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 ... -
Advancing Ocean Observation with an AI-driven Mobile Robotic Explorer
Saad, Aya; Stahl, Annette; Våge, Andreas; Davies, Emlyn John; Nordam, Tor; Aberle-Malzahn, Nicole; Ludvigsen, Martin; Johnsen, Geir; Sousa, João; Rajan, Kanna (Journal article; Peer reviewed, 2020)Rapid assessment and enhanced knowledge of plankton communities and their structure in the productive upper water column is of crucial importance to understand the impact of the changing climate on upper ocean processes. ... -
Aerial & Underwater Hyperspectral Imagery For Shallow Benthic Nature Type Mapping
Bjerkvoll, Mikkel (Master thesis, 2022)Natur i Norge (NiN) systemet klassifiserer naturtyper basert på miljøvariabler. Storskala kartlegging av bentiske naturtyper er vanskelig, ettersom lys utslukkes fort på dype områder, og grunt vann er vanskelig å forsere. ... -
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 ... -
All-sky camera system providing high temporal resolution annual time series of irradiance in the arctic
Johnsen, Geir; Zolich, Artur; Grant, Stephen; Bjorgum, Rune; Cohen, Jonathan H.; Mckee, David; Kopec, Tomasz Piotr; Vogedes, Daniel Ludwig; Berge, Jorgen (Journal article; Peer reviewed, 2021)The ArcLight observatory provides hourly continuous time series of light regime data (intensity, spectral composition, and photoperiod) from the Arctic, Svalbard at 79° N. Until now, no complete annual time series of ... -
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 ... -
Autonomous Underwater Vehicle (AUV) based study of zooplankton communities, using a silhouette camera and artificial intelligence
Nøland, Annecken (Master thesis, 2022)Autonome undervannsfarkoster (AUV), som kan tilpasses med en montert sensorpakke, har vist seg å være nyttige for økologistudier av plankton ved å gi kontinuerlige romlige og tidsmessige observasjoner over mesoskalaen. En ... -
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 ... -
Blinks in the dark - Detecting and characterizing flash kinetics of bioluminescence for in situ species recognition of zooplankton
Krohn-Pettersen, Gitte (Master thesis, 2023)Med biodiversitetkrisen jorden står overfor, hvor presset på biologisk mangfold øker og effekter av menneskelige handlinger på de naturlige økosystemene vokser, er det et presserende behov for overvåkningsprogrammer og ... -
Bryozoan larvae (cyphonauts) growth and encrustation in Saccharina latissima: analysis of biotic and abiotic interactions.
Thomason, Peter Benjamin (Master thesis, 2023)Havbruk av tang er et essensielt verktøy for å fø verdens befolkning i det 21. århundre, i tillegg til å bidra til å nå flere FNs bærekraftige utviklingsmål som klimahandling og liv under vann. Biobegroing, vekst av ... -
Campaign For Hyperspectral Data Validation In North Atlantic Coastal Waters
Oudijk, Esmée; Hasler, Oliver Kevin; Overaas, H; Marty, Sabine; Williamson, David; Svendsen, T; Berg, Simen; Birkeland, Roger; Halvorsen, D; Bakken, S; Henriksen, Marie Bøe; Alver, Morten; Johnsen, Geir; Johansen, Tor Arne; Stahl, Annette; Kvaløy, Pål; Dallolio, Alberto; Majaneva, Sanna; Fragoso, Glaucia Moreira; Garrett, Joseph (Peer reviewed; Journal article, 2022)The high photosynthetic productivity of the Mausund bank on the coast of mid-Norway has given the area important economic and ecologic value. Monitoring chlorophyll-a (chl-a) production can assist in managing the local ... -
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 ... -
Contrasting phytoplankton-zooplankton distributions observed through autonomous platforms, in-situ optical sensors and discrete sampling
Fragoso, Glaucia Moreira; Davies, Emlyn John; Fossum, Trygve Olav; Ullgren, Jenny; Majaneva, Sanna; Aberle-Malzahn, Nicole; Ludvigsen, Martin; Johnsen, Geir (Peer reviewed; Journal article, 2022)Plankton distributions are remarkably ‘patchy’ in the ocean. In this study, we investigated the contrasting phytoplankton-zooplankton distributions in relation to wind mixing events in waters around a biodiversity-rich ... -
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 ...