Seasonal variation in total phenolic content of Dictyopteris polypodioides (Dictyotaceae) and Cystoseira amentacea (Sargassaceae) from the Sicilian coast

This study focuses on the differences in total phenolic content and its seasonal variations in two temperate brown algae, Cystoseira amentacea (C. Agardh) Bory and Dictyopteris polypodioides (A.P. De Candolle) J.V. Lamouroux, inhabiting respectively the infralittoral fringe and the upper infralittoral zone. Phenolic compounds are secondary metabolites, found in almost all brown algal orders, that function as defense against grazers, epiphytes and UV radiation. Total phenolic content was determined colorimetrically with the Folin-Ciocalteu reagent. Results showed significant differences in total phenol content between D. polypodioides and C. amentacea with higher values observed in the first one. Differences in the seasonal pattern of total phenolic content and in the period of maximum production were also observed between the two species. The observed differences could result from differences in morphology, life-cycle and bathymetric level.