Blar i NIVA Open Access Archive på forfatter "Hjermann, Dag Øystein"
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Larvae drift simulations of the Pacific oyster in Skagerrak – influence of climate change on larvae development, survival and dispersal
Rinde, Eli; Hjermann, Dag Øystein; Staalstrøm, Andre (NIVA-rapport;7016, Research report, 2016)We have investigated the extent to which warmer climate in recent years has led to greater opportunities for successful spreading of Pacific oyster (Crassostrea gigas) larvae from Danish and Swedish coastal areas to Norway, ... -
Mercury concentration trend as a possible result of changes in cod population demography
Ruus, Anders; Hjermann, Dag Øystein; Beylich, Bjørnar; Schøyen, Merete; Øxnevad, Sigurd; Green, Norman Whitaker (Journal article; Peer reviewed, 2017)Mercury (Hg) in Atlantic cod (Gadus morhua) is one of many parameters that are monitored through OSPAR's Joint Assessment and Monitoring Programme. Time series for cod in the Inner Oslofjord (Norway) go back to 1984. Until ... -
Nitrogen in surface waters: time trends and geographical patterns explained by deposition levels and catchment characteristics
Austnes, Kari; Hjermann, Dag Øystein; Sample, James Edward; Wright, Richard Frederic; Kaste, Øyvind; de Wit, Heleen (NIVA-rapport;7728-2022, Research report, 2022)The report presents a statistical analysis of controls (deposition, land cover, climate) on spatial variability and long-term trends (1992-2016) in surface water concentrations of nitrate (NO3) and carbon to nitrogen (C/N) ... -
The Norwegian river monitoring programme 2019 – water quality status and trends
Braaten, Hans Fredrik Veiteberg; Gundersen, Cathrine Brecke; Kaste, Øyvind; Sample, James Edward; Hjermann, Dag Øystein; Norling, Magnus Dahler; Guerrero, Jose-Luis; Allan, Ian; Nizzetto, Luca (NIVA-rapport;7564, Research report, 2020)In the Norwegian River Monitoring Programme (in Norwegian: Elveovervåkingsprogrammet) 20 rivers along the Norwegian coastline are monitored for chemical and hydrological parameters. It is a continuation of river monitoring ... -
The Norwegian river monitoring programme 2020 – water quality status and trends
Kaste, Øyvind; Gundersen, Cathrine Brecke; Poste, Amanda; Sample, James Edward; Hjermann, Dag Øystein (NIVA-rapport;7738-2022, Research report, 2022)In the Norwegian River Monitoring Programme (in Norwegian: Elveovervåkingsprogrammet) 20 rivers along the Norwegian coastline are monitored for chemical and hydrological parameters. It is a continuation of the RID programme ... -
The Norwegian river monitoring programme 2021 – water quality status and trends
Kaste, Øyvind; Gundersen, Cathrine Brecke; Sample, James Edward; Hjermann, Dag Øystein; Skancke, Liv Bente; Allan, Ian; Jenssen, Marthe Torunn Solhaug; Bæk, Kine; Poste, Amanda (NIVA-rapport;7760-2022, Research report, 2022)In the Norwegian River Monitoring Programme (in Norwegian: Elveovervåkingsprogrammet) 20 rivers along the Norwegian coast are monitored for physical and chemical parameters. This report presents the current status (2021) ... -
The Norwegian river monitoring programme – water quality status and trends in 2018
Gundersen, Cathrine Brecke; Kaste, Øyvind; Sample, James Edward; Braaten, Hans Fredrik Veiteberg; Selvik, John Rune; Hjermann, Dag Øystein; Norling, Magnus Dahler; Guerrero, Jose-Luis (NIVA-rapport;7441, Research report, 2019)In the Norwegian River Monitoring Programme (Elveovervåkingsprogrammet) 20 rivers along the Norwegian coastline are monitored for chemical and hydrological parameters. It is a continuation of a former monitoring programme, ... -
Overvåking av miljøgifter i Kristiansandsfjorden i 2013.Undersøkelse av blåskjell.
