Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential
<p>Sedimentary bulk organic matter and various molecular organic components exhibit strong CO<span class="inline-formula"><sub>2</sub></span>-dependent carbon isotope fractionation relative to dissolved inorganic carbon sources. This fractionation (<span cl...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-11-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/4651/2023/bg-20-4651-2023.pdf |
| _version_ | 1797450804405207040 |
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| author | J. Frieling J. Frieling L. van Roij I. Kleij G.-J. Reichart G.-J. Reichart A. Sluijs |
| author_facet | J. Frieling J. Frieling L. van Roij I. Kleij G.-J. Reichart G.-J. Reichart A. Sluijs |
| author_sort | J. Frieling |
| collection | DOAJ |
| description | <p>Sedimentary bulk organic matter and various molecular organic components exhibit strong CO<span class="inline-formula"><sub>2</sub></span>-dependent carbon isotope fractionation relative to dissolved inorganic carbon sources. This fractionation (<span class="inline-formula"><i>ε</i><sub>p</sub></span>) has been employed as a proxy for paleo-<span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>. Yet, culture experiments indicate that CO<span class="inline-formula"><sub>2</sub></span>-dependent <span class="inline-formula"><i>ε</i><sub>p</sub></span> is highly specific at genus and even species level, potentially hampering the use of bulk organic matter and non-species-specific organic compounds. In recent years, significant progress has been made towards a CO<span class="inline-formula"><sub>2</sub></span> proxy using controlled growth experiments with dinoflagellate species, also showing highly species-specific <span class="inline-formula"><i>ε</i><sub>p</sub></span> values. These values were, however, based on motile specimens, and it remains unknown whether these relations also hold for the organic-walled resting cysts (dinocysts) produced by these dinoflagellate species in their natural environment. We here analyze dinocysts isolated from core tops from the Atlantic Ocean and Mediterranean Sea, representing several species (<i>Spiniferites elongatus</i>, <i>S.</i> (cf.) <i>ramosus</i>, <i>S. mirabilis</i>, <i>Operculodinium centrocarpum</i> sensu Wall and Dale (1966) (hereafter referred to as <i>O. centrocarpum</i>) and <i>Impagidinium aculeatum</i>) using laser ablation–nano-combustion–gas-chromatography–isotope ratio mass spectrometry (LA/nC/GC-IRMS). We find that the dinocysts produced in the natural environment are all appreciably more <span class="inline-formula"><sup>13</sup></span>C-depleted compared to the cultured motile dinoflagellate cells, implying higher overall <span class="inline-formula"><i>ε</i><sub>p</sub></span> values, and, moreover, exhibit large isotope variability. Where several species could be analyzed from a single location, we often record significant differences in isotopic variance and offsets in mean <span class="inline-formula"><i>δ</i><sup>13</sup></span>C values between species, highlighting the importance of single-species carbon isotope analyses. The most geographically expanded dataset, based on <i>O. centrocarpum</i>, shows that <span class="inline-formula"><i>ε</i><sub>p</sub></span> correlates significantly with various environmental parameters. Importantly, <i>O. centrocarpum</i> shows a CO<span class="inline-formula"><sub>2</sub></span>-dependent <span class="inline-formula"><i>ε</i><sub>p</sub></span> above <span class="inline-formula">∼</span> 240 <span class="inline-formula">µ</span>atm <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>. Similar to other marine autotrophs, relative insensitivity at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> is in line with active carbon-concentrating mechanisms at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>, although we here cannot fully exclude that we partly underestimated <span class="inline-formula"><i>ε</i><sub>p</sub></span> sensitivity at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> values due to the relatively sparse sampling in that range. Finally, we use the relation between <span class="inline-formula"><i>ε</i><sub>p</sub></span> and <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> in <i>O. centrocarpum</i> to propose a first <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> proxy based on a single dinocyst species.</p> |
| first_indexed | 2024-03-09T14:44:55Z |
| format | Article |
| id | doaj.art-dd6080a692d74fd88b260a6b5bda8809 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-03-09T14:44:55Z |
