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Ocean productivity in the Gulf of Cadiz over the last 50 kyr
  • +8
  • Aurélie Penaud,
  • Frédérique Eynaud,
  • Johan Etourneau,
  • Jérôme Bonnin,
  • Anne deVernal,
  • Sébastien Zaragosi,
  • Jung Hyun Kim,
  • Sujin Kang,
  • Jong-Ku Gal,
  • Dulce Oliveiraa,
  • Claire Waelbroeck
Aurélie Penaud
Univ Brest (UBO), CNRS, UMR 6538 Laboratoire Géosciences Océan (LGO)

Corresponding Author:[email protected]

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Frédérique Eynaud
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Johan Etourneau
EPHE/PSL Research University
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Jérôme Bonnin
Univ. Bordeaux, CNRS, EPOC, UMR 5805
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Anne deVernal
U. Quebec Montreal
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Sébastien Zaragosi
Univ. Bordeaux, CNRS, EPOC, UMR 5805
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Jung Hyun Kim
Korea Polar Research Institute
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Sujin Kang
Hanyang University ERICA
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Jong-Ku Gal
Korea Polar Research Institute
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Dulce Oliveiraa
Divisão de Geologia e Georecursos Marinhos, Instituto Português do Mar e da Atmosfera (IPMA)
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Claire Waelbroeck
LOCEAN/IPSL, Sorbonne Université-CNRS-IRD-MNHN, UMR7159
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Reconstructions of ocean primary productivity (PP) help to explain past and present biogeochemical cycles and climate changes in the oceans. We document PP variations over the last 50 kyr in a currently oligotrophic subtropical region, the Gulf of Cadiz (GoC). Data combine refined results from previous investigations on dinoflagellate cyst (dinocyst) assemblages, alkenones, and stable isotopes (18O, 13C) in planktonic (Globigerina bulloides) and endobenthic (Uvigerina mediterranea) foraminifera from cores MD04-2805 CQ and MD99-2339 with new isotopic measurements on epibenthic (Cibicidoides species) foraminifera and dinocyst-based estimates of PP using the new n = 1,968 modern database. We thus constrain paleoproductivity variations and export production by integrating qualitative information from micropaleontological bio-indicators with quantitative reconstructions of parameters such as dinocyst-based PP and seasonal sea-surface temperature (SST), as well as information about remineralization from the benthic Dd13C. We show that PP, carbon export, and remineralization were generally high in the NE subtropical Atlantic Ocean during the last glacial period and that the Last Glacial Maximum (LGM) had lower Dd13C than the Heinrich Stadials with sustained high PP, likely allowing enhanced carbon sequestration. This study also provides vital information on the dynamics PP regime changes, as the dataset includes alkenone-based SST and total organic carbon (TOC). We link these stimulated PP periods to seasonal intensification of upwelling, active almost year-round during stadials, but restricted to spring–summer during interstadials and LGM, like today. During interstadials, nutrient advection through freshwater inputs during autumn–winter rains need to be considered to fully understand PP regimes.
Feb 2022Published in Paleoceanography and Paleoclimatology volume 37 issue 2. 10.1029/2021PA004316