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The distribution of floating litter in marine waters, influenced by currents and wind drag, often determines the dispersal of its encrusting fauna. In the present paper, we observed for the first time the colonization of rafting floats from abandoned, lost or derelict fishing gears (ALDFG) by the four protected deep-sea species: Errina aspera, Desmophyllum pertusum, Madrepora oculata Pachylasma giganteum. Overall, 41 floats, colonized by deep benthic species, were found stranded on the shore of the Sicilian coast of the Strait of Messina, between 2016 and 2019. Species composition, number and occurrence of colonizing organisms were analyzed. On the basis of the species composition (the association between E. aspera, P. giganteum and Megabalanus tulipiformis), the knowledge on their ecology, biogeography, path of local currents, it was possible to define that the area of origin of the most part of these fishing net floats was the Strait of Messina.

Vulnerable Marine Ecosystems (VMEs) are characterized by prominent biological features susceptible to anthropogenic disturbances. Following international guidelines, the identification and protection of VMEs require a detailed documentation regarding both the community structure and the fishing footprint in the area. This combined information is lacking for the majority of the Mediterranean mesophotic rocky reefs that, similarly to deep-seabottoms, are known to host valuable animal forests. A deep coralligenous site exploited by artisanal fishermen in the NW Mediterranean Sea is here used as a model to assess the vulnerability of animal forests at mesophotic depths and evaluate the sustainability of artisanal fishing practices, particularly lobster trammel net. The Remotely Operated Vehicle (ROV) footage is used to document the biodiversity and health status of the megabenthic communities, while discard data are employed to quantify the entanglement risk, discard rates of fragile species and threats to sea floor integrity. A multidisciplinary approach is proposed for the assessment of the vulnerability criteria of an EU Special Area of Conservation, leading to specific management measures, including the delineation of fishing restrictions.

This study presents a description of Bispira riccardi sp. nov., a new habitat-forming sabellid polychaete from the mesophotic NW Mediterranean Sea. Individuals, up to 20 cm long, show a peculiar morphology of radioles, thoracic uncini, companion chaetae and ventral shield of the collar. The phylogenetic position of this new taxon in the genus Bispira has been validated using nuclear (18S rRNA) and mitochondrial (COI) markers. Aggregations of B. riccardi sp. nov. were found by ROV on horizontal muddy bottoms between 56 and 85 m, in areas subjected to high trophic inputs. Patches are fragmented and dense (up to 943 individuals m 2) probably accounting for various hectares. A 5-days continuous monitoring, carried out using an autonomous lander, revealed that the contraction of the branchial crown was positively affected by temperature and current, rapidly responding to meteorological events. The filtering activity and high density of these fields suggest a considerable impact on the pelagic-benthic coupling and the amount of organic matter in the sediments. Indeed, meiofaunal abundance and diversity within the aggregations resulted significantly higher than in outer stations. These findings highlight the undisclosed potential of the deep Mediterranean Sea for sabellid diversity and their importance as habitat-forming species on mesophotic soft bottoms.

On marine rocky shores, several physical, chemical and biological processes operate to maintain the benthic assemblages’ heterogeneity, but among the abiotic factors, the composition and texture of the rocky substrata have been only sporadically considered. However, biomineralogical studies have demonstrated an unsuspected ability of the benthic organisms to interact at different levels with rocky substrata. Therefore, the mineralogy of the substratum can affect the structure of benthic communities. To evaluate this hypothesis, the macrobenthic assemblages developed on two different ophiolitic rocks (serpentinites and metagabbros) in contact at a restricted stretch of the western Ligurian Riviera (western Mediterranean Sea), with identical environmental and climatic conditions, were analysed. Samplings were carried out at four bathymetric levels (+1m, 0m, -1m, and -3m respect to the mean sea level) and the analysis of the data evidenced differences in terms of species distribution and percent coverage. Algal communities growing on metagabbros were poorer in species richness and showed a much simpler structure when compared to the assemblages occurring on the serpentinites. The most widely distributed animal organism, the barnacle Chthamalus stellatus, was dominant on serpentinites, and virtually absent on metagabbros. Our results suggest a complex pattern of interactions between lithology and benthic organisms operating through processes of inhibition/facilitation related to the mineral properties of the substratum.

