The role of annual macroalgal morphology in driving its epifaunal assemblages

• Epifaunal assemblages associated with annual macroalgae.
• Multiple morphological measures are needed to characterise macroalgal complexity.
• Landscape and taxon dispersion ability may influence epifaunal assemblages.
• Biomass and fractal area best predictors of epifaunal assemblages on macroalgae.

Coastal vegetated habitats harbour higher epifaunal abundance and diversity compared with non-vegetated habitats. In this study, intertidal annual macroalgae were used as model organisms to test the role of macroalgal morphology in driving the structure of their associated epifaunal assemblages. For this aim, 6 macroalgal species, apparently different in morphology, were sampled from two intertidal rocky shores to examine the effects of habitat morphology on the number of individuals, taxa richness and the structure of its associated epifaunal assemblages by means of univariate and multivariate techniques. To provide a complete overview of macroalgal morphology, biomass was used as a proxy of habitat quantity and fractal measures as proxies of habitat complexity. Results showed that almost all the studied pairs of macroalgae showed significant differences at least for one of the morphological measures used. Moreover, epifaunal assemblages showed significant differences between macroalgae mainly due to the different identities and relative abundance of epifaunal species. However, differences in the abundance and structure of assemblages were shore dependent, possibly due to the surrounding landscape heterogeneity. Finally, the quantity of habitat was a better predictor variable than fractal measures but fractal area was also important particularly for the abundance of the total assemblage and crustaceans.