title: Size-fractionated diversity of eukaryotic microbial communities in the Eastern Tropical North Pacific oxygen minimum zone.
abstract: Oxygen minimum zones (OMZs) caused by water column stratification appear to expand in parts of the world's ocean, with consequences for marine biogeochemical cycles. OMZ formation is often fueled by high surface primary production, and sinking organic particles can be hotspots of interactions and activity within microbial communities. This study investigated the diversity of OMZ protist communities in two biomass size fractions (>30 and 30-1.6 μm filters) from the world's largest permanent OMZ in the Eastern Tropical North Pacific. Diversity was quantified via Illumina MiSeq sequencing of V4 region of 18S SSU rRNA genes in samples spanning oxygen gradients at two stations. Alveolata and Rhizaria dominated the two size fractions at both sites along the oxygen gradient. Community composition at finer taxonomic levels was partially shaped by oxygen concentration, as communities associated with versus anoxic waters shared only ∼32% of operational taxonomic unit (OTU) (97% sequence identity) composition. Overall, only 9.7% of total OTUs were recovered at both stations and under all oxygen conditions sampled, implying structuring of the eukaryotic community in this area. Size-fractionated communities exhibited different taxonomical features (e.g. Syndiniales Group I in the 1.6-30 μm fraction) that could be explained by the microniches created on the surface-originated sinking particles.
authors: Laboratoire d'Océanologie et de Géosciences, Université du Littoral, CNRS-UMR LOG 8187, 62930 Wimereux, France.
authors: Manon T
authors: MT
authors: Duret
authors: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors: Maria G
authors: MG
authors: Pachiadaki
authors: School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors: Frank J
authors: FJ
authors: Stewart
authors: School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors: Neha
authors: N
authors: Sarode
authors: Laboratoire d'Océanologie et de Géosciences, Université du Littoral, CNRS-UMR LOG 8187, 62930 Wimereux, France.
authors: Urania
authors: U
authors: Christaki
authors: Laboratoire d'Océanologie et de Géosciences, Université du Littoral, CNRS-UMR LOG 8187, 62930 Wimereux, France.
authors: Sébastien
authors: S
authors: Monchy
authors: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
authors: Ankita
authors: A
authors: Srivastava
authors: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA vedgcomb@whoi.edu.
authors: Virginia P
authors: VP
authors: Edgcomb
mesh_terms: D056893:Alveolata / Q000145:classification* / Q000235:genetics; D000693:Anaerobiosis / Q000502:physiology*; D001483:Base Sequence; D044822:Biodiversity; D018533:Biomass; D016054:DNA, Protozoan / Q000032:analysis / Q000235:genetics*; D064307:Microbiota / Q000235:genetics; D010100:Oxygen / Q000032:analysis; D010140:Pacific Ocean; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D056901:Rhizaria / Q000145:classification* / Q000235:genetics; D012623:Seawater / Q000737:chemistry / Q000469:parasitology*; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S; D010100:Oxygen
keywords: 18S SSU rRNA; particle-associated; protist diversity; water-column