Castellan Giorgio

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  • Article
    Identifying priorities for the protection of deep Mediterranean Sea ecosystems through an integrated approach
    (Frontiers Media, 2021-07-22) Fanelli, Emanuela ; Bianchelli, Silvia ; Foglini, Federica ; Canals, Miquel ; Castellan, Giorgio ; Güell-Bujons, Queralt ; Galil, Bella S. ; Goren, Menachem ; Evans, Julian ; Fabri, Marie-Claire ; Vaz, Sandrine ; Ciuffardi, Tiziana ; Schembri, Patrick J. ; Angeletti, Lorenzo ; Taviani, Marco ; Danovaro, Roberto
    Benthic habitats of the deep Mediterranean Sea and the biodiversity they host are increasingly jeopardized by increasing human pressures, both direct and indirect, which encompass fisheries, chemical and acoustic pollution, littering, oil and gas exploration and production and marine infrastructures (i.e., cable and pipeline laying), and bioprospecting. To this, is added the pervasive and growing effects of human-induced perturbations of the climate system. International frameworks provide foundations for the protection of deep-sea ecosystems, but the lack of standardized criteria for the identification of areas deserving protection, insufficient legislative instruments and poor implementation hinder an efficient set up in practical terms. Here, we discuss the international legal frameworks and management measures in relation to the status of habitats and key species in the deep Mediterranean Basin. By comparing the results of a multi-criteria decision analysis (MCDA) and of expert evaluation (EE), we identify priority deep-sea areas for conservation and select five criteria for the designation of future protected areas in the deep Mediterranean Sea. Our results indicate that areas (1) with high ecological relevance (e.g., hosting endemic and locally endangered species and rare habitats),(2) ensuring shelf-slope connectivity (e.g., submarine canyons), and (3) subject to current and foreseeable intense anthropogenic impacts, should be prioritized for conservation. The results presented here provide an ecosystem-based conservation strategy for designating priority areas for protection in the deep Mediterranean Sea.
  • Article
    Drawing the borders of the mesophotic zone of the Mediterranean Sea using satellite data
    (Nature Research, 2022-04-04) Castellan, Giorgio ; Angeletti, Lorenzo ; Montagna, Paolo ; Taviani, Marco
    The 30–150 m bathymetric range is commonly adopted in the literature to constrain the mesophotic zone. However, such depth interval varies depending on sunlight penetration, which is primarily a function of solar radiation incidence and water clarity. This is especially obvious in the Mediterranean Sea with its peculiar biophysical properties. Integrating information on light regime in the estimation of the bathymetric range of the mesophotic zone would provide a more robust definition, orienting conservation actions targeting its ecosystems. We present a first assessment of the spatial and vertical extension of the mesophotic zone in the Mediterranean Sea based upon light penetration, comparing our prediction with literature data. Our study also represents a baseline to monitor future variations in the bathymetric interval associated with the mesophotic zone in the Mediterranean Sea in relation to global changes.
  • Article
    Application of hyperspectral imaging to underwater habitat mapping, Southern Adriatic Sea
    (MDPI, 2019-05-16) Foglini, Federica ; Grande, Valentina ; Marchese, Fabio ; Bracchi, Valentina A. ; Prampolini, Mariacristina ; Angeletti, Lorenzo ; Castellan, Giorgio ; Chimienti, Giovanni ; Hansen, Ingrid M. ; Gudmundsen, Magne ; Meroni, Agostino N. ; Mercorella, Alessandra ; Vertino, Agostina ; Badalamenti, Fabio ; Corselli, Cesare ; Erdal, Ivar ; Martorelli, Eleonora ; Savini, Alessandra ; Taviani, Marco
    Hyperspectral imagers enable the collection of high-resolution spectral images exploitable for the supervised classification of habitats and objects of interest (OOI). Although this is a well-established technology for the study of subaerial environments, Ecotone AS has developed an underwater hyperspectral imager (UHI) system to explore the properties of the seafloor. The aim of the project is to evaluate the potential of this instrument for mapping and monitoring benthic habitats in shallow and deep-water environments. For the first time, we tested this system at two sites in the Southern Adriatic Sea (Mediterranean Sea): the cold-water coral (CWC) habitat in the Bari Canyon and the Coralligenous habitat off Brindisi. We created a spectral library for each site, considering the different substrates and the main OOI reaching, where possible, the lower taxonomic rank. We applied the spectral angle mapper (SAM) supervised classification to map the areal extent of the Coralligenous and to recognize the major CWC habitat-formers. Despite some technical problems, the first results demonstrate the suitability of the UHI camera for habitat mapping and seabed monitoring, through the achievement of quantifiable and repeatable classifications.
