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Mud and fluids migration producing active seepage at the seafloor is a global phenomenon documented in different geodynamic contexts. Scoglio d’Affrica islet is one of the culminations of the Elba-Pianosa Ridge (northern Tyrrhenian Sea), where submarine methane emissions have been studied since the 1960’s, sometimes evolving in violent gas outbursts such as those occurred in 2017. In the study area, the seafloor is punctuated by more than 250 small pockmarks with mean diameter of 10 m and occurring mainly between 20 and 60 m water depth. Pockmarks are characterized by planform shapes from sub-circular to elongated and U/V-shaped cross-sections. They are predominantly arranged as isolated or in clusters or minorly organised in strings-oriented about N-S, running almost parallel to the fault escarpments which represent one of the main structural features of the study area. Pockmarks have been classified on the basis of their size parameters (i.e., depth, mean diameter) according to the recent literature and they resulted to belong mainly to the morphological classes of the "unit pockmark" and minorly to the “normal pockmark”. The complex seafloor morphology of the area is also characterised by several positive features, showing very different shapes and sizes (up to 35 m high and 600 m wide). In this work, we select 67 positive features (named as M1-67) more than 2 meters high and perform on them the first morphometric analysis by means of high-resolution bathymetric data. The obtained morphometric parameters (e.g., flatness value, mean slope), which allow us to classify the positive features as mounded, flat topped and conical features, are compared with those of other submarine mud volcanoes from literature, showing often high similarity. In view of that, we suggest that M1-67 have an origin likely linked to the migration of fluidised mud or mud breccia (a mud matrix with clasts), probably from shallow mud sources, rising through the thick Eocene-Early Miocene siliciclastic succession and overlying sedimentary layers. We interpret as mud volcanoes the larger sub-circular positive features (M1-7) since they are characterised by the occurrence of lobate flows along their flanks, widespread mud-breccia and focused emissions of CH4 observed on ROV videos. Whilst, with the available data, to avoid any speculation, we propose for M8-67 an alternative and more generic explanation interpreting them as “piercement structures” formed due to the seafloor deformation associated with a rising mud diapirism. Considering the high-magnitude outburst occurred in 2017 and the shallow water setting with evidence of active fluid seepage (as vertical focused gas bubbles) documented by ROV videos, the morphometric analysis of mud and fluids migration morphologies is an important baseline study since it can provide insight for a marine geohazard assessment around Scoglio d’Affrica islet.

Plastic pollution affects all oceans and sequestration of plastics in sediments is considered its ultimate sink. We report evidence of macroplastic burial retrieved within a sediment core collected at 38 m depth at the mouth of the Mazzarrà River, a torrential river able to carry a large amount of sediment during seasonal flash-floods. Two macroplastic items were found at 68 and 255 cm below the core top (corresponding to the seafloor). Their association with terrestrial vegetal debris and their inclusion in decimetre-thick sandy/silty intervals showing coarsening- and fining-upward trends, suggest that they were deposited by hyperpycnal flows possibly triggered by flood events. These findings testify the potential of sedimentary flows in burying macroplastic at depth below the seafloor, especially in nearshore prodelta environments. Furthermore they raise the quest on the magnitude of macroplastic storage in the subsurface and on the lack of specific devices and strategies for their reckoning.

Microplastics (plastics

We present a very high-resolution bathy-morphological map of the offshore sector around the Scoglio d’Affrica islet (northern Tyrrhenian Sea, Italy). The study area covers a sector of 45 km2, between 3 and 85 m depth. Its central part, i.e. the apex of the Ridge, is characterised by a flat or gently sloping seafloor, where three mud volcanoes, and 250 pockmarks are recognised. Differently, the western and eastern Ridge flanks are steeper and characterised by 60 quasi-rectilinear escarpments and small ridges, more than 20 morphological highs, and elongated channels occasionally floored by bedforms. The seafloor shallower than 40 m is covered by Posidonia oceanica, forming compact and continuous or fragmented meadows intermingled with sandy patches. The main map represents the bathy-morphological setting of the area, which is largely affected by fluid seepage, providing insights for habitat mapping and preliminary marine geohazard assessment due to the violent gas outburst from mud volcanoes.

