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A 14‐ka Record of Dust Input and Phytoplankton Regime Changes in the Subtropical NE Pacific: Oceanic and Terrestrial Processes Linked by Teleconnections at Suborbital Scales

Arellano‐Torres, Elsa ; Álvarez‐Covelli, Catalina ; Kasper‐Zubillaga, Juan José ; Lozano‐García, María del Socorro

Paleoceanography and paleoclimatology, 2019-01, Vol.34 (1), p.35-53 [Periódico revisado por pares]

Hoboken: Blackwell Publishing Ltd

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  • Título:
    A 14‐ka Record of Dust Input and Phytoplankton Regime Changes in the Subtropical NE Pacific: Oceanic and Terrestrial Processes Linked by Teleconnections at Suborbital Scales
  • Autor: Arellano‐Torres, Elsa ; Álvarez‐Covelli, Catalina ; Kasper‐Zubillaga, Juan José ; Lozano‐García, María del Socorro
  • Assuntos: Advection ; Algae ; Atmospheric particulates ; Basins ; biogenic proxies ; Calcium ; Calcium carbonate ; Calcium carbonates ; California Current ; Carbon ; carbon export ; Carbonates ; Climate ; Convergence zones ; Deglaciation ; Dust ; Dust storms ; El Nino ; El Nino phenomena ; El Nino-Southern Oscillation event ; Exports ; Extreme weather ; Fluvial transport ; Grain size ; Gypsum ; Holocene ; Hydrology ; Inorganic carbon ; Intertropical convergence zone ; Mineral nutrients ; Natural phenomena ; Nutrient sources ; Nutrient uptake ; Nutrients ; Ocean circulation ; Ocean currents ; Oceans ; Organic carbon ; Organic matter ; Organisms ; Pacific Decadal Oscillation ; Particle size ; Phytoplankton ; Productivity ; Ratios ; Sediment ; Sediments ; Southern Oscillation ; Teleconnections ; time series analyses ; Total organic carbon ; Upwelling ; Variability ; Weather
  • É parte de: Paleoceanography and paleoclimatology, 2019-01, Vol.34 (1), p.35-53
  • Descrição: We study shifts in phytoplankton proxies linked to terrigenous inputs and teleconnections in a core from Soledad Basin, Gulf of Ulloa, NW Mexico, spanning the end of the deglaciation and the Holocene. We used biogenic opal (% opal), organic carbon (% total organic carbon [TOC]), and inorganic carbon (% CaCO3) as proxies of productivity and opal/TOC and CaCO3/TOC ratios as proxies of nutrient uptake and C‐export by siliceous and carbonate organisms. We reconstructed terrestrial inputs and identified authigenic gypsum. Based on opal/TOC and CaCO3/TOC ratios, we found periodic changes of ~0.5, 1.1–1.8 ka cycle in phytoplankton proxies exporting siliceous and carbonate skeletal debris to the sediments. An increase in carbonate organisms occurred during 14–8.7 ka, corresponding to reduced El Niño–Southern Oscillation (ENSO)‐like variability, in parallel to the northward displacement of the Intertropical Convergence Zone (ITCZ) and an overall negative phase of the Pacific Decadal Oscillation (PDO). An increase in siliceous organisms occurred between 6 and 3 ka, coincident with strong ENSO‐like conditions, southern migration of ITCZ, and less intense but more frequent positive PDO‐hydrological variability. Grain size analyses show significant amounts of fine fraction (dust <6.6 μm) present during the early‐ to mid‐Holocene in agreement to extreme weather on land, with episodes of eolian and fluvial transport to the sea. The ENSO‐like variations influenced biological C‐export producers on a scale of 1.1–1.8 ka, but PDO‐related variability is uncertain. We suggest that Holocene drivers for phytoplankton successions are changes in insolation, ITCZ migration, California Current upwelling, nutrient inputs by advection, and terrestrial sources. Plain Language Summary We worked on a marine core off SW Baja California, Mexico, to study past changes in microscopic algal groups (phytoplankton) over the last 14,000 years. We study the role of nutrients from terrestrial and marine sources and investigate the role of ocean currents and natural phenomena like El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) along NE Pacific margin. To reconstruct biological productivity, we analyzed the remains of ancient organisms like silicon (opal), calcium carbonate (CaCO3), and organic matter (TOC) content and determine the algal group that grows more efficiently and deposits more organic matter in the sediments. To reconstruct terrestrial sources, we measure the sediments' grain size. We found cyclical periods that alternate siliceous versus carbonate algae every 500, 1,100, and 1800 years. Carbonate phytoplankton was more abundant between 14,000 and 8,000 years ago, and siliceous phytoplankton was more abundant between 6,000 and 3,000 years ago. Reconstructions of terrestrial climate suggest that during humid periods land nutrients and carbonate phytoplankton increase in parallel, whereas during the strength of the California Current, ocean nutrients and siliceous phytoplankton grow together, proving that an important connection exists between land climate, ocean circulation, and biological productivity. Key Points A 14‐ka record of productivity proxies in the California Current shows shifts in phytoplankton linked to dust inputs and continental climate Opal/TOC and CaCO3/TOC molar ratios show changes of 0.5, 1.1, and 1.8 ka cycle linked to ENSO‐like variability and ITCZ latitudinal migration Main drivers of C‐export by calcareous and siliceous communities include upwelling, nutrient advection, and inputs from land
  • Editor: Hoboken: Blackwell Publishing Ltd
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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