Blar i forfatter "Hansen, Haakon"

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    • Alien plants, animals, fungi and algae in Norway: an inventory of neobiota 

      Sandvik, Hanno; Dolmen, Dag; Elven, Reidar; Falkenhaug, Tone; Forsgren, Elisabet; Hansen, Haakon; Hassel, Kristian; Husa, Vivian; Kjærstad, Gaute; Ødegaard, Frode; Pedersen, Hans Christian; Solheim, Halvor; Stokke, Bård Gunnar; Åsen, Per Arvid; Åström, Sandra Charlotte Helene; Brandrud, Tor Erik; Elven, Hallvard; Endrestøl, Anders; Finstad, Anders Gravbrøt; Fredriksen, Stein; Gammelmo, Øivind; Gjershaug, Jan Ove; Gulliksen, Bjørn; Hamnes, Inger Sofie; Hatteland, Bjørn Arild; Hegre, Hanne; Hesthagen, Trygve H.; Jelmert, Anders; Jensen, Thomas Correll; Johnsen, Stein Ivar; Karlsbakk, Egil; Magnusson, Christer; Nedreaas, Kjell Harald; Nordén, Björn; Oug, Eivind; Pedersen, Oddvar; Pedersen, Per Anker; Sjøtun, Kjersti; Skei, Jon Kristian; Solstad, Heidi; Sundheim, Leif; Swenson, Jon; Syvertsen, Per Ole; Talgø, Venche; Vandvik, Vigdis; Westergaard, Kristine Bakke; Wienerroither, Rupert; Ytrehus, Bjørnar; Hilmo, Olga; Henriksen, Snorre; Gederaas, Lisbeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-03)
      We present the results of an inventory and status assessment of alien species in Norway. The inventory covered all known multicellular neobiota, 2496 in total, 1039 of which were classified as naturalised. The latter constitute c. 3% of all species known to be stably reproducing in Norway. These figures are higher than expected from Norway’s latitude, which may be due a combination of ...

    • Alien species in Norway: results from quantitative ecological impact assessments 

      Sandvik, Hanno; Hilmo, Olga; Henriksen, Snorre; Elven, Reidar; Åsen, Per Arvid; Hegre, Hanne; Pedersen, Oddvar; Pedersen, Per Anker; Solstad, Heidi; Vandvik, Vigdis; Westergaard, Kristine Bakke; Ødegaard, Frode; Åström, Sandra Charlotte Helene; Elven, Hallvard; Endrestøl, Anders; Gammelmo, Øivind; Hatteland, Bjørn Arild; Solheim, Halvor; Nordén, Björn; Sundheim, Leif; Talgø, Venche; Falkenhaug, Tone; Gulliksen, Bjørn; Jelmert, Anders; Oug, Eivind; Sundet, Jan Henry; Forsgren, Elisabet; Finstad, Anders Gravbrøt; Hesthagen, Trygve H.; Nedreaas, Kjell Harald; Wienerroither, Rupert; Husa, Vivian; Fredriksen, Stein; Sjøtun, Kjersti; Steen, Henning; Hansen, Haakon; Hamnes, Inger Sofie; Karlsbakk, Egil; Magnusson, Christer; Ytrehus, Bjørnar; Pedersen, Hans Christian; Swenson, Jon; Syvertsen, Per Ole; Stokke, Bård Gunnar; Gjershaug, Jan Ove; Dolmen, Dag; Kjærstad, Gaute; Johnsen, Stein Ivar; Jensen, Thomas Correll; Hassel, Kristian; Gederaas, Lisbeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-20)
      1. Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation.<p><p> 2. We risk-assessed all alien plants, animals, fungi and algae, within certain ...

    • Determinants of parasite distribution in Arctic charr populations: catchment structure versus dispersal potential 

      Paterson, Rachel Anne; Knudsen, Rune; Blasco-Costa, Isabel; Dunn, Alison M; Hytterød, Sigurd; Hansen, Haakon (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-18)
      Parasite distribution patterns in lotic catchments are driven by the combined influences of unidirectional water flow and the mobility of the most mobile host. However, the importance of such drivers in catchments dominated by lentic habitats are poorly understood. We examined parasite populations of Arctic charr Salvelinus alpinus from a series of linear-connected lakes in northern Norway to ...

