70 research outputs found

    Ancient Divergence in the Trans-Oceanic Deep-Sea Shark Centroscymnus crepidater

    Get PDF
    Unravelling the genetic structure and phylogeographic patterns of deep-sea sharks is particularly challenging given the inherent difficulty in obtaining samples. The deep-sea shark Centroscymnus crepidater is a medium-sized benthopelagic species that exhibits a circumglobal distribution occurring both in the Atlantic and Indo-Pacific Oceans. Contrary to the wealth of phylogeographic studies focused on coastal sharks, the genetic structure of bathyal species remains largely unexplored. We used a fragment of the mitochondrial DNA control region, and microsatellite data, to examine genetic structure in C. crepidater collected from the Atlantic Ocean, Tasman Sea, and southern Pacific Ocean (Chatham Rise). Two deeply divergent (3.1%) mtDNA clades were recovered, with one clade including both Atlantic and Pacific specimens, and the other composed of Atlantic samples with a single specimen from the Pacific (Chatham Rise). Bayesian analyses estimated this splitting in the Miocene at about 15 million years ago. The ancestral C. crepidater lineage was probably widely distributed in the Atlantic and Indo-Pacific Oceans. The oceanic cooling observed during the Miocene due to an Antarctic glaciation and the Tethys closure caused changes in environmental conditions that presumably restricted gene flow between basins. Fluctuations in food resources in the Southern Ocean might have promoted the dispersal of C. crepidater throughout the northern Atlantic where habitat conditions were more suitable during the Miocene. The significant genetic structure revealed by microsatellite data suggests the existence of present-day barriers to gene flow between the Atlantic and Pacific populations most likely due to the influence of the Agulhas Current retroflection on prey movements

    Multi-marker metabarcoding approach to study mesozooplankton at basin scale

    Get PDF
    Zooplankton plays a pivotal role in marine ecosystems and the characterisation of its biodiversity still represents a challenge for marine ecologists. In this study, mesozooplankton composition from 46 samples collected in summer along the western Adriatic Sea, was retrieved by DNA metabarcoding analysis. For the first time, the highly variable fragments of the mtDNA COI and the V9 region of 18S rRNA genes were used in a combined matrix to compile an inventory of mesozooplankton at basin scale. The number of sequences retrieved after quality filtering were 824,148 and 223,273 for COI and 18S (V9), respectively. The taxonomical assignment against reference sequences, using 95% (for COI) and 97% (for 18S) similarity thresholds, recovered 234 taxa. NMDS plots and cluster analysis divided coastal from offshore samples and the most representative species of these clusters were distributed according to the dominant surface current pattern of the Adriatic for the summer period. For selected sampling sites, mesozooplankton species were also identified under a stereo microscope providing insights on the strength and weakness of the two approaches. In addition, DNA metabarcoding was shown to be helpful for the monitoring of non-indigenous marine metazoans and spawning areas of commercial fish species. We defined pros and cons of applying this approach at basin scale and the benefits of combining the datasets from two genetic markers

    Zoantharians (Hexacorallia: Zoantharia) associated with cold-water corals in the azores region: New species and associations in the deep sea

    Get PDF
    Zoantharians are a group of cnidarians that are often found in association with marine invertebrates, including corals, in shallow and deep-sea environments. However, little is known about deep-sea zoantharian taxonomy, specificity and nature of their associations with their coral hosts. In this study, analyses of molecular data (mtDNA COI, 16S, and 12S rDNA) coupled with ecological and morphological characteristics were used to examine zoantharian specimens associated with cold-water corals (CWC) at depths between 110 and 800 m from seamounts and island slopes in the Azores region. The zoantharians examined were found living in association with stylasterids, antipatharians and octocorals. From the collected specimens, four new species were identified: (1) Epizoanthus martinsae sp. n. associated with the antipatharian Leiopathes sp.; (2) Parazoanthus aliceae sp. n. associated with the stylasterid Errina dabneyi (Pourtalès, 1871); (3) Zibrowius alberti sp. n. associated with octocorals of the family Primnoidae [Paracalyptrophora josephinae (Lindström, 1877)] and the family Plexauridae (Dentomuricea aff. meteor Grasshoff, 1977); (4) Hurlizoanthus hirondelleae sp. n. associated with the primnoid octocoral Candidella imbricata (Johnson, 1862). In addition, based on newly collected material, morphological and molecular data and phylogenic reconstruction, the zoantharian Isozoanthus primnoidus Carreiro-Silva, Braga-Henriques, Sampaio, de Matos, Porteiro & Ocaña, 2011, associated with the primnoid octocoral Callogorgia verticillata (Pallas, 1766), was reclassified as Zibrowius primnoidus comb. nov. The zoantharians, Z. primnoidus comb. nov., Z. alberti sp. n., and H. hirondelleae sp. n. associated with octocorals showed evidence of a parasitic relationship, where the zoantharian progressively eliminates gorgonian tissue and uses the gorgonian axis for structure and support, and coral sclerites for protection. In contrast, the zoantharian P. aliceae sp. n. associated with the stylasterid E. dabneyi and the zoantharian E. martinsae sp. n. associated with the antipatharian Leiopathes sp., appear to use the coral host only as support with no visible damage to the host. The monophyly of octocoral-associated zoantharians suggests that substrate specificity is tightly linked to the evolution of zoantharians.publishedVersio

    Towards Naples Ecological REsearch for Augmented Observatories (NEREA): The NEREA-Fix module, a stand-alone platform for long-term deep-sea ecosystem monitoring

