Multivariate patterns of algal sensitivity to chemicals in relation to phylogeny.

Species-dependent variations in algal sensitivity make predictions from conventional algal growth tests uncertain. The use of test batteries comprising several unialgal tests improves the predictive value drastically. To select the members for an optimal test battery is a multivariate problem. To be an efficient member of the battery a species should have a sensitivity pattern that is complementary to the other members. Sensitivity patterns were analyzed with a principal component method (SIMCA). Toxicity data for 19 chemical compounds and 16 microalgal strains were used as input in the analysis. Two separate groups with significantly different sensitivity patterns were recognized, belonging to Chlorococcales and Cyanophyta, respectively. No algal species, belonging to other taxa of Chlorophyta or to Xanthophyta, had sensitivity patterns that fitted into any of the two groups. It is concluded that the phylogeny of the algae is toxicologically relevant and as a tentative strategy for test battery design we suggest that a taxonomically wide range of algal species should be used.