Stein Fredriksen

Fredriksen S. & H. Christie 2003. Zostera marina (Angiospermae) and Fucus serratus (Phaeophyceae) as habitat for flora and fauna – seasonal and local variation. Proceedings 17^th International Seaweed Symposium, Cape Town, South Africa. pp 357-364

Norderhaug K.M., S. Fredriksen & K. Nygaard 2003. The trophic importance of Laminaria hyperborea to kelp forest consumers and the importance of bacterial degradation on food value. Marine Ecology Progress Series 255:135-144

Bjærke M.R. & S. Fredriksen 2003. Epiphytes on the invasive species Sargassum muticum at Verdens Ende, South Norway. Sarsia 88:353-364.

Fredriksen S. 2003 Food web studies in a Norwegian kelp forest based on stable isotope (d¹³C and d¹⁵N) analysis. Marine Ecology Progress Series  260:71-81.

Fredriksen S., H. Christie & C. Boström. 2004. Deterioration of eelgrass (Zostera marina L.) by destructive grazing by the gastropod Rissoa membranacea (J. Adams) Sarsia 89:218-222.

Abdullah M.I. & S. Fredriksen^. 2004. Production, Respiration and Exudation of Dissolve Organic Matter by the kelp Laminaria hyperborea (Gunnerus) Foslie along the west coast.of Norway. Journal of the Marine Biollogical Association of the  United Kingdom. 84:887-894

Fredriksen S,., H. Christie & B.A. Sæthre 2005. Species richness in macroalgae and macrofauna assemblages on Fucus serratus L. (Phaeophyceae) and Zostera marina L. (Angiospermae) in Skagerrak, Norway.  Marine Biology Research 1:2-19.

Norderhaug K.M., H. Christie, J.H. Fosså & S. Fredriksen. 2005. Fish-macrofauna interactions in a kelp (Laminaria hyperborea) forest. Journal of the Marine Biological Association of the United Kingdom. 85:1279-1286.

Norderhaug K.M., K. Nygaard & S. Fredriksen. 2006. Importance of phlorotannin content and C:N ratio of Laminaria hyperborea in determining its palatability as food for consumers. Marine Biology Research 2:367 – 371.

Norderhaug K.M., H. Christie & S. Fredriksen. 2007. Is habitat size an important factor for faunal abundance on kelp (Laminaria hyperborea)? Journal of Sea Research 58:120-124.

Mutchler T., K.H. Dunton, A. Townsend-Small, S. Fredriksen & M.K. Rasser. 2007. Isotopic and elemental indicators of nutrient sources and status of coastal habitats in the Caribbean Sea, Yucatan Peninsula, Mexico. Estuarin, Coastal and Shelf Science 74:449-457.

Nilsen M., T. Pedersen, E.M. Nilsen & S. Fredriksen 2008. Trophic studies in a high-latitude fjord ecosystem – a comparison of stable isotope analyses (d¹³C and d¹⁵N) and trophic-level estimates from a mass-balance model. Canadian Journal of Fisheries and Aquatic Sciences 65:2791-2806.

Christie H., K.M. Norderhaug & S. Fredriksen 2009. Macrophytes as habitat for fauna. Marine Ecology Progress Series. 396:221-233

Fredriksen S., A. de Backer, C. Boström & H. Christie 2010. Infauna from Zostera marina (L.) meadows in Norway. Differences in vegetated and unvegetated areas.

Marine Biology Research 6:189-200.

Mutchler T., R.F. Mooney, S. Wallace, L. Podsim, S. Fredriksen & K. Dunton. 2010. Origins and fate of inorganic-nitrogen from land to coastal ocean on the Yucatan Peninsula, Mexico. In: Kennish M.J. & H.W. Paerl (eds) Coastal lagoons. Critical habitats of environmental change. S. 283-305. CRC Press. Taylor & Francis Group. USA.

