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dc.contributor.authorVonnahme, Tobias
dc.contributor.authorPersson, Emma
dc.contributor.authorDietrich, Ulrike
dc.contributor.authorHejdukova, Eva
dc.contributor.authorDybwad, Christine
dc.contributor.authorElster, Josef
dc.contributor.authorChierici, Melissa
dc.contributor.authorGradinger, Rolf
dc.date.accessioned2021-06-15T08:19:08Z
dc.date.available2021-06-15T08:19:08Z
dc.date.created2021-04-27T15:34:30Z
dc.date.issued2021
dc.identifier.citationThe Cryosphere. 2021, 15 2083-2107.en_US
dc.identifier.issn1994-0416
dc.identifier.urihttps://hdl.handle.net/11250/2759469
dc.description.abstractSubglacial upwelling of nutrient-rich bottom water is known to sustain elevated summer primary production in tidewater-glacier-influenced fjord systems. However, the importance of subglacial upwelling during the early spring season has not been considered yet. We hypothesized that subglacial discharge under sea ice is present in early spring and that its flux is sufficient to increase phytoplankton primary productivity. We evaluated the effects of the submarine discharge on primary production in a seasonally fast-ice covered Svalbard fjord (Billefjorden) influenced by a tidewater outlet glacier in April and May 2019. We found clear evidence for subglacial discharge and upwelling. Although the estimated bottom-water entrainment factor (1.6) and total fluxes were lower than in summer studies, we still observed substantial impact on the fjord ecosystem and primary production at this time of the year. The subglacial discharge leads to a salinity-stratified surface water layer and sea ice formation with low bulk salinity and permeability. The combination of the stratified surface layer, a 2-fold higher under-ice irradiance due to thinner snow cover, and higher N and Si concentrations at the glacier front supported phytoplankton primary production 2 orders of magnitude higher (42.6 mg C m−2 d−1) compared to a marine reference site at the fast-ice edge. Reciprocal transplant experiments showed that nutrient supply increased phytoplankton primary production by approximately 30 %. The brackish-water sea ice at the glacier front with its low bulk salinity contained a reduced brine volume, limiting the inhabitable brine channel space and nutrient exchange with the underlying seawater compared to full marine sea ice. Microbial and algal communities were substantially different in subglacial-influenced water and sea ice compared to the marine reference site, sharing taxa with the subglacial outflow water. We suggest that with climate change, the retreat of tidewater glaciers in early spring could lead to decreased under-ice phytoplankton primary production. In contrast, sea ice algae production and biomass may become increasingly important, unless sea ice disappears first, in which case spring phytoplankton primary production may increase.en_US
dc.language.isoengen_US
dc.titleEarly spring subglacial discharge plumes fuel under-ice primary production at a Svalbard tidewater glacieren_US
dc.typePeer revieweden_US
dc.typeJournal articleen_US
dc.description.versionpublishedVersionen_US
dc.source.pagenumber2083-2107en_US
dc.source.volume15en_US
dc.source.journalThe Cryosphereen_US
dc.identifier.doi10.5194/tc-15-2083-2021
dc.identifier.cristin1906748
cristin.ispublishedtrue
cristin.fulltextoriginal
cristin.qualitycode2


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