Fig 7.

Aggregation is dependent on divalent cations. (A) Aggregation in artificial seawater is inhibited by the addition of EDTA and EGTA (right) compared to that for the untreated control (left). (B) Dose-dependent effect of calcium and magnesium on aggregation, showing increasing aggregation with increasing concentrations of calcium or magnesium. Points and error bars represent the means and standard errors, respectively, of four independent aggregation reactions. A value of 100% is aggregation of all algal cells.