The effect of benzalkonium chloride concentration on nine species of marine diatom

The effect of varying concentrations of benzalkonium chloride (BAK) on nine diatom species is measured, and related to the variation in tolerance levels of different species seen elsewhere in the literature. Different species showed different effective levels; however, all species were non-viable at 1×10−3% BAK. The technique being laboratory based and, therefore, immune from seasonal influences, is quick to perform and is easily adapted for bioassay work.