Growth, nutrient and toxin characteristics of nutrient-limited cultures. Cell densities were recorded daily in nitrate- (A) and phosphate- (B) limited cultures of A. fundyense. Arrows indicate the day that samples were collected for MPSS analysis. After harvest, the cultures were enriched with the limiting nutrient and changes in cell number were monitored. Nutrient concentrations (open symbols) and toxin per cell (closed symbols) were also monitored daily in the nitrate- (C) and phosphate- (D) limited cultures.