A new index of ecological status, named Mesophotic Assemblages Ecological Status (MAES) index, was elaborated on the basis of ROV (Remotely Operated Vehicle) photography and video footage in order to assess the status of mesophotic megabenthic assemblages from hard bottom. The index was tested on seven sites located between 50 and 150 m depth in the Ligurian and Tyrrhenian seas (western Mediterranean Sea). The MAES index considers three main parameters: (i) the community structure (number of megabenthic taxa, percent biotic cover in the basal layer, density of erect species); (ii) the condition of the dominant erect species (average height, percent of colonies with epibiosis/necrosis); (iii) the visible human impact (density of marine litter, including lost fishing gears). Two versions of the index have been elaborated, the complete version (MAES) and the quick version ( q -MAES), which showed comparable results, therefore suggesting the possibility of fastening assessment times. The sensitivity of the MAES index was correlated with the putative human pressure acting upon the site (semi-quantitatively assessed considering fishing effort and coastal urbanization). A standard working protocol related to the evaluation of the MAES index is here proposed with the intent to create an effective monitoring tool for the assessment of the ecological status of mesophotic assemblages on a large scale, as required by the EU Marine Strategy Framework Directive. MAES index will enhance the comprehension of the dynamics of mesophotic Mediterranean megabenthic assemblages with respect to human pressures and will also provide marine scientists and managers with a valuable tool specifically designed for the conservation of such vulnerable marine ecosystems.

The gorgonians Paramuricea clavata (Risso, 1826) and Eunicella cavolini (Koch, 1887) are important habitat-forming species within the Mediterranean coralligenous habitats, creating complex, three-dimensional forests that greatly contribute to the underwater landscape of the coastal hard grounds. Dense forests of both species are present within the Portofino Marine Protected Area (Ligurian Sea, NW Mediterranean Sea), showing a distinct bathymetric separation and site-specific differences. Quantitative evidences obtained with a monitoring census conducted in 2016 in 16 sites within the MPA support the existence of a widespread damage on these populations partially due to the mechanical injuries inflicted by recreational and professional demersal fishing gears. Considering all the studied populations, it resulted that 53% of the colonies of P. clavata and 36% of the colonies of E. cavolini were showing traces of impact, of which 10% in P. clavata and 7% in E. cavolini were due to direct entanglements with lost longlines. In the last decades, recurrent massive mortalities related to temperature anomalies and storms, have greatly reduced the gorgonian populations in this area and fishing impact severely affects survived or recovering colonies. Considering the vulnerable status of these species, and the increasing stress due to climate change, a correct management of the anthropic pressures is strongly needed to help preserving these relevant ecosystems.

Trophic relationships significantly influence ecosystem functioning, ultimately affecting populations’ abundance, size structure and distribution. There is still a substantial knowledge gap on the trophic ecology of deep-sea organisms, particularly those living in the mesophotic depths (30–150 m), despite their crucial importance as ecosystem engineers. The trophic ecology of the most common mesophotic black coral species of the Mediterranean Sea, Antipathella subpinnata (Ellis & Solander, 1786), was studied by means of stable isotopes analysis in two seasons. The δ13C and δ15N analysis of the tissue of A. subpinnata, of the sediment, as well as the main planktonic fractions (pico-nanoplankton, microplankton, and mesozooplankton) indicate a diet based on pico-nanoplankton in autumn and mesozooplankton in spring. We calculated a trophic enrichment of 1‰ in δ13C and of 2.5‰ δ15N between prey and predator. Such information contributes towards drawing a complete picture of the pelagic-benthic coupling in the Mediterranean mesophotic coral forests.

Deep-water fishing activities are impacting deep-water habitats worldwide, yet the extent of the damage caused is mainly unseen and not quantified. We used Remotely Operated Vehicle surveys to assess the extent of fishing impacts on rocky substrata on four offshore banks between 70 and 280 m depth in the Mediterranean Sea. Video analysis of the abundance and diversity of megafauna revealed communities dominated by arborescent cnidarian passive suspension feeders at all studied depth ranges. Between 19% and 62% of the video frames showed clear impacts from lost debris, the majority of which is ascribable to both professional and recreational fishing activities and the occurrence of fishing impact is generally correlated with the presence of entangled and overgrown corals. Broken coral colonies and strips where habitat-forming species were scattered provided additional evidence of widespread fishing disturbance. These data evidence the widespread impact of fishing activities on benthic hard bottom communities and suggest the need of specific conservation measures in coastal and off-shore management plans at both local and national levels in order to protect unique ecosystems that are progressively disappearing even before being studied.

Until now, there is a lack of knowledge about the presence of chitin in numerous representatives of corals (Cnidaria). However, investigations concerning the chitin-based skeletal organization in different coral taxa are significant from biochemical, structural, developmental, ecological and evolutionary points of view. In this paper, we present a thorough screening for the presence of chitin within the skeletal formations of a poorly investigated Mediterranean black coral, Parantipathes larix (Esper, 1792), as a typical representative of the Schizopathidae family. Using a wide array variety of techniques ( 13 C solid state NMR, Fourier transform infrared (FTIR), Raman, NEXAFS, Morgan-Elson assay and Calcofluor White Staining), we unambiguously show for the first time that chitin is an important component within the skeletal stalks as well as pinnules of this coral.