    • Diagnostikk av parasittsykdommer 

      Dale, Ole Bendik; Hansen, Haakon; Tørud, Brit; Erkinharju, Toni; Gjessing, Mona Cecilie (Journal article; Tidsskriftartikkel, 2022)
      Parasitter er alle snyltere, men de tilhører svært ulike grupper og har et mangfoldig levesett!

    • Forekomst av ulike parasitter hos rognkjeks i oppdrett 

      Erkinharju, Toni; Wüstner, Stefanie Caroline; Furnesvik, Lisa; Hansen, Miroslava; Hansen, Anette; Hansen, Haakon (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
      Rognkjeks (<i>Cyclopterus lumpus</i> L.) brukes som rensefisk for såkalt biologisk bekjempelse av lakselus (<i>Lepeophtheirus salmonis</i>) i lakseoppdrett. Produksjon av rognkjeks har økt i takt med et økende behov i næringen, og arten er i dag den nest vanligste i norsk akvakultur når det gjelder antall fisk produsert (40 millioner i 2018). Det er påvist en rekke encellede og ...

    • Forekomst av ulike parasitter hos rognkjeks i oppdrett 

      Erkinharju, Toni; Wüstner, Stefanie Caroline; Furnesvik, Lisa; Hansen, Miroslava; Hansen, Anette; Hansen, Haakon (Journal article; Tidsskriftartikkel, 2019)

    • Gyrodactylus triglopsi n. sp. (Monogenea: Gyrodactylidae) from the Gills of Triglops nybelini Jensen, 1944 (Teleostei: Cottidae) in the Barents Sea 

      Hansen, Haakon; Alvestad, Anja Helene; MacKenzie, Ken; Darrud, Mari; Karlsbakk, Egil; Hemmingsen, Willy; Arneberg, Per (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-28)
      <i>Introduction</i> - Monogeneans of the genus <i>Gyrodactylus</i> were found on the gills of specimens of the bigeye sculpin <i>Triglops nybelini</i> Jensen, 1944 caught by trawl in the Barents Sea in January–February 2016.<p> <p><i>Methods</i> - Morphological preparations of the parasites were examined and photographed under a microscope at magnifcations of×100–1000 and morphometric analyses ...

    • Infeksjoner med parasitten Nucleospora cyclopteri (Microsporidia) i rognkjeks, Cyclopterus lumpus 

      Hansen, Haakon; Thoen, Even; Alarcon, Marta; Devold, Magnus; Klingenberg, Oda; Nilsen, Kathrine; Warland, Benedicte R. E.; Markussen, Turhan Ali Dadasbilge; Faller, Randi; Mohammad, Saima; Seternes, Tore; Weli, Simon Chioma; Karlsbakk, Egil (Research report; Forskningsrapport, 2019)
      <p><i>Nucleospora cyclopteri</i> (Microsporidia) is one of many parasites infecting lumpfish, <i>Cyclopterus lumpus</i>, and has been shown to cause disease and mortality in lumpfish. Infections in fish are often multifactorial and the impact of one agent on the development of disease can be difficult to elucidate. In addition to mortality, infections in lumpfish can lead to diseases with subsequently ...

    • Parasite faunas of farmed cod and adjacent wild cod populations in Norway: a comparison 

      Heuch, Peter Andreas; Jansen, Peder Andreas; Hansen, Haakon; Sterud, Erik; MacKenzie, Ken; Haugen, Pål; Hemmingsen, Willy (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-07-14)
      Atlantic cod Gadus morhua L. is host to more than 120 parasite species. Background abundance of these parasite species on adjacent wild hosts determines the infection pressure on cod farmed in open pens. In 2006, 2007 and 2008, 343 cod were collected from 4 locations along the coast of Norway: Øksfjord, Kvarøy, Brønnøysund and Ålesund. Freshly killed wild local cod, wild migratory cod, hatchery-reared ...