Coralligenous reefs are typical underwater seascapes of the Mediterranean Sea and are ranked among the most relevant ecosystems of the basin and a pole of biodiversity. For their critical importance for ecosystems conservation, coralligenous reefs are included among the indicators that should be assessed under the Marine Strategy Framework Directive (MSFD). However, information regarding their spatial distribution and the influence of environmental factors on their structure and biological characteristics is still poor. As part of monitoring regional programs for the implementation of the MSFD in Italy, an extensive study was performed along the Latium continental shelf, aimed to define and map the distribution of coralligenous reefs and to assess their environmental status in three different study areas, characterized by different environmental conditions and subjected to different potential levels of human pressure. For each area, a large dataset was collected, including multibeam bathymetry, side scan sonar records and ROV video transects. The integrated analysis of geophysical data and ROV videos allowed to identify the morpho-acoustic facies indicative of coralligenous outcrops and to map their distribution across the study areas. In parallel, a quantitative analysis of video transects was carried out, in order to characterize the megabenthic communities in terms of species composition, abundance, health status of structural species, and to evaluate the abundance of marine litter. The environmental status of the coralligenous communities was then assessed through the application of the Mesophotic Assemblages Conservation Status (MACS) index. The results obtained showed a large variability in the distribution and characteristics of coralligenous reefs and associated assemblages along the Latium continental shelf, likely reflecting the different environmental conditions and human pressure in the different areas. Coralligenous reefs were reported from all the investigated areas, hosting a rich and varied associated fauna with dense gorgonian forests, also featuring species of relevance for conservation such as Corallium rubrum. The application of MACS index allowed to distinguish among a wide range of ecological conditions of the coralligenous communities, spanning from high to poor environmental status across different sites. The assessment of the extent and diversity of coralligenous assemblages through the combination of geomorphological analysis, acoustic mapping and quantitative video analysis represents an efficient tool, which may help governments and stakeholders making informed management decisions for future coastal planning and conservation strategies.

Living (Rose-Bengal stained) benthic foraminifera were investigated in eleven stations sampled along transects following a depth gradient from Polcevera and Bisagno canyons and the adjacent open slope (Ligurian Sea), in a depth interval ranging from 200 to 2000 m. In order to understand which environmental factors influence the abundance and taxonomical composition of the foraminiferal assemblages in these two domains (canyon and open slope), qualitative and quantitative foraminiferal data were correlated to the sediment biochemical composition (in terms of phytopigments, proteins, lipids, carbohydrates and biopolymeric carbon), grain size and the main hydrological characteristics (salinity, temperature, dissolved oxygen). The Cluster Analysis and Canonical Correspondence Analysis allowed us to detect two sectors (coastal and offshore) characterized by contrasting trophic conditions. The coastal sector reflects spread meso-eutrophic conditions in both physiographic domains being possibly more impacted by the river inputs and sediment transport processes from land. In fact, the narrow continental shelf of the Ligurian Sea favors the deposition of sediment transported by riverine processes on the immediately adjacent coastal areas. As a result homogenization of sea-bottom conditions occurs, leading to an unclear differentiation between open slope and canyon foraminiferal assemblages. Conversely, the offshore sector is less affected by physical disturbance due to the sedimentary flows decreasing in relation to the larger distance from the coastline. Consequently, the lower organic matter content and lower food quality (expressed in terms of contribution of the primary material to the biopolymeric carbon pool) lead to a more oligotrophic condition, which favors the development of peculiar assemblages dominated by Glomospira charoides, Ammolagena clavata and epifaunal taxa. The first finding ever of a warm tropical species (Amphistegina lessonii) in the Ligurian Sea sediments at 500-m depth can be considered the first evidence of upward expansion of tropical species to the Northern portion of the Mediterranean Sea, which is experiencing an evident water warming linked to the ongoing global climate change.

