Environmental characteristics of Agulhas rings affect interocean plankton transport

Villar, Emilie ... et. al.-- 11 pages, 8 figures, supplementary materials www.sciencemag.org/content/348/6237/1261447/suppl/DC1Agulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic. © 2015, American Association for the Advancement of Science. All rights reservedWe appreciate the commitment of the following people and sponsors: CNRS (in particular, Groupement de Recherche GDR3280); European Molecular Biology Laboratory (EMBL); Genoscope/CEA; VIB; Stazione Zoologica Anton Dohrn; UNIMIB; Fund for Scientific Research–Flanders; Rega Institute, KU Leuven; the French Ministry of Research; the French government Investissements d’Avenir programmes OCEANOMICS (ANR-11-BTBR-0008), FRANCE GENOMIQUE (ANR-10-INBS-09-08), MEMO LIFE (ANR-10-LABX-54), PSL* Research University (ANR-11-IDEX-0001-02), and ANR (projects POSEIDON/ ANR-09-BLAN- 0348, PHYTBACK/ANR-2010-1709-01, PROMETHEUS/ANR-09-PCS-GENM-217, SAMOSA/ANR-13-ADAP-0010, and TARAGIRUS/ANR-09-PCS-GENM-218); European Union FP7 (MicroB3/No.287589, IHMS/HEALTH-F4-2010-261376, and MaCuMBA/No.311975); ERC Advanced Grant Award to C.B. (Diatomite: 294823); Gordon and Betty Moore Foundation grant (no. 3790) to M.B.S.; Spanish Ministry of Science and Innovation grant CGL2011-26848/BOS MicroOcean PANGENOMICS to S.G.A.; TANIT (CONES 2010-0036) from the Agència de Gestió d´Ajusts Universitaris i Reserca to S.G.A.; JSPS KAKENHI grant no. 26430184 to H.O.; NASA Ocean Biology and Biogeochemistry program (NNX11AQ14G and NNX09AU43G) to E.B.; The Italian Research for the Sea (Flagship Project RITMARE) to D.I.; and FWO, BIO5, and Biosphere 2 to M.B.S.We also appreciate the support and commitment of Agnès b. and Etienne Bourgois, the Veolia Environment Foundation, Region Bretagne, Lorient Agglomeration, World Courier, Illumina, the EDF Foundation, FRB, the Prince Albert II de Monaco Foundation, and the Tara schooner and its captains and crew. We thank MERCATOR-CORIOLIS and ACRI-ST for providing daily satellite data during the expedition. We are also grateful to the French Ministry of Foreign Affairs for supporting the expedition and to the countries that graciously granted sampling permissions. Tara Oceans would not exist without continuous support from 23 institutes (http://oceans.taraexpeditions.org)Peer Reviewe

Environmental characteristics of Agulhas rings affect interocean plankton transport

International audienceAgulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic