Patterns of eukaryotic diversity from the surface to the deep-ocean sediment
This article is contribution 125 of Tara Oceans.-- 13 pages, 5 figures, supplementary materials https://doi.org/10.1126/sciadv.abj9309.-- Data and materials availability: The raw sediment sequencing data have been deposited to the ENA under project accessions PRJEB48517 (deep_sea) and PRJEB33873 (eDNAbyss). Accession numbers of additional raw sequencing data of pelagic and sediment samples analyzed in this study can be found in respective publications listed in table S2. All the metadata and R code to process the raw sequencing data and to reproduce the results and figures are available through a GitHub repository: https://github.com/trtcrd/DOS_V9 ; Remote deep-ocean sediment (DOS) ecosystems are among the least explored biomes on Earth. Genomic assessments of their biodiversity have failed to separate indigenous benthic organisms from sinking plankton. Here, we compare global-scale eukaryotic DNA metabarcoding datasets (18S-V9) from abyssal and lower bathyal surficial sediments and euphotic and aphotic ocean pelagic layers to distinguish plankton from benthic diversity in sediment material. Based on 1685 samples collected throughout the world ocean, we show that DOS diversity is at least threefold that in pelagic realms, with nearly two-thirds represented by abundant yet unknown eukaryotes. These benthic communities are spatially structured by ocean basins and particulate organic carbon (POC) flux from the upper ocean. Plankton DNA reaching the DOS originates from abundant species, with maximal deposition at high latitudes. Its seafloor DNA signature predicts variations in POC export from the surface and reveals previously overlooked taxa that may drive the biological carbon pump ; We further thank the following sponsors for support: the Swiss National Science Foundation (grants 31003A_159709, 31003A_1791259, and P2GEP3_171829), the Swiss Network for International Studies award (20170024), the European Research Council (grant 818449 AGENSI), CNRS (in particular, FR022), Sorbonne University, the French Government "Investissement d'Avenir" program OCEANOMICS (ANR-11-BTBR-0008), France Génomique, the Genoscope-CEA (ANR-10-INBS-09) for the project eDNAbyss (AP2016-228), Ifremer for the project Merlin "Pourquoi pas les Abysses," the German Research Foundation (grants BR1121/20-1 and BR1121/41-1 and the Center/Cluster of Excellence "The Ocean Floor—Earth's Uncharted Interface"), the German Ministry for Science and Education (grants 03G0223A and 03G0227A), EU JPIO-Oceans project MinigImpact-2 (German BMBF contract 03F0812E), Spanish Ministry of Economy and Competitiveness (CTM2016-75083-R), European Union's Horizon 2020 Research and Innovation Program (grant 678760 ATLAS), and the Gordon and Betty Moore Foundation (grant GBMF5257 UniEuk). Samples from the UK-1 and OMS license areas in the Clarion-Clipperton Zone were collected as part of the ABYSSLINE project, funded by UK Seabed Resources Development Ltd. (contract SRDL SRD100100) ; With the institutional support of the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed