Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia
<p>Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjord...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-02-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/523/2023/bg-20-523-2023.pdf |
| _version_ | 1797934965586919424 |
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| author | W. Majewski W. Szczuciński A. J. Gooday A. J. Gooday |
| author_facet | W. Majewski W. Szczuciński A. J. Gooday A. J. Gooday |
| author_sort | W. Majewski |
| collection | DOAJ |
| description | <p>Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjords of South Georgia, including fjords with and without tidewater glaciers. Their distribution is analyzed in the light of new fjord water and sediment property data, including grain size and sorting, total organic carbon, total sulfur, and <span class="inline-formula"><i>δ</i><sup>13</sup>C</span> of bulk organic matter. Four well-defined foraminiferal assemblages are recognized. <i>Miliammina earlandi</i> dominates in the most restricted, near-shore and glacier-proximal habitats, <i>Cassidulinoides</i> aff. <i>parkerianus</i> in mid-fjord areas, and <i>Globocassidulina</i> aff. <i>rossensis</i> and an assemblage dominated by <i>Ammobaculites rostratus</i>, <i>Reophax subfusiformis</i>, and <i>Astrononion echolsi</i> are in the outer parts of the fjords. <i>Miliammina earlandi</i> can tolerate strong glacial influence, including high sedimentation rates in fjord heads and sediment anoxia, as inferred from sediment color and total organic carbon <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="527256ea34e0af356380afd605ccefc0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-523-2023-ie00001.svg" width="8pt" height="14pt" src="bg-20-523-2023-ie00001.png"/></svg:svg></span></span> sulfur ratios. This versatile species thrives both in the food-poor inner reaches of fjords that receive mainly refractory petrogenic organic matter from glacial meltwater and in shallow-water coves, where it benefits from an abundant supply of fresh, terrestrial, and marine organic matter. A smooth-walled variant of <i>C.</i> aff. <i>parkerianus</i>, apparently endemic to South Georgia, is the calcareous rotaliid best adapted to inner-fjord conditions characterized by moderate glacial influence and sedimentation rates and showing no preference for particular sedimentary redox conditions. The outer parts of fjords with clear, well-oxygenated bottom water are inhabited by <i>G.</i> aff. <i>rossensis</i>. <i>Ammobaculites rostratus</i>, <i>R. subfusiformis</i>, and <i>A. echolsi</i> dominate in the deepest-water settings, with water salinities <span class="inline-formula">≥</span> 33.9 <span class="inline-formula">PSU</span> and temperatures 0.2–1.4 <span class="inline-formula"><sup>∘</sup>C</span>, characteristic of winter water and Upper Circumpolar Deep Water. The inner- and mid-fjord foraminiferal assemblages seem specific to South Georgia, although with continued warming and deglaciation, they may become more widespread in the Southern Ocean.</p> |
| first_indexed | 2024-04-10T18:08:13Z |
| format | Article |
| id | doaj.art-703cdfe65f7c40048e4de88deb51c23d |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-10T18:08:13Z |
| publishDate | 2023-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-703cdfe65f7c40048e4de88deb51c23d2023-02-02T12:10:08ZengCopernicus PublicationsBiogeosciences1726-41701726-41892023-02-012052354410.5194/bg-20-523-2023Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South GeorgiaW. Majewski0W. Szczuciński1A. J. Gooday2A. J. Gooday3Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, PolandGeohazards Research Unit, Institute of Geology, Adam Mickiewicz University, Poznań, Bogumiła Krygowskiego 12, 61-680 Poznań, PolandOcean BioGeosciences, National Oceanography Centre, European Way, Southampton SO14 3ZH, UKLife Sciences Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK<p>Sub-Antarctic fjords are among the environments most affected by the recent climate change. In our dynamically changing world, it is essential to monitor changes in these vulnerable settings. Here, we present a baseline study of “living” (rose-bengal-stained) benthic foraminifera from fjords of South Georgia, including fjords with and without tidewater glaciers. Their distribution is analyzed in the light of new fjord water and sediment property data, including grain size and sorting, total organic carbon, total sulfur, and <span class="inline-formula"><i>δ</i><sup>13</sup>C</span> of bulk organic matter. Four well-defined foraminiferal assemblages are recognized. <i>Miliammina earlandi</i> dominates in the most restricted, near-shore and glacier-proximal habitats, <i>Cassidulinoides</i> aff. <i>parkerianus</i> in mid-fjord areas, and <i>Globocassidulina</i> aff. <i>rossensis</i> and an assemblage dominated by <i>Ammobaculites rostratus</i>, <i>Reophax subfusiformis</i>, and <i>Astrononion echolsi</i> are in the outer parts of the fjords. <i>Miliammina earlandi</i> can tolerate strong glacial influence, including high sedimentation rates in fjord heads and sediment anoxia, as inferred from sediment color and total organic carbon <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="527256ea34e0af356380afd605ccefc0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-523-2023-ie00001.svg" width="8pt" height="14pt" src="bg-20-523-2023-ie00001.png"/></svg:svg></span></span> sulfur ratios. This versatile species thrives both in the food-poor inner reaches of fjords that receive mainly refractory petrogenic organic matter from glacial meltwater and in shallow-water coves, where it benefits from an abundant supply of fresh, terrestrial, and marine organic matter. A smooth-walled variant of <i>C.</i> aff. <i>parkerianus</i>, apparently endemic to South Georgia, is the calcareous rotaliid best adapted to inner-fjord conditions characterized by moderate glacial influence and sedimentation rates and showing no preference for particular sedimentary redox conditions. The outer parts of fjords with clear, well-oxygenated bottom water are inhabited by <i>G.</i> aff. <i>rossensis</i>. <i>Ammobaculites rostratus</i>, <i>R. subfusiformis</i>, and <i>A. echolsi</i> dominate in the deepest-water settings, with water salinities <span class="inline-formula">≥</span> 33.9 <span class="inline-formula">PSU</span> and temperatures 0.2–1.4 <span class="inline-formula"><sup>∘</sup>C</span>, characteristic of winter water and Upper Circumpolar Deep Water. The inner- and mid-fjord foraminiferal assemblages seem specific to South Georgia, although with continued warming and deglaciation, they may become more widespread in the Southern Ocean.</p>https://bg.copernicus.org/articles/20/523/2023/bg-20-523-2023.pdf |
| spellingShingle | W. Majewski W. Szczuciński A. J. Gooday A. J. Gooday Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia Biogeosciences |
| title | Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia |
| title_full | Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia |
| title_fullStr | Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia |
| title_full_unstemmed | Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia |
| title_short | Unique benthic foraminiferal communities (stained) in diverse environments of sub-Antarctic fjords, South Georgia |
| title_sort | unique benthic foraminiferal communities stained in diverse environments of sub antarctic fjords south georgia |
| url | https://bg.copernicus.org/articles/20/523/2023/bg-20-523-2023.pdf |
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