Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr
A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. O...
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doaj-a8c0713a6b554717bd0aaf6df2f915142020-11-24T22:35:20ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-08-0113164823484110.5194/bg-13-4823-2016Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyrW. Hardy0A. Penaud1F. Marret2G. Bayon3T. Marsset4L. Droz5UMR 6538 Domaines Océaniques, IUEM-UBO, 29280 Plouzané, FranceUMR 6538 Domaines Océaniques, IUEM-UBO, 29280 Plouzané, FranceSchool of Environmental Sciences, University of Liverpool, Liverpool, L69 7ZT, UKIFREMER, UR Géosciences Marines, BP 70-29280 Plouzané, FranceIFREMER, UR Géosciences Marines, BP 70-29280 Plouzané, FranceUMR 6538 Domaines Océaniques, IUEM-UBO, 29280 Plouzané, FranceA new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to correlate fluvial-sensitive taxa to monsoonal mechanisms related to precession minima–obliquity maxima combinations. While upwelling mechanisms appear as the main drivers for dinoflagellate productivity during MIS 2, dissolved nutrient-enriched Congo River inputs to the ocean also played a significant role in promoting dinoflagellate productivity between approximately 15.5 and 5 ka BP. Finally, this high-resolution dinocyst study permits us to precisely investigate the suborbital timing of the last glacial–interglacial termination, including an atypical warm and wet oceanic LGM signature, northern high-latitude abrupt climate change impacts in the equatorial eastern Atlantic, as well as a two-step decrease in moisture conditions during the Holocene at around 7–6 and 4–3.5 ka BP.http://www.biogeosciences.net/13/4823/2016/bg-13-4823-2016.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
W. Hardy A. Penaud F. Marret G. Bayon T. Marsset L. Droz |
spellingShingle |
W. Hardy A. Penaud F. Marret G. Bayon T. Marsset L. Droz Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr Biogeosciences |
author_facet |
W. Hardy A. Penaud F. Marret G. Bayon T. Marsset L. Droz |
author_sort |
W. Hardy |
title |
Dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial Atlantic over the last 44 kyr |
title_short |
Dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial Atlantic over the last 44 kyr |
title_full |
Dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial Atlantic over the last 44 kyr |
title_fullStr |
Dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial Atlantic over the last 44 kyr |
title_full_unstemmed |
Dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial Atlantic over the last 44 kyr |
title_sort |
dinocyst assemblage constraints on oceanographic and atmospheric processes
in the eastern equatorial atlantic over the last 44 kyr |
publisher |
Copernicus Publications |
series |
Biogeosciences |
issn |
1726-4170 1726-4189 |
publishDate |
2016-08-01 |
description |
A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts
(dinocysts) is presented from a marine sediment core collected on the
Congolese margin with the aim of reconstructing past hydrological changes in the
equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our
high-resolution dinocyst record indicates that significant temperature and
moisture variations occurred across the glacial period, the last deglaciation
and the Holocene. The use of specific dinocyst taxa, indicative of fluvial,
upwelling and Benguela Current past environments for instance, provides
insights into the main forcing mechanisms controlling palaeohydrological
changes on orbital timescales. In particular, we are able, for the last
44 kyr, to correlate fluvial-sensitive taxa to monsoonal mechanisms related
to precession minima–obliquity maxima combinations. While upwelling
mechanisms appear as the main drivers for dinoflagellate productivity during
MIS 2, dissolved nutrient-enriched Congo River inputs to the ocean also
played a significant role in promoting dinoflagellate productivity between
approximately 15.5 and 5 ka BP. Finally, this high-resolution dinocyst
study permits us to precisely investigate the suborbital timing of the last
glacial–interglacial termination, including an atypical warm and wet oceanic
LGM signature, northern high-latitude abrupt climate change impacts in the
equatorial eastern Atlantic, as well as a two-step decrease in moisture
conditions during the Holocene at around 7–6 and 4–3.5 ka BP. |
url |
http://www.biogeosciences.net/13/4823/2016/bg-13-4823-2016.pdf |
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