Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea)
Rose-Bengal-stained foraminiferal assemblages (> 150 μm) were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible <i>Shinkai...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-08-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/5005/2015/bg-12-5005-2015.pdf |
| _version_ | 1818113661633298432 |
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| author | C. Caulle M. Mojtahid A. J. Gooday F. J. Jorissen H. Kitazato |
| author_facet | C. Caulle M. Mojtahid A. J. Gooday F. J. Jorissen H. Kitazato |
| author_sort | C. Caulle |
| collection | DOAJ |
| description | Rose-Bengal-stained foraminiferal assemblages (> 150 μm)
were analysed along a five-station bathymetric transect across the core and
the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the
Arabian Sea. Sediment cores were collected using the manned submersible
<i>Shinkai</i> 6500 during the RV <i>Yokosuka</i> cruise YK08-11 in the post-monsoon season (October 2008) at
water depths ranging from 535 to 2000 m, along a gradient from almost anoxic
to well-oxygenated (0.3 to 108 μM) bottom waters. Stained
benthic foraminifera were investigated from two different size fractions
(150–300 μm and > 300 μm). Stained foraminiferal
densities were very high in the core of the OMZ (at 535 and 649 m) and
decreased at deeper sites. The faunas (> 150 μm) were
dominated (40–80 %) by non-calcareous taxa at all stations. These were
mainly species of <i>Reophax</i> and <i>Lagenammina</i> but also included delicate monothalamous taxa
(organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids
and tubular forms). These new data from the Indian margin are compared to
previous studies from the Murray Ridge, the Pakistan margin and the Oman
margin. The fact that similar species were found at sites with comparable
bottom-water oxygen concentrations but with very different surface water
productivity suggests that, within the strongly developed Arabian Sea OMZ,
bottom-water oxygen concentration, and not the organic flux to the sea
floor, is the main factor controlling the species composition of the
foraminiferal communities. Several foraminiferal species (e.g.
<i>Praeglobobulimina</i> sp. 1, <i>Ammodiscus</i> sp. 1, <i>Bolivina</i> aff. <i>dilatata</i>) were confined to the core of the OMZ. These species are
presently known only from the Arabian Sea. Because of their association with
extremely low oxygen concentrations, these species may be good markers for
very low oxygen concentrations, and could be used to reconstruct past OMZ
variability in the Arabian Sea. |
| first_indexed | 2024-12-11T03:38:23Z |
| format | Article |
| id | doaj.art-da77ad3dc0db450f8bf1a4b66e5dec2b |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-11T03:38:23Z |
| publishDate | 2015-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-da77ad3dc0db450f8bf1a4b66e5dec2b2022-12-22T01:22:12ZengCopernicus PublicationsBiogeosciences1726-41701726-41892015-08-0112165005501910.5194/bg-12-5005-2015Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea)C. Caulle0M. Mojtahid1A. J. Gooday2F. J. Jorissen3H. Kitazato4UMR CNRS6112 LPG-BIAF, Recent and Fossil Bio-Indicators, Angers University, 2 Bd Lavoisier, 49045 Angers CEDEX 01, FranceUMR CNRS6112 LPG-BIAF, Recent and Fossil Bio-Indicators, Angers University, 2 Bd Lavoisier, 49045 Angers CEDEX 01, FranceNational Oceanographic Centre, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH, UKUMR CNRS6112 LPG-BIAF, Recent and Fossil Bio-Indicators, Angers University, 2 Bd Lavoisier, 49045 Angers CEDEX 01, FranceJapan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushimacho, Yokosuka 237-0061, JapanRose-Bengal-stained foraminiferal assemblages (> 150 μm) were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible <i>Shinkai</i> 6500 during the RV <i>Yokosuka</i> cruise YK08-11 in the post-monsoon season (October 2008) at water depths ranging from 535 to 2000 m, along a gradient from almost anoxic to well-oxygenated (0.3 to 108 μM) bottom waters. Stained benthic foraminifera were investigated from two different size fractions (150–300 μm and > 300 μm). Stained foraminiferal densities were very high in the core of the OMZ (at 535 and 649 m) and decreased at deeper sites. The faunas (> 150 μm) were dominated (40–80 %) by non-calcareous taxa at all stations. These were mainly species of <i>Reophax</i> and <i>Lagenammina</i> but also included delicate monothalamous taxa (organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids and tubular forms). These new data from the Indian margin are compared to previous studies from the Murray Ridge, the Pakistan margin and the Oman margin. The fact that similar species were found at sites with comparable bottom-water oxygen concentrations but with very different surface water productivity suggests that, within the strongly developed Arabian Sea OMZ, bottom-water oxygen concentration, and not the organic flux to the sea floor, is the main factor controlling the species composition of the foraminiferal communities. Several foraminiferal species (e.g. <i>Praeglobobulimina</i> sp. 1, <i>Ammodiscus</i> sp. 1, <i>Bolivina</i> aff. <i>dilatata</i>) were confined to the core of the OMZ. These species are presently known only from the Arabian Sea. Because of their association with extremely low oxygen concentrations, these species may be good markers for very low oxygen concentrations, and could be used to reconstruct past OMZ variability in the Arabian Sea.http://www.biogeosciences.net/12/5005/2015/bg-12-5005-2015.pdf |
| spellingShingle | C. Caulle M. Mojtahid A. J. Gooday F. J. Jorissen H. Kitazato Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) Biogeosciences |
| title | Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) |
| title_full | Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) |
| title_fullStr | Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) |
| title_full_unstemmed | Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) |
| title_short | Living (Rose-Bengal-stained) benthic foraminiferal faunas along a strong bottom-water oxygen gradient on the Indian margin (Arabian Sea) |
| title_sort | living rose bengal stained benthic foraminiferal faunas along a strong bottom water oxygen gradient on the indian margin arabian sea |
| url | http://www.biogeosciences.net/12/5005/2015/bg-12-5005-2015.pdf |
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