| publishDate | 2023-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-dd6080a692d74fd88b260a6b5bda88092023-11-27T09:51:11ZengCopernicus PublicationsBiogeosciences1726-41701726-41892023-11-01204651466810.5194/bg-20-4651-2023Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potentialJ. Frieling0J. Frieling1L. van Roij2I. Kleij3G.-J. Reichart4G.-J. Reichart5A. Sluijs6Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8, 3584CB Utrecht, the Netherlandsnow at: Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, Oxford, UKDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8, 3584CB Utrecht, the NetherlandsDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8, 3584CB Utrecht, the NetherlandsDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8, 3584CB Utrecht, the NetherlandsDepartment of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, Landsdiep 4, 1797SZ 't Horntje, Texel, the NetherlandsDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8, 3584CB Utrecht, the Netherlands<p>Sedimentary bulk organic matter and various molecular organic components exhibit strong CO<span class="inline-formula"><sub>2</sub></span>-dependent carbon isotope fractionation relative to dissolved inorganic carbon sources. This fractionation (<span class="inline-formula"><i>ε</i><sub>p</sub></span>) has been employed as a proxy for paleo-<span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>. Yet, culture experiments indicate that CO<span class="inline-formula"><sub>2</sub></span>-dependent <span class="inline-formula"><i>ε</i><sub>p</sub></span> is highly specific at genus and even species level, potentially hampering the use of bulk organic matter and non-species-specific organic compounds. In recent years, significant progress has been made towards a CO<span class="inline-formula"><sub>2</sub></span> proxy using controlled growth experiments with dinoflagellate species, also showing highly species-specific <span class="inline-formula"><i>ε</i><sub>p</sub></span> values. These values were, however, based on motile specimens, and it remains unknown whether these relations also hold for the organic-walled resting cysts (dinocysts) produced by these dinoflagellate species in their natural environment. We here analyze dinocysts isolated from core tops from the Atlantic Ocean and Mediterranean Sea, representing several species (<i>Spiniferites elongatus</i>, <i>S.</i> (cf.) <i>ramosus</i>, <i>S. mirabilis</i>, <i>Operculodinium centrocarpum</i> sensu Wall and Dale (1966) (hereafter referred to as <i>O. centrocarpum</i>) and <i>Impagidinium aculeatum</i>) using laser ablation–nano-combustion–gas-chromatography–isotope ratio mass spectrometry (LA/nC/GC-IRMS). We find that the dinocysts produced in the natural environment are all appreciably more <span class="inline-formula"><sup>13</sup></span>C-depleted compared to the cultured motile dinoflagellate cells, implying higher overall <span class="inline-formula"><i>ε</i><sub>p</sub></span> values, and, moreover, exhibit large isotope variability. Where several species could be analyzed from a single location, we often record significant differences in isotopic variance and offsets in mean <span class="inline-formula"><i>δ</i><sup>13</sup></span>C values between species, highlighting the importance of single-species carbon isotope analyses. The most geographically expanded dataset, based on <i>O. centrocarpum</i>, shows that <span class="inline-formula"><i>ε</i><sub>p</sub></span> correlates significantly with various environmental parameters. Importantly, <i>O. centrocarpum</i> shows a CO<span class="inline-formula"><sub>2</sub></span>-dependent <span class="inline-formula"><i>ε</i><sub>p</sub></span> above <span class="inline-formula">∼</span> 240 <span class="inline-formula">µ</span>atm <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>. Similar to other marine autotrophs, relative insensitivity at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> is in line with active carbon-concentrating mechanisms at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span>, although we here cannot fully exclude that we partly underestimated <span class="inline-formula"><i>ε</i><sub>p</sub></span> sensitivity at low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> values due to the relatively sparse sampling in that range. Finally, we use the relation between <span class="inline-formula"><i>ε</i><sub>p</sub></span> and <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> in <i>O. centrocarpum</i> to propose a first <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> proxy based on a single dinocyst species.</p>https://bg.copernicus.org/articles/20/4651/2023/bg-20-4651-2023.pdf |
| spellingShingle | J. Frieling J. Frieling L. van Roij I. Kleij G.-J. Reichart G.-J. Reichart A. Sluijs Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential Biogeosciences |
| title | Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential |
| title_full | Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential |
| title_fullStr | Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential |
| title_full_unstemmed | Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential |
| title_short | Single-species dinoflagellate cyst carbon isotope fractionation in core-top sediments: environmental controls, CO<sub>2</sub> dependency and proxy potential |
| title_sort | single species dinoflagellate cyst carbon isotope fractionation in core top sediments environmental controls co sub 2 sub dependency and proxy potential |
| url | https://bg.copernicus.org/articles/20/4651/2023/bg-20-4651-2023.pdf |
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