    Get PDF
    Deep-sea ecological monitoring is increasingly recognized as indispensable for the comprehension of the largest biome on Earth, but at the same time it is subjected to growing human impacts for the exploitation of biotic and abiotic resources. Here, we present the Naples Ecological REsearch (NEREA) stand-alone observatory concept (NEREA-fix), an integrated observatory with a modular, adaptive structure, characterized by a multiparametric video-platform to be deployed in the Dohrn canyon (Gulf of Naples, Tyrrhenian Sea) at ca. 650 m depth. The observatory integrates a seabed platform with optoacoustic and oceanographic/geochemical sensors connected to a surface transmission buoy, plus a mooring line (also equipped with depth-staged environmental sensors). This reinforced high-frequency and long-lasting ecological monitoring will integrate the historical data conducted over 40 years for the Long-Term Ecological Research (LTER) at the station “Mare Chiara”, and ongoing vessel-assisted plankton (and future environmental DNA-eDNA) sampling. NEREA aims at expanding the observational capacity in a key area of the Mediterranean Sea, representing a first step towards the establishment of a bentho-pelagic network to enforce an end-to-end transdisciplinary approach for the monitoring of marine ecosystems across a wide range of animal sizes (from bacteria to megafauna).This research was funded by PON “Iniziative in supporto al consolidamento e potenziamento dell’infrastruttura EMSO e delle sue attività (InSEA)” - European Union - Italian Ministry of University and Research, grant number PIR01_00030.Peer ReviewedPostprint (published version

    First record of the opal chimaera, Chimaera opalescens (Holocephali: Chimaeridae) and revision of the occurrence of the rabbitfish Chimaera monstrosa in the Azores waters

    Get PDF
    The presence of the opal chimaera, Chimaera opalescens, is reported for the first time in the deep waters of the Azores, with the capture of four specimens by fishermen and the video recording of an additional five individuals. Species identification was supported by the 646 bp sequenced fragment of the mitochondrial gene cytochrome oxidase subunit I. Because C. opalescens is a recently recognised species that had been recurrently misidentified as rabbitfish, Chimaera monstrosa, the historical data of C. monstrosa in the Azores were reviewed to assess the possible presence of both Chimaera species in the region. Although several authors have reported the occurrence of C. monstrosa in the Azorean waters since the 1800s, the majority of these are based on only three specimens caught during the late 1800s. The investigation performed using literature and examination of the museum specimens still available concluded that the most likely scenario is that C. monstrosa is absent from the Azores and past records of that species in the region are most likely misidentifications of C. opalescens.publishedVersio

    An Insightful Model to Study Innate Immunity and Stress Response in Deep‐Sea Vent Animals: Profiling the Mussel Bathymodiolus azoricus

    Get PDF
    Deep‐sea environments are, in some cases, largely unexplored ecosystems, where life thrives driven by the geochemical features of each location. Among these environments, chemosynthesis‐based ecosystems, in the Mid Atlantic Ridge, have an exclusive combination of high depth, high sulfur, and high methane concentrations. This is believed to modulate the biological composition of vent communities and influence the overall vent animal transcriptional activity of genes involved in adaptation processes to extreme environments. This opens, thus, the possibility of finding gene expression signatures specific to a given hydrothermal vent field. Regardless of the extreme physicochemical conditions that characterize deep‐sea hydrothermal vents, the animals dwelling around the vent sites exhibit high productivity and thus must cope with toxic nature of vent surrounding, seemingly deleterious to the animals, while developing surprisingly successful strategies to withstand adverse environmental conditions, including environmental microbes and mechanical stress whether ensuing from animal predation or venting activity. The deep‐sea vent mussel Bathymodiolus azoricus has adapted well to deep‐sea extreme environments and represents the dominating faunal community from hydrothermal vent sites in the Mid‐Atlantic Ridge, owing its successful adaptation and high biomasses to specialized exploitation of methane and sulfide sources from venting activity. Its extraordinary capabilities of adapting and thriving in chemosynthesis‐based environments, largely devoid of photosynthetic primary production and characterized by rapid geochemical regime changes are due to symbiotic associations with chemosynthetic bacteria within its large gills. In an attempt to understand physiological reactions in animals normally set to endure extreme deep‐sea environments, our laboratory has undertaken, for the last few years, a series of investigations, aimed at characterizing molecular indicators of adaptation processes of which components of the host defense system has received most attention. This study reviews recent advances on the characterization of molecules and genes participating in immune reactions, using in vivo and ex vivo models, to elucidate cellular and humoral defense mechanisms in vent mussels and the strategies they have adopted to survive under extreme environments

    Marine Science Can Contribute to the Search for Extra-Terrestrial Life

    Get PDF
    Life on our planet likely evolved in the ocean, and thus exo-oceans are key habitats to search for extraterrestrial life. We conducted a data-driven bibliographic survey on the astrobiology literature to identify emerging research trends with marine science for future synergies in the exploration for extraterrestrial life in exo-oceans. Based on search queries, we identified 2592 published items since 1963. The current literature falls into three major groups of terms focusing on (1) the search for life on Mars, (2) astrobiology within our Solar System with reference to icy moons and their exo-oceans, and (3) astronomical and biological parameters for planetary habitability. We also identified that the most prominent research keywords form three key-groups focusing on (1) using terrestrial environments as proxies for Martian environments, centred on extremophiles and biosignatures, (2) habitable zones outside of “Goldilocks” orbital ranges, centred on ice planets, and (3) the atmosphere, magnetic field, and geology in relation to planets’ habitable conditions, centred on water-based oceans
    corecore