Blar i NTNU Open på forfatter "Johnsen, Geir"
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Development and calibration of a high dynamic range and autonomous ocean-light instrument to measure sub-surface profiles in ice-covered waters
Schartmuller, Bernhard; Anderson, Philip; Mckee, David; Connan-McGinty, Stacey; Kopec, Tomasz Piotr; Daase, Malin Hildegard Elisabeth; Johnsen, Geir; Berge, Jørgen (Journal article; Peer reviewed, 2023)The optical chain and logger (OptiCAL) is an autonomous ice-tethered observatory equipped with multiple light sensors for mapping the variation of light with depth. We describe the instrument and present an ensemble ... -
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 ... -
Evaluating hyperspectral Secchi depth retrieval through hybrid modeling and regression
Bakken, Sivert; Luis, Kelly; Johnsen, Geir; Johansen, Tor Arne (Peer reviewed; Journal article, 2023)This work compares different regression models combined with hybrid modeling to estimate water clarity using hyper-spectral remote sensing data. The Secchi depth, a proxy of water clarity, can be modeled using first ... -
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 ... -
Guidance and Control of Marine Robotics for Ocean Mapping and Monitoring
Nornes, Stein M. (Doctoral theses at NTNU;2018:202, Doctoral thesis, 2018)The ocean is an integral part of life on Earth, both as a source of food and oxygen, a medium of transportation and a major influence on weather and climate. Unfortunately, proper management and preservation of the ocean ... -
High Arctic Sea-Ice Algae - The Use of Rapid Light Curves to Assess Photosynthetic Performance of Different Ice-Algal Communities
Sandbu, Marthe (Master thesis, 2017)The maximum quantum yield of charge separation in photosystem II (ФPSIImax) was assessed for studying the physiological state of different ice algal communities. By using Rapid Light Curves, relative electron transfer rates ... -
How Lamina Age Influence Photosynthetic Response to Light Variations in Saccharina latissima
Kvernvik, Ane-Cecilie (Master thesis, 2014)Fotosyntetisk rate, målt på grunnlag av in vivo klorofyll a fluorescens, som en funksjon av økende lamina alder ble undersøkt i Saccharina latissima fra Trondheimfjorden, Norge i vinter, sommer og høst 2013. Sesongens ... -
How Photosynthesis in Laminaria digitata and Saccharina latissima is Affected by Water Temperature
Aamot, Inga Arnesen (Master thesis, 2011)The aim of this thesis is to give insight into how a short term exposure to higher water temperatures affect photosynthesis in two of the most important species of the Norwegian kelp forest; Laminaria digitata and Saccharina ... -
Hyperspectral imaging as an emerging tool to analyze microplastics: A systematic review and recommendations for future development
Faltynkova, Andrea; Johnsen, Geir; Wagner, Martin (Peer reviewed; Journal article, 2021)A central challenge in microplastics (MP, diameter < 5 mm) research is the analysis of small plastic particles in an efficient manner. This review focuses on the recent application of infrared hyperspectral imaging (HSI) ... -
Hyperspectral Push-broom Systems: Operations, Software Development, and Spatial Resolution
Langer, Dennis (Doctoral theses at NTNU;2024:19, Doctoral thesis, 2024)Remote sensing satellites that provide hyperspectral imagery promise to be a valuable source of information and enable new applications. The _rst satellite from the NTNU Small-Satellite laboratory, the Hyperspectral Small ... -
HYPSO-1 CubeSat: First Images and In-Orbit Characterization
Bakken, Sivert; Henriksen, Marie Bøe; Birkeland, Roger; Langer, Dennis David; Oudijk, Adriënne Esmeralda; Berg, Simen; Pursley, Yeshi; Garrett, Joseph Landon; Gran-Jansen, Fredrik; Honoré-Livermore, Evelyn; Grøtte, Mariusz Eivind Santora; Kristiansen, Bjørn Andreas; Orlandic, Milica; Gader, Paul; Sørensen, Asgeir Johan; Sigernes, Fred; Johnsen, Geir; Johansen, Tor Arne (Peer reviewed; Journal article, 2023)The HYPSO-1 satellite, a 6U CubeSat carrying a hyperspectral imager, was launched on 13 January 2022, with the Goal of imaging ocean color in support of marine research. This article describes the development and current ... -
Identification of Marine Plastics using Hyperspectral Imaging and Raman Spectroscopy
Stien, Andreas Ø. R.; Dahl, Emilie M. Hyrum (Master thesis, 2019)Dagens Næringsliv (DN) hadde følgende overskrift 28. Mai i år (forfatter: Jørn Aass); ”Alarmerende forskning: Plast i havet påvirker oksygenet vi puster inn”. Plastforsøpling påvirker havet, som igjen er en sentral del av ... -
Identification of Marine Plastics using Hyperspectral Imaging and Raman Spectroscopy
Dahl, Emilie M. Hyrum; Stien, Andreas Ø. R. (Master thesis, 2019)Dagens Næringsliv (DN) hadde følgende overskrift 28. Mai i år (forfatter: Jørn Aass); ”Alarmerende forskning: Plast i havet påvirker oksygenet vi puster inn”. Plastforsøpling påvirker havet, som igjen er en sentral del av ...