Distribution and diversity of epiphytic macroalgae in Digenea (Rhodophyta: Ceramiales) in a Caribbean rocky shore

Abstract

The diversity of epiphytic macroalgae in the intertidal rocky shore could be modulated by the zonation patterns of the host macroalgal thallus and the exposure to waves. This study characterized the spatial variation of the taxonomic and functional diversity of epiphytic macroalgae on the thallus of Digenea in the Caribbean intertidal rocky shore of Cuba. Alpha diversity was quantified by calculating species diversity (q0, q1, and q2) and functional diversity (CWM, Fric, FEve, FDiv, FDis). Changes in the structure (taxonomic and functional) were quantified using the Sorensen Index. On the thallus of Digenea, 21 epiphytic macroalgae with a dominance of rhodophytes were recorded. Based on frequency of occurrence, these epiphytes are characterized by the prevalence of rare species with erect and branched thalli, fast growth rates, and perennial longevity. The greatest taxonomic richness and diversity were observed in secondary branches and exposed environments. In contrast, the greatest diversity of functional traits was found in sheltered environments and secondary branches of the thallus. These findings suggest that species occupy different ecological niches that complement each other, avoiding competition and facilitating coexistence. There is a low taxonomic and functional dissimilarity between the assemblages, which, together with the similarity of the CWM values, is indicative of the functional convergence of macroalgal epiphytism in Digenea. Incorporating compositional and functional diversity analysis allowed the identification of patterns in the composition and structure of the epiphytic macroalgal assemblages.