The tectonically-controlled margins off Southern Italy are carved by several shelf-indenting submarine canyons that are periodically flushed by sedimentary gravity flows. In this study, the distribution of benthic and demersal megafauna within the thalweg of some of these canyons (i.e. the Gioia-Petrace and Caulonia Marina canyons in the Tyrrhenian and the Ionian Calabrian margins, respectively, and the Sant’Agata, San Gregorio, Tremestieri and Messina canyons in the Messina Strait) was studied using Remotely Operated Vehicle video transects. The relationships between fauna distribution and environmental conditions (i.e. seafloor type, depth, slope, aspect and canyon system) extracted from video footage and bathymetric data were assessed to identify the main physical drivers influencing the megafaunal assemblages within active submarine canyons. These latter have their heads in shallow water, so representing highly dynamic environments affected by present-day sediment transport. Hierarchical Cluster Analysis allowed to distinguish seven different assemblages occurring in the study areas. PERMANOVA analysis showed significant differences among species groups associated to different seafloor types, depth ranges and canyon systems. Distance-based linear modeling (DistLM) identified the canyon system as the main factor explaining the variability of the megafaunal assemblages across the study areas. In the Gioia and Petrace canyons, both characterized by homogenous fine-grained sediment, the assemblages were mainly dominated by Polychaeta Sabellidae and Ceriantharia. The almost total absence of sessile fauna at the canyons’ head was interpreted as an effect of a strong physical disturbance due to the impact of sedimentary flows. In the canyons of the Messina Strait, the presence of more varied seafloor encompassing fine and coarse sediment along with an higher spatial heterogeneity of physical disturbance, determined more diversified faunal assemblages, featuring species associated with hard and soft substrates. More in detail, in the Sant’Agata, San Gregorio and Messina canyons the colonization of cobbles and boulders by slow-growing species vulnerable to physical disturbance such as the gorgonians Acanthogorgia hirsuta and Swiftia dubia was recorded. For the Tremestieri canyons a stronger impact by sedimentary flows was reflected both by a very high abundance of land-based litter and the lowest values of species richness. Interactions between megafauna and marine litter, whose widespread occurrence was recorded on the floor of all these canyons, have been also presented and discussed. Although in several cases litter caused entanglement of benthic species, the anthropogenic debris was also used as growing substrate or shelter by some invertebrates and fishes, suggesting complex fauna-litter interactions that should be better explored. Overall, the large variability in morphology and seafloor characteristics across the studied canyons is reflected on the variability of megafauna assemblages, suggesting a strong influence of the physical conditions specific of each canyon in controlling fauna distribution.

To understand the fate of plastic in oceans and the interaction with marine organisms, we investigated the incorporation of (bio)polymers and microplastics in selected benthic foraminiferal species by applying FTIR (Fourier Transform Infrared) microscopy. This experimental methodology has been applied to cultured benthic foraminifera Rosalina globularis, and to in situ foraminifera collected in a plastic remain found buried into superficial sediment in the Mediterranean seafloor, Rosalina bradyi, Textularia bocki and Cibicidoides lobatulus. In vitro foraminifera were treated with bis-(2-ethylhexyl) phthalate (DEHP) molecule to explore its internalization in the cytoplasm. Benthic foraminifera are marine microbial eukaryotes, sediment-dwelling, commonly short-lived and with reproductive cycles which play a central role in global biogeochemical cycles of inorganic and organic compounds. Despite the recent advances and investigations into the occurrence, distribution, and abundance of plastics, including microplastics, in marine environments, there remain relevant knowledge gaps, particularly on their effects on the benthic protists. No study, to our knowledge, has documented the molecular scale effect of plastics on foraminifera. Our analyses revealed three possible ways through which plastic-related molecules and plastic debris can enter a biogeochemical cycle and may affect the ecosystems: 1) foraminifera in situ can grow on plastic remains, namely C. lobatulus, R. bradyi and T. bocki, showing signals of oxidative stress and protein aggregation in comparison with R. globularis cultured in negative control; 2) DEHP can be incorporated in the cytoplasm of calcareous foraminifera, as observed in R. globularis; 3) microplastic debris, identified as epoxy resin, can be found in the cytoplasm and the agglutinated shell of T. bocki. We hypothesize that plastic waste and their associated additives may produce modifications related to the biomineralization process in foraminifera. This effect would be added to those induced by ocean acidification with negative consequences on the foraminiferal biogenic carbon (C) storage capacity.

