Community structure of nongeniculate coralline red algae (Corallinales, Rhodophyta) in three boulder habitats in southern Australia

Nongeniculate coralline red algae (NCA) (Corallinales, Rhodophyta) were exa mined in three boulder habitats in southern Australia. In total, 12 species were recorded; two [Mesophyllum engelhartii (Foslie) Adey and Sporolithon durum (Foslie) Townsend et Woelkerling] occurred at all three sites. Taylor Island was the most diverse locality (10 species), closely followed by Wes t Island (nine species); only three species were present at Willliamstown. The species-growth form relationships of the dominant species varied betwee n sites. Five growth forms were recognized: the encrusting growth form was dominant at all sites. An Ecklonia radiata (C. Agardh) J. Agardh (Phaeophyt a) canopy had a positive effect on the diversity of nongeniculate coralline red algae, but overall, percent cover was reduced. Smaller boulders, which were more likely to be overturned, supported higher cover than larger boul ders at two of the three sites.