Andersen G. S., H. Steen, H. Christie, S. Fredriksen & F. Moy 2011. Seasonal patterns of sporophyte growth, fertility, fouling and mortality of Saccharina latissima in Skagerrak, Norway. Implications for forest recovery. Journal of Marine Biology (Open access journal). Volume 2011. doi:10.1155/2011/690375

Fredriksen S. & M. Røst Kile 2012. The algal vegetation in the outer part of Isfjorden, Spitsbergen: A revisit of Per Svendsens sites after 50 years. Polar Research 31, 17538, DOI: 10.3402/polar.v31i0.17538

Pedersen MF, Nejrup LB, Fredriksen S, Christie H &  KM Norderhaug 2012. Effects of wave exposure on population structure, demography, biomass and productivity of the kelp Laminaria hyperborea. Marine Ecology Progress Series 451:45-60.

Boström C, Baden S, Bockelman AC, Dromph K, Fredriksen S, Gustavsson C, Krause Jensen D, Möller T, Nielsen SL, Olesen B, Olsen J, Pihl L & E Rinde 2014. Distribution, structure and function of Nordic eelgrass (Zostera marina) ecosystems: implications for coastal management and conservation. Aquatic conservation: Marine and freshwater ecosystems. DOI: 10.1002/aqc.2424

Abdullah MI & S Fredriksen 2014. The exudation of nitrate by the kelp Laminaria hyperborea, an observation during in situ incubation experimants. Marine Biology Research 10: 725-730

Fagerli CW, Norderhaug KM, Christie H, Pedersen MF & S Fredriksen 2014. Predators of the destructive sea urchin grazer Strongylocentrotus droebachiensis on the Norwegian coast. Marine Ecology Progress Series 502: 207-218

Fredriksen S, Bartsch I & C Wiencke 2014. New additions to the benthic marine flora of Kongsfjorden, Western Svalbard and comparison between 1996/98 and 2012/13, Botanica Marina 57: 203-216

Pedersen MF, Nejrup LB, Pedersen TM & S Fredriksen 2014. Sub-canopy light conditions only allow low annual net productivity of epiphytic algae on kelp Laminaria hyperborea. Marine Ecology Progress Series 516:163-176.

Fagerli CM, Stadnizenko SG, Pedersen MF, Christie H, Fredriksen S & KM Norderhaug 2015. Population dynamics of Strongylocentrotus droebachiensis in kelp forest and barren grounds in Norway. Marine Biology DOI 10.1007/s00227-015-2663-3

Duffy Emmett J., Pamela L. Reynolds, Christoffer Boström, James A. Coyer, Mathieu Cusson, Serena Donadi, James G. Douglass, Johan S. Eklöf, Aschwin H. Engelen, Britas Klemens Eriksson^, Stein Fredriksen, Lars Gamfeldt, Camilla Gustafsson, Galice Hoarau, Masakazu Hori, Kevin Hovel, Katrin Iken, Jonathan S. Lefcheck, Per-Olav Moksnes, Masahiro Nakaoka, Mary I. O'Connor, Jeanine L. Olsen, J. Paul Richardson, Jennifer L. Ruesink, Erik E. Sotka, Jonas Thormar^, Matthew A. Whalen & John J. Stachowicz 2015. Biodiversity mediates top–down control in eelgrass ecosystems: a global comparative-experimental approach. Ecology letters 18: 696-705. DOI: 10.1111/ele.12448

Fredriksen S, Gabrielsen TM, Kile MR & K Sivertsen. 2015. Benthic algal vegetation in Isfjorden, Svalbard. A survey from the main fjord area. Polar Research. http://dx.doi.org/10.3402/polar.v34.25994

Bartsch I, Paar M, Fredriksen S, Schwanitz M, Daniel C, Hop H & C Wiencke  2016. Changes in kelp forest biomass and depth distribution in Kongsfjorden, Svalbard, between 1996-1998 and 2012-2014 reflect Arctic warming. Polar Biology DOI 10.1007/s00300-015-1870-1 

Fredriksen S, Karsten U, Bartsch I, Woelfel J, Koblowsky M, Schumann R, Moy SR, Steneck RS, Wiktor J, Hop H & C Wiencke In press. Biodiversity of benthic macro- and microalgae from Svalbard with special focus on Kongsfjorden. Advances in Polar Ecology

Eva Ramirez-Llodra, Eli Rinde, Hege Gundersen, Hartvig Christie, Camilla With Fagerli, Stein Fredriksen, Janne Kim Gitmark, Karl Norling, Mats Gunnar Walday &
Kjell Magnus Norderhaug. 2016. A snap shot of the short-term response of crustaceans to macrophyte detritus in the deep Oslofjord. Scientific Report 6, 23800. doi: 10.1038/srep23800 

