Blar i NTNU Open på forfatter "Johnsen, Geir"
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A pilot study assessing drones for mapping and monitoring of European shags
Graham, Lisa Kristine (Master thesis, 2019)Sjøfuglpopulasjoner er sensitive til forandringer i sitt miljø. De kan derfor studeres som indikatorer for endringer i økosystemer. I mellomtiden har droneteknologier økt i viktighet som verktøy i økologistudier og de har ... -
Algal colonization of young arctic sea ice in spring
Kauko, Hanna Maria; Olsen, Lasse Mork; Duarte, Pedro; Peeken, Ilka; Granskog, Mats A.; Johnsen, Geir; Fernández-Méndez, Mar; Pavlov, Alexey; Mundy, Christopher John; Assmy, Philipp (Journal article; Peer reviewed, 2018)The importance of newly formed sea ice in spring is likely to increase with formation of leads in a more dynamic Arctic icescape. We followed the ice algal species succession in young ice (≤ 0.27 m) in spring at high ... -
An ice-tethered buoy for fish and plankton research
Zolich, Artur Piotr; De La Torre, Pedro R.; Rodwell, Shane; Geoffroy, Maxime; Johnsen, Geir; Berge, Jørgen (Chapter, 2018)I.In this paper the authors present bio-acoustical icetethered platform for optical, physical and ecological sensors (POPE), i.e. an ice-tethered buoy, equipped with an AZFP scientific echosounder for fish and plankton ... -
An integrated analysis of molecular acclimation to high light in the marine diatom Phaeodactylum tricornutum
Nymark, Marianne; Valle, Kristin Collier; Brembu, Tore; Winge, Per; Hancke, Kasper; Andresen, Kjersti; Johnsen, Geir; Bones, Atle M. (Journal article; Peer reviewed, 2009-11-03)Photosynthetic diatoms are exposed to rapid and unpredictable changes in irradiance and spectral quality, and must be able to acclimate their light harvesting systems to varying light conditions. Molecular mechanisms behind ... -
Arctic complexity: A case study on diel vertical migration of zooplankton
Berge, Jørgen; Cottier, Finlo; Varpe, Øystein; Renaud, Paul; Falk-Petersen, Stig; Kwasniewski, Sawomir; Griffiths, Colin; Søreide, Janne; Johnsen, Geir; Aubert, Anais; Bjærke, Oda; Hovinen, Johanna Emilia Heidi; Jung-Madsen, Signe; Tveit, Martha; Markkula, Sanna (Journal article; Peer reviewed, 2014) -
Artificial light during the polar night disrupts Arctic fish and zooplankton behavior down to 200 m depth
Berge, Jørgen; Geoffroy, Maxime; Daase, Malin; Cottier, Finlo Robert; Priou, Pierre; Cohen, Jonathan H.; Johnsen, Geir; McKee, David; Kostakis, I; Renaud, Paul E.; Vogedes, Daniel Ludwig; Anderson, Philip J.; Last, Kim; Gauthier, Stephane (Peer reviewed; Journal article, 2020)For organisms that remain active in one of the last undisturbed and pristine dark environments on the planet—the Arctic Polar Night—the moon, stars and aurora borealis may provide important cues to guide distribution and ... -
Astaxanthin as a biomarker for fish feed loading in the marine ecosystem
Sporsheim, Kamilla (Master thesis, 2017)Organic waste released from a fish farm, is one of the main challenges facing aquaculture today, and to increase fish, production it is important to minimize the impact this have on the environment. The aim of this study ... -
Benthic Communities on the Mohn’s Treasure Mound: Implications for Management of Seabed Mining in the Arctic Mid-Ocean Ridge
Ramirez-Llodra, Eva; Hilário, Ana; Paulsen, Emil; Costa, Carolina; Bakken, Torkild; Johnsen, Geir; Rapp, Hans Tore (Peer reviewed; Journal article, 2020)The Mohn’s Treasure, described as an inactive sulfide mound, was discovered at 2,600- m depth on the Arctic Mid-Ocean Ridge (AMOR) in 2002. In 2015, we conducted the first biological survey of Mohn’s Treasure using remotely ... -
Bio-optical diversity on cold water coral habitats
Andersson, Ingvild Henriette Kristin (Master thesis, 2017)This study aimed to elucidate the bio-optical diversity of cold water coral habitats and to further improve the accuracy and efficiency of seafloor mapping with the use of an Underwater Hyperspectral Imager (UHI). Comparison ... -
Bioluminescence as an ecological factor during high Arctic polar night