  • Article
    Benthic habitat map of the southern Adriatic Sea (Mediterranean Sea) from object-based image analysis of multi-source acoustic backscatter data
    (MDPI, 2021-07-24) Prampolini, Mariacristina ; Angeletti, Lorenzo ; Castellan, Giorgio ; Grande, Valentina ; Le Bas, Tim ; Taviani, Marco ; Foglini, Federica
    A huge amount of seabed acoustic reflectivity data has been acquired from the east to the west side of the southern Adriatic Sea (Mediterranean Sea) in the last 18 years by CNR-ISMAR. These data have been used for geological, biological and habitat mapping purposes, but a single and consistent interpretation of them has never been carried out. Here, we aimed at coherently interpreting acoustic data images of the seafloor to produce a benthic habitat map of the southern Adriatic Sea showing the spatial distribution of substrates and biological communities within the basin. The methodology here applied consists of a semi-automated classification of acoustic reflectivity, bathymetry and bathymetric derivatives images through object-based image analysis (OBIA) performed by using the ArcGIS tool RSOBIA (Remote Sensing OBIA). This unsupervised image segmentation was carried out on each cruise dataset separately, then classified and validated through comparison with bottom samples, images, and prior knowledge of the study areas.
  • Article
    Visual imaging of benthic carbonate-mixed factories in the Ross Sea region Marine Protected Area, Antarctica
    (MDPI, 2021-07-31) Castellan, Giorgio ; Angeletti, Lorenzo ; Canese, Simonepietro ; Mazzoli, Claudio ; Montagna, Paolo ; Schiaparelli, Stefano ; Taviani, Marco
    Marine biogenic skeletal production is the prevalent source of Ca-carbonate in today’s Antarctic seas. Most information, however, derives from the post-mortem legacy of calcifying organisms. Prior imagery and evaluation of Antarctic habitats hosting calcifying benthic organisms are poorly present in the literature, therefore, a Remotely Operated Vehicle survey was carried out in the Ross Sea region Marine Protected Area during the 2013–2014 austral summer. Two video surveys of the seafloor were conducted along transects between 30 and 120 m (Adelie Cove) and 230 and 260 m (Terra Nova Bay “Canyon”), respectively. We quantified the relative abundance of calcifiers vs. non-calcifiers in the macro- and mega-epibenthos. Furthermore, we considered the typology of the carbonate polymorphs represented by the skeletonized organisms. The combined evidence from the two sites reveals the widespread existence of carbonate-mixed factories in the area, with an overwhelming abundance of both low-Mg and (especially) high-Mg calcite calcifiers. Echinoids, serpulids, bryozoans, pectinid bivalves and octocorals prove to be the most abundant animal producers in terms of abundance. The shallower Adelie Cove site also showed evidence of seabed coverage by coralline algae. Our results will help in refining paleoenvironmental analyses since many of the megabenthic calcifiers occur in the Quaternary record of Antarctica. We set a baseline to monitor the future response of these polar biota in a rapidly changing ocean.
  • Article
    The "Corsica Channel Cold-Water Coral Province" (Mediterranean Sea)
    (Frontiers Media, 2020-08-20) Angeletti, Lorenzo ; Castellan, Giorgio ; Montagna, Paolo ; Remia, Alessandro ; Taviani, Marco
    Over 25 mounds have been identified in the Corsica Channel (Mediterranean Sea) through multibeam bathymetric mapping at depth of 400–430 m, with dimensions ranging from 70 to 330 m, achieving maximum heights of 25 m. Two mounds have been explored in detail using a remotely operated vehicle, revealing thick coral growth with a predominance of the branching scleractinian Madrepora oculata as main frame builder and subordinate Desmophyllum pertusum. The solitary scleractinians Desmophyllum dianthus and Javania cailleti add to the biodiversity here, which accounts for at least 50 macro- and megabenthic species. In consideration of the remarkable surface (ca. 5.3 km2) covered by living corals, their density and healthy appearance, and discontinuity with other major cold-water coral (CWC) occurrences in the Mediterranean Sea, we propose that this area represents a distinct CWC province in a sector already known for the presence of pre-modern CWC mounds. Noticeably, well-developed contourite drift systems occur in the Corsica Channel, lending support to their strict spatial link with coral establishment at depth. The ecosystemic value of the new CWC province calls for proper conservation measures to ensure their present Good Environmental Status.
