Browsing USN Open Archive by Author "Lydersen, Espen"
Now showing items 1-18 of 18
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An In Situ Experimental Study of Effects on Submerged Vegetation After Activated Carbon Amendment of Legacy Contaminated Sediments
Olsen, Marianne; Moy, Frithjof Emil; Mjelde, Marit; Lydersen, Espen (Journal article; Peer reviewed, 2018)Activated carbon (AC) amendment has been shown to reduce bioavailability of hydrophobic contaminants in the bioactive layer of sediment. Unwanted secondary effects of AC amendment could be particularly undesirable for ... -
Brood‐stock management and early hatchery rearing of Arctic charr (Salvelinus alpinus (Linnaeus))
Olk, Tom Robin; Thorarensen, Helgi Thor; Jeuthe, Henrik; Wollebæk, Jens; Lydersen, Espen (Journal article; Peer reviewed, 2019)Arctic charr (Salvelinus alpinus (Linnaeus)) is a stenothermic cold‐water fish, which has been cultured in Northern Europe and North America since the 1980s. The industry has remained relatively small with an annual ... -
Environmental factors influencing mercury speciation in Subarctic and Boreal lakes
Braaten, Hans Fredrik Veiteberg; de Wit, Heleen; Fjeld, Eirik; Rognerud, Sigurd; Lydersen, Espen; Larssen, Thorjørn (Journal article; Peer reviewed, 2014)Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes ... -
Factors determining parasite abundance in European perch, Perca fluviatilis, European whitefish, Coregonus lavaretus, and Arctic charr, Salvelinus alpinus, in an oligotrophic lake, southern Norway
Olk, Tom Robin; Henriksen, Ann-Cecilie; Dolven, Solveig Irene; Haukø, Mathias Leithe; Lydersen, Espen; Mo, Tor Atle (Peer reviewed; Journal article, 2020)Temporal and spatial variations in macroparasite status were investigated in European perch, Perca fluviatilis, European whitefish, Coregonus lavaretus, and Arctic charr, Salvelinus alpinus in Lake Norsjø (Southern Norway), ... -
Fiskebiologiske undersøkelser i forbindelse med pålegg om fysiske utbedringer i Vallaråi, Seljord i Telemark
Heggenes, Jan; Bergan, Frode; Lydersen, Espen (HiT skrift, Research report, 2011-12-15)Den 1,2 km lange Vallaråi, innløp Seljordsvatn i Seljord kommune, har et sterkt modifisert elveleie og vannførings- og temperaturregime, hovedsakelig som følge av reguleringsinngrep, bl.a. betydelig grad av effektkjøring. ... -
Formalin treatments before eyeing and hand-picking of Arctic charr (Salvelinus alpinus) eggs; re-evaluating the timing of antifungal treatments
Olk, Tom Robin; Wollebæk, Jens; Lydersen, Espen (Peer reviewed; Journal article, 2019)Arctic charr (Salvelinus alpinus) eggs in hatcheries are treated for fungal infections using formalin before, and hand-picking during the eyed stage. The relative effectiveness of these two treatments was evaluated using ... -
Improved Environmental Status: 50 Years of Declining Fish Mercury Levels in Boreal and Subarctic Fennoscandia
Braaten, Hans Fredrik Veiteberg; Åkerblom, Staffan; Kahilainen, Kimmo Kalevi; Rask, Martti; Vuorenmaa, Jussi; Mannio, Jaakko; Malinen, Tommi; Lydersen, Espen; Poste, Amanda; Amundsen, Per-Arne; Kashulin, Nicholas; Kashulina, Tatiana; Terentjev, Petr; Christensen, Guttorm; de Wit, Heleen (Journal article; Peer reviewed, 2019)Temporally (1965–2015) and spatially (55°–70°N) extensive records of total mercury (Hg) in freshwater fish showed consistent declines in boreal and subarctic Fennoscandia. The database contains 54 560 fish entries (n: pike ... -
Mikronisert Solaritt (Ca-silikat) for bruk i vassdragskalking
Lydersen, Espen; Høgberget, Rolf; Fjeld, Eirik (NIVA-rapport;, Research report, 2019)To typer av mikronisert solaritt (Ca2SiO4); Sol.2 og Sol.3, ble undersøkt for egnethet til bruk i vassdragskalking. Solarittene ble sammenliknet med de tradisjonelle kalkingsmidlene CaCO3 og NaOH i labforsøk for å studere ... -
Novel terrestrial haul-out behaviour by ringed seals (Pusa hispida) in Svalbard, in association with harbour seals (Phoca vitulina)
Lydersen, Christian; Vaquie-Garcia, Jade; Lydersen, Espen; Christensen, Guttorm; Kovacs, Kit M. (Journal article; Peer reviewed, 2017)Ringed seals ( Pusa hispida ) are the most ice-associated of all Arctic pinnipeds. In the Svalbard area, this species has always given birth, moulted and rested on sea ice. In addition, much of their food has been comprised ... -
Rehabilitering av elvehabitat i Vallaråi, Seljord i Telemark: Forslag til tiltak
