Keywords: 
• Cu /
• Pb /
• Heterosigma akashiwo /
• maximum algae density /
• sustained growth time /
• specific growth rate

Abstract: The objective of this work was to identify the effects of two heavy metals (Cu and Pb) on the growth of Heterosigma akashiwo and the interaction effects between each other. Correlations between the maximum algae density, sustained growth time, the specific growth rate of algae and Cu or Pb treatments were studied by culturing Heterosigma akashiwo in f/2 medium supplemented with CuSO₄ and Pb(NO₃)₂ in different concentrations. The results indicated that the alga was promoted when either Cu was in 0-0.02 mg·L^-1 or Pb was in 0-0.32 mg·L^-1. Regardless of the concentration of Pb, the growth of Heterosigma akashiwo was significantly inhibited, or even unable to grow when the Cu concentration reached 0.5-2.5 mg·L^-1. Regardless of the concentration of Cu, the inhibitory growth effect of the alga was strengthened gradually with Pb concentration increased between 1 and 9 mg·L^-1. Cu or Pb or both of them had extremely significant effects on the maximum density and sustained growth time of algae when Cu concentration was 0-0.5 mg·L^-1 and Pb concentration was 1-9 mg·L^-1 (P<0.01). Cu and Pb did not have significant effect on the specific growth rate of Heterosigma akashiwo, and the interaction effect was not obvious either. The potential ecological effects of heavy metals in Zhanjiang Bay were further evaluated based on the actual contents of these two heavy metals reported in Zhanjiang Bay.