Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Foraminiferal Mn/Ca as Bottom-Water Hypoxia Proxy: An Assessment of Nonionella stella in the Santa Barbara Basin, USA

Brinkmann, I. LU orcid ; Ni, S. LU ; Schweizer, M. ; Oldham, V. E. ; Quintana Krupinski, N. B. LU ; Medjoubi, K. ; Somogyi, A. ; Whitehouse, M. J. ; Hansel, C. M. and Barras, C. , et al. (2021) In Paleoceanography and Paleoclimatology 36(11).
Abstract

Hypoxia is of increasing concern in marine areas, calling for a better understanding of mechanisms leading to decreasing dissolved oxygen concentrations ([O2]). Much can be learned about the processes and implications of deoxygenation for marine ecosystems using proxy records from low-oxygen sites, provided proxies, such as the manganese (Mn) to calcium (Ca) ratio in benthic foraminiferal calcite, are available and well calibrated. Here we report a modern geochemical data set from three hypoxic sites within the Santa Barbara Basin (SBB), USA, where we study the response of Mn/Caforam in the benthic foraminifer Nonionella stella to variations in sedimentary redox conditions (Mn, Fe) and bottom-water dissolved... (More)

Hypoxia is of increasing concern in marine areas, calling for a better understanding of mechanisms leading to decreasing dissolved oxygen concentrations ([O2]). Much can be learned about the processes and implications of deoxygenation for marine ecosystems using proxy records from low-oxygen sites, provided proxies, such as the manganese (Mn) to calcium (Ca) ratio in benthic foraminiferal calcite, are available and well calibrated. Here we report a modern geochemical data set from three hypoxic sites within the Santa Barbara Basin (SBB), USA, where we study the response of Mn/Caforam in the benthic foraminifer Nonionella stella to variations in sedimentary redox conditions (Mn, Fe) and bottom-water dissolved [O2]. We combine molecular species identification by small subunit rDNA sequencing with morphological characterization and assign the SBB N. stella used here to a new phylotype (T6). Synchrotron-based scanning X-ray fluorescence (XRF) imaging and Secondary Ion Mass Spectrometry (SIMS) show low Mn incorporation (partition coefficient DMn < 0.05) and limited proxy sensitivity of N. stella, at least within the range of dissolved [O2] (2.7–9.6 μmol/l) and Mnpore-water gradients (2.12–21.59 μmol/l). Notably, even though intra- and interspecimen Mn/Ca variability (33% and 58%, respectively) was only partially controlled by the environment, Mn/Caforam significantly correlated with both pore-water Mn and bottom-water [O2]. However, the prevalent suboxic bottom-water conditions and limited dissolved [O2] range complicate the interpretation of trace-elemental trends. Additional work involving other oxygenation proxies and samples from a wider oxygen gradient should be pursued to further develop foraminiferal Mn/Ca as an indicator for hypoxic conditions.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; ; and (Less)
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
benthic foraminifera, Deoxygenation, micro-analytical techniques, Mn, Ca, proxy calibration
in
Paleoceanography and Paleoclimatology
volume
36
issue
11
article number
e2020PA004167
publisher
Wiley-Blackwell
external identifiers
  • scopus:85119838704
ISSN
2572-4517
DOI
10.1029/2020PA004167
project
Tracing past bottom water oxygenation in the sea: a microanalytical approach to improve calcium carbonate based proxies (TOPICaL)
Tracing coastal bottom-water oxygenation: a microanalytical approach to improve calcium carbonate based proxies
language
English
LU publication?
yes
additional info
Funding Information: We acknowledge funding from the Swedish Research Council VR (grant numbers 2017‐04190 and 2017‐00671), the Crafoord Foundation, and the Royal Physiographic Society in Lund, Sweden. Shiptime provided by US NSF IOS 1557430. We acknowledge SOLEIL for provision of synchrotron radiation facilities and the beamline NANOSCOPIUM (proposal number 20181115). The synchrotron‐based experiments were supported by CALIPSOplus under the EU Framework Programme for Research and Innovation HORIZON 2020 (grant agreement 730872). The SIMS analyses were jointly supported by the Swedish Museum of Natural History and Swedish Research Council. This is NordSIMS contribution No. 694. J. M. Bernhard and C. M. Hansel also acknowledge funding from the US National Science Foundation (IOS 1557430). Robert Gordon Sproul Nonionella Publisher Copyright: © 2021. The Authors.
id
95c837ab-aa65-41ff-a116-ac98adb4ea6c
date added to LUP
2021-12-08 18:07:31
date last changed
2023-02-21 11:25:31
@article{95c837ab-aa65-41ff-a116-ac98adb4ea6c,
  abstract     = {{<p>Hypoxia is of increasing concern in marine areas, calling for a better understanding of mechanisms leading to decreasing dissolved oxygen concentrations ([O<sub>2</sub>]). Much can be learned about the processes and implications of deoxygenation for marine ecosystems using proxy records from low-oxygen sites, provided proxies, such as the manganese (Mn) to calcium (Ca) ratio in benthic foraminiferal calcite, are available and well calibrated. Here we report a modern geochemical data set from three hypoxic sites within the Santa Barbara Basin (SBB), USA, where we study the response of Mn/Ca<sub>foram</sub> in the benthic foraminifer Nonionella stella to variations in sedimentary redox conditions (Mn, Fe) and bottom-water dissolved [O<sub>2</sub>]. We combine molecular species identification by small subunit rDNA sequencing with morphological characterization and assign the SBB N. stella used here to a new phylotype (T6). Synchrotron-based scanning X-ray fluorescence (XRF) imaging and Secondary Ion Mass Spectrometry (SIMS) show low Mn incorporation (partition coefficient D<sub>Mn</sub> &lt; 0.05) and limited proxy sensitivity of N. stella, at least within the range of dissolved [O<sub>2</sub>] (2.7–9.6 μmol/l) and Mn<sub>pore-water</sub> gradients (2.12–21.59 μmol/l). Notably, even though intra- and interspecimen Mn/Ca variability (33% and 58%, respectively) was only partially controlled by the environment, Mn/Ca<sub>foram</sub> significantly correlated with both pore-water Mn and bottom-water [O<sub>2</sub>]. However, the prevalent suboxic bottom-water conditions and limited dissolved [O<sub>2</sub>] range complicate the interpretation of trace-elemental trends. Additional work involving other oxygenation proxies and samples from a wider oxygen gradient should be pursued to further develop foraminiferal Mn/Ca as an indicator for hypoxic conditions.</p>}},
  author       = {{Brinkmann, I. and Ni, S. and Schweizer, M. and Oldham, V. E. and Quintana Krupinski, N. B. and Medjoubi, K. and Somogyi, A. and Whitehouse, M. J. and Hansel, C. M. and Barras, C. and Bernhard, J. M. and Filipsson, H. L.}},
  issn         = {{2572-4517}},
  keywords     = {{benthic foraminifera; Deoxygenation; micro-analytical techniques; Mn; Ca; proxy calibration}},
  language     = {{eng}},
  number       = {{11}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Paleoceanography and Paleoclimatology}},
  title        = {{Foraminiferal Mn/Ca as Bottom-Water Hypoxia Proxy: An Assessment of <i>Nonionella stella</i> in the Santa Barbara Basin, USA}},
  url          = {{http://dx.doi.org/10.1029/2020PA004167}},
  doi          = {{10.1029/2020PA004167}},
  volume       = {{36}},
  year         = {{2021}},
}