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Cold-water corals (CWCs) are bioengineering species that can increase habitat heterogeneity and improve the deep sea’s biological diversity and ecosystem functioning. Knowledge of their distribution provides a critical baseline for assessing the effect of natural and anthropogenic impacts on these important deep-sea habitats. The aims of this study are: i) provide new data on the spatial distribution of six CWCs species in the Strait of Sicily, ii) describe the principal environmental and anthropogenic variables that play a role in shaping their distribution, iii) identify hotspots in which individuals belonging to the various species co-occur. Presence-only data of six CWCs species, ten environmental variables (depth, slope, rugosity, aspect, flowdir, temperature, salinity, north bottom current, east bottom current, chlorophyll-a), and one variable relating to bottom trawling effort (Automatic Information System – AIS) were used to predict the suitable habitats. We used Maximum Entropy modelling (MaxEnt) approach and used the AUC (area under the receiver operating characteristic curve) and TSS (true skill statistics) to evaluate the model performance. The results showed excellent AUC, TSS and AUC’s standard deviation mean values for all six species. The validation show high predictive performance. MaxEnt identified slope, depth, and rugosity as the most important predictors, showing the highest percentage contribution for all six species considered. Throughout the study area, highlyinterspecific persistent density hotspot of CWCs co-occurrence were discovered, with a total extension of 4.05 km2 where all species co-occur. Although studies on the effect of environmental and anthropogenic factors that impact the distribution of these species of conservation interest remain scarce, the results of this study offer useful guidance for decision-makers to develop necessary conservation measures. [ABSTRACT FROM AUTHOR]

Dendrophyllia ramea is a poorly known arborescent scleractinian coral, whose worldwide distribution is limited to the southern part of the Mediterranean basin, and to the Atlantic Ocean between Macaronesia and Gulf of Cadiz. The geographical distribution and abundance of D. ramea were herein updated, considering a total of 19 records, seven of which have never previously been reported in scientific papers.Between 2010 and 2017, five Remotely Operative Vehicle surveys carried out along the Sicilian coast recorded 89 colonies. No exhaustive data on density and ecology of this species have been published to date. Data for two areas off the north‐eastern Sicilian waters (Aeolian Island and Gulf of Patti) are reported, including the species' bathymetric distribution, abundance, population density, colony morphometry, population size structure and surrounding habitat description.Size structure and density of D. ramea populations were compared with lost fishing gear density. Around the Aeolian Islands, where little lost fishing gear was observed, the D. ramea population was denser compared with the populations at two sites within the Gulf of Patti, where a greater amount of lost fishing gear was observed. The analysis of D. ramea size classes (single corallite, 2–5 polyps, >5 polyps) at different sites showed that impact varied with fishing gear typology: while lines damage the branches of larger colonies, nets can completely remove them.The limited distribution of D. ramea in some areas also makes this species very vulnerable to impacts such as changes in the chemical–physical characteristics and circulation of sea water. Dendrophyllia ramea is classified as 'Vulnerable' according to the Mediterranean IUCN Red List, and it is listed in the Barcelona Convention (Annex B). Data on the distribution of D. ramea allows us to review the species' classification and propose that its status be changed to 'Endangered'. [ABSTRACT FROM AUTHOR]

Commercially harvested since ancient times, the highly valuable red coral Corallium rubrum (Linnaeus, 1758) is an octocoral endemic to the Mediterranean Sea and adjacent Eastern Atlantic Ocean, where it occurs on rocky bottoms over a wide bathymetric range. Current knowledge is restricted to its shallow populations (15-50 m depth), with comparably little attention given to the deeper populations (50-200 m) that are nowadays the main target of exploitation. In this study, red coral distribution and population structure were assessed in three historically exploited areas (Amalfi, Ischia Island and Elba Island) in the Tyrrhenian Sea (Western Mediterranean Sea) between 50 and 130 m depth by means of ROV during a cruise carried out in the summer of 2010. Red coral populations showed a maximum patch frequency of 0.20 ± 0.04 SD patches·m−1 and a density ranging between 28 and 204 colonies·m−2, with a fairly continuous bathymetric distribution. The highest red coral densities in the investigated areas were found on cliffs and boulders mainly exposed to the east, at the greatest depth, and characterized by medium percentage sediment cover. The study populations contained a high percentage (46% on average) of harvestable colonies (>7 mm basal diameter). Moreover, some colonies with fifth-order branches were also observed, highlighting the probable older age of some components of these populations. The Ischia population showed the highest colony occupancy, density and size, suggesting a better conservation status than the populations at the other study locations. These results indicate that deep dwelling red coral populations in non-stressed or less-harvested areas may diverge from the inverse size-density relationship previously observed in red coral populations with increasing depth. [ABSTRACT FROM AUTHOR]

In this study we characterized the deep assemblages dwelling at 200-250 m depth on a large shoal off Capo St. Vito Promontory ( Northwestern coast of Sicily, South Tyrrhenian Sea) by means of ROV-imaging. Two assemblages of suspension feeders, dominated by the gorgonian Callogorgia verticillata and by the black coral Leiopathes glaberrima, together with a tanatocoenosis of the colonial yellow scleractinian coral Dendrophyllia cornigera, were examined. The three main species were significatively distributed into two areas corresponding to different habitat preferences: a more elevated hardground hosting black corals and a gently sloping, silted rocky bottom hosting the other coral species. The study area is subjected to a heavy pressure from the professional fishery, resulting in the mechanical damage of numerous colonies, some of which are then overgrown by various epibionts including a parasitic bioluminescent zoanthid, new for the Mediterranean fauna, and tentatively identified as Isozoanthus primoidus. In the Mediterranean Sea, these deep off-shore rocky banks are widely known among recreational and professional fishermen due to their rich fish fauna. However, there has been still little effort into quantifying and characterizing the extent of the impact and its consequences on the benthic communities, which may represent, as in this case, only a partial picture of their original structure and extent. [ABSTRACT FROM AUTHOR]