Description of two new genera and two new species of antipatharian corals in the family Aphanipathidae (Cnidaria: Anthozoa: Antipatharia).

Two new genera and two new species of black corals are recognized in the family Aphanipathidae. The new genus Anozopathes, with the species A. hawaiiensis sp. nov. and A. palauensis, sp. nov. is characterized by a sparsely and irregularly branched corallum with relatively long branches which can be straight, curved or crooked. The genus Aphanostichopathes, with the type species Cirripathes paucispina Brook, is characterized by an unbranched corallum with a long, curved stem with loose distal coils. Mitochondrial DNA data (nad5-IGR-nad1 for Anozopathes and cox3-cox1 for Aphanostichopathes) indicate that both taxa are related to the genera Aphanipathes, Phanopathes and Acanthopathes in the family Aphanipathidae, and morphologically they both share the characteristic of having spines with distinct conical tubercles. The two new species of Anozopathes are separated primarily by differences in colony growth form and in the size and shape of the skeletal spines. Species of Aphanostichopathes are separated primarily by differences in the size and shape of the spines and by size and density of the tubercles on the surface of the spines.

Fate of lost fishing gears: Experimental evidence of biofouling colonization patterns from the northwestern Mediterranean Sea.

ALDFGs (abandoned, lost or otherwise discharged fishing gears) represent a major pollutant in the world's oceans, including the Mediterranean Sea, but very little is known about their long-term fate in the underwater environment. Here we investigate the destiny of ALDFGs in a coralligenous benthic community by studying the biofouling growing on them at 30 m depth over a three-year period. Results indicate that ALDFGs are quickly covered by biofouling, reaching maximum values of cover in one year. At this depth, the biofouling community results highly influenced by light-dependent seasonal cycles and a general four-steps colonization scheme is tentatively depicted: i) biofouling community is initially dominated by fast-growing organisms, with algae and hydrozoans settling after two weeks; ii) small-sized carbonatic organisms (e.g. bryozoans) appear after two months; iii) the same organisms (including coralline algae) become abundant after five to eight months; iv) conspicuous carbonatic skeletons (serpulids, bivalves and bryozoans) occur after one year increasing in complexity in the following months. The biofouling settled on ALDFGs, as well as growth rates of large carbonatic species, could provide useful information to estimate the age of lost lines and nets in retrieved material and in situ photo footage complementing the overview of the fishing impact in this specific environment. Finally, no signs of nylon degradation are reported, suggesting that the prevailing physical conditions and the biofouling cover extent could alter microplastics release from nylon ALDFGs.

Local Conditions Influence the Prokaryotic Communities Associated With the Mesophotic Black Coral Antipathella subpinnata.

Black corals are important habitat-forming species in the mesophotic and deep-sea zones of the world's oceans because of their arborescent colony structure and tendency to form animal forests. Although we have started unraveling the ecology of mesophotic black corals, the importance of the associated microbes to their health has remained unexplored. Here, we provide in-depth assessments of black coral-microbe symbioses by investigating the spatial and temporal stability of these associations, and make comparisons with a sympatric octocoral with similar colony structure. To this end, we collected samples of Antipathella subpinnata colonies from three mesophotic shoals situated along the Ligurian Coast of the Mediterranean Sea (Bordighera, Portofino, Savona) in the spring of 2017. At the Portofino shoal, samples of A. subpinnata and the gorgonian Eunicella cavolini were collected in November 2016 and May 2017. Bacterial communities were profiled using 16S rRNA gene amplicon sequencing. The bacterial community of E. cavolini was consistently dominated by Endozoicomonas. Contrastingly, the black coral microbiome was more diverse, and was primarily composed of numerous Bacteroidetes, Alpha- and Gammaproteobacterial taxa, putatively involved in all steps of the nitrogen and sulfur cycles. Compositional differences in the A. subpinnata microbiome existed between all locations and both time points, and no phylotypes were consistently associated with A. subpinnata. This highlights that local conditions may influence the bacterial community structure and potentially nutrient cycling within the A. subpinnata holobiont. But it also suggests that this coral holobiont possesses a high degree of microbiome flexibility, which may be a mechanism to acclimate to environmental change.

Shallow-water black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia) from SW Madagascar.

