title: Insights into global diatom distribution and diversity in the world's ocean.
abstract: Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered.
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France;
authors.forename: Shruti
authors.initials: S
authors.lastname: Malviya
authors.affiliation: Stazione Zoologica Anton Dohrn, 80121 Naples, Italy;
authors.forename: Eleonora
authors.initials: E
authors.lastname: Scalco
authors.affiliation: CNRS, UMR 7144, Station Biologique de Roscoff, 29680 Roscoff, France;
authors.forename: Stéphane
authors.initials: S
authors.lastname: Audic
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France;
authors.forename: Flora
authors.initials: F
authors.lastname: Vincent
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France;
authors.forename: Alaguraj
authors.initials: A
authors.lastname: Veluchamy
authors.affiliation: Institut de Génomique, GENOSCOPE, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, 91057 Évry, France;
authors.forename: Julie
authors.initials: J
authors.lastname: Poulain
authors.affiliation: Institut de Génomique, GENOSCOPE, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, 91057 Évry, France; UMR 8030, CNRS, CP5706, 91057 Évry, France; UMR 8030, Université d'Evry, CP5706, 91057 Évry, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Wincker
authors.affiliation: Stazione Zoologica Anton Dohrn, 80121 Naples, Italy;
authors.forename: Daniele
authors.initials: D
authors.lastname: Iudicone
authors.affiliation: CNRS, UMR 7144, Station Biologique de Roscoff, 29680 Roscoff, France;
authors.forename: Colomban
authors.initials: C
authors.lastname: de Vargas
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France;
authors.forename: Lucie
authors.initials: L
authors.lastname: Bittner
authors.affiliation: Stazione Zoologica Anton Dohrn, 80121 Naples, Italy;
authors.forename: Adriana
authors.initials: A
authors.lastname: Zingone
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France; cbowler@biologie.ens.fr.
authors.forename: Chris
authors.initials: C
authors.lastname: Bowler
mesh_terms: D059001:Aquatic Organisms; D044822:Biodiversity; D004275:DNA, Ribosomal; D016208:Databases, Factual; D017377:Diatoms / Q000145:classification / Q000235:genetics*; D017753:Ecosystem; D008853:Microscopy / Q000379:methods; D009792:Oceans and Seas; D010839:Phytoplankton; D015203:Reproducibility of Results
chemical_list: D004275:DNA, Ribosomal
keywords: Tara Oceans; biodiversity; choke points; diatoms; metabarcoding