Heggenes, Jan; Bergan, Frode; Lydersen, Espen; Sageie, Jostein (HiT skrift, Research report, 2013-02-04)Den 1,2 km lange Vallaråi, Seljord kommune, har et sterkt modifisert elveleie og vannførings- og temperaturregime, hovedsakelig som følge av reguleringsinngrep og betydelig grad av effektkjøring. Elva har en lokal bestand ... -
Seasonal variation of mercury and δ15N in fish from Lake Heddalsvatn, southern Norway
Moreno Vicente, Clara Enedina; Fjeld, Eirik; Deshar, Min Kaji; Lydersen, Espen (Journal article; Peer reviewed, 2014)Seasonal variations of mercury (Hg) concentration in muscle tissue of northern pike (Esox lucius L), European whitefish (Coregonus lavaretus L) and European perch (Perca fluviatilis L) have been investigated in Lake ... -
Seasonal Variations in the Use of Profundal Habitat among Freshwater Fishes in Lake Norsjø, Southern Norway, and Subsequent Effects on Fish Mercury Concentrations
Olk, Tom Robin; Karlsson, Kent Magnus Tobias; Lydersen, Espen; Økelsrud, Asle (Journal article; Peer reviewed, 2016)This study is based on monthly sampling of fish from grates mounted at an industrial water intake, located at a depth of 50 m in Lake Norsjø (Southern Norway) during the year 2014, to investigate seasonal variations in the ... -
Spatial and temporal trends of mercury in freshwater fish in Fennoscandia (1965-2015)
Braaten, Hans Fredrik Veiteberg; Åkerblom, Staffan; de Wit, Heleen; Skotte, Gunnar; Rask, Martti; Vuorenmaa, Jussi; Kahilainen, Kimmo Kalevi; Malinen, Tommi; Rognerud, Sigurd; Lydersen, Espen; Amundsen, Per-Arne; Kashulin, Nicholas; Kashulina, Tatiana; Terentyev, Petr; Christensen, Guttorm; Jackson-Blake, Leah Amber; Lund, Espen; Rosseland, Bjørn Olav (NIVA-rapport;, Research report, 2017)Mercury (Hg) emissions to the atmosphere cause elevated Hg levels in fish, even in many remote regions of the world. Here we present an extensive database of more than 50 000 measurements of Hg in fish, including 2 775 ... -
The effects of wildfire on the water chemistry of dilute, acidic lakes in southern Norway
Lydersen, Espen; Høgberget, Rolf; Moreno Vicente, Clara Enedina; Garmo, Øyvind Aaberg; Hagen, Per Chr. (Journal article; Peer reviewed, 2014-01-22)Changes in lake water chemistry were studied for >4 years following a large wildfire in a boreal forest area in Mykland, southern Norway, an area characterized by thin and patchy, base-poor and slow-weathering soils and ... -
The influence of a submerged meadow on uptake and trophic transfer of legacy mercury from contaminated sediment in the food web in a brackish Norwegian fjord
Olsen, Marianne; Fjeld, Eirik; Lydersen, Espen (Journal article; Peer reviewed, 2019)There are contradicting results on the importance of legacy mercury (Hg) contaminated sediments to Hg fish tissue concentrations. Still, sediment remediation actions often aim at minimizing ecosystem exposure and human ... -
The influence of permanently submerged macrophytes on sediment mercury distribution, mobility and methylation potential in a brackish Norwegian fjord
Olsen, Marianne; Schaanning, Morten; Braaten, Hans Fredrik Veiteberg; Eek, Espen; Moy, Frithjof Emil; Lydersen, Espen (Journal article; Peer reviewed, 2018)Macrophytes are shown to affect the microbial activity in different aqueous environments, with an altering of the sediment cycling of mercury (Hg) as a potential effect. Here, we investigated how a meadow with permanently ... -
Tilførsler av næringsstoffer, metaller og andre miljøgifter til Grenlandsfjordene 2008
Lydersen, Espen; Trasti, Anne; Sageie, Jostein (HiT skrift, Research report, 2010-10-29)Hovedhensikten med denne rapporten har vært å oppdatere tilførselsberegningene av næringsstoffer, metaller og andre miljøgifter til grenlandsfjordene. Hovedfokus har vært på utslipp i 2008, og er derfor en oppdatering av ... -
Water chemistry, zooplankton and benthos in small lakes within the distribution area of the rare European pool frog Pelophylax lessonae (Camerano) in Norway
Lydersen, Espen; Holtan, Marijanne; Korslund, Lars; Raddum, Gunnar; Dolmen, Dag; Wærvågen, Svein Birger; Fjeld, Eirik (Peer reviewed; Journal article, 2020)In June 2018, water chemistry, benthos and zooplankton were investigated in 7 small lakes/ponds within the key area of the European pool frog Pelophylax lessonae (Camerano) in Norway. The geographic distribution of the ...