Species-Area Relationship (SAR) models as tools for estimating faunal biodiversity associated with habitat builder species in sensitive areas: the case of the Mediterranean stony coral (Cladocora caespitosa)

Abstract

Biodiversity associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767) was investigated at three levels: "microscale", focused on macrobenthic invertebrates within colonies; "mesoscale", focused on epibenthic megafauna among colonies; "macroscale", focused on associated ichthyofauna. The aim was to quantify associated diversity in terms of species richness, testing the efficiency of colony size (surface covered by a single colony) for the "microscale", and colony density or total coral coverage for "meso-" and "macroscale" as predictors and the consistency of models based on Species-Area Relationship (SAR) for those estimations. At level of "microscale", colony size was a good predictor, with richness of invertebrates increasing with the increasing of surface covered by each colony of C. caespitosa, following Arrhenius model. At levels of "mesoscale" and "macroscale", richness of epibenthic megafauna and fish were not related neither to colony density nor total coral coverage, but to sampled area, and frequency-based estimates of richness were used. The importance of C. caespitosa varied according to the investigation level, with most of taxa richness detected at the level of "microscale".

Keywords: Benthos; Cladocora caespitosa; Habitat builder species; Ichthyofauna; Invertebrates; Mediterranean Sea; Species-Area Relationship (SAR).