Araujo R, Assis J, Aguillar R, .. Fredriksen S, 22 more. 2016. Status, trends and drivers of kelp forests in Europe: an expert assessment. Biodiversity and Conservation. DOI: 10.1007/s10531-016-1141-7

Fagerli CW, Stadniczenko SG, Pedersen MF, Christie H, Fredriksen S, Norderhaug KM. 2016. Are skeletal ossicles in echinoids unreliable chronometers? Reply to Russell and Narváez comment on “Population dynamics
of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway” by Fagerli et al. 2015. Marine Biology 163: 160-161.

Kai Bischof, Christian Buschbaum, Stein Fredriksen, Francisco J.L. Gordillo, 
Sandra Heinrich, Carlos Jiménez, Cornelius Lütz, Markus Molis, 
Michael Y. Roleda, Max Schwanitz, Christian Wiencke. In Press
. Kelps and environmental changes in Kongsfjorden: 
Stress perception and responses. Advances in Polar Ecology

Abdullah MI, Fredriksen S, Christie H. In press. The impact of the kelp (Laminaria hyperborea) forest on the organic matter content in sediment of the west coast of Norway. Marine Biology Research. DOI: 10.1080/17451000.2016.1240369

Silberberger M, Thormar J, Fredriksen S. 2016. Small scale removal of seagrass (Zostera marina): Effects on the infaunal community. Marine Biology Research 12: 993-1002. DOI: 10.1080/17451000.2016.1225959 

Viviana Peña, Line Le Gall, Vivian Husa, Ellen Sofie Grefsrud, Jason Hall-Spencer, Bob Steneck, Stein Fredriksen, Olivier De Clerck, Janne Gitmark, Marc Angles d'Auriac, Trine Bekkby, Hartvig Christie & Eli Rinde. 2016. Reseña de proyecto: Coralalg, la biodiversidad marina oculta en noruega: búsqueda de especies crípticas en algas rojas coralinas (Norway's hidden marine biodiversity: the hunt for cryptic species within the coralline algae). Algas: Boletín Informativo de la Sociedad Española de Ficología 52: 55-58.

• Anglès d'Auriac, Marc; Le Gall, Line; Peña, Viviana; Hall-Spencer, Jason M.; Steneck, Robert S.; Fredriksen, Stein; Gitmark, Janne Kim; Christie, Hartvig C; Husa, Vivian; Grefsrud, Ellen Sofie & Rinde, Eli (2019). Efficient coralline algal psbA mini barcoding and High Resolution Melt HRM) analysis using a simple custom DNA preparation. Scientific Reports.  ISSN 2045-2322.  9(1) . doi: 10.1038/s41598-018-36998-6 Fulltekst i vitenarkiv. Vis sammendrag

  Coralline algae form extensive maerl and rhodolith habitats that support a rich biodiversity. Calcium carbonate harvesting as well as trawling activities threatens this ecosystem. Eleven species were recorded so far as maerl-forming in NE Atlantic, but identification based on morphological characters is unreliable. As for most red algae, we now use molecular characters to resolve identification of these taxa. However, obtaining DNA sequences requires time and resource demanding methods. The purpose of our study was to improve methods for achieving simple DNA extraction, amplification, sequencing and sequence analysis to allow robust identification of maerl species and other coralline algae. Our novel and easy DNA preparation method for coralline algae was of sufficient quality for qPCR amplification and sequencing of all 47 tested samples. The new psbA qPCR assay successfully amplified a 350 bp fragment identifying six species and uncovering two new Operational Taxonomic Units. Molecular results were corroborated with anatomical examination using i.e. scanning electron microscopy. Finally, the qPCR assay was coupled with High Resolution Melt analysis that successfully differentiated the closely related species Lithothamnion erinaceum and L. cf. glaciale. This DNA preparation and qPCR technique should vitalize coralline research by reducing time and cost associated with molecular systematics.