13 pages, 10 figures, 3 tables, Megabenthic assemblages in deep-sea sedimentary environments receive far less attention than those occurring on rocky environments, despite they have been widely impacted by destructive trawling activities, mainly due to their association with important commercial species. ROV dives conducted on bathyal muds of the Alboran Sea continental slope (western Mediterranean) were used to characterize megabenthic assemblages, as well as assess their response to trawling and benthic litter. We identified a multispecific assemblage, dominated by the isidid Isidella elongata, and two monospecific assemblages composed by the sea-pens Funiculina quadrangularis and Kophobelemnon stelliferum. These assemblages are defined as vulnerable marine ecosystems by international institutions. Trawled areas exhibit significant low densities of habitat-forming species and a striking impoverishment of habitat complexity and diversity. Plastic debris and lost fishing gears were the most abundant components of the marine litter. This study highlights the destructive effects of human activities on bathyal muds, emphasizing the need for urgent conservation measures, The data for this study were collected during the Spanish national project SHAKE (CGL2011-3005-C02-02) funded by the Spanish Ministery of Economy, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

This study provides a first characterization of the geomorphic features and relative habitats of the Francesc Pages Bank, located on the upper slope of the Moroccan continental margin in the southern Alboran Sea, western Mediterranean. The Francesc Pages Bank is an ellipsoidal structural high covering 80 km2 within a depth range of 76–580 m. High-resolution swath mapping allowed to recognize different geomorphic features on the top of the Bank, including crests, banks and ridges. An automatic classification of multibeam sonar data has been performed to identify and map the different physical habitats using terrain parameters derived from the bathymetry as surrogate descriptors. A remotely operated vehicle (ROV) video track acquired in the area showed the occurrence of several dense and uncommonly well-preserved megabenthic assemblages composed of gorgonians, soft corals, and several demosponge species. Multivariate statistical analyses performed on species abundance and terrain parameters derived from ROV observations allowed to define the main substrates governing the distribution of the observed benthic species, which coincide with some of the physical habitats detected by the multibeam automated classification.

Litter is a significant environmental issue, threatening all ocean environments including the deep sea, where little is known about the extent of the threat. This study collected underwater videos on shelf-indenting canyons (the Gioia and Petrace Canyon) and adjacent sectors to characterize benthic litter and its distribution patterns. A high density of litter was present in the canyon thalwegs (up to 56.3 items/100 m), where ∼95 % of observed debris was concentrated. Litter primarily comprised of plastic (∼90 %). The presence of household objects intermingled with vegetal material indicates a strong influence of land-based sources for litter in these areas. Sedimentary gravity flow processes transported natural and anthropogenic debris downslope and may determine its burial beneath the seafloor. Another litter transport mechanism is the presence of light items, observed while drifting above the seafloor under the action of down-canyon bottom currents. This phenomenon was frequently documented within Gioia Canyon, where up to 74 drifting items were counted in one hour of video. Conversely, a lower litter concentration was found along the continental margin, where items were mostly fishing-related. Findings from this study confirm that canyons act as conduits for land-sourced debris and litter transport from coastal to deep-sea environments. The funnelling of a large amount of plastic to the deep sea through multiple processes indicates that the magnitude of this pollution may be greater than expected. This pollution could concentrate in canyons along continental margins and possibly at the mouths of canyons at the base of the slope. This issue requires urgent attention, as understanding of deep-sea litter distribution is still limited and potential impacts to benthic ecosystems are poorly understood.

