Abstract

An understanding of the life history of Laminaria digitata is crucial to implementing efficient management practices that can ensure the persistence of the kelp forest. L. digitata shows an obligate haplo-diplont heteromorphic life cycle with alternation of a large sporophyte and dioecious microscopic gametophytes. The study of growth and reproduction in culture conditions demonstrated different strategies in male and female gametophytes: Males grew vegeta- tively and reproduced simultaneously, whereas females stopped growing after reproduction. In addition, we demonstrated that males were able to fragment to give new gametophyte individuals. These results suggest that male and female gametophytes have developed two contrasting reproductive strategies with semelparous females and iteroparous males enhancing the reproductive success of the species.