Interspecific and temporal variation in phlorotannin levels in an assemblage of brown algae

We report here on a survey of phenolic contents in all seaweeds forming belts on a sheltered rocky shore in Brittany (France). Eight species of brown algae (7 Fucales and 1 Laminariales) were investigated over a 14-month period. Levels of phenolic compounds in members of the Fucales were generally above 2% DW and exceeded those found in the Laminariales by a factor of ten. The highest contents were found in species growing at mid-tide level, with a decrease above and below this shore level. There was a seasonal pattern, with a summer maximum for the Fucales and winter maximum for a member of the Laminariales.