The interplay between the surface and bottom water environment within the Benguela Upwelling System over the last 70 ka
McKay, C.L.; Filipsson, H.L.; Romero, O.E.; Stuut, J.-B. W.; Bjorck, S. (2016). The interplay between the surface and bottom water environment within the Benguela Upwelling System over the last 70 ka. Paleoceanography 31(2): 266–285. dx.doi.org/10.1002/2015PA002792
In: Paleoceanography. American Geophysical Union: Washington, DC. ISSN 0883-8305; e-ISSN 1944-9186, more
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| Authors | | Top |
- McKay, C.L.
- Filipsson, H.L.
- Romero, O.E.
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- Stuut, J.-B. W., more
- Bjorck, S.
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| Abstract |
The Benguela Upwelling System (BUS), located between 30 and 20°S, is one of the fundamentalhigh-productivity systems of the world ocean. The BUS has previously been studied in terms of primaryproductivity and ecology over glacial-interglacial timescales; however, the response and coupling with thebenthic environment have received little attention. Here, for the ?rst time, we present a high-resolutionreconstruction of the BUS highlighting the link between surface and benthic productivity and their responseto climatic and oceanographic changes over the last 70 ka. The study is based on benthic foraminiferal faunalanalysis together with analyses of diatom assemblages, grain size of the terrigenous fraction, and stable Oand C isotopic and bulk biogenic components of core GeoB3606-1. We reveal signi?cant shifts in benthicforaminiferal assemblage composition. Tight coupling existed between the surface and bottom waterenvironment especially throughout marine isotope stages 4 and 3 (MIS4 and MIS3). Due to the high exportproduction, the site has essentially experienced continuous low oxygen conditions; however, there are timeperiods where the hypoxic conditions were even more notable. Two of these severe hypoxic periods wereduring parts of MIS4 and MIS3 where we ?nd an inverse relationship between diatom and benthicforaminifera accumulation, meaning that during times of extremely high phytodetritus export we notestrongly suppressed benthic productivity. We also stress the importance of food source for the benthosthroughout the record. Shifts in export productivity are attributed not only to upwelling intensity and?lament front position, but also, regional-global climatic and oceanographic changes had signi?cant impacton the BUS dynamics. |
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