Antipatharians, also known as black corals, represent a small group of anthozoan hexacorallians found in all oceans of the world. They are generally considered a deep-water taxon; however, some of the most diverse communities are known from tropical shallow waters. With a few poorly detailed exceptions, shallow-water black corals from the Indian Ocean and especially those from Madagascar are mostly unknown. In this study, we report for the first time a highly diverse black coral assemblage of the Western Indian Ocean thriving in shallow waters and upper mesophotic depths (10-52 m depth) along the SW coast of Madagascar. A total of 22 species belonging to six genera (Antipathes, Arachnopathes, Cirrhipathes, Cupressopathes, Myriopathes and Stichopathes) and two families (Antipathidae and Myriopathidae) are described, of which 20 are found in the northern pass of the Great Reef of Toliara, thus representing the most diverse site of the areas investigated. Most of the shallow-water species from the Indian Ocean were originally described more than a century ago, sometimes without being reported again until now. All the descriptions herein rely solely on morphology and include detailed in situ pictures and scanning electron microscope images, in addition to range expansions for many species.

Electrochemical Approach for Isolation of Chitin from the Skeleton of the Black Coral Cirrhipathes sp. (Antipatharia).

The development of novel and effective methods for the isolation of chitin, which remains one of the fundamental aminopolysaccharides within skeletal structures of diverse marine invertebrates, is still relevant. In contrast to numerous studies on chitin extraction from crustaceans, mollusks and sponges, there are only a few reports concerning its isolation from corals, and especially black corals (Antipatharia). In this work, we report the stepwise isolation and identification of chitin from Cirrhipathes sp. (Antipatharia, Antipathidae) for the first time. The proposed method, aiming at the extraction of the chitinous scaffold from the skeleton of black coral species, combined a well-known chemical treatment with in situ electrolysis, using a concentrated Na2SO4 aqueous solution as the electrolyte. This novel method allows the isolation of α-chitin in the form of a microporous membrane-like material. Moreover, the extracted chitinous scaffold, with a well-preserved, unique pore distribution, has been extracted in an astoundingly short time (12 h) compared to the earlier reported attempts at chitin isolation from Antipatharia corals.

Assessment and distribution of seafloor litter on the deep Ligurian continental shelf and shelf break (NW Mediterranean Sea).

Litter has become a common component of marine ecosystems, and its assessment and monitoring are now of primary interest. Here, we characterized seafloor litter in the mesophotic depth range of the Ligurian Sea, one of the most urbanized basins of the Mediterranean Sea. Eighty sites (30-220 m depth) were investigated by by means of ROV video transects. Data regarding environmental parameters and anthropic pressures were used to explain the distribution of human-derived objects. Litter resulted widely distributed in all the investigated areas, with maximum densities of 7900 items ha-1. It was mainly represented by abandoned fishing gears, with highest abundances found on the deep coastal rocky shoals exploited by artisanal and recreational fishermen. Urban litter, primarily represented by plastics, was generally higher close to shore, especially near river mouths and large harbors. Litter densities reported here are among the highest ever recorded in Europe, denoting the urgency for specific actions to prevent further spreading.

The sponge fauna of the Seno Magdalena and Puyuhuapi Fjord (Chile), with a description of two new species.

The presence of fjords, islands and channels originating from glacial erosion and ice cap retreat, makes the Chilean benthic biodiversity difficult to explore and study. Our survey of this region allowed the identification of 29 Demospongiae species in total. Two of them are new to science and here described: Biemna lutea sp. nov., and Hamigera cleistochela sp. nov.. Two species (Clathria (Clathria) microxa and Lissodendoryx (Ectyodoryx) patagonica,) are new for the region and the Chilean fjords. Lissodendoryx (Ectyodoryx) patagonica was found for the second time after the original description by Ridley Dendy, 132 years ago. These results - considering the small number of species identified on the whole - are promising and confirm that the marine biodiversity of Chilean fjords is remarkable but not well known yet.

Megabenthic communities of the Ligurian deep continental shelf and shelf break (NW Mediterranean Sea).

