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Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

dc.rights.licenseopenen_US
hal.structure.identifierLaboratoire Géosciences Océan [LGO]
hal.structure.identifierLaboratoire des Sciences de l'Environnement Marin (LEMAR) [LEMAR]
dc.contributor.authorLAMBERT, Clément
hal.structure.identifierLaboratoire Géosciences Océan [LGO]
dc.contributor.authorPÉNAUD, Aurélie
hal.structure.identifierLaboratoire Géosciences Océan [LGO]
dc.contributor.authorVIDAL, Muriel
hal.structure.identifierUnité Dynamiques des Écosystèmes Côtiers [DYNECO]
dc.contributor.authorKLOUCH, Khadidja
hal.structure.identifierUnité Géosciences Marines [GM]
dc.contributor.authorGREGOIRE, Gwendoline
hal.structure.identifierInstitut Français de Recherche pour l'Exploitation de la Mer [IFREMER]
dc.contributor.authorEHRHOLD, Axel
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorEYNAUD, Frederique
IDREF: 144113570
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorSCHMIDT, Sabine
IDREF: 131836129
hal.structure.identifierLaboratoire des Sciences de l'Environnement Marin (LEMAR) [LEMAR]
dc.contributor.authorRAGUENEAU, Olivier
hal.structure.identifierUnité Dynamiques des Écosystèmes Côtiers [DYNECO]
dc.contributor.authorSIANO, Raffaele
dc.date.accessioned2024-05-04T09:39:55Z
dc.date.available2024-05-04T09:39:55Z
dc.date.issued2018-01
dc.identifier.issn0921-8181en_US
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/199618
dc.description.abstractEnFor the first time a very high resolution palynological study (mean resolution of 1 to 5 years) was carried out over the last 150 years in a French estuarine environment (Bay of Brest; NW France), allowing direct comparison between the evolution of landscapes, surface water, and human practices on Bay of Brest watersheds, through continental (especially pollen grains) and marine (phytoplanktonic microalgae: cysts of dinoflagellates or dinocysts) microfossils. Thanks to the small size of the watersheds and the close proximity of the depositional environment to the mainland, the Bay of Brest represents an ideal case study for palynological investigations. Palynological data were then compared to published palaeo-genetic analyses conducted on the same core and to various available instrumental data, allowing us to better characterize past environmental variability since the second half of the 19th century in Western Brittany. We provide evidence of some clues of recent eutrophication and/or pollution that affected phytoplankton communities and which appears linked with increased runoff (higher precipitations, higher percentages of riparian forest pollen, decline of salt marsh-type indicators, and higher values of the XRF Ti/Ca signal), mainly explained by the evolution of agricultural practices since 1945 superimposed on the warming climate trend. We assume that the significant relay observed between dinocyst taxa: Lingulodinium machaerophorum and Spiniferites bentorii around 1965 then followed by Spiniferites membranaceus after 1985, attests to a strong and recent eutrophication of Bay of Brest surface waters induced by high river runoff combined with abnormally elevated air temperatures, especially obvious in the data from 1990. The structure of the dinocyst community has thus been deeply altered, accompanied by an unprecedented increase of Alexandrium minutum toxic form at the same period, as confirmed by the genetic quantification. Despite this recent major anthropogenic forcing, the fossil pollen sequence also records natural climate variability. We highlight, for the first time, a possible connection between climate (AMO modes) and fossil pollen records (especially tree pollination rates) in coastal sediments using tree percentage fluctuations as an indirect proxy for past sea surface and atmospheric temperatures.
dc.description.sponsorshipLabexMER Marine Excellence Research: a changing oceanen_US
dc.language.isoENen_US
dc.subject.enPollen grains
dc.subject.enDinoflagellate cysts
dc.subject.enEstuarine dynamics
dc.subject.enRiver runoff
dc.subject.enClimate variability
dc.subject.enAcl
dc.title.enHuman-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)
dc.typeArticle de revueen_US
dc.identifier.doi10.1016/j.gloplacha.2017.11.004en_US
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Paléontologieen_US
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Océanographieen_US
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Tectoniqueen_US
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Volcanologieen_US
dc.subject.halSciences de l'environnement/Biodiversité et Ecologieen_US
bordeaux.journalGlobal and Planetary Changeen_US
bordeaux.page109 - 122en_US
bordeaux.volume160en_US
bordeaux.hal.laboratoriesEPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805en_US
bordeaux.institutionUniversité de Bordeauxen_US
bordeaux.institutionCNRSen_US
bordeaux.teamPALEOen_US
bordeaux.peerReviewedouien_US
bordeaux.inpressnonen_US
bordeaux.import.sourcehal
hal.identifierhal-01901989
hal.version1
hal.popularnonen_US
hal.audienceInternationaleen_US
hal.exportfalse
workflow.import.sourcehal
dc.rights.ccPas de Licence CCen_US
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Global%20and%20Planetary%20Change&rft.date=2018-01&rft.volume=160&rft.spage=109%20-%20122&rft.epage=109%20-%20122&rft.eissn=0921-8181&rft.issn=0921-8181&rft.au=LAMBERT,%20Cl%C3%A9ment&P%C3%89NAUD,%20Aur%C3%A9lie&VIDAL,%20Muriel&KLOUCH,%20Khadidja&GREGOIRE,%20Gwendoline&rft.genre=article


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