DOI: 10.5281/zenodo.10036230
title: Coralligenous cliffs' diversity patterns

description: The repository contains raw data coralligenous cliffs' structures, environmental, and connectivity dataset used for the analysis carried out for the manuscropt entitled "Structure and diversity patterns of coralligenous cliffs across three ecoregions in the Central-Western Mediterranean Sea".
Coralligenous reefs are the main marine bioconstructions in terms of spatial distribution within the Mediterranean basin. When occurring on sub-vertical slopes (cliffs), they develop between approximately 20 and 50 m depth. Despite their importance for monitoring and conservation efforts, observations regarding the variability of biogeographical patterns are scarce. In this manuscript, we aimed to assess the differences in the composition and structure of these cliffs across ecoregions and estimate the relative role of abiotic environmental features, geographic location, and connectivity in shaping diversity patterns. The study was carried out in the Central-Western Mediterranean Sea. Samples were collected in 3 Sampling Unit at 65 sites across the Algero-Provençal Basin, Ionian Sea, and Tyrrhenian Sea. We assessed the composition and structure of coralligenous cliffs through photographic samplings collected by scuba divers: algae and sessile invertebrates were identified and percentage cover was calculated. Patterns in α- and β-diversity were associated with 9 abiotic environmental variables, a latitudinal and longitudinal gradient, and connectivity measures using Generalized Additive (GAM) and Conditional Autoregressive (CAR) models. Coralligenous cliffs were primarily composed of algae and displayed a high degree of variability. The Partition Around Medoids (PAM) clustering method successfully delineated seven distinct clusters with a non-uniform distribution within the studied ecoregions. Observations differed across ecoregions. The α-diversity displayed both latitudinal and longitudinal patterns. Temperature and nutrient concentration significantly affected both α- and β-diversity. The CAR model showed that β-diversity increased within connected sites. Coralligenous cliffs diversity responds both to the physico-chemical features of the habitat and between-habitats connectivity. However, our findings suggest that small-scale abiotic and biotic processes could contribute to explaining the variability observed. These findings can significantly enhance the monitoring and conservation efforts of this Mediterranean endemic ecosystem.
The repository contains 3 dataset: "Assemblage_dataset.csv" --> percentage cover of the 36 sessile taxa/taxonomical-morphological groups used to characterized the coralligenous cliffs in each of the 195 Sampling Units (SUs). "Environmental-Connvectivity_parameters.csv" --> Coordinates, values of the 9 environmental parameters, and number of connectivity cluster as identified by Andrello et al. (2015; https://doi.org/10.1111/ecog.00975) for each SUs. "Taxa:ID_morpho-groups.xls" --> List of the 36 sessile taxa/taxonomical-morphological groups with their relative IDs, as named in "Assemblage_dataset.csv", and the morpho-functional category they belong to.