A Pliocene to recent history of the Bering Sea at Site U1340A, IODP Expedition 323

Stroynowski, Zuzia; Ravelo, A. C.; Andreasen, Dyke

doi:10.1002/2015pa002866

Cited by 18 publications

(19 citation statements)

References 89 publications

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“…4), where open water conditions were likely present during glacials over the past 270 kyr . Older diatom records do not exist from Bowers Ridge, but low-resolution records from Bering slope Sites U1343 and U1344 do show a reduction in pack-ice-related diatom species from ∼ 500 ka (Stroynowski et al, 2017), consistent with our suggestion. This time period approximately coincides with the MBT, for which alkenone-based sea surface temperatures indicate that North Pacific (Site 882; Fig.…”

Section: Discussionsupporting

confidence: 87%

“…4). Our records may therefore suggest that the Bering Sea responded to regional warming during the MBT after initial cooling and sea ice expansion in the mid-Pleistocene (Stroynowski et al, 2015(Stroynowski et al, , 2017.…”

Section: Discussionmentioning

confidence: 85%

“…Studies have shown that sea ice was present in the Bering Sea through at least the last 2.5 Myr, became more prevalent during the mid-Pleistocene (Stroynowski et al, 2015(Stroynowski et al, , 2017Detlef et al, 2018), and likely resulted in GNPIW expansion (Horikawa et al, 2010;Knudson and Ravelo, 2015;Kender et al, 2018;Worne et al, 2019) and a reduced OMZ. However, high-resolution Bering Sea records of organic carbon flux and OMZ presence have not yet been produced over the MBT.…”

Section: Introductionmentioning

confidence: 99%

“…However, high-resolution Bering Sea records of organic carbon flux and OMZ presence have not yet been produced over the MBT. Existing low-resolution records at the Bering Sea slope do suggest that sea ice was reduced at ∼ 500 ka (Stroynowski et al, 2017), but there are no existing records with the resolution required to test the sea ice influence on productivity at a marginal location in the central Bering Sea. Diatom assemblage records from several piston cores in the Bering Sea and North Pacific have been used to reconstruct Quaternary sea ice variation (see Leventer et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition

Kender

Aturamu

Zalasiewicz

et al. 2019

J. Micropalaeontol.

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Abstract. 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 CO2 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 Bulimina exilis, Takayanagia delicata, Alabaminella weddellensis, Gyroidina sp. 2, Cassidulina laevigata, Islandiella norcrossi, and Uvigerina bifurcata, consistent with broadly high net primary production throughout the last 600 kyr. Correspondence analysis shows that the most significant Assemblage 1 comprises B. exilis, T. delicata, Bolivina spissa, and Brizalina, 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 A. weddellensis, I. norcrossi, and C. laevigata, indicative of seasonal phytoplankton blooms. Before the MBT, more numerous intervals of the very high-productivity Assemblage 1 and A. weddellensis 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.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition

Kender

Aturamu

Zalasiewicz

et al. 2019

J. Micropalaeontol.

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“…Stratigraphic range of P. barboi and P. curvirostris in Core U1340A (this study;Stroynowski et al, 2015). Red horizontal line signals the appearance of the intermediate forms (Sample U1340A-24H-5; 1.39±0.1Ma) and the yellow bar indicates the interval where specimens with variations of the secondary spine occur.…”

mentioning

confidence: 68%

Morphology, biostratigraphy, and evolution of PliocenePleistocene diatoms Proboscia barboi...

Andrade

Legoinha

Stroynowski

et al. 2019

GeActa

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Proboscia barboi and Proboscia curvirostris are two important diatom biostratigraphic markers from the high latitudes of the North Pacific and North Atlantic Oceans, dating back to the Pliocene-Pleistocene time. This study analyzes the biostratigraphic events and describes the morphology of P. barboi and P. curvirostris, particularly the morphologic variations of the latter species, based on observations of samples of Core U1340A from the IODP Expedition 323 in the Bering Sea. In Site U1340, the First Occurrence of P. curvirostris is observed at 1.52Ma and its First Common Occurrence at 1.39Ma, where morphologic variations were found abundantly. The Last Occurrence of P. curvirostris was found at 0.33Ma, while P. barboi's Last Occurrence is found at 0.67Ma. Based on the morphological similarity and known biostratigraphic distribution, previous authors have assumed that P. curvirostris descends from P. barboi, although this hypothesis is still in debate. At 1.39Ma P. curvirostris shows an increased size and thickness, which is typical of P. barboi, and some specimens display an incipient structure characteristic of P. curvirostris -the secondary spine. This morphology is intermediate between the two species and suggests an evolutionary transition from P. barboi to P. curvirostris. However, P. curvirostris already existed since 1.9Ma in the subarctic indicating that its speciation happened much earlier than 1.39Ma. Furthermore, since P. barboi co-occurs with P. curvirostris in the North Pacific, this evolutionary process was cladogenetic. Besides being evidence for a phylogenetic relationship, the abundant occurrence of intermediate forms at 1.39Ma may constitute a bioevent for a short time interval in the Bering Sea.Probosciaceae. Proboscis. Longitudinal ridges. Site U1340. Quaternary. KEYWORDS

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Biogeochemical cycling in the Bering Sea over the onset of major Northern Hemisphere Glaciation

2016

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The Bering Sea is one of the most biologically productive regions in the marine system and plays a key role in regulating the flow of waters to the Arctic Ocean and into the subarctic North Pacific Ocean. Cores from Integrated Ocean Drilling Program (IODP) Expedition 323 to the Bering Sea provide the first opportunity to obtain reconstructions from the region that extend back to the Pliocene. Previous research at Bowers Ridge, south Bering Sea, has revealed stable levels of siliceous productivity over the onset of major Northern Hemisphere Glaciation (NHG) (circa 2.85–2.73 Ma). However, diatom silica isotope records of oxygen (δ18Odiatom) and silicon (δ30Sidiatom) presented here demonstrate that this interval was associated with a progressive increase in the supply of silicic acid to the region, superimposed on shift to a more dynamic environment characterized by colder temperatures and increased sea ice. This concluded at 2.58 Ma with a sharp increase in diatom productivity, further increases in photic zone nutrient availability and a permanent shift to colder sea surface conditions. These transitions are suggested to reflect a gradually more intense nutrient leakage from the subarctic northwest Pacific Ocean, with increases in productivity further aided by increased sea ice‐ and wind‐driven mixing in the Bering Sea. In suggesting a linkage in biogeochemical cycling between the south Bering Sea and subarctic Northwest Pacific Ocean, mainly via the Kamchatka Strait, this work highlights the need to consider the interconnectivity of these two systems when future reconstructions are carried out in the region.

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A Pliocene to recent history of the Bering Sea at Site U1340A, IODP Expedition 323

Cited by 18 publications

References 89 publications

Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition

Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition

Morphology, biostratigraphy, and evolution of PliocenePleistocene diatoms Proboscia barboi...

Biogeochemical cycling in the Bering Sea over the onset of major Northern Hemisphere Glaciation

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