Herbivore-Algal relationships on a coastal rock platform (Cape Banks, N.S.W.)

Abstract

A fifty-three metre inter-tidal transect on a headland near Sydney, New South Wales, has been studied. Its profile, fauna and flora are illustrated and described.Figures were prepared indicating the herbivore standing crop on this transect at various seasons, and some evidence of seasonal changes in the marine algal flora is presented.All macroscopic herbivorous animals were removed from the transect at two-weekly intervals during a twelve month period. After the initiation of this treatment no species of alga in the transect appeared outside the zone in which it normally occurred. There was thus no indication that animal browsing normally restricts algae to particular (vertical) zones on this rock platform. The abundance of certain species was, however, affected by the removal of the herbivores. First to flourish were the green algae; contrary to results obtained in other parts of the world, brown algae did not then become established to form a climax community. It is suggested that the rapid reinvasion by herbivores noted at Cape Banks may account for differences in these results from those recorded elsewhere.Some algal taxonomic notes are appended.