Antipathella subpinnata (Ellis and Solander 1786) is one of the most frequently observed black corals at mesophotic depths (60–200 m) of the Mediterranean Sea, particularly in the northwestern part of the basin, where its populations can reach high densities and create forest-like aggregations, both along the coast and in offshore locations such as seamounts. Similar to other marine underwater forests, black coral gardens host a rich associated fauna and attract numerous species of commercial interest. As such, these corals are targeted by recreational and artisanal fisheries and are vulnerable to human impact due to their arborescent morphology and low growth rates. Genetic connectivity can provide valuable insight into the processes of population maintenance and replenishment following environmental disturbance and is often used as a proxy for population resilience. In our study, a restriction-site associated DNA analysis (2bRAD) was used to evaluate fine-scale population structure of the Mediterranean black coral A. subpinnata, and to understand which populations could serve as a potential source of genetic diversity for adjacent populations. Colonies from two offshore localities (a Ligurian seamount and a Tyrrhenian canyon) and four coastal populations from Liguria and Sicily were sampled and genotyped. Significant genetic differentiation was recorded between coastal and offshore localities. Moreover, offshore localities were genetically distinct from one another, while all coastal populations were characterized by panmixia. This indicates that offshore A. subpinnata gardens are potentially less resilient to human impact (i.e., demersal fishing activities) due to a limited influx of larvae from adjacent habitats. In addition, they are unlikely to supply coral propagules to coastal populations. Overall, this study highlights the vulnerability of Mediterranean A. subpinnata forests, and the importance of enforcing conservation and management measures to achieve Good Environmental Status (GES, EU Marine Strategy Framework Directive) of these valuable marine ecosystems.

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29Gorgonians play an important structural and functional role promoting high diversity 30and biomass of associated fauna. Up to now, studies on gorgonian ecology in the 31 Mediterranean Sea have been focused mainly on the SCUBA diving depth range. 32

This study aims to evaluate the presence of marine litter in relation to the main human activities and during some different meteorological conditions. Five surveys were performed along Boccasette spit to collect the stranded items, in order to assess the density of debris and the beach cleanliness. The main litter macro-category is represented by artificial polymer materials (96%), while the others macro-categories represent the 4% of collected items. The main sources of the marine litter have been attributed to improper waste disposal and fishing/aquaculture activities.

This correction is published as the electronic supplementary material was incorrectly published.Out of 13 Supplemental materials, 9 were correctly available (6 figures and 3 tables), 4 were missing. Figure legends of the Supplemental Figures (Fig. S1 to S6) also did not appear in the text.Original article has thus been updated.