18 pages, 10 figures, 2 tables, Scleractinian cold-water coral (CWC)reefs are key habitats for benthic fauna as they enhance spatial heterogeneity and biodiversity. Understanding their environmental and ecological dynamics has therefore important implications for biodiversity conservation. This is especially true for the Mediterranean Sea, where living cold-water coral reefs are rare. In this study, we present a quantitative analysis of the CWC assemblages from Cabliers Coral Mound Province, located in the Alboran Sea (westernmost Mediterranean). The province extends for 25 km, with some mounds rising up to 140 m from the surrounding seafloor and being partly topped by living CWC reefs. The observed megabenthic species were quantified through video analysis of three Remotely Operated Vehicle (ROV)dives (280–485 m water depth)and their distribution was related to mound geomorphic characteristics and seafloor terrain parameters, extracted from a high-resolution Autonomous Underwater Vehicle (AUV)multi-beam bathymetry. The pronounced abundance and size of scleractinian CWCs among the observed assemblages, makes Cabliers the only known coral mound province in the Mediterranean Sea with currently growing reefs. Within these reefs, several recruits and juveniles of the sebastid Helicolenus dactylopterus were observed, confirming the use of such habitats as nursery grounds by some commercially valuable fish species. The qualitative comparison between the fauna of Cabliers and Atlantic coral mounds suggest that the number of species associated with CWC mounds worldwide is even higher than previously thought. This finding has important implications for the conservation and management of CWC habitats in different geographic regions, Guillem Corbera is funded by the Graduate School of the National Oceanography Centre Southampton (GSNOCS), with the collaboration of the NGO OCEANA. The data for this study was collected during the Spanish national project SHAKE (CGL2011-30005-C02-02, PI: Eulàlia Gràcia

Marine litter is an emerging environmental threat affecting all world’s oceans including the deep seafloor, where the extent of the phenomenon is still largely unknown. We report the spatial patterns of macro-litter distribution within the Messina Strait’s channels (Central Mediterranean), focusing on the transfer mechanisms responsible for its emplacement, a key information to better understand litter distribution. Litter is patchy but pervasive on all surveyed channels, reaching densities up to ~200 items/10 m, the highest reported for the deep sea until now. Litter is often arranged in large accumulations formed by hundreds of land-sourced items, mixed to vegetal and coarse-grained debris, indicating an emplacement from sedimentary gravity flows. Such impressive amount of litter can be explained by the superposition of a very efficient source-to-sink sedimentary transport and a strong urbanization of the coastal area. These findings point out that macro-benthic litter pollution is a major, often overlooked, threat for deep-sea ecosystems. Further explorations are thus required in similar marine settings to fully understand the magnitude of the problem, since they may represent the largest litter hotspots in the deep-sea.

Special issue Bridging the gap between the shallow and deep oceans: The key role of submarine canyons.-- 13 pages, 9 figures, 2 tables, The impacts of fishing activities on ecosystems represent an acknowledged environmental issue, especially considering the increasing demands for the conservation of biodiversity. Submarine canyons are complex environments that can harbor high biodiversity of benthic ecosystems and high biomass of fish species, thus representing preferential fishing areas for bottom trawling fleets. The effects of bottom trawling on the benthic epifauna were investigated over the soft-bottom margins of the Gioia Canyon (Southeastern Tyrrhenian Sea) by means of quantitative analysis of Remote Operated Vehicle (ROV) video transects and compared with the recent pattern of trawling intensity, reconstructed through processing of data collected with the Vessel Monitoring System (VMS). Four ROV transects were then performed at 320–540 m depth in areas affected by different trawling pressure. The analysis was focused on the bamboo coral Isidella elongata and the sea pen Funiculina quadrangularis, which are considered indicator taxa of Vulnerable Marine Ecosystems (VMEs) and relevant in terms of sustainable management priorities. I. elongata only occurred at the two deeper stations, below 400 m depth. This species showed a clear relationship with trawling intensity, since its abundance was significantly higher under low trawling intensity, where coexistence of large (>20 cm height) and small colonies was observed. The relatively high prevalence of small colonies in areas exposed to higher trawling effort was interpreted as a consequence of the trawling activity that removed the larger colonies. However, the frequent occurrence of dead colonies and the diffuse presence of epibionts (e.g. the anemone Amphianthus dohrnii and the hydroid Clytia linearis) on living colonies indicate stressful conditions for I. elongata even in areas where trawling intensity was lower. Conversely, the relationship between trawling intensity and species abundance was not straightforward for F. quadrangularis; despite the lowest abundance of this species was recorded in areas subject to high trawling intensity, relatively high abundances were observed in areas with intermediate trawling effort. Although such distribution may be driven by other environmental factors, it suggests that vulnerability to bottom trawling can be different for the two species

