Benthic Foraminiferal Mn/Ca as Low-Oxygen Proxy in Fjord Sediments
(2023) In Global Biogeochemical Cycles 37(5).- Abstract
Fjord systems are typically affected by low-oxygen conditions, which are increasing in extent and severity, forced by ongoing global changes. Fjord sedimentary records can provide high temporal resolution archives to aid our understanding of the underlying mechanisms and impacts of current deoxygenation. However, such archives can only be interpreted with well-calibrated proxies. Bottom-water oxygen conditions determine redox regime and availability of redox-sensitive trace elements such as manganese, which in turn may be recorded by manganese-to-calcium ratios (Mn/Ca) in biogenic calcium carbonates (e.g., benthic foraminifera tests). However, biological influences on Mn incorporation (e.g., species-specific Mn fractionation, ontogeny,... (More)
Fjord systems are typically affected by low-oxygen conditions, which are increasing in extent and severity, forced by ongoing global changes. Fjord sedimentary records can provide high temporal resolution archives to aid our understanding of the underlying mechanisms and impacts of current deoxygenation. However, such archives can only be interpreted with well-calibrated proxies. Bottom-water oxygen conditions determine redox regime and availability of redox-sensitive trace elements such as manganese, which in turn may be recorded by manganese-to-calcium ratios (Mn/Ca) in biogenic calcium carbonates (e.g., benthic foraminifera tests). However, biological influences on Mn incorporation (e.g., species-specific Mn fractionation, ontogeny, living and calcification depths) are still poorly constrained. We analyzed Mn/Ca of living benthic foraminifera (Bulimina marginata, Nonionellina labradorica), sampled at low- to well-oxygenated conditions over a seasonal gradient in Gullmar Fjord, Swedish West coast (71–217 μmol/L oxygen (O2)), by laser-ablation ICP-MS. High pore-water Mn availability in the fjord supported Mn incorporation by foraminifera. B. marginata recorded contrasting Mn redox regimes sensitively and demonstrated potential as proxy for low-oxygen conditions. Synchrotron-based scanning X-ray fluorescence nanoimaging of Mn distributions across B. marginata tests displayed Mn/Ca shifts by chambers, reflecting bottom-water oxygenation history and/or ontogeny-driven life strategy preferences. In contrast, Mn/Ca signals of N. labradorica were extremely high and insensitive to environmental variability. We explore potential biologically controlled mechanisms that could potentially explain this species-specific response. Our data suggest that with the selection of sensitive candidate species, the Mn/Ca proxy has potential to be further developed for quantitative oxygen reconstructions in the low-oxygen range.
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- author
- Brinkmann, Inda LU ; Barras, Christine ; Jilbert, Tom ; Paul, K. Mareike ; Somogyi, Andrea ; Ni, Sha LU ; Schweizer, Magali ; Bernhard, Joan M. and Filipsson, Helena L. LU
- organization
- publishing date
- 2023-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- benthic foraminifera, coastal environments, foraminiferal Mn/Ca, hypoxia, proxy development
- in
- Global Biogeochemical Cycles
- volume
- 37
- issue
- 5
- article number
- e2023GB007690
- publisher
- American Geophysical Union (AGU)
- external identifiers
-
- scopus:85160430835
- ISSN
- 0886-6236
- DOI
- 10.1029/2023GB007690
- project
- Tracing past bottom-water oxygenation in the sea: a microanalytical approach to improve calcium carbonate-based proxies
- Tracing coastal bottom-water oxygenation: a microanalytical approach to improve calcium carbonate based proxies
- Tracing past bottom water oxygenation in the sea: a microanalytical approach to improve calcium carbonate based proxies (TOPICaL)
- language
- English
- LU publication?
