Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition
<p>The Mid-Brunhes Transition (MBT) saw an increase in the amplitude of glacial cycles expressed in ice core and deep ocean records from about 400 ka, but its influence on high-latitude climates is not fully understood. The Arctic Ocean is thought to have warmed and exhibited reduce...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-12-01
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| Series: | Journal of Micropalaeontology |
| Online Access: | https://www.j-micropalaeontol.net/38/177/2019/jm-38-177-2019.pdf |
| _version_ | 1798044722048008192 |
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| author | S. Kender S. Kender A. Aturamu A. Aturamu J. Zalasiewicz M. A. Kaminski M. Williams |
| author_facet | S. Kender S. Kender A. Aturamu A. Aturamu J. Zalasiewicz M. A. Kaminski M. Williams |
| author_sort | S. Kender |
| collection | DOAJ |
| description | <p>The Mid-Brunhes Transition (MBT) saw an increase in the
amplitude of glacial cycles expressed in ice core and deep ocean records
from about 400 ka, but its influence on high-latitude climates is not fully
understood. The Arctic Ocean is thought to have warmed and exhibited reduced
sea ice, but little is known of sea ice marginal locations such as the
Bering Sea. The Bering Sea is the link between the Arctic and Pacific
Ocean and is an area of high productivity and <span class="inline-formula">CO<sub>2</sub></span> ventilation; it
hosts a pronounced oxygen minimum zone (OMZ) and is thought to be the
location of Glacial North Pacific Intermediate Water (GNPIW) formation in
the Pleistocene. To understand palaeoceanographic change in the region, we
analysed benthic foraminiferal faunas from Bowers Ridge (Site U1342, 800 m
of water depth) over the past 600 kyr, as they are uniquely well preserved and
sensitive to changes in deep and surface ocean conditions. We identified and
imaged 71 taxa and provide a full taxonomy. Foraminiferal preservation is
markedly higher during glacials, indicating the presence of less corrosive
GNPIW. The most abundant species are <i>Bulimina exilis</i>, <i>Takayanagia delicata</i>, <i>Alabaminella weddellensis</i>, <i>Gyroidina</i> sp. 2, <i>Cassidulina laevigata</i>, <i>Islandiella norcrossi</i>, and <i>Uvigerina bifurcata</i>, consistent with
broadly high net primary production throughout the last 600 kyr.
Correspondence analysis shows that the most significant Assemblage 1 comprises
<i>B. exilis</i>, <i>T. delicata</i>, <i>Bolivina spissa</i>, and <i>Brizalina</i>, which occur sporadically within intervals of laminated,
biogenic-rich sediment, mostly during glacials and also some deglacials, and
are interpreted as indicating very high productivity. Other assemblages
contain the phytodetritivore species <i>A. weddellensis</i>, <i>I. norcrossi</i>, and <i>C. laevigata</i>, indicative of seasonal
phytoplankton blooms. Before the MBT, more numerous intervals of the very
high-productivity Assemblage 1 and <i>A. weddellensis</i> occur, which we suggest reflect a time of
more sea-ice-related seasonal stratification and ice edge blooms. Our
inference of a decrease in sea ice meltwater stratification influence in the
central Bering Sea after the MBT is consistent with records showing that the
Arctic and Pacific Ocean warmed during glacials and suggests that high-latitude
productivity and sea ice changes were an important feature of this climate
event.</p> |
| first_indexed | 2024-04-11T23:08:50Z |
| format | Article |
| id | doaj.art-8c1288e21ef64f2fb56635ba1c125494 |
| institution | Directory Open Access Journal |
| issn | 0262-821X 2041-4978 |
| language | English |
| last_indexed | 2024-04-11T23:08:50Z |
| publishDate | 2019-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Journal of Micropalaeontology |
