Polyphenols from Stypopodium zonale (Phaeophyceae): Intrapopulational variation, induction by simulated herbivory, and epibiosis effects

• Induction of chemical defense in the macroalga Stypopodium zonale by simulated herbivory.
• Phlorotannin contents vary among individuals in the population of this macroalga.
• These chemicals can act as an effective antifouling.

Phlorotannins are exclusive chemical components of brown macroalgae active against herbivores and fouling, but several dynamic aspects of these chemicals remain underexplored or unexplored, such as intra-populational variability, response to wounding damage in tropical macroalgae, and correlation to levels of coverage by epibionts on the macroalgal surface. In this study, we investigated (i) the variation of phlorotannin content in response to artificial damage (induction experiments), (ii) the relationship between phlorotannin contents and epibiosis levels (low, medium, or high percentage of cover on the macroalga Stypopodium zonale), and (iii) the variation of phlorotannins content within-population of this tropical macroalga. Clipping elicited an increase in phlorotannin concentration only after 2 days. In addition, we detected higher phlorotannin concentrations in individuals exposed to low and medium epibiosis coverage and a lower concentration of these chemicals in individuals with a high level of epibiosis. We detected a broad variation in phlorotannin content among S. zonale individuals, from 0.63 to 3.24% (dry weight). These results suggest that the varying levels of phlorotannins found in the tropical macroalga S. zonale may result from different levels of exposure to herbivores in nature. Similarly, our results suggest that S. zonale phlorotannins may be effective antifoulants.