Grazers modify the dinoflagellate relationship between toxin production and cell growth

•Cellular toxin content of the dinoflagellate Alexandrium catenella during a laboratory-simulated bloom increased with time and plateaued after the stationary phase.•There was a significantly positive relationship between growth rate and constitutive toxin production, predominantly in the exponential phase.•Grazer-induced toxin production was evident throughout the bloom and greatest in the exponential phase.•Cell growth rate was negatively related to grazer-induced toxin production, consistent with a defense-growth trade-off.•The dynamics of cell growth vs toxin production are fundamentally different for constitutive and inducible defense.