• Evankow, Ann; Christie, Hartvig C; Hancke, Kasper; Brysting, Anne Krag; Junge, Claudia; Fredriksen, Stein & Thaulow, Jens (2019). Genetic heterogeneity of two bioeconomically important kelp species along the Norwegian coast. Conservation Genetics.  ISSN 1566-0621.  20(3), s 615- 628 . doi: 10.1007/s10592-019-01162-8
• Filbee-Dexter, Karen; Wernberg, Thomas; Fredriksen, Stein; Norderhaug, Kjell Magnus & Pedersen, Morten Foldager (2019). Arctic kelp forests: Diversity, resilience and future. Global and Planetary Change.  ISSN 0921-8181.  172, s 1- 14 . doi: 10.1016/j.gloplacha.2018.09.005
• Abdullah, Mohamed I; Fredriksen, Stein & Christie, Hartvig (2017). The impact of the kelp (Laminaria hyperborea) forest on the organic matter content in sediment of the west coast of Norway. Marine Biology Research.  ISSN 1745-1000.  13(2), s 151- 160 . doi: 10.1080/17451000.2016.1240369
• Husa, Vivian; Hansen, Pia Kupka; Bannister, Raymond; Kutti, Tina & Fredriksen, Stein (2017). Utslipp av partikulære og løste stoffer fra matfiskanlegg. Fisken og Havet, Særnummer.  ISSN 0802-0620.  (2), s 99- 116
• Bartsch, Inka; Paar, Martin; Fredriksen, Stein; Schwanitz, Max; Daniel, Claudia; Hop, Haakon & Wiencke, Christian (2016). Changes in kelp forest biomass and depth distribution in Kongsfjorden, Svalbard, between 1996–1998 and 2012–2014 reflect Arctic warming. Polar Biology.  ISSN 0722-4060.  39, s 2021- 2036 . doi: 10.1007/s00300-015-1870-1
• de Araújo, Rita M. dos Santos Fernandes; Assis, Jorge; Aguillar, Ricardo; Airoldi, Laura; Bárbara, Ignacio; Bartsch, Inka; Bekkby, Trine; Christie, Hartvig C; Davoult, Dominique; Derrien-Courtel, Sandrine; Fernández, Consolación; Fredriksen, Stein; Gevaert, Francois; Gundersen, Hege; Le Gal, Aodren; Lévêque, Laurent; Mieszkowska, Nova; Norderhaug, Kjell Magnus; Oliveira, Pedro; Puente, Araceli; Rico, José M.; Rinde, Eli; Schubert, Hendrik; Strain, Elisabeth M.A.; Valero, Myriam; Viard, Frédérique & Sousa-Pinto, Isabel (2016). Status, trends and drivers of kelp forests in Europe: an expert assessment. Biodiversity and Conservation.  ISSN 0960-3115.  25(7), s 1319- 1348 . doi: 10.1007/s10531-016-1141-7
• Peña, Viviana; Le Gall, L; Husa, Vivian; Grefsrud, Ellen Sofie; Hall-Spencer, Jason M.; Steneck, Robert S.; Fredriksen, Stein; De Clerck, Olivier; Gitmark, Janne Kim; Anglès d'Auriac, Marc; Bekkby, Trine; Christie, Hartvig C & Rinde, Eli (2016). Reseña de proyecto: Coralalg, la biodiversidad marina oculta en noruega: búsqueda de especies crípticas en algas rojas coralinas (Norway's hidden marine biodiversity: the hunt for cryptic species within the coralline algae).. Algas: Boletín Informativo de la Sociedad Española de Ficología.  ISSN 1695-8160.  52, s 55- 58
• Ramirez-Llodra, Eva; Rinde, Eli; Gundersen, Hege; Christie, Hartvig; Fagerli, Camilla With; Fredriksen, Stein; Gitmark, Janne Kim; Norling, Karl; Walday, Mats Gunnar & Norderhaug, Kjell Magnus (2016). A snap shot of the short-term response of crustaceans to macrophyte detritus in the deep Oslofjord. Scientific Reports.  ISSN 2045-2322.  6 . doi: 10.1038/srep23800 Fulltekst i vitenarkiv.
• Silberberger, Marc Jürgen; Thormar, Jonas & Fredriksen, Stein (2016). Small-scale removal of seagrass (Zostera marina L.): effects on the infaunal community. Marine Biology Research.  ISSN 1745-1000.  12, s 993- 1002 . doi: 10.1080/17451000.2016.1225959
• Duffy, J. Emmett; Reynolds, Pamela L.; Boström, Christoffer; Coyer, James A.; Cusson, Mathieu; Donadi, Serena; Douglass, James G.; Eklöf, Johan S.; Engelen, Aschwin H.; Eriksson, Britas Klemens; Fredriksen, Stein; Gamfeldt, Lars; Gustafsson, Camilla; Hoarau, Galice; Hori, Masakazu; Hovel, Kevin; Iken, Katrin; Lefcheck, Jonathan S.; Moksnes, Per-Olav; Nakaoka, Masahiro; O'Connor, Mary I.; Olsen, Jeanine L.; Richardson, J. Paul; Ruesink, Jennifer L.; Sotka, Erik E.; Thormar, Jonas Gjaldbæk; Whalen, Matthew A. & Stachowicz, John J. (2015). Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach. Ecology Letters.  ISSN 1461-023X.  18(7), s 696- 705 . doi: 10.1111/ele.12448
• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten Foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2015). Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway. Marine Biology.  ISSN 0025-3162.  162(6), s 1215- 1226 . doi: 10.1007/s00227-015-2663-3
• Fredriksen, Stein; Gabrielsen, Tove M.; Kile, Maia Røst & Sivertsen, Knut (2015). Benthic algal vegetation in Isfjorden, Svalbard. Polar Research.  ISSN 0800-0395.  34, s 1- 9 . doi: 10.3402/polar.v34.25994 Fulltekst i vitenarkiv.
• Abdullah, Mohamed I & Fredriksen, Stein (2014). The exudation of nitrate by the kelp Laminaria hyperborea, an observation during in situ incubation experiments. Marine Biology Research.  ISSN 1745-1000.  10(7), s 725- 730 . doi: 10.1080/17451000.2013.850514
• Boström, Christoffer; Baden, Susanne; Bockelmann, Anna-Christina; Dromph, Karsten; Fredriksen, Stein; Gustafsson, Camilla; Krause-Jensen, Dorte; Möller, Tiia; Nielsen, Søren Laurentius; Olesen, Birgit; Olsen, Jeanine; Pihl, Leif & Rinde, Eli (2014). Distribution, structure and function of Nordic eelgrass (Zostera marina) ecosystems: Implications for coastal management and conservation. Aquatic conservation.  ISSN 1052-7613.  24(3), s 410- 434 . doi: 10.1002/aqc.2424 Fulltekst i vitenarkiv. Vis sammendrag