Hudson Canyon is the largest shelf-sourced canyon system off the east coast of the United States, and hosts a productive ecosystem that supports key fisheries. Here we report the results of a multi-year interdisciplinary study of the geological, geochemical, and physical oceanographic features and processes in the canyon that underpin that ecosystem. High-resolution multi-beam bathymetric and backscatter data show that the contrasting morphology of the two perpendicularly oriented branches at the head of the Hudson Canyon is indicative of different states of geomorphological activity and sediment transport. Tightly spaced ridges and gullies extend perpendicularly towards the canyon axis from the canyon walls. Numerous depressions are found at the base of the canyon walls or along the canyon axis at depths from 300 m to 600 m. Elevated concentrations of dissolved methane in the water column, where the highest density of depressions occur, suggests that methane is actively venting there. The topography and reflective floors of circular depressions in canyon walls and their association with methane maxima suggest that these represent active methane gas release-collapse pockmarks with carbonate floors. Patterns of irregular, low-relief, reflective depressions on the canyon floor may also represent methane release points, either as gas release or cold-seep features. The presence of methane maxima in a region of strong advective currents suggests continuous and substantial methane supply. Hydrographic observations in the canyon show that multiple layers of distinct inter-leaved shelf (cold, fresh) and slope (warm, salty) water masses occupy the head of the canyon during the summer. Their interactions with the canyon and with each other produce shifting fronts, internal waves, and strong currents that are influenced by canyon topography. Strong tidal currents with along-canyon-axis flow shear help to drive the advection, dispersion and mixing of dissolved materials in the water column that likely help support the rich canyon ecosystem.

15 pages, 10 figures, 2 tables, 1 appendix, The distribution of megabenthic communities at the head of Hudson Canyon and adjacent continental shelf was studied by means of underwater video transects and still photo imagery collected using a towed camera system. The goal was to explore the relationships between faunal distribution and physical seafloor conditions and to test the hypothesis that increased seafloor heterogeneity in the Hudson Canyon supports a larger diversity of benthic communities, compared with the adjacent continental shelf. Hierarchical cluster analysis was performed to identify benthic assemblages as defined in imagery. The BIO-ENV procedure and the Canonical Correspondence Analysis were carried out to elucidate species groupings in relation to terrain variables extracted from bathymetric data. Species accumulation curves were generated to evaluate species turn over in and out of Hudson Canyon. The results indicate that seafloor morphology is the main physical factor related to benthic community composition and distribution. Assemblages dominated by sponges, zoanthids and cup corals colonized the canyon margins and flanks, and were associated with coarse-grained sediments, while sea pen assemblages were observed along muddy seafloor within the thalweg. An assemblage dominated by sea stars occurred on the shelf, associated with a sandy seafloor. Some assemblages were exclusively observed in the canyon area, suggesting that the increased variability of seafloor composition, together with the oceanographic processes specific to the canyon area, enhance beta diversity. The colonization by benthic suspension feeders within the canyon, in contrast to shelf assemblages, mainly composed of carnivores and detritus feeders could be favored the intense hydrodynamics at the canyon head that increase the availability of suspended organic matter. From the perspective of management and conservation of marine resources, the results obtained support the relevance of Hudson Canyon as a biodiversity hotspot. Such results are of particular significance in light of the recent action promoted by the Mid-Atlantic Fisheries Management Council, that restricts bottom trawling in most of the submarine canyons of the US Atlantic margin, including the Hudson Canyon, to protect cold-water corals from damage by fishing gear