Schøyen, Merete; Håvardstun, Jarle; Hjermann, Dag Øystein; Øxnevad, Sigurd (NIVA-rapport;6695, Research report, 2014)Overvåkingsprogrammet i Kristiansandsfjorden startet i 2010. Denne rapporten omtaler innholdet av miljøgifter i blåskjell innsamlet på sju stasjoner i Kristiansandsfjorden i 2013. Det ble analysert for kvikksølv (Hg) og ... -
Possible adverse impact of contaminants on Atlantic cod population dynamics in coastal ecosystems
Ono, Kotaro; Knutsen, Halvor; Olsen, Esben Moland; Ruus, Anders; Hjermann, Dag Øystein; Stenseth, Nils Christian (Journal article; Peer reviewed, 2019)While many in-laboratory ecotoxicological studies have shown the adverse impact of pollutants to the fitness of an individual, direct evidence from the field on the population dynamics of wildlife animals has been lacking. ... -
Rapid expansion of the invasive oyster Crassostrea gigas at its northern distribution limit in Europe: Naturally dispersed or introduced?
Angles d'Auriac, Marc; Rinde, Eli; Norling, Pia Carina; Lapegue, Sylvie; Staalstrøm, Andre; Hjermann, Dag Øystein; Thaulow, Jens (Journal article; Peer reviewed, 2017)The Pacific oyster, Crassostrea gigas, was introduced to Europe for aquaculture purposes, and has had a rapid and unforeseen northward expansion in northern Europe. The recent dramatic increase in number of C. gigas ... -
Relating environmental pressures to littoral biological water quality indicators in Western Balkan lakes: Can we fill the largest gaps?
Vermaat, Jan E.; Biberdžić, Vera; Braho, Vjola; Gjoreska, Biljana Budzakoska; Cara, Magdalena; Dana, Zamira; Đurašković, Pavle; Eriksen, Tor Erik; Hjermann, Dag Øystein; Imeri, Alma; Jovanović, Katarina; Krizmanić, Jelena; Kupe, Lirika; Loshkoska, Tatjana; Kemp, Joanna Lynn; Marković, Aleksandra; Patceva, Suzana; Rakočević, Jelena; Stojanović, Katarina; Talevska, Marina; Trajanovska, Sonja; Trajanovski, Sasho; Veljanovska-Sarafiloska, Elizabeta; Vidaković, Danijela; Zdraveski, Konstantin; Zivic, Ivana; Schneider, Susanne C (Peer reviewed; Journal article, 2021)Along six transects in each of six lakes across the Western Balkans, we collected data for three groups of littoral biological water quality indicators: epilithic diatoms, macrophytes, and benthic invertebrates. We assessed ... -
SPI og bløtbunnsfauna – Sammenligning av klassifisering og vurdering av bruksområder
Beylich, Bjørnar; Borgersen, Gunhild; Trannum, Hilde Cecilie; Hjermann, Dag Øystein (NIVA-rapport;7328, Research report, 2019)Vi har sammenlignet tilstandsklassifisering med BHQ (Benthic Habitat Quality)-indeksen for SPI (Sediment Profile Imagery) og nEQR (normalisert Ecological Quality Ratio) for bløtbunnsfauna. Tilstandsklassifiseringen hadde ... -
Statistical analyses of chlorophyll-a data sampled by a Ferrybox on the Oslo-Kiel ferry and by the NOVANA programme
Andersen, Jesper Harbo; Harvey, Therese; Kallenbach, Emilie; Murray, Ciaran Joseph; Hjermann, Dag Øystein; Kristiansen, Trond; Sørensen, Kai; Carstensen, Jacob; Erichsen, Anders; Hansen, Lars Boye (NIVA-rapport;7167, Research report, 2017)This project has analysed a large chlorophyll-a data set sampled by the Ferrybox on the ferry between Oslo and Kiel and compared it with data sampled in the Danish NOVANA programme. A partnership consisting of NIVA Denmark ... -
