Tagged plants belonging to five algal species were measured regularly to determine seasonal growth patterns at Fancy Point, Tasmania. The standing crops of Sargassum bracteolosum J. Ag. and Caulocystis cephalomithos (Labill.) Aresch. were maximal in summer, but the denuded primary axes of Caulocystis continued to grow and reached their maximum annual lengths in autumn. Sargassum verruculosum (Mert.) C. Ag. grew most rapidly during summer and plants reached their maximum lengths in late autumn. Cystophora retroflexa (Labill.) J. Ag. grew continuously over several years with slight annual decreases in length in autumn. Zonaria turneriana J. Ag. also showed a minor decrease in size in autumn. Only a small proportion of tagged plants, however, survived longer than a year. Monthly sampling of the phytal animal assemblages associated with these algal species showed that the abundances of almost all animal species peaked in late summer-early autumn and faunistic differences between the erect algae were obscured at this time. This occurred independently of the phenologies of the macro-algae and corresponded closely to a seasonal epiphyte bloom. Predation pressure and epiphytic biomass are considered to influence directly fluctuations in phytal populations.