Blar i Bergen Open Research Archive på forfatter "Larsen, Aud"
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Asynchronous Accumulation of Organic Carbon and Nitrogen in the Atlantic Gateway to the Arctic Ocean
Paulsen, Maria Lund; Seuthe, Lena; Reigstad, Marit; Larsen, Aud; Cape, Matthias; Vernet, Maria (Peer reviewed; Journal article, 2018-11-15)Nitrogen (N) is the main limiting nutrient for biological production in the Arctic Ocean. While dissolved inorganic N (DIN) is well studied, the substantial pool of N bound in organic matter (OM) and its bioavailability ... -
Bacterial community composition responds to changes in copepod abundance and alters ecosystem function in an Arctic mesocosm study
Tsagaraki, Tatiana Margo; Pree, Bernadette; Leiknes, Øystein; Larsen, Aud; Bratbak, Gunnar; Øvreås, Lise; Egge, Jorun Karin; Spanek, Roman; Paulsen, Maria Lund; Olsen, Yngvar; Vadstein, Olav; Thingstad, T. Frede (Peer reviewed; Journal article, 2018)Combining a minimum food web model with Arctic microbial community dynamics, we have suggested that top-down control by copepods can affect the food web down to bacterial consumption of organic carbon. Pursuing this ... -
Biological transformation of Arctic dissolved organic matter in a NE Greenland fjord
Paulsen, Maria Lund; Müller, Oliver; Larsen, Aud; Møller, Eva Friis; Middelboe, Mathias; Sejr, Mikael Kristian; Stedmon, Colin A. (Peer reviewed; Journal article, 2018-12-07)Arctic waters are often enriched with terrestrial dissolved organic matter (DOM) characterized by having elevated visible wavelength fluorescence (commonly termed humic-like). Here, we have identified the sources of ... -
Bioorthogonal Non-canonical Amino Acid Tagging Combined With Flow Cytometry for Determination of Activity in Aquatic Microorganisms
Lindivat, Mathilde; Larsen, Aud; Hess-Erga, Ole-Kristian; Bratbak, Gunnar; Hoell, Ingunn (Journal article; Peer reviewed, 2020)In this study, we have combined bioorthogonal non-canonical amino acid tagging (BONCAT) and flow cytometry (FCM) analysis, and we demonstrate the applicability of the method for marine prokaryotes. Enumeration of active ... -
Carbon Bioavailability in a High Arctic Fjord Influenced by Glacial Meltwater, NE Greenland
Paulsen, Maria Lund; Nielsen, Sophia Elisabeth Bardram; Müller, Oliver; Møller, Eva Friis; Stedmon, Colin A.; Juul-Pedersen, Thomas; Markager, Stiig; Sejr, Mikael Kristian; Delgado Huertas, Antonio; Larsen, Aud; Middelboe, Mathias (Peer reviewed; Journal article, 2017-06-08)The land-to-ocean flux of organic carbon is increasing in glacierized regions in response to increasing temperatures in the Arctic (Hood et al., 2015). In order to understand the response of the coastal ecosystem metabolism ... -
Contrasting response to nutrient manipulation in Arctic mesocosms are reproduced by a minimum microbial food web model
Larsen, Aud; Egge, Jorun Karin; Nejstgaard, Jens Christian; Di Capua, Iole; Thyrhaug, Runar; Bratbak, Gunnar; Thingstad, Tron Frede (Peer reviewed; Journal article, 2015-01-27)A minimum mathematical model of the marine pelagic microbial food web has previously shown to be able to reproduce central aspects of observed system response to different bottom-up manipulations in a mesocosm experiment ... -
Dual staining with CFDA-AM and SYTOX Blue in flow cytometry analysis of UV-irradiated Tetraselmis suecica to evaluate vitality
Olsen, Ranveig Ottøy; Hess-Erga, Ole-Kristian; Larsen, Aud; Hoffmann, Friederike; Thuestad, Gunnar; Hoell, Ingunn Alne (Peer reviewed; Journal article, 2016)After disinfection of ballast water, it is crucial to detect organisms and determine their vitality to assess the performance of the chosen treatment technique. Ultraviolet (UV) irradiation is a treatment technology commonly ... -
Emerging interaction patterns in the Emiliania huxleyi-EhV system
Ruiz Martinez, Eliana; Oosterhof, Monique; Sandaa, Ruth-Anne; Larsen, Aud; Pagarete, António (Journal article, 2017-03-22)Viruses are thought to be fundamental in driving microbial diversity in the oceanic planktonic realm. That role and associated emerging infection patterns remain particularly elusive for eukaryotic phytoplankton and their ... -
Flow Cytometric Analysis of Bacterial Protein Synthesis: Monitoring Vitality After Water Treatment
Lindivat, Mathilde; Bratbak, Gunnar; Larsen, Aud; Hess-Erga, Ole-Kristian; Hoell, Ingunn Alne (Journal article; Peer reviewed, 2021)Bacterial vitality after water disinfection treatment was investigated using bio-orthogonal non-canonical amino acid tagging (BONCAT) and flow cytometry (FCM). Protein synthesis activity and DNA integrity (BONCAT–SYBR ... -
High CO2 concentration and iron availability determine the metabolic inventory in an Emiliania huxleyi-dominated phytoplankton community
Mausz, Michaela A.; Segovia, María; Larsen, Aud; Berger, Stella Angela; Egge, Jorun Karin; Pohnert, Georg (Journal article; Peer reviewed, 2020)Ocean acidification (OA), a consequence of anthropogenic carbon dioxide (CO2) emissions, strongly impacts marine ecosystems. OA also influences iron (Fe) solubility, affecting biogeochemical and ecological processes. We ... -
