Changes in distribution of macro-algal epiphytes on stems of the seagrass Amphibolis antarctica along a salinity gradient in Shark Bay, Western Australia

Sixty-six species of macro-algal epiphytes were recorded on the seagrass Amphibolis antarctica from 34 locations along a permanent hyper salinity gradient (38–60‰)in Shark Bay, Western Australia. Fifty percent of the species are endemic to southern temperate Australia. Species richness of epiphytic communities was negatively correlated with salinity (r = 0.84; P < 0.001). Diversity (Ho1) was less strongly correlated (r = 0.63; P = 0.003), as the evenness of the epiphytic communities had little to no correlation with salinity. The largest amount of total variation in epiphyte community structure from principal components analysis was significantly correlated with salinity. Cluster analysis of epiphytic species gave three major groups: species that have high relative abundances in areas of salinity greater than 50‰ but occur throughout the salinity range; species that only occur in areas with salinities less than 50‰;and species that show no relationship between their relative abundances and salinity