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

Marine Ecology Progress Series

Williams Yupanqui¹  Dennis Romero¹  Jorge Cardich¹  Robert Marquina¹  Juana Solís¹  Luis Quipúzcoa¹  Anthony Rathburn¹  Wilson Carhuapoma¹  Dimitri Gutiérrez¹  Abdelfettah Sifeddine¹  Alexander Pérez¹ 

关键词: Benthic foraminifera;    Anoxia;    Sulfide;    Labile organic matter;   

DOI  :  10.3354/meps11409

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

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.

【 授权许可】

Unknown