title: Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean.
abstract: Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ(13)C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations.
authors.affiliation: Department of Ocean Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. Institute for Marine Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Kelton W
authors.initials: KW
authors.lastname: McMahon
authors.affiliation: Department of Ocean Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: McCarthy
authors.affiliation: Institute of Arctic and Alpine Research, University of Colorado-Boulder, Boulder, CO 80309, USA.
authors.forename: Owen A
authors.initials: OA
authors.lastname: Sherwood
authors.affiliation: Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Larsen
authors.affiliation: Department of Ocean Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. Institute for Marine Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Guilderson
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D037421:Anthozoa / Q000737:chemistry / Q000378:metabolism*; D001272:Atmosphere / Q000737:chemistry; D002244:Carbon / Q000378:metabolism; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D057231:Climate Change; D000458:Cyanobacteria / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D058086:Microalgae / Q000145:classification / Q000378:metabolism*; D010140:Pacific Ocean; D012623:Seawater
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D002244:Carbon