Reproduction and establishment of Sargassum heterophyllum (Turner) C.Ag. (Phaeophyceae, Fucales)

Abstract

Algal communities of the intertidal rocky shore environment of the Natal coast of South Africa are commonly exposed to high wave-energy activity, together with biotic pressure from grazers. One of the more common members of this environment belongs to the genus Sargassum (Phaeophycae, Fucales). Members of this genus from Natal possess a morphological form which is streamlined, yet maximizes photosynthetic capacity. Under conditions of extreme battering from waves, the form may be dwarfed.

Sargassum possesses a haplobiontic, diploid type of life history; the dominant morph is the sporophyte and there is no alternation of generations. Meoitic gametogenesis results in oogamous union of gametes. These studies further outline the role of “incubation” (postfertilization retention) of the germinating zygote, on the receptacle surface. Germlings are only released from the parent at a stage when they possess sticky rhizoids for immediate attachment and a multicellular thallus which can grow rapidly, thereby increasing the potential for survival.