How microbial food web interactions shape the arctic ocean bacterial community revealed by size fractionation experiments
Müller, Oliver; Seuthe, Lena; Pree, Bernadette; Bratbak, Gunnar; Larsen, Aud; Paulsen, Maria Lund (Journal article; Peer reviewed, 2021-11-17)In the Arctic, seasonal changes are substantial, and as a result, the marine bacterial community composition and functions differ greatly between the dark winter and light-intensive summer. While light availability is, ... -
Molecular gut content analysis demonstrates that Calanus grazing on Phaeocystis pouchetii and Skeletonema marinoi is sensitive to bloom phase but not prey density
Ray, Jessica Louise; Skaar, Katrine Sandnes; Simonelli, Paolo; Larsen, Aud; Troedsson, Christofer (Peer reviewed; Journal article, 2016-01-19)Mesozooplankton grazing selection in complex marine microbial communities is a poorly understood yet critical structuring component of marine microbial food webs. We wished to quantitatively assess how relative grazing by ... -
The potential of sedimentary ancient DNA for reconstructingpast sea ice evolution
De Schepper, Stijn; Ray, Jessica Louise; Skaar, Katrine Sandnes; Sadatzki, Henrik; Ijaz, Umer Zeeshan; Stein, Ruediger; Larsen, Aud (Peer reviewed; Journal article, 2019-06-24)Sea ice is a crucial component of the Arctic climate system, yet the tools to document the evolution of sea ice conditions onhistorical and geological time scales are few and have limitations. Such records are essential ... -
Removal of large viruses and their dispersal through fecal pellets of the appendicularian Oikopleura dioica during Emiliania huxleyi bloom conditions
Mayers, Kyle; Lawrence, Janice; Skaar, Katrine Sandnes; Töpper, Joachim Paul; Petelenz-Kurdziel, Elzbieta Anna; Saltvedt, Marius Rydningen; Sandaa, Ruth-Anne; Larsen, Aud; Bratbak, Gunnar; Ray, Jessica Louise (Journal article; Peer reviewed, 2021)Despite their importance in shaping the structure and function of marine microbial food webs, little is known about factors regulating marine virus abundance. Previous work demonstrated clearance of laboratory-cultured ... -
Reproducing the virus-to-copepod link in Arctic mesocosms using host fitness optimization.
Thingstad, T. Frede; Larsen, Aud; Bratbak, Gunnar; Våge, Selina; Egge, Jorun Karin; Sandaa, Ruth-Anne; Nejstgaard, Jens Christian (Journal article; Peer reviewed, 2020)By shunting material out of the predatory pathway toward detritus and dissolved material, viruses are believed to have an important impact on biogeochemical functions of the pelagic microbial food web. To include viruses ... -
The Response of Heterotrophic Prokaryote and Viral Communities to Labile Organic Carbon Inputs Is Controlled by the Predator Food Chain Structure
Sandaa, Ruth-Anne; Pree, Bernadette; Larsen, Aud; Våge, Selina; Tøpper, Birte; Töpper, Joachim Paul; Thyrhaug, Runar; Thingstad, Tron Frede (Peer reviewed; Journal article, 2017-08-23)Factors controlling the community composition of marine heterotrophic prokaryotes include organic-C, mineral nutrients, predation, and viral lysis. Two mesocosm experiments, performed at an Arctic location and bottom-up ... -
Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing
Egge, Elianne Sirnæs; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente (Peer reviewed; Journal article, 2015-06)Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance ... -
Seasonal dynamics of haptophytes and dsDNA algal viruses suggest complex virus-host relationship
Johannessen, Torill Vik; Larsen, Aud; Bratbak, Gunnar; Pagarete, António; Edvardsen, Bente; Egge, Elianne Dunthorn; Sandaa, Ruth-Anne (Peer reviewed; Journal article, 2017-04-20)Viruses influence the ecology and diversity of phytoplankton in the ocean. Most studies of phytoplankton host–virus interactions have focused on bloom-forming species like Emiliania huxleyi or Phaeocystis spp. The role of ... -
A simple adjustment to test reliability of bacterivory rates derived from the dilution method
Pree, Bernadette; Kuhlisch, Constanze; Pohnert, Georg; Sazhin, Andrey; Jakobsen, Hans Henrik; Paulsen, Maria Lund; Frischer, Marc E.; Stoecker, Diane K.; Nejstgaard, Jens C.; Larsen, Aud (Peer reviewed; Journal article, 2016-02)Quantification of grazing losses of marine heterotrophic bacteria is critical for understanding nutrient and carbon pathways in aquatic systems. The dilution method is a commonly used experimental approach for quantifying ... -
Simple models combining competition, defence and resource availability have broad implications in pelagic microbial food webs
Våge, Selina; Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal; Larsen, Aud; Norland, Svein; Paulsen, Maria Lund; Pree, Bernadette; Sandaa, Ruth-Anne; Skjoldal, Evy Foss; Tsagaraki, Tatiana Margo; Øvreås, Lise; Thingstad, T. Frede (Peer reviewed; Journal article, 2018-09)In food webs, interactions between competition and defence control the partitioning of limiting resources. As a result, simple models of these interactions contain links between biogeochemistry, diversity, food web structure ...