Structure and biodiversity of coralligenous assemblages dominated by the precious red coral Corallium rubrum over broad spatial scales

Abstract

Data on species diversity and structure in coralligenous outcrops dominated by Corallium rubrum are lacking. A hierarchical sampling including 3 localities and 9 sites covering more than 400 km of rocky coasts in NW Mediterranean, was designed to characterize the spatial variability of structure, composition and diversity of perennial species inhabiting coralligenous outcrops. We estimated species/taxa composition and abundance. Eight morpho-functional groups were defined according to their life span and growth to characterize the structural complexity of the outcrops. The species composition and structural complexity differed consistently across all spatial scales considered. The lowest and the highest variability were found among localities (separated by >200 km) and within sites (separated by 1–5 km), respectively supporting differences in diversity indices. The morpho-functional groups displayed a consistent spatial arrangement in terms of the number, size and shape of patches across study sites. These results contribute to filling the gap on the understanding of assemblage composition and structure and to build baselines to assess the response of this of this highly threatened habitat to anthropogenic disturbances.

Coralligenous formations dominated by Eunicella cavolini (Koch, 1887) in the NE Mediterranean: biodiversity and structure

“…This observation is in agreement with previous reports regarding other regions of the Aegean Sea and the rest of the Mediterranean, which suggest that due to the higher water temperatures and more oligotrophic conditions, large anthozoans are usually limited to deeper waters (Pérès & Picard, 1958;Laborel, 1960;Zabala & Ballesteros, 1989;Salomidi et al, 2009). The total number of taxa (including both perennial and seasonal) recorded in the Aegean is comparable to the total numbers reported from coralligenous assemblages dominated by the red gorgonian Paramuricea clavata in the Central and Northern Adriatic (Kipson, 2013) and the NW Mediterranean (Kipson et al, 2011; et al, 2015), as well as those dominated by the red coral Corallium rubrum in the NW Mediterranean (Kipson et al, 2011;Casas-Güell et al, 2016). Regarding perennial species alone (which represent the core community of coralligenous assemblages), a low variability was observed both at the level of sites (range: 23-33 taxa) and at the level of localities (range: 52-58 taxa).…”

STAR: An integrated and standardized procedure to evaluate the ecological status of coralligenous reefs

“…Coralligenous assemblages show a homogeneous structure when subjected to similar environmental conditions, at least within the same geographic area (Casas‐Güell et al, ; Casas‐Güell, Teixidó, Garrabou, & Cebrian, ; Piazzi et al, ). They are thus characterized by low variability at spatial scales between hundreds of metres to kilometres, while variability at smaller spatial scales (from metres to tens of metres) is usually high (Abbiati et al, ; Balata et al, ; Balata et al, ; Ferdeghini et al, ; Piazzi et al, , ).…”

“…Thus, the β‐diversity of assemblages may be considered a valuable indicator of human pressure on coralligenous reefs (Balata, Piazzi, & Benedetti‐Cecchi, ; Piazzi et al, ; Ponti, Falace, et al, ). β‐diversity, in general, can be calculated through different methods (Gray, ); in the case of coralligenous assemblages, variability of species composition among sampling units (heterogeneity of assemblages) has been measured in terms of multivariate dispersion calculated on the basis of distance from centroids (Casas‐Güell et al, ; Casas‐Güell et al, ; Cecchi et al, ; Piazzi, Gennaro, et al, ) through permutational analysis of multivariate dispersion (PERMDISP; Anderson, ). Thus, any changes in compositional variability displayed by PERMDISP may be directly interpretable as changes of β‐diversity (Anderson, Ellingsen, & McArdle, ).…”

Sharing and Distinction in Biodiversity and Ecological Role of Bryozoans in Mediterranean Mesophotic Bioconstructions

“…Indeed, the bioconstructions here investigated are in poor light availability conditions, which are shared with the coralligenous and coastal detritic. Therefore, contrary to differences in the primary bioconstructors (calcareous algae vs. animals), both coralligenous and mesophotic habitats share a similar complex substrata, where the presence of heterogeneous surfaces rich in interstices and crevices offer a wide range of microhabitats suitable for the bryozoans (Harmelin, 1985;Ferdeghini et al, 2001;Ballesteros, 2006;Casas Güell et al, 2016). In particular, in the investigated mesophotic habitats, the highest number of bryozoan species is shared with the coralligenous (40% of species) and the detritic bottoms (30% of species); intermediate numbers of species are shared with hard bottoms and both shallow shelf and sciaphilic habitats (25-12% of species); finally, a small number of species (<10%) shows ecological affinity for other habitats, such as Posidonia meadow and deepwater coral banks.…”