Marie-Claire Fabri

Cryptic species of Archinome (Annelida: Amphinomida) from vents and seeps

Since its description from the Galapagos Rift in the mid-1980s, Archinome rosacea has been recorded at hydrothermal vents in the Pacific, Atlantic and Indian Oceans. Only recently was a second species described from the Pacific Antarctic Ridge. We inferred the identities and evolutionary relationships of Archinome representatives sampled from across the hydrothermal vent range of the genus, which is now extended to cold methane seeps. Species delimitation using mitochondrial cytochrome c oxidase subunit I (COI) recovered up to six lineages, whereas concatenated datasets (COI, 16S, 28S and ITS1) supported only four or five of these as clades. Morphological approaches alone were inconclusive to verify the identities of species owing to the lack of discrete diagnostic characters. We recognize five Archinome species, with three that are new to science. The new species, designated based on molecular evidence alone, include: Archinome levinae n. sp., which occurs at both vents and seeps in the east Pacific, Archinome tethyana n. sp., which inhabits Atlantic vents and Archinome jasoni n. sp., also present in the Atlantic, and whose distribution extends to the Indian and southwest Pacific Oceans. Biogeographic connections between vents and seeps are highlighted, as are potential evolutionary links among populations from vent fields located in the east Pacific and Atlantic Oceans, and Atlantic and Indian Oceans; the latter presented for the first time.

Composition and Biogeography of Hydrothermal Vent Communities in Western Pacific Back‐Arc Basins

Deep-sea hydrothermal vent communities have been located and studied over different geological and dynamic contexts: fast to slow mid-ocean ridges, back-arc basins, volcanic arcs, and active seamounts. The associated vent faunas belong to a small set of mostly endemic taxa relying on chemoautotrophic microbial production, able to stand extreme habitat conditions and to persist in a discontinuous and ephemeral environment. Because of their obligate relations to hydrothermal venting, they disperse only along ridges, stepping from one active hydrothermal vent to another. Discontinuities of the ridges or hydrological barriers can limit along-axis dispersal and thus favor allopatric speciation. Western Pacific back-arc basins are isolated spreading centers, which remain active during a short period of geological time, in the proximity of active and passive continental margins where cold seeps are frequent. The Rim of Fire region thus represents a complex area of potential exchanges between chemosynthetic-based ecosystems. Our present knowledge is restricted to active areas situated in five back-arc basins (Lau and North Fiji Basins, Manus Basin, Mariana Trough, Okinawa Trough) and two are volcanoes (Izu-Ogasawara, Kermadec Arc). We here review the distribution and composition of vent-associated biological communities in these basins and arcs, and discuss the faunal affinities among them and the possible migration routes between them and the mid-ocean ridges.

Biological data extraction from imagery – How far can we go? A case study from the Mid-Atlantic Ridge

In the past few decades, hydrothermal vent research has progressed immensely, resulting in higher-quality samples and long-term studies. With time, scientists are becoming more aware of the impacts of sampling on the faunal communities and are looking for less invasive ways to investigate the vent ecosystems. In this perspective, imagery analysis plays a very important role. With this study, we test which factors can be quantitatively and accurately assessed based on imagery, through comparison with faunal sampling. Twelve instrumented chains were deployed on the Atlantic Eiffel Tower hydrothermal edifice and the corresponding study sites were subsequently sampled. Discrete, quantitative samples were compared to the imagery recorded during the experiment. An observer-effect was tested, by comparing imagery data gathered by different scientists. Most factors based on image analyses concerning Bathymodiolus azoricus mussels were shown to be valid representations of the corresponding samples. Additional ecological assets, based exclusively on imagery, were included.

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

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 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 (Pourtales, 1871); (3) Zibrowius alberti sp. n. associated with octocorals of the family Primnoidae (Paracalyptrophora josephinae (Lindstrom, 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 & Ocana, 2011, associated with the primnoid octocoral Callogorgia verticillata (Pallas, 1766), was reclassified of 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.