Size-specific concentrations of phlorotannins (anti-herbivore compounds) in three species of Fucus

Using the Folin-Denis assay, we demonstrated significant ( p < 0.05) differences in phlorotannin concentrations among large and small individuals of Fucus vesjculosus. This finding correlates with previously published differ- ences in grazing susceptibility among the 2 size-classes of plants. However, in 2 other species of Fucus (F. evanescens and spiralis), there were no significant differences ( p > 0.05) in phlorotannin concentrations among size-classes.