G
Geir Johnsen
Researcher at Norwegian University of Science and Technology
Publications - 153
Citations - 6469
Geir Johnsen is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Arctic & Polar night. The author has an hindex of 43, co-authored 143 publications receiving 5597 citations. Previous affiliations of Geir Johnsen include University of California, Santa Barbara & University Centre in Svalbard.
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Journal ArticleDOI
Ocean temperature oscillations enable reappearance of blue mussels Mytilus edulis in Svalbard after a 1000 year absence
TL;DR: The first observations of settled blue mussels Mytilus edulis L. in the high Arctic Archipelago of Svalbard for the first time since the Viking Age were reported in this article.
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An Integrated Analysis of Molecular Acclimation to High Light in the Marine Diatom Phaeodactylum tricornutum
Marianne Nymark,Kristin Collier Valle,Tore Brembu,Kasper Hancke,Per Winge,Kjersti Andresen,Geir Johnsen,Atle M. Bones +7 more
TL;DR: The integrated results indicate that P. tricornutum is capable of swift and efficient execution of photoprotective mechanisms, followed by changes in the composition of the photosynthetic machinery that enable the diatoms to utilize the excess energy available in HL.
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Detection of harmful algal blooms using photopigments and absorption signatures: A case study of the Florida red tide dinoflagellate, Gymnodinium breve
David F. Millie,Oscar Schofield,Gary J. Kirkpatrick,Geir Johnsen,Patricia A. Tester,Bryan T. Vinyard +5 more
TL;DR: The utility of photopigments and absorption signatures to detect and enumerate the red tide dinoflagellate, Gymnodinium breve, was evaluated in laboratory cultures and in natural assemblages and difficulty in distinguishing among spectra can be minimized by using the similarity algorithm in conjunction with fourth-derivative analysis.
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Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice
Philipp Assmy,Mar Fernández-Méndez,Pedro Duarte,Amelie Meyer,Achim Randelhoff,Achim Randelhoff,Christopher John Mundy,Lasse Mork Olsen,Hanna M. Kauko,Allison Bailey,Melissa Chierici,Lana Cohen,Anthony P. Doulgeris,Jens K. Ehn,Agneta Fransson,Sebastian Gerland,Haakon Hop,Haakon Hop,Stephen R. Hudson,Nick Hughes,Polona Itkin,Geir Johnsen,Geir Johnsen,J. King,Boris P. Koch,Zoé Koenig,Slawomir Kwasniewski,Samuel R. Laney,Marcel Nicolaus,Alexey Pavlov,Chris Polashenski,Christine Provost,Anja Rösel,Marthe Sandbu,Gunnar Spreen,Gunnar Spreen,Lars Henrik Smedsrud,Lars Henrik Smedsrud,Arild Sundfjord,Torbjørn Taskjelle,Agnieszka Tatarek,Józef Wiktor,Penelope Mae Wagner,Anette Wold,Harald Steen,Mats A. Granskog +45 more
TL;DR: Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall.
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Actinomycetes from sediments in the Trondheim fjord, Norway: diversity and biological activity.
TL;DR: It is suggested that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents and strong antibiotic-producing potential among them.