Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2024
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Abstract
Eutrophication of coastal ecosystems often stimulates massive and uncontrolled growth of green macroalgae, causing serious ecological problems. These green tides are frequently exposed to light intensities that can reduce their growth via the production of reactive oxygen species (ROS). To understand the physiological and biochemical mechanisms leading to the formation and maintenance of green tides, the interaction between inorganic nitrogen (Ni) and light was studied. In a bi-factorial physiological experiment simulating eutrophication under different light levels, the bloom-forming green macroalga Ulva rigida was exposed to a combination of ecologically relevant nitrate concentrations (3.8–44.7 µM) and light intensities (50–1100 µmol photons m−2 s−1) over three days. Although artificial eutrophication (≥ 21.7 µM) stimulated nitrate reductase activity, which regulated both nitrate uptake and vacuolar storage by a feedback mechanism, nitrogen assimilation remained constant. Growth was solely controlled by the light intensity because U. rigida was Ni-replete under oligotrophic conditions (3.8 µM), which requires an effective photoprotective mechanism. Fast declining Fv/Fm and non-photochemical quenching (NPQ) under excess light indicate that the combined photoinhibitory and PSII-reaction centre quenching avoided ROS production effectively. Thus, these mechanisms seem to be key to maintaining high photosynthetic activities and growth rates without producing ROS. Nevertheless, these photoprotective mechanisms allowed U. rigida to thrive under the contrasting experimental conditions with high daily growth rates (12–20%). This study helps understand the physiological mechanisms facilitating the formation and persistence of ecologically problematic green tides in coastal areas.
Authors
Martin S. Mullett Anna R. Harris Bruno Scanu Kris Van Poucke Jared LeBoldus Elizabeth Stamm Tyler B. Bourret Petya K. Christova Jonás Oliva Miguel A. Redondo Venche Talgø Tamara Corcobado Ivan Milenković Marília Horta Jung Joan Webber Kurt Heungens Thomas JungAbstract
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Authors
Anders Ræbild Kesara Anamthawat-Jónsson Ulrika Egertsdotter Juha Immanen Anna Monrad Jensen Athina Koutouleas Helle Jakobe Martens Kaisa Nieminen Jill Katharina Olofsson Anna-Catharina Röper Jarkko Salojärvi Martina Strömvik Mohammad Vatanparast Adam Vivian-SmithAbstract
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Abstract
Vegetasjon langs bekker og vannveier er viktig for biologisk mangfold, jordvern, erosjonskontroll, reduksjon av risiko for flom og tørke, og for elvens hydromorfologi. Copernicus Land Monitoring Service tilbyr geografiske produkter til støtte for forvaltning av land og vann. I denne rapporten analyserer vi potensialet til Riparian Zones temakart (RZ) for bruk til kartlegging og overvåking av vegetasjon langs bekker og vannveier i Norge og Polen. Vi inkluderer også analyser av temakartet Small Woody Features (SWF) innenfor områder kartlagt i RZ. Vi sammenlignet RZ med nasjonale data og flybilder for å verifisere kvaliteten til datasettet, både for status og endringer i arealdekke og arealbruk langs bekker og vannveier. Vi konkluderer med at den tematiske nøyaktigheten var ganske god for vann, jordbruksareal og skog, men at andre klasser ikke korresponderte like godt med de nasjonale dataene. Mange av avvikene kan skyldes forskjeller i klassifiseringssystemene, kildedatene og kartleggingsinstruksene for de forskjellige datasettene. I tillegg fant vi at den romlige oppløsningen av RZ er utilstrekkelig for detaljert overvåking, særlig i jordbrukslandskap. Likevel gir RZ en standardisert og harmonisert metodikk for hele Europa, og er et steg i riktig retning for å kunne overvåke arealdekke og arealbruk i disse dynamiske og viktige områdene.
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Authors
Bert van der Veen Robert Brian O'Hara Francis K. C. Hui Knut Anders HovstadAbstract
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