Secular to Interannual Climatic, Oceanographic and Ecological Changes in the Peruvian Upwelling System Revealed by Multiproxies Sedimentary Records of the Past 250 Years

HR: 11:20h
AN: PP52C-05 [Abstracts]
TI: Secular to Interannual Climatic, Oceanographic and Ecological Changes in the Peruvian Upwelling System Revealed by Multiproxies Sedimentary Records of the Past 250 Years
AU: * Gutierrez, D
EM: dgutierrez@imarpe.gob.pe
AF: Instituto del Mar del Peru, Esquina Gamarra y General Valle s/n, Callao, CALLAO 01 Peru
AU: Sifeddine, A
EM: Sifeddine@bondy.ird.fr
AF: UR Paleotropique, Institut de Recherche pour le D‚veloppement, 32, Henri Varagnat, Bondy, 93143 France
AU: Ortlieb, L
EM: Luc.Ortlieb@bondy.ird.fr
AF: UR Paleotropique, Institut de Recherche pour le D‚veloppement, 32, Henri Varagnat, Bondy, 93143 France
AU: Velazco, F
EM: fvelazco@imarpe.gob.pe
AF: Instituto del Mar del Peru, Esquina Gamarra y General Valle s/n, Callao, CALLAO 01 Peru
AU: Baumgartner, T
EM: tbaumgar@cicese.mx
AF: CICESE, Km. 107 Carretera Tijuana - Ensenada, Ensenada, 22860 Mexico
AU: Reyss, J
PP52C-05 AF: Laboratoire du Sciences de Climat et le Environnement, CEA/CNRS, avenue de la Terrasse, Batiment 10A, Gif-Sur-Yvette, 91198 France
AU: Vargas, G
PP52C-05 AF: Departamento de Geolog¡a, Facultad de Ciencias F¡sicas y Matem ticas, Universidad de Chile, Avenida Beaucheff # 850, Santiago, 6640022 Chile
AU: Salvatteci, R
PP52C-05 AF: Instituto del Mar del Peru, Esquina Gamarra y General Valle s/n, Callao, CALLAO 01 Peru
AU: Tapia, P
PP52C-05 AF: Laboratorio de Palinologia y Paleobot nica, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Mart¡n de Porras , Lima, LIMA 31 Peru
AU: Field, D
PP52C-05 AF: Fisheries Resources Division, Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, CA 92037-1508 United States
AU: Ferreira, V
PP52C-05 AF: CICESE, Km. 107 Carretera Tijuana - Ensenada, Ensenada, 22860 Mexico
AU: Valdes, J
PP52C-05 AF: Laboratorio de Sedimentologia y Paleoambientes, Universidad de Antofagasta, Avenida Jaime Guzm n s/n, Antofagasta, 170 Chile
AU: Solis, J
PP52C-05 AF: Instituto del Mar del Peru, Esquina Gamarra y General Valle s/n, Callao, CALLAO 01 Peru
AU: Soler, P
PP52C-05 AF: UMR LOCEAN, Universite Paris VI/IRD/CNRS, France, 5 Place Jussieu, Paris, 75005 France
AU: Boussafir, M
PP52C-05 AF: Institut des Sciences de la Terre (ISTO), Universit‚ de Orl‚ans, 2 rue de la Ferollerie, Orleans, 45071 France
AU: Taffoureau, E
PP52C-05 AF: Institut des Sciences de la Terre (ISTO), Universit‚ de Orl‚ans, 2 rue de la Ferollerie, Orleans, 45071 France
AU: Boucher, H
PP52C-05 AF: UR Paleotropique, Institut de Recherche pour le D‚veloppement, 32, Henri Varagnat, Bondy, 93143 France
AU: Mandeng Yogo, M
PP52C-05 AF: UR Paleotropique, Institut de Recherche pour le D‚veloppement, 32, Henri Varagnat, Bondy, 93143 France
AU: Bouloubassi, I
PP52C-05 AF: UMR LOCEAN, Universite Paris VI/IRD/CNRS, France, 5 Place Jussieu, Paris, 75005 France
AB: We conducted high-resolution studies of two box-cores collected 300 km apart in the central Peruvian margin at 300 m and at 184 m depth off Pisco and Callao, respectively. While the Callao site is located closer to the upper boundary of the Oxygen Minimum Zone (OMZ) and to episodical continental sources, the Pisco site is located in the center of the OMZ and off a more desertic coastal fringe. The chronology was established from excess 210Pb activities, calibrated by downcoe spikes of the bomb-derived 241Am in the uppermost layer, and combined with sedimentological fingerprints of historically well-known seismic or volcanic events and AMS radiocarbon ages for the period before 1870 AD. Despite the differences in location, depth, exposure to oxygen-depleted waters and to terrestrial inputs, both cores reveal striking similarities in downcore sedimentological composition and in TOC fluxes. Two major periods are marked by a secular change around 1835 AD. The first period is characterized by a lower and less variable total organic carbon (TOC) flux, as well as a higher quartz content (compared to the following period). Off Pisco, sediment structure also shows a higher (interannual to higher) frequency in the variability of X-ray gray level, in accordance to the presence of laminations. The second major period is characterized at both sites by higher, but more variable, TOC fluxes with a positive trend, and with significantly lower quartz content in the sediment. During the past 50 years, the positive trend of TOC fluxes is intensified and the quartz content increases at both sites, coinciding with records of increasing alongshore wind stress off the Peruvian coast in the same period. Other proxies analyzed off Pisco, as fish scales and diatoms, also indicate less productive conditions before 1835 AD(lower abundance of diatoms and anchovy scales), as well as remarkable signals of interdecadal variability after 1870 AD. These results strongly suggest that the current productivity level of the Peruvian upwelling system is unprecedented for the last 250 years, and that a major re-organization of the ecosystem occurred around the mid-nineteenth century.
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0460 Marine systems (4800)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005