Statistisk analyse av volum av forurenset sediment i Borg 1 og Flyndregrunnen, basert på samlet kjemisk analysemateriale fram til 2017
Hjermann, Dag Øystein (NIVA-rapport;7277, Research report, 2018)Det er foretatt statistiske beregninger av volummengden av forurenset sediment i området Røsvikrenna (nordligste del av leden til Borg havn, tiltaksområde Borg 1) samt Flyndregrunnen (den nordligste grunna i tiltaksområde ... -
Synthesis of climate relevant results from selected monitoring programs in the coastal zone. Part 2: Quantitative analyses
Frigstad, Helene; Andersen, Guri Sogn; Trannum, Hilde Cecilie; Naustvoll, Lars Johan; Kaste, Øyvind; Hjermann, Dag Øystein (NIVA-rapport;7311, Research report, 2018)This report is Part 2 of the project Synthesis of climate relevant results from selected monitoring programs in the coastal zone (Klima-Overblikk). The overall aim of this report was to document changes over the period ... -
Tallknusing av sukkertaredata
Gundersen, Hege; Norderhaug, Kjell Magnus; Christie, Hartvig C; Moy, Frithjof Emil; Hjermann, Dag Øystein; Vedal, Jens; Ledang, Anna Birgitta; Gitmark, Janne Kim; Walday, Mats (NIVA-rapport;6737, Research report, 2014)Norsk institutt for vannforskning (NIVA) og Havforskningsinstituttet (HI) har gjennomført prosjektet «Tallknusing av sukkertare-data», på oppdrag fra Miljødirektoratet. Gjennom prosjektet har tilgjengelige data som kan ... -
The occurrence and spread of Gonyostomum semen (Ehr.) Diesing (Raphidophyceae) in Norwegian lakes
Hagman, Camilla H. Corneliussen; Ballot, Andreas; Hjermann, Dag Øystein; Skjelbred, Birger; Brettum, Pål; Ptacnik, Robert (Journal article; Peer reviewed, 2014)The invasive and nuisance microalga Gonyostomum semen has recently expanded its geographical distribution and increased its biomass in Sweden and Finland. Temperatures, total organic carbon (TOC), water colour and phosphorous ... -
Three decades of change in the Skagerrak coastal ecosystem, shaped by eutrophication and coastal darkening
Frigstad, Helene; Andersen, Guri Sogn; Trannum, Hilde Cecilie; Mcgovern, Maeve; Naustvoll, Lars Johan; Kaste, Øyvind; Deininger, Anne; Hjermann, Dag Øystein (Peer reviewed; Journal article, 2023)Global coastal ecosystems are under accelerating pressure from human activities and climate change. In this study we explore a long-term time series (mostly 1990–2016) from major Norwegian rivers, together with coastal ... -
Tiltaksorientert overvåking av Årdalsfjorden i 2019. Overvåking for Hydro Aluminium Årdal.
Øxnevad, Sigurd; Hjermann, Dag Øystein (NIVA-rapport;7467, Research report, 2020)NIVA har gjennomført tiltaksorientert overvåking av Årdalsfjorden i 2019 på oppdrag for Hydro Aluminium Årdal. Overvåkingsprogrammet er utført i henhold til vannforskriften på bakgrunn av hvilke stoffer som bedriften har ... -
Tiltaksorientert overvåking av Årdalsfjorden i 2021. Overvåking for Hydro Aluminium Årdal.
Øxnevad, Sigurd; Håvardstun, Jarle; Hjermann, Dag Øystein (NIVA-rapport;7715-2022, Research report, 2022)NIVA har utført tiltaksorientert overvåking av Årdalsfjorden i 2021 på oppdrag for Hydro Aluminium Årdal. I overvåkingen er det gjort analyser av polysykliske aromatiske hydrokarboner (PAH-forbindelser) og tungmetaller ...