- yes
- additional info
- Funding Information: The authors thank the captain and crew of the R/V Oscar von Sydow and R/V Skagerak for technical assistance; Sami Jokinen and Hanna Nilsson, as well as the staff of the Kristineberg Center for Marine Research and Innovation for their support during the field campaigns; Tomas Næraa (Department for Geology, Lund University, Sweden) for technical guidance during LA-ICP-MS analyses and data processing. We thank the Editor and Reviewers for their thoughtful and valuable comments on a previous version of this paper. We acknowledge SOLEIL for the 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). This research has been supported by the Swedish Research Council VR (Grant 2017-04190), the Royal Physiographic Society in Lund, and the Crafoord Foundation. TJ acknowledges funding from the Academy of Finland. JMB acknowledges funding from The Investment in Science Fund at WHOI. The hydrographic data used in this project are from SMHI's database SHARK, funded by the Swedish Environmental Protection Agency. Funding Information: The authors thank the captain and crew of the R/V and R/V for technical assistance; Sami Jokinen and Hanna Nilsson, as well as the staff of the Center for Research and Innovation for their support during the field campaigns; Tomas Næraa (Department for Geology, Lund University, Sweden) for technical guidance during LA‐ICP‐MS analyses and data processing. We thank the Editor and Reviewers for their thoughtful and valuable comments on a previous version of this paper. We acknowledge SOLEIL for the 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). This research has been supported by the Swedish Research Council VR (Grant 2017‐04190), the Royal Physiographic Society in Lund, and the Crafoord Foundation. TJ acknowledges funding from the Academy of Finland. JMB acknowledges funding from The Investment in Science Fund at WHOI. The hydrographic data used in this project are from SMHI's database SHARK, funded by the Swedish Environmental Protection Agency. Oscar von Sydow Skagerak Kristineberg Marine Publisher Copyright: © 2023. The Authors.
- id
- 2f956cfc-322c-4b06-bb6e-48c404015072
- date added to LUP
- 2023-06-09 08:27:04
- date last changed
- 2024-03-08 01:58:45
@article{2f956cfc-322c-4b06-bb6e-48c404015072, abstract = {{<p>Fjord systems are typically affected by low-oxygen conditions, which are increasing in extent and severity, forced by ongoing global changes. Fjord sedimentary records can provide high temporal resolution archives to aid our understanding of the underlying mechanisms and impacts of current deoxygenation. However, such archives can only be interpreted with well-calibrated proxies. Bottom-water oxygen conditions determine redox regime and availability of redox-sensitive trace elements such as manganese, which in turn may be recorded by manganese-to-calcium ratios (Mn/Ca) in biogenic calcium carbonates (e.g., benthic foraminifera tests). However, biological influences on Mn incorporation (e.g., species-specific Mn fractionation, ontogeny, living and calcification depths) are still poorly constrained. We analyzed Mn/Ca of living benthic foraminifera (Bulimina marginata, Nonionellina labradorica), sampled at low- to well-oxygenated conditions over a seasonal gradient in Gullmar Fjord, Swedish West coast (71–217 μmol/L oxygen (O<sub>2</sub>)), by laser-ablation ICP-MS. High pore-water Mn availability in the fjord supported Mn incorporation by foraminifera. B. marginata recorded contrasting Mn redox regimes sensitively and demonstrated potential as proxy for low-oxygen conditions. Synchrotron-based scanning X-ray fluorescence nanoimaging of Mn distributions across B. marginata tests displayed Mn/Ca shifts by chambers, reflecting bottom-water oxygenation history and/or ontogeny-driven life strategy preferences. In contrast, Mn/Ca signals of N. labradorica were extremely high and insensitive to environmental variability. We explore potential biologically controlled mechanisms that could potentially explain this species-specific response. Our data suggest that with the selection of sensitive candidate species, the Mn/Ca proxy has potential to be further developed for quantitative oxygen reconstructions in the low-oxygen range.</p>}}, author = {{Brinkmann, Inda and Barras, Christine and Jilbert, Tom and Paul, K. Mareike and Somogyi, Andrea and Ni, Sha and Schweizer, Magali and Bernhard, Joan M. and Filipsson, Helena L.}}, issn = {{0886-6236}}, keywords = {{benthic foraminifera; coastal environments; foraminiferal Mn/Ca; hypoxia; proxy development}}, language = {{eng}}, number = {{5}}, publisher = {{American Geophysical Union (AGU)}}, series = {{Global Biogeochemical Cycles}}, title = {{Benthic Foraminiferal Mn/Ca as Low-Oxygen Proxy in Fjord Sediments}}, url = {{http://dx.doi.org/10.1029/2023GB007690}}, doi = {{10.1029/2023GB007690}}, volume = {{37}}, year = {{2023}}, }