The distribution and abundance of macroalgae growing on Avicennia mangrove pneumatophores is described for Woolooware Bay in Botany Bay, New South Wales, Australia. Sampling from a permanent transect was undertaken throughout a 13 month period. The algal species collected included those typical of the 'Bostrychia-Caloglossa Association' with Catenella nipae contributing the greatest biomass. Abundance, measured as dry weight of algae per pneumatophore, was variable with no clear seasonal pattern observed. On the basis of fluctuation in biomass throughout the year a minimum annual productivity of 87.5 g DW m ฯช2 y ฯช1 can be derived.
The distribution and abundance of the six epiphytic algae are described in relation to distance from shore. Total biomass was greatest at high levels on the shore though there were differences between species: Catenella nipae, Bostrychia tenella and Bostrychia moritziana were the most abundant algae on the upper shore, Bostrychia tenuissima on the lower shore, with Caloglossa leprieurii present throughout. Algal biomass was independent of the size and density of pneumatophores. Photosynthetically active radiation levels under the canopy were similar across the shore and no correlation was found with algal abundance.