  • Article
    The yellow coral Dendrophyllia cornigera in a warming ocean
    (Frontiers Media, 2019-11-08) Castellan, Giorgio ; Angeletti, Lorenzo ; Taviani, Marco ; Montagna, Paolo
    Ocean warming is expected to impinge detrimentally on marine ecosystems worldwide up to impose extreme environmental conditions capable to potentially jeopardize the good ecological status of scleractinian coral reefs at shallow and bathyal depths. The integration of literature records with newly acquired remotely operated vehicle (ROV) data provides an overview of the geographic distribution of the temperate coral Dendrophyllia cornigera spanning the eastern Atlantic Ocean to the whole Mediterranean Sea. In addition, we extracted temperature values at each occurrence site to define the natural range of this coral, known to maintain its physiological processes at 16°C. Our results document a living temperature range between ∼7°C and 17°C, suggesting that the natural thermal tolerance of this eurybathic coral may represent an advantage for its survival in a progressively warming ocean.
  • Article
    Unveiling deep-sea habitats of the Southern Ocean-facing submarine canyons of southwestern Australia
    (Elsevier, 2022-11-03) Trotter, Julie A. ; Taviani, Marco ; Foglini, Federica ; Sadekov, Aleksey ; Skrzypek, Grzegorz ; Mazzoli, Claudio ; Remia, Alessandro ; Santodomingo, Nadia ; Castellan, Giorgio ; McCulloch, Malcolm ; Pattiaratchi, Charitha ; Montagna, Paolo
    The first expedition to the depths of the Southern Ocean facing Bremer canyon systems. First ROV images of these unique deep-sea environments and inhabitants (180 to 3300 m) Discovery of spectacular ‘animal forests’ in the Bremer and Hood canyons. Scleractinian corals found well below the aragonite saturation horizon (>1000 m) Major fossil coral deposits occur at all three study areas, especially Mount Gabi.Here we present the outcomes of the first deep-sea remotely operated vehicle study of previously unexplored submarine canyon systems along the southwest Australian continental margin. This was conducted around: (1) the Bremer Marine Park; (2) the Mount Gabi seamount and nearby slope-shelf margin at the interface of the Southern and Indian oceans; with new information from (3) the Perth Canyon Marine Park located in the SE Indian Ocean. These canyons differ from many explored around the world in having no connectivity to continental river systems, thus little detrital input, with the Bremer systems and Mount Gabi facing the Southern Ocean which plays a key role in the global ocean circulation and climate systems. Such studies in the vast deep waters around the Australian continent are rare given the lack of local ROV capability available for research, thus little is known about these environments.Using the resources of the Schmidt Ocean Institute, we characterised the submarine topography from high-resolution bathymetric mapping, geology, physical and chemical oceanography, and provide an overview of these environments including the fauna observed and collected. We show that these Southern Ocean-influenced environments incorporate South Indian Central Water, Subantarctic Mode Water, Antarctic Intermediate Water, and Upper and Lower Circumpolar Deep Water, with Antarctic Bottom Water present in deep water just south of the Bremer canyon systems. The richness in megabenthos, especially along the steep, rocky substrates of the canyon heads and walls around the Bremer canyon systems, contrasts to the comparatively depauperate fauna of the more northerly Perth Canyon. Various corals serve as important substrates for a range of other species and often exhibit particular faunal associations. Especially notable are distinct ecological zones including a bryozoan and sponge-dominated (animal) forest on the shelf edge, spectacular coral gardens along canyon margins, and the occurrence of solitary scleractinians well below the aragonite saturation horizon. Subfossil coral deposits were discovered across all three study areas, reflecting periodic waxing and waning of deep-water Scleractinia throughout this southwest region. Extensive pre-modern assemblages at Mount Gabi contrast markedly with the sparse populations of living species and suggest that it might have once been a major coral hotspot, or whether they reflect long-term coral aggregations is yet to be determined. Nevertheless, stark differences in both living and past coral distribution patterns across our study sites point to at least localised fluctuations in Southern Ocean-derived nutrient and/or oxygen supplies to these deep-sea communities.