| spelling | doaj.art-8c1288e21ef64f2fb56635ba1c1254942022-12-22T03:57:55ZengCopernicus PublicationsJournal of Micropalaeontology0262-821X2041-49782019-12-013817718710.5194/jm-38-177-2019Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes TransitionS. Kender0S. Kender1A. Aturamu2A. Aturamu3J. Zalasiewicz4M. A. Kaminski5M. Williams6Camborne School of Mines, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UKBritish Geological Survey, Environmental Sciences Centre, Keyworth, Nottingham, NG12 5GG, UKSchool of Geography, Geology and the Environment, University of Leicester, Leicester, LE1 7RH, UKDepartment of Geology, Ekiti State University, P.M.B. 5363, Ado-Ekiti, NigeriaSchool of Geography, Geology and the Environment, University of Leicester, Leicester, LE1 7RH, UKGeosciences Department, King Fahd University of Petroleum and Minerals, P.O. Box 701, Dhahran, 21361, Saudi ArabiaSchool of Geography, Geology and the Environment, University of Leicester, Leicester, LE1 7RH, UK<p>The Mid-Brunhes Transition (MBT) saw an increase in the amplitude of glacial cycles expressed in ice core and deep ocean records from about 400 ka, but its influence on high-latitude climates is not fully understood. The Arctic Ocean is thought to have warmed and exhibited reduced sea ice, but little is known of sea ice marginal locations such as the Bering Sea. The Bering Sea is the link between the Arctic and Pacific Ocean and is an area of high productivity and <span class="inline-formula">CO<sub>2</sub></span> ventilation; it hosts a pronounced oxygen minimum zone (OMZ) and is thought to be the location of Glacial North Pacific Intermediate Water (GNPIW) formation in the Pleistocene. To understand palaeoceanographic change in the region, we analysed benthic foraminiferal faunas from Bowers Ridge (Site U1342, 800 m of water depth) over the past 600 kyr, as they are uniquely well preserved and sensitive to changes in deep and surface ocean conditions. We identified and imaged 71 taxa and provide a full taxonomy. Foraminiferal preservation is markedly higher during glacials, indicating the presence of less corrosive GNPIW. The most abundant species are <i>Bulimina exilis</i>, <i>Takayanagia delicata</i>, <i>Alabaminella weddellensis</i>, <i>Gyroidina</i> sp. 2, <i>Cassidulina laevigata</i>, <i>Islandiella norcrossi</i>, and <i>Uvigerina bifurcata</i>, consistent with broadly high net primary production throughout the last 600 kyr. Correspondence analysis shows that the most significant Assemblage 1 comprises <i>B. exilis</i>, <i>T. delicata</i>, <i>Bolivina spissa</i>, and <i>Brizalina</i>, which occur sporadically within intervals of laminated, biogenic-rich sediment, mostly during glacials and also some deglacials, and are interpreted as indicating very high productivity. Other assemblages contain the phytodetritivore species <i>A. weddellensis</i>, <i>I. norcrossi</i>, and <i>C. laevigata</i>, indicative of seasonal phytoplankton blooms. Before the MBT, more numerous intervals of the very high-productivity Assemblage 1 and <i>A. weddellensis</i> occur, which we suggest reflect a time of more sea-ice-related seasonal stratification and ice edge blooms. Our inference of a decrease in sea ice meltwater stratification influence in the central Bering Sea after the MBT is consistent with records showing that the Arctic and Pacific Ocean warmed during glacials and suggests that high-latitude productivity and sea ice changes were an important feature of this climate event.</p>https://www.j-micropalaeontol.net/38/177/2019/jm-38-177-2019.pdf |
| spellingShingle | S. Kender S. Kender A. Aturamu A. Aturamu J. Zalasiewicz M. A. Kaminski M. Williams Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition Journal of Micropalaeontology |
| title | Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition |
| title_full | Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition |
| title_fullStr | Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition |
| title_full_unstemmed | Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition |
| title_short | Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition |
| title_sort | benthic foraminifera indicate glacial north pacific intermediate water and reduced primary productivity over bowers ridge bering sea since the mid brunhes transition |
| url | https://www.j-micropalaeontol.net/38/177/2019/jm-38-177-2019.pdf |
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