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MEPS 535:63-87 (2015)  -  DOI: https://doi.org/10.3354/meps11409

Calcareous benthic foraminifera from the upper central Peruvian margin: control of the assemblage by pore water redox and sedimentary organic matter

Jorge Cardich1,2,3,*, Dimitri Gutiérrez1,2, Dennis Romero1,2, Alexander Pérez1,2, Luis Quipúzcoa2, Robert Marquina2, Williams Yupanqui2, Juana Solís2, Wilson Carhuapoma2, Abdelfettah Sifeddine3,4, Anthony Rathburn

1Programa de Maestría en Ciencias del Mar, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, Lima 31, Peru
2Dirección General de Investigaciones Oceanográficas y Cambio Climático, Instituto del Mar del Perú (IMARPE), Av. Gamarra y Gral. Valle, s/n, Chucuito, Callao 01, Peru
3Departamento de Geoquimica, Universidade Federal Fluminense, LMI PALEOTRACES, Niteroi, RJ 24020-141, Brazil
4Centre IRD France-Nord, LOCEAN, UMR 7159, 32 Avenue Henri Varagnat, 93143 Bondy cedex, France
5Geology Program, Indiana State University, Science Building 159, Terre Haute, Indiana 47809, USA
*Corresponding author:

ABSTRACT: We studied ‘living’ (stained) benthic foraminifera in the upper border of the Peruvian oxygen minimum zone (OMZ) to determine the relationship between species’ distribution and pore water and sediment geochemistry under oxygen deficiency. Superficial sediments were sampled between 2009 and 2011 from 2 bathymetric transects off central Peru (45 to 300 m depth). The quantity (total organic carbon, total nitrogen and chloroplastic pigment equivalents [CPE]) and quality (chlorophyll a/phaeopigments ratio) of organic matter (OM) were evaluated. Benthic foraminifera were sampled in the top 5 cm of sediment. Commonly, the inner shelf sediments were sulfidic and labile OM-rich, whereas the outer shelf and upper slope sediments exhibited postoxic conditions (e.g. anoxic and non-sulfidic) with less labile OM, typical of OMZ core sediments. Mixed conditions were found in shelf sediment samples from April 2010, when the effects of El Niño 2009/2010 were withdrawing. Foraminiferal assemblages exhibited differences according to redox conditions and OM quality, and were concentrated in the topmost sediment. A canonical correspondence analysis and non-parametric correlations indicated that Bolivina costata, Nonionella auris and Virgulinella fragilis were characteristic of sulfidic/labile OM sediments, thriving slightly deeper in the sediment. In contrast, Bolivina pacifica headed the assemblage representative of postoxia/less labile OM. Bolivina seminuda and Buliminella tenuata (both dominant under postoxia) were not associated with any specific measured parameter, although were present in sulfidic sediments, suggesting other factors were involved in their distribution.


KEY WORDS: Benthic foraminifera · Anoxia · Sulfide · Labile organic matter


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Cite this article as: Cardich J, Gutiérrez D, Romero D, Pérez A and others (2015) Calcareous benthic foraminifera from the upper central Peruvian margin: control of the assemblage by pore water redox and sedimentary organic matter. Mar Ecol Prog Ser 535:63-87. https://doi.org/10.3354/meps11409

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