title: Comparative analysis between protist communities from the deep-sea pelagic ecosystem and specific deep hydrothermal habitats.
abstract: Protist communities associated with deep seawater and bivalves from six hydrothermal sites in the Pacific Ocean were characterized by microscopy and molecular rRNA gene surveys (18S rRNA) and compared with planktonic communities from Pacific deep-pelagic seawater (from 500 to 3000 m in depth). Genetic libraries from larger size fractions (>3 µm) of deep-pelagic water were mainly dominated by Dinophyceae, whereas small size fractions (<3 µm) mainly revealed radiolarians and Syndiniales. In contrast, more specific opportunistic detritivores and grazers, mostly belonging to Stramenopiles and Cercozoa, were detected from water surrounding vent chimneys. Protist communities were different in the pallial cavity of the giant hydrothermal bivalves Bathymodiolus thermophilus and Calyptogena magnifica, dominated by Ciliophora (primarily belonging to Phyllopharyngea, Oligohymenophorea and Oligotrichea) and Cercozoa. Interestingly, protist communities retrieved from the pallial cavity liquid of hydrothermal bivalves were remarkably homogeneous along the Southern East Pacific Rise, in contrast to bivalves collected on the Mid-Atlantic Ridge hydrothermal vents and cold seeps from the Gulf of Mexico. Hence, complex protist communities seem to occur inside hydrothermal bivalves, and these metazoa may constitute a stable micro-niche for micro-eukaryotes, including grazers, detritivores, symbionts and potential parasites. From these communities, new lineages within the ciliates may emerge.
authors.affiliation: CNRS, UMR 7144, Groupe Plancton Océanique, Station Biologique de Roscoff, BP 74, 29682 Roscoff, France. sauvadet@sb-roscoff.fr
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Sauvadet
authors.forename: Angélique
authors.initials: A
authors.lastname: Gobet
authors.forename: Laure
authors.initials: L
authors.lastname: Guillou
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D044822:Biodiversity; D058448:Biota; D049872:Bivalvia / Q000145:classification / Q000235:genetics; D020732:Cytogenetic Analysis; D017753:Ecosystem; D056890:Eukaryota / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D015723:Gene Library; D014644:Genetic Variation; D006358:Hot Temperature; D056186:Metagenomics; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010140:Pacific Ocean; D010802:Phylogeny; D010933:Plankton / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000145:classification; D012623:Seawater
chemical_list: D012337:RNA, Ribosomal, 18S