  1. This paper focuses on the marine foundation eelgrass species, Zostera marina , along a gradient from the northern Baltic Sea to the north-east Atlantic. This vast region supports a minimum of 1480km 2 eelgrass (maximum > 2100km 2 ), which corresponds to more than four times the previously quanti fi ed area of eelgrass in Western Europe. 2. Eelgrass meadows in the low salinity Baltic Sea support the highest diversity (4 – 6 spp.) of angiosperms overall, but eelgrass productivity is low ( < 2g dw m -2 d -1 ) and meadows are isolated and genetically impoverished. Higher salinity areas support monospeci fi c meadows, with higher productivity (3 – 10g dw m -2 d -1 ) and greater genetic connectivity. The salinity gradient further imposes functional differences in biodiversity and food webs, in particular a decline in number, but increase in biomass of mesograzers in the Baltic. 3. Signi fi cant declines in eelgrass depth limits and areal cover are documented, particularly in regions experiencing high human pressure. The failure of eelgrass to re-establish itself in affected areas, despite nutrient reductions and improved water quality, signals complex recovery trajectories and calls for much greater conservation effort to protect existing meadows.

• Fagerli, Camilla With; Norderhaug, Kjell Magnus; Christie, Hartvig C; Pedersen, Morten Foldager & Fredriksen, Stein (2014). Predators of the destructive sea urchin grazer Strongylocentrotus droebachiensis on the Norwegian coast. Marine Ecology Progress Series.  ISSN 0171-8630.  502, s 207- 218 . doi: 10.3354/meps10701 Fulltekst i vitenarkiv. Vis sammendrag

  : In central Norway, populations of the green sea urchin Strongylocentrotus droe- bachiensis are collapsing, but the factors controlling its population density have not yet been elucidated. Through field sampling, we identified several sea urchin predators and investigated their predation rates on recently settled S. droebachiensis in laboratory experiments. Tethering experiments in kelp forest and on barren ground study sites in the area where sea urchin popula- tions are collapsing confirmed predation by some of the predators tested in laboratory experi- ments. The edible crab Cancer pagurus was the most efficient sea urchin predator, and it was more abundant at kelp forest sites than on barren grounds. Stocks of C. pagurus have increased dramatically in central Norway since the 1990s, and predation by C. pagurus may contribute to the decline in sea urchin densities, allowing kelp recovery and conferring resilience of the new kelp forest state.

