandrium species, *Alexandrium minutum* and *A. catenella*. The experiments were conducted using two levels of turbulent kinetic energy dissipation rates (ε = 0.4 and 27 cm² s⁻³) to simulate different turbulent conditions. The results show that high levels of turbulence significantly reduced the exponential growth rate and final biomass yield of both species, particularly when exposed for more than 4 days. Inhibition of ecdysal cyst production was observed immediately and during the period of exposure to stirring, with cyst abundances recovering upon the cessation of turbulence. The toxin content of *A. catenella* decreased significantly in cultures exposed to high turbulence, while *A. minutum* showed a trend towards lower toxin content. These findings suggest that high levels of small-scale turbulence can modulate the harmful bloom dynamics of dinoflagellates through the interaction between toxin production and cyst formation.This study investigates the effects of small-scale turbulence on the dynamics of ecdysal cysts and toxins in two Alexandrium species, *Alexandrium minutum* and *A. catenella*. The experiments were conducted using two levels of turbulent kinetic energy dissipation rates (ε = 0.4 and 27 cm² s⁻³) to simulate different turbulent conditions. The results show that high levels of turbulence significantly reduced the exponential growth rate and final biomass yield of both species, particularly when exposed for more than 4 days. Inhibition of ecdysal cyst production was observed immediately and during the period of exposure to stirring, with cyst abundances recovering upon the cessation of turbulence. The toxin content of *A. catenella* decreased significantly in cultures exposed to high turbulence, while *A. minutum* showed a trend towards lower toxin content. These findings suggest that high levels of small-scale turbulence can modulate the harmful bloom dynamics of dinoflagellates through the interaction between toxin production and cyst formation.