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dc.contributor.authorAgustí, Susana
dc.contributor.authorKrause, Jeffrey W.
dc.contributor.authorMarquez, Israel A.
dc.contributor.authorWassmann, Paul
dc.contributor.authorKristiansen, Svein
dc.contributor.authorDuarte, Carlos M.
dc.date.accessioned2020-11-11T12:55:33Z
dc.date.available2020-11-11T12:55:33Z
dc.date.issued2020-01-03
dc.description.abstractDiatoms tend to dominate the Arctic spring phytoplankton bloom, a key event in the ecosystem including a rapid decline in surface-water <i>p</i>CO<sub>2</sub>. While a mass sedimentation event of diatoms at the bloom terminus is commonly observed, there are few reports on the status of diatoms' health during Arctic blooms and its possible role on sedimentary fluxes. Thus, we examine the idea that the major diatom-sinking event which occurs at the end of the regional bloom is driven by physiologically deteriorated cells. Here we quantify, using the Bottle-Net, Arctic diatom stocks below and above the photic zone and assess their cell health status. The communities were sampled around the Svalbard islands and encompassed pre- to post-bloom conditions. A mean of 24.2±6.7 % SE (standard error) of the total water column (max. 415 m) diatom standing stock was found below the photic zone, indicating significant diatom sedimentation. The fraction of living diatom cells in the photic zone averaged 59.4±6.3 % but showed the highest mean percentages (72.0 %) in stations supporting active blooms. In contrast, populations below the photic layer were dominated by dead cells (20.8±4.9 % living cells). The percentage of diatoms' standing stock found below the photic layer was negatively related to the percentage of living diatoms in the surface, indicating that healthy populations remained in the surface layer. Shipboard manipulation experiments demonstrated that (1) dead diatom cells sank faster than living cells, and (2) diatom cell mortality increased in darkness, showing an average half-life among diatom groups of 1.025±0.075 d. The results conform to a conceptual model where diatoms grow during the bloom until resources are depleted and supports a link between diatom cell health status (affected by multiple factors) and sedimentation fluxes in the Arctic. Healthy Arctic phytoplankton communities remained at the photic layer, whereas the physiologically compromised (e.g., dying) communities exported a large fraction of the biomass to the aphotic zone, fueling carbon sequestration to the mesopelagic and material to benthic ecosystems.en_US
dc.identifier.citationAgustí, W. Krause, A. Marquez, Wassmann, Kristiansen, M. Duarte. Arctic (Svalbard islands) active and exported diatom stocks and cell health status. Biogeosciences. 2020;17(1):35-45en_US
dc.identifier.cristinIDFRIDAID 1834929
dc.identifier.doi10.5194/bg-17-35-2020
dc.identifier.issn1726-4170
dc.identifier.issn1726-4189
dc.identifier.urihttps://hdl.handle.net/10037/19817
dc.language.isoengen_US
dc.publisherEuropean Geosciences Union (EGU)en_US
dc.relation.journalBiogeosciences
dc.relation.projectIDinfo:eu-repo/grantAgreement/RCN/PETROSENTR/228107/Norway/Research Centre for Arctic Petroleum Exploration/ARCEx/en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2020 The Author(s)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450en_US
dc.titleArctic (Svalbard islands) active and exported diatom stocks and cell health statusen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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