• Fredriksen, Stein; Bartsch, I & Wiencke, Christian (2014). New additions to the benthic marine flora of Kongsfjorden, western Svalbard, and comparison between 1996/1998 and 2012/2013. Botanica Marina.  ISSN 0006-8055.  57(3), s 203- 216 . doi: 10.1515/bot-2013-0119
• Pedersen, Morten foldager; Nejrup, Lars; Pedersen, Troels & Fredriksen, Stein (2014). Sub-canopy light conditions only allow low annual net productivity of epiphytic algae on kelp Laminaria hyperborea. Marine Ecology Progress Series.  ISSN 0171-8630.  516, s 163- 176 . doi: 10.3354/meps11019
• Fredriksen, Stein & Kile, Maia Røst (2012). The algal vegetation in the outer part of Isfjorden, Spitsbergen: revisiting Per Svendsen's sites 50 years later. Polar Research.  ISSN 0800-0395.  31 . doi: 10.3402/polar.v31i0.17538
• Pedersen, Morten F; Nejrup, Lars B; Fredriksen, Stein; Christie, Hartvig C & Norderhaug, Kjell Magnus (2012). Effects of wave exposure on population structure, demography, biomass and productivity of the kelp Laminaria hyperborea. Marine Ecology Progress Series.  ISSN 0171-8630.  451, s 45- 60 . doi: 10.3354/meps09594
• Andersen, Guri Sogn; Steen, Henning; Christie, Hartvig C; Fredriksen, Stein & Moy, Frithjof (2011). Seasonal Patterns of Sporophyte Growth, Fertility, Fouling, and Mortality of Saccharina latissima in Skagerrak, Norway: Implications for Forest Recovery. Journal of Marine Biology.  ISSN 1687-9481.  2011 . doi: 10.1155/2011/690375
• Fredriksen, Stein; De Backer, Annelies; Boström, C. & Christie, Hartvig C (2010). Infauna from Zostera marina L. meadows in Norway. Differences in vegetated and unvegetated areas. Marine Biology Research.  ISSN 1745-1000.  6, s 189- 200 . doi: 10.1080/17451000903042461
• Mutchler, T; Mooney, R.F; Wallace, S; Podsim, L; Fredriksen, Stein & Dunton, KH (2010). Origins and fate of inorganic-nitrogen from land to coastal ocean on the Yucatan Peninsula, Mexico, In MJ Kennish & HW Paerl (ed.),  Coastal lagoons. Critical habitats of environmental change.  CRC Press.  ISBN 978-1-4200-8830-4.  Chapter 12.  s 283 - 305
• Christie, H.; Norderhaug, K.M. & Fredriksen, Stein (2009). Macrophytes as habitat for fauna. Marine Ecology Progress Series.  ISSN 0171-8630.  396, s 221- 233 . doi: 10.3354/meps08351
• Nilsen, Marianne; Pedersen, Torstein; Nilsen, Einar Magnus & Fredriksen, Stein (2008). Trophic studies in a high-latitude fjord ecosystem – a comparison of stable isotope analyses (δ13C and δ15N) and trophic-level estimates from a mass-balance model. Canadian Journal of Fisheries and Aquatic Sciences.  ISSN 0706-652X.  65, s 2791- 2806
• Nilsen, marianne; Pedersen, Torstein; Nilssen, Einar Magnus & Fredriksen, Stein (2008). Trophic studies in a high-latitude fjord ecosystem - a comparison of stable isotope analyses (delta 13C and delta 15N)and trophic-level estimates from a mass-balance model. Canadian Journal of Fisheries and Aquatic Sciences.  ISSN 0706-652X.  65(12), s 2791- 2806 . doi: 10.1016/j.dsr2.2008.05.008
• Mutchler, T; Dunton, K; Townsend-Small, A; Fredriksen, Stein & Rasser, M (2007). Isotopic and elemental indicators of nutrient sources and status of coastal habitats in the Caribbean Sea, Yucatan Peninsula, Mexico. Estuarine, Coastal and Shelf Science.  ISSN 0272-7714.  74, s 449- 457 . doi: 10.1016/j.ecss.2007.04.005
• Norderhaug, K.M.; Christie, H. & Fredriksen, Stein (2007). Is habitat size an important factor for faunal abundances on kelp (Laminaria hyperborea)?. Journal of Sea Research.  ISSN 1385-1101.  58, s 120- 124 . doi: 10.1016/j.seares.2007.03.001
• Norderhaug, K.M.; Nygaard, K. & Fredriksen, Stein (2006). Importance of phlorotannin content and C:N ratio of Laminaria hyperborea in determining its palatability as food for consumers. Marine Biology Research.  ISSN 1745-1000.  2, s 367- 371
• Rueness, Jan; Bjærke, M.R.; Fredriksen, Stein; Langangen, Anders; Lindstrøm, Eli Anne; Moy, Frithjof & Sjøtun, Kjersti (2006). Alger. Cyanophyta, Rhodophyta, Phaeophyta, Ulvophyceae, Charophyceae, I: J.A. Kålås; Å. Viken & T. Bakken (red.),  Norsk Rødliste 2006.  Artsdatabanken.  ISBN 8292838007.  Kapittel.  s 95 - 101
• Fredriksen, Stein; Christie, H. & Sæthre, Bjarte Andre (2005). Species richness in macroalgae and macrofauna assemblages on Fucus serratus L. (Phaeophyceae) and Zostera marina L. (Angiospermae) in Skagerrak, Norway. Marine Biology Research.  ISSN 1745-1000.  1(1), s 2- 19 Vis sammendrag