Recent underwater archaeological surveys recovered hundreds of flint artefacts between depths of 18 and 21 m at cala tramontana, a small bay located in the eastern part of pantelleria island. Most of the flint artefactsindicate debitage, and are characterized by cores and flakes without any specific morphology. Different lithic tools were also identified, such as fragments of blades, truncations, end-scrapers, points and crested blades. Aninitial hypothesis is that this lithic industry represents the oldest traces of human visitation to the island,possibly related to the exploitation of the nearby obsidian source, and favoured because of the sheltered coastalconfiguration of cala tramontana and cala levante with respect to the dominant winds and related storms. However,the present-day coastal setting in the bay is rather inhospitable, with high cliffs and difficult marine access.in contrast, palaeo-landscape reconstructions by means of high-resolution multibeam bathymetry reveal thepossible presence of a small palaeobeach in the inner part of the bay when the sea level was 15 m lower than at present.By comparing this palaeo-sea level with the eustatic curve (and by excluding possible vertical movements), we roughly estimate an age of the lithic industry of 9.6-7.7 cal ka BP © The geological society of london 2016.

17 pages, 13 figures, 4 tables supplementary data https://dx.doi.org/10.1016/j.jmarsys.2016.01.005, In this paper, we used multibeam bathymetry and backscatter, high-resolution seismic profiles, ROV video images and sediment samples to identify the principal morpho-sedimentary features and related megabenthic communities along the upper reach of the Gioia Canyon (depth < 600 m) and the surrounding shelf and slope areas. Interpretation of the multidisciplinary dataset was undertaken to evaluate the relationships between seafloor characteristics and faunal distribution along a submarine canyon in an active tectonic setting. The results from this study indicate that physical disturbance on the seafloor at the canyon head and surrounding shelf, related to high sedimentation rates and occasional turbidite flows, may limit the variability of megabenthic communities. Evidence of diffuse trawl marks over soft sedimentary bottoms indicates anthropogenic impact due to fishing activities, which could explain low abundances of megabenthic species observed locally. The canyon margins and flanks along the continental slope host octocorals Funiculina quadrangularis and Isidella elongata, species that are indicative of vulnerable marine ecosystems (VMEs) and relevant in terms of sustainable management priorities. At the Palmi Ridge, the occurrence of outcropping rocks and bottom currents related to the presence of Levantine Intermediate Waters, provide conditions for the development of hard-bottom assemblages, including the black coral Antipathella subpinnata and deep-sea sponges fields, This research was performed in the framework of the Flagship Project RITMARE (SP4-WP2-A1)

Applying improved processing techniques to increasingly high resolution data can produce extremely high resolution results that reveal features invisible on standard resolution images. Increasing demand for resources from the deep sea demands imaging the seabed in ever-more remote areas with increased accuracy. For economic, safety, and legal reasons, lessors of offshore real estate survey the seafloor and shallow sub-seafloor prior to conducting seafloor operations. A standard geohazards survey includes multibeam bathymetry, side-scan sonar and CHIRP subbottom profiling and will yield useful data at 5-25 m (16-82 ft) resolution. However, higher resolution surveys are now possible and, though more time-consuming (and costly), yield potentially critical information not visible in coarser resolution surveys: morphologic features, structure, biota, etc. Recovering such information has become increasingly important for reasons that include 1) identification of natural seafloor features (i.e., fault traces, protected seafloor communities, seeps, mud volcanoes); 2) selection/elimination of target locations; 3) identification of unnatural features (shipwrecks, instruments, pipelines); 4) siting structures on the seafloor; and 5) instrument location/recovery. Using coarser resolution surveying for regional studies, then focusing higher resolution surveys on areas of particular interest, and applying meticulous processing of acoustic data, our team has produced 1 m (3 ft) resolution seafloor images that have enabled us to identify a host of small-scale features not routinely imaged at coarser resolutions. Here we present significant results including small-scale morphologic features associated with seeps, instrument locations, and benthic fauna habitat in the Gulf of Mexico.