FIG 5.

Activity of C_i uptake systems of five Microcystis strains, inferred from O₂ evolution. The strains were acclimated to either low CO₂ levels (A to E) or high CO₂ levels (F to J). O₂ evolution was measured after addition of different concentrations of KHCO₃, NaCl, and LiCl to induce or block the activity of specific C_i uptake systems, as indicated in Table 1. Error bars indicate standard deviations (n = 4 biological replicates per treatment). Different letters above the bars indicate significant differences between the treatments, as tested by one-way analysis of variance with post hoc comparison of the means based on Tukey's HSD test (α = 0.05).