  The macrophytes Fucus serratus and Zostera marina form similar substrates for associated flora and fauna in shallow waters in Norway. While F. serratus forms a more or less continuous belt on rocky substrate along the coast, Z. marina forms disjunct populations on sandy or muddy bottoms. This study has focused on the organisms associated with these two macrophytes on two localities in the Skagerrak region. A total of 131 taxa of epiphytic organisms were identified, 22 green algae, 41 red algae, 32 brown algae, 8 diatoms and 28 sessile animals. 127 taxa of mobile macrofauna were registered. The dominant group was crustaceans, with amphipods as the order containing most species. Many species of both plants and animals preferred the one or the other habitat. It is concluded that coastal macrophyte systems have high species diversity.

• Norderhaug, K.M.; Christie, H.; Fosså, Jan Helge & Fredriksen, Stein (2005). Fish - macrofauna interactions in a kelp (Laminaria hyperborea) forest. Journal of the Marine Biological Association of the United Kingdom.  ISSN 0025-3154.  85, s 1279- 1286
• Abdullah, Mohamed I & Fredriksen, Stein (2004). Production, respiration, and exudation of dissolved organic matter by the kelp Laminaria hyperborea along the west coast of Norway. Journal of the Marine Biological Association of the United Kingdom.  ISSN 0025-3154.  84, s 887- 894
• Fredriksen, Stein; Christie, H. & Boström, Christoffer (2004). Deterioration of eelgrass (Zostera marina L.) through destructive grazing by the gastropod Rissoa membranacea (J. Adams). Sarsia.  ISSN 0036-4827.  89, s 218- 222
• Bjærke, M.R. & Fredriksen, Stein (2003). Epiphytes on the invasive species Sargassum muticum at Verdens Ende, South Norway. Sarsia.  ISSN 0036-4827.  88, s 353- 364
• Fredriksen, Stein (2003). Food web studies in a Norwegian kelp forest based on stable isotope (?13C and ?15N) analysis. Marine Ecology Progress Series.  ISSN 0171-8630.  260, s 71- 81
• Fredriksen, Stein (2003). Zostera marina (Angiospermae) and Fucus serratus (Phaeophyceae) as habitat for flora and fauna � seasonal and local variation. Proceedings / International Seaweed Symposium.  17, s 357- 364
• Norderhaug, Kjell Magnus; Fredriksen, Stein & Nygaard, K. (2003). The trophic importance of Laminaria hyperborea to kelp forest consumers and the importance of bacterial degradation on food value. Marine Ecology Progress Series.  ISSN 0171-8630.  255, s 135- 144
• Raven, J.; Johnston, A.M.; Kübler, J.E.; Korb, R.; McInroy, S.G.; Handley, L.L.; Scrimgeour, C.M.; Walker, D.I.; Berdall, J.; Clayton, M.N.; Vanderklift, M.; Fredriksen, Stein & Dunton, K.H. (2002). Seaweeds in cold seas: evolution and carbon acquisition. Annals of Botany.  ISSN 0305-7364.  90, s 525- 536
• Raven, J.; Johnston, A.M.; Kübler, J.E.; Korb, R.; McInroy, S.G.; Handley, L.L.; Scrimgeour, C.M.; Walker, D.I.; Berdall, J.; Vanderklift, M.; Fredriksen, Stein & Dunton, K.H. (2002). Mecanistic interpretation of carbon isotope discrimination by marine macroalgae and seagrasses. Functional Plant Biology.  ISSN 1445-4408.  29, s 355- 378