The Ligurian Sea is one of the most studied Mediterranean basins. Since the beginning of the last century, many research expeditions have characterized its benthic and pelagic fauna through scuba diving and trawl surveys. However, a large knowledge gap exists about the composition of benthic communities extending into the so-called mesophotic or twilight depth range, currently under intense pressure from commercial and recreational fishing. A series of visual surveys, carried out by means of remotely operated vehicles between 2012 and 2018, were conducted along the Ligurian deep continental shelf and shelf break, between 30 and 210 m depth, in order to characterize the main benthic biocoenoses dwelling at this depth range and to determine the most relevant environmental factors that explain their spatial distribution. Deep circalittoral communities of the Ligurian Sea were represented by a mixture of species belonging to the deepest extension of shallow-water habitats and deep circalittoral ones. Twelve major biocoenoses were identified, each one characterized by specific preferences in depth range, substrate type and seabed slope. Those biocoenoses included gorgonian and hydrozoan forests, dense keratose sponge grounds, Dendrophyllia cornigera gardens, bryozoan beds and soft-bottom meadows of sabellid polychaetes and soft-corals. Other less common aggregations included six forests of black corals and two populations of Paramuricea macrospina. A georeferenced database has been created in order to provide information to managers and stakeholders about the location of the identified communities and high-diversity areas, aiming to facilitate sustainable long-term conservation of the Ligurian benthic ecosystem.

Colonization of floats from submerged derelict fishing gears by four protected species of deep-sea corals and barnacles in the Strait of Messina (central Mediterranean Sea).

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.

Mediterranean Bioconstructions Along the Italian Coast.

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.

Exceptional discovery of a shallow-water hydrothermal site in the SW area of Basiluzzo islet (Aeolian archipelago, South Tyrrhenian Sea): An environment to preserve.

The geological, biological and geochemical features of a particular field of hydrothermal vents, discovered in the Panarea Volcanic Complex during a research survey carried out in 2015, are described for the first time. The site, located at 70-80 m depth off the South-western coast of the islet of Basiluzzo, was named Smoking Land for the presence of a large number of wide and high active chimneys and was characterized in terms of dissolved benthic fluxes, associated macrofauna and megafauna communities and preliminary mineralogy and geochemistry of chimney structures. On the whole field, a total of 39 chimneys, different in size and shape, were closely observed and described; 14 of them showed emission of low temperature hydrothermal fluids of marine origin characterized by acidified chemical conditions. The CTD and benthic chamber measurements highlighted that the Smoking Land is able to form a sea water bottom layer characterized by variable acidity and high DIC and trace elements concentrations; these characteristics weaken moving away from the chimney mouths. The SEM-EDS analysis of the collected solid samples revealed a chimney structure principally composed by amorphous and low crystalline Fe-oxyhydroxides of hydrothermal origins. The ROV explorations revealed a wide coverage of red algae (Peyssonnelia spp.) colonized by the green algae Flabiella petiolata and by suspension feeders, mainly sponges, but also bryozoans, and tubicolous polychaetes. Although novent-exclusive species were identified, the benthic communities found in association to the chimneys included more taxa than those observed in the surrounding no-vent rocky areas. These first findings evidence a submarine dynamic habitat where geological, chemical and biological processes are intimately connected, making the Smoking Land an important site in terms of marine heritage that should be safeguarded and protected.

Habitat constraints and self-thinning shape Mediterranean red coral deep population structure: implications for conservation practice.

The Mediterranean red coral, Corallium rubrum, is one of the most precious corals worldwide. Below 50 m depth, C. rubrum populations are generally characterised by large and sparse colonies, whereas shallow populations (above 50 m depth) show high densities of small colonies. We show here instead that populations dwelling between 80 and 170 m depth exhibited a continuous range of population density (from 2 to 75 colonies per 0.25 m(2)), with less than 1% of variance explained by water depth. An inverse relationship between maximum population density and mean colony height was found, suggesting that self-thinning processes may shape population structure. Moreover, demographically young populations composed of small and dense colonies dominated along rocky vertical walls, whereas mature populations characterised by large and sparsely distributed colonies were found only in horizontal beds not covered by sediment. We hypothesise that, in the long term, shallow protected populations should resemble to present deep populations, with sparsely distributed large colonies. Since the density of red coral colonies can decay as a result of self-thinning mechanisms, we advise that future protection strategies should be based also on a measure of red coral spatial coverage instead of population density.

Persistence of pristine deep-sea coral gardens in the Mediterranean Sea (SW Sardinia).