Cronin, Heather; Cohen, Jonathan H.; Berge, Jørgen; Johnsen, Geir; Moline, Mark A. (Journal article; Peer reviewed, 2016)Bioluminescence commonly influences pelagic trophic interactions at mesopelagic depths. Here we characterize a vertical gradient in structure of a generally low species diversity bioluminescent community at shallower ... -
Capital or Income Breeder: The Role of Lipids and Fatty Acid Composition for Successful Reproduction in Calanus glacialis
Hatlebakk, Maja Karoline (Master thesis, 2014)Dette er den første tidsseriestudie som undersøker gonade modning og eggproduksjon hos Calanus glacialis i sesongislagte fjorder på Svalbard, og den første studien som undersøker sammenhengen mellom næringsstatus og ... -
Development of bryozoan fouling on cultivated kelp (Saccharina latissima) in Norway
Førde, Henny (Master thesis, 2014)Biofouling of cultivated kelp is a major challenge for the seaweed industry, and hard to avoid during the cultivation process. Several species are involved in the fouling in temperate waters, and among them are the encrusting ... -
Diatom biogeography from the Labrador Sea revealed through a trait-based approach
Fragoso, Glaucia Moreira; Poulton, Alex J.; Yashayaev, Igor M.; Head, Erica J.H.; Johnsen, Geir; Purdie, Duncan A. (Journal article; Peer reviewed, 2018)Diatoms are a keystone algal group, with diverse cell morphology and a global distribution. The biogeography of morphological, functional, and life-history traits of marine diatoms were investigated in Arctic and Atlantic ... -
Diel vertical migration of Arctic zooplankton during the polar night
Berge, Jørgen; Cottier, Finlo; Last, Kim S.; Varpe, Øystein; Leu, Eva; Søreide, Janne; Eiane, Ketil; Falk-Petersen, S.; Willis, Kate; Nygård, Henrik; Vogedes, Daniel; Griffiths, Collin; Johnsen, Geir; Lorentzen, Dag Arne; Brierley, A.S. (Journal article; Peer reviewed, 2009)High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar ... -
Eco-physiological responses of cold-water corals to anthropogenic sedimentation and particle shape
Liefmann, Stephanie (Master thesis, 2016)Cold-water coral habitats have been known to science for centuries, but only recently have scientists stated to study them. Among these habitats, also soft corals are found, and they have been even less investigated than ... -
Eco-physiology of the Arctic kelp Laminaria solidungula: - using divers, Remotely Operated Vehicle and Pulse Amplitude Modulated fluorometry
Belseth, Elen (Master thesis, 2012)! -
Elemental Composition in various Marine Brown, Green and Red Macroalgae with respect to Season and Tissue-Age
Kleiven, Wanda (Master thesis, 2014)Macro algae are important for the ecosystem as they provide food and shelter for many organisms. Trace metal or Rare Earth Elements (REE) content of macro algae are very little understood and there is a great need for ... -
Eyes beneath the surface - using a miniROV to reveal the habitat and dietary choices of the European shag
Strømsholm, Jørgen (Master thesis, 2018)The population of sea birds in Norway is drastically declining, and numbers of breeding European shag (Phalacrocorax aristotelis) in the nesting colony in Runde, Norway, has declined with ~96% in the last 40 years. Mapping ... -
First hyperspectral imaging survey of the deep seafloor: High-resolution mapping of manganese nodules
Dumke, Ines; Nornes, Stein Melvær; Purser, Autun; Marcon, Yann; Ludvigsen, Martin; Ellefmo, Steinar Løve; Johnsen, Geir; Søreide, Fredrik (Journal article; Peer reviewed, 2018)Hyperspectral seafloor surveys using airborne or spaceborne sensors are generally limited to shallow coastal areas, due to the requirement for target illumination by sunlight. Deeper marine environments devoid of sunlight ... -
Gastropods Associated with Laminaria hyperborea and Saccorhiza polyschides in a Norwegian Kelp Forest: Comparison of Sampling and In Situ Imaging Techniques
Andersen, Hanne Kile (Master thesis, 2011)The snail fauna (class Gastropoda) associated with the two kelp species Laminaria hyperborea and Saccorhiza polyschides was sampled during September and December 2009, and March 2011. Over 1000 gastropod individuals ...