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• Bekkby, Trine; Andersen, Guri Sogn; Angeltveit, Gro; Broch, Ole Jacob; Bøe, Reidulv; Christie, Hartvig C; Erikstad, Lars; Espeland, Sigurd Heiberg; Fagerli, Camilla With; Fredriksen, Stein; Gitmark, Janne Kim; Gundersen, Hege; Hancke, Kasper; Kile, Maia Røst; Moy, Frithjof Emil; Moy, Siri Røang; Norderhaug, Kjell Magnus; Rinde, Eli; Smit, Cecilie; Steen, Henning & Tveiten, Lise Ann (2019). Added values from the large-scale and long-lasting program for mapping marine habitats.
• Rinde, Eli; Peña, Viviana; LeGall, Lene; Angles d'Auriac, Marc; Hall-Spencer, Jason M.; Robert S, Steneck; Gitmark, Janne Kim; Husa, Vivian; Grefsrud, Ellen Sofie; Fredriksen, Stein; Bekkby, Trine & Christie, Hartvig C (2019). De allestedsnærværende kalkalgene - et svært, rosa kunnskapshull langs norskekysten?.
• Gundersen, Hege; Bekkby, Trine; Oug, Eivind; Norderhaug, Kjell Magnus; Fredriksen, Stein & Rinde, Eli (2018). Marin gruntvann. Rødlista for naturtyper 2018.
• Rinde, Eli; Angles d'Auriac, Marc; Bekkby, Trine; Christie, Hartvig C; Fredriksen, Stein; Gitmark, Janne Kim; Grefsrud, Ellen Sofie; Hall-Spencer, Jason M.; Husa, Vivian; Le Gall, L; Peña, Viviana & Steneck, Robert S. (2018). Norways hidden marine biodiversity: the hunt for cryptic species within the coralline algae.
• Bartsch, Inka; Paar, Martin; Fredriksen, Stein; Hop, Haakon; Asmus, Ragnhild; Asmus, Harald; Zacher, Katharina; Bischof, Kai & Wiencke, Christian (2017). Arctic warming affects kelp forest with associated fauna in Kongsfjorden, Svalbard.
• Bischof, Kai; Paar, Martin; Fredriksen, Stein; Wiencke, Christian; Hop, Haakon & Bartsch, Inka (2017). Retreating sea ice in coastal systems – Implications for seaweed communities in Kongsfjorden (Svalbard) and beyond.
• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2016). Are skeletal ossicles in echinoids unreliable chronometers? Reply to Russell and Narváez comment on “Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway” by Fagerli et al. 2015. Marine Biology.  ISSN 0025-3162.  163(7), s 160- 161 . doi: 10.1007/s00227-016-2928-5
• Bartsch, Inka; Paar, Martin; Fredriksen, Stein & Wiencke, Christian (2015). Changes in kelp forest biomass and depth distribution in Kongsfjorden (Spitsbergen) reflect Arctic warming.
• Bischof, Kai; Bartsch, Inka; Zachler, Katharina; Fredriksen, Stein & Wiencke, Christian (2015). Seaweed Biology in a changing Arctic.
• Bøe, Mari; Fredriksen, Stein & Karlsen, Hans Erik (2015). Seasonal variