LACK OF SHORT-TERM INDUCTION OF PHLOROTANNINS IN THE AUSTRALASIAN BROWN-ALGAE ECKLONIA-RADIATA AND SARGASSUM-VESTITUM

I measured changes in phlorotannin (polyphenolic) levels in the Australian brown seaweeds Ecklonia radiata (Order Laminariales) and Sargassum vestitum (Fucales) following simulated herbivory. No significant changes in phlorotannin levels following damage were observed for either species over periods varying between 4 d and 8 wk. While there are few studies of inducible chemical defenses in seaweeds on which to base general conclusions, I suggest that because of predictable variation in the intensity of herbivory in benthic marine systems, inducible defenses in seaweeds may be relatively less important than persistent, constitutive defenses.