Leiopathes glaberrima is a tall arborescent black coral species structuring important facies of the deep-sea rocky bottoms of the Mediterranean Sea that are severely stifled by fishing activities. At present, however, no morphological in vivo description, ecological characterization, age dating and evaluation of the possible conservation actions have ever been made for any population of this species in the basin. A dense coral population was reported during two Remotely Operated Vehicle (ROV) surveys conducted on a rocky bank off the SW coasts of Sardinia (Western Mediterranean Sea). L. glaberrima forms up to 2 m-tall colonies with a maximal observed basal diameter of nearly 7 cm. The radiocarbon dating carried out on a colony from this site with a 4 cm basal diameter revealed an approximately age of 2000 years. Considering the size-frequency distribution of the colonies in the area it is possible to hypothesize the existence of other millennial specimens occupying a supposedly very stable ecosystem. The persistence of this ecosystem is likely guaranteed by the heterogeneous rocky substrate hosting the black coral population that represents a physical barrier against the mechanical impacts acted on the surrounding muddy areas, heavily exploited as trawling fishing grounds. This favorable condition, together with the existence of a nursery area for catsharks within the coral ramifications and the occurrence of a meadow of the now rare soft bottom alcyonacean Isidella elongata in small surviving muddy enclaves, indicates that this ecosystem have to be considered a pristine Mediterranean deep-sea coral sanctuary that would deserve special protection.

Distribution and assessment of marine debris in the deep Tyrrhenian Sea (NW Mediterranean Sea, Italy).

Marine debris is a recognized global ecological concern. Little is known about the extent of the problem in the Mediterranean Sea regarding litter distribution and its influence on deep rocky habitats. A quantitative assessment of debris present in the deep seafloor (30-300 m depth) was carried out in 26 areas off the coast of three Italian regions in the Tyrrhenian Sea, using a Remotely Operated Vehicle (ROV). The dominant type of debris (89%) was represented by fishing gears, mainly lines, while plastic objects were recorded only occasionally. Abundant quantities of gears were found on rocky banks in Sicily and Campania (0.09-0.12 debris m(-2)), proving intense fishing activity. Fifty-four percent of the recorded debris directly impacted benthic organisms, primarily gorgonians, followed by black corals and sponges. This work provides a first insight on the impact of marine debris in Mediterranean deep ecosystems and a valuable baseline for future comparisons.

Linking environmental forcing and trophic supply to benthic communities in the Vercelli Seamount area (Tyrrhenian Sea).

Seamounts and their influence on the surrounding environment are currently being extensively debated but, surprisingly, scant information is available for the Mediterranean area. Furthermore, although the deep Tyrrhenian Sea is characterised by a complex bottom morphology and peculiar hydrodynamic features, which would suggest a variable influence on the benthic domain, few studies have been carried out there, especially for soft-bottom macrofaunal assemblages. In order to fill this gap, the structure of the meio-and macrofaunal assemblages of the Vercelli Seamount and the surrounding deep area (northern Tyrrhenian Sea - western Mediterranean) were studied in relation to environmental features. Sediment was collected with a box-corer from the seamount summit and flanks and at two far-field sites in spring 2009, in order to analyse the metazoan communities, the sediment texture and the sedimentary organic matter. At the summit station, the heterogeneity of the habitat, the shallowness of the site and the higher trophic supply (water column phytopigments and macroalgal detritus, for instance) supported a very rich macrofaunal community, with high abundance, biomass and diversity. In fact, its trophic features resembled those observed in coastal environments next to seagrass meadows. At the flank and far-field stations, sediment heterogeneity and depth especially influenced the meiofaunal distribution. From a trophic point of view, the low content of the valuable sedimentary proteins that was found confirmed the general oligotrophy of the Tyrrhenian Sea, and exerted a limiting influence on the abundance and biomass of the assemblages. In this scenario, the rather refractory sedimentary carbohydrates became a food source for metazoans, which increased their abundance and biomass at the stations where the hydrolytic-enzyme-mediated turnover of carbohydrates was faster, highlighting high lability.

Deep coral oases in the South Tyrrhenian Sea.

A Mediterranean "roche du large" ecosystem, represented by four rocky shoals, located a few miles apart on a muddy bottom at 70-130 m depth in the gulf of St. Eufemia (Calabria, South Tyrrhenian Sea), was studied by means of Remotely Operated Vehicle (ROV) photo imaging. The shoals host highly diversified coral communities, mainly composed of arborescent colonies of gorgonians (Callogorgia verticillata, Paramuricea clavata, Paramuricea macrospina, Bebryce mollis, Villogorgia bebrycoides, Corallium rubrum, and Leptogorgia sarmentosa), and antipatharians (Antipathella subpinnata, Antipathes dichotoma and Parantipathes larix). The coral colonies reach high densities (up to ca. 17 colonies m(-2)) and large sizes, such as the over 1.5 m wide antipatharian colonies. We hypothesized that the abundance and composition of the coral assemblages differed significantly among the rocky shoals and with respect to the surrounding soft bottoms. Various environmental variables were tested as possible explanatory factors of the observed differences. Moreover, due to their off-coast localization, we report here that these unique ecosystems are potentially subjected to a strong pressure from the local fishing activities, which were tentatively characterized. The recorded coral ß-diversity among the shoals supports the hypothesis that these habitats behave like small oases of hard substrata interspersed in a muddy bottom. Because of their intrinsic beauty and rarity and their biological and ecological value, we stress the need of specific actions aimed at the urgent protection of these oases of biodiversity.

Biodiversity of prokaryotic communities associated with the ectoderm of Ectopleura crocea (Cnidaria, Hydrozoa).

The surface of many marine organisms is colonized by complex communities of microbes, yet our understanding of the diversity and role of host-associated microbes is still limited. We investigated the association between Ectopleura crocea (a colonial hydroid distributed worldwide in temperate waters) and prokaryotic assemblages colonizing the hydranth surface. We used, for the first time on a marine hydroid, a combination of electron and epifluorescence microscopy and 16S rDNA tag pyrosequencing to investigate the associated prokaryotic diversity. Dense assemblages of prokaryotes were associated with the hydrant surface. Two microbial morphotypes were observed: one horseshoe-shaped and one fusiform, worm-like. These prokaryotes were observed on the hydrozoan epidermis, but not in the portions covered by the perisarcal exoskeleton, and their abundance was higher in March while decreased in late spring. Molecular analyses showed that assemblages were dominated by Bacteria rather than Archaea. Bacterial assemblages were highly diversified, with up to 113 genera and 570 Operational Taxonomic Units (OTUs), many of which were rare and contributed to <0.4%. The two most abundant OTUs, likely corresponding to the two morphotypes present on the epidermis, were distantly related to Comamonadaceae (genus Delftia) and to Flavobacteriaceae (genus Polaribacter). Epibiontic bacteria were found on E. crocea from different geographic areas but not in other hydroid species in the same areas, suggesting that the host-microbe association is species-specific. This is the first detailed report of bacteria living on the hydrozoan epidermis, and indeed the first study reporting bacteria associated with the epithelium of E. crocea. Our results provide a starting point for future studies aiming at clarifying the role of this peculiar hydrozoan-bacterial association.

Isolation and identification of chitin in the black coral Parantipathes larix (Anthozoa: Cnidaria).

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.

Helicospiral growth in the whip black coral Cirrhipathes sp. (Antipatharia, Antipathidae).

The coiling pattern of the whip black coral Cirrhipathes sp. (Antipatharia, Antipathidae) was studied in four sites of the Bunaken Marine Park (North Sulawesi, Indonesia) characterized by different hydrodynamic conditions. The colonies show a helicospiral growth, with the polyps irregularly arranged on the external convex side of the turns of the stem. Only the colonies living in a very slow current environment reach the greatest lengths (up to 5 m) and show the highest number of rotations (up to 10, 3600°). The turns shape changes along the stem of the colonies, from the base to the apex, as evidenced by the ratio between the pitch and the diameter of each coil. In particular, the turns close to the basal plate have a smaller diameter and a larger pitch, while in the most distal turns, the diameter increases and the pitch decreases concurrently. We hypothesize that the shape variation of the whorls is triggered by the relationship between the growing stem and the intensity of the prevailing current. In this way, the colony can initially grow fast, moving away from the bottom, and then extend into the current, maximizing the plankton capture.

Characteristics of the mesophotic megabenthic assemblages of the vercelli seamount (north tyrrhenian sea).

The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount) is described using Remotely Operated Vehicle (ROV) video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i) the top shows a dense covering of the kelp Laminaria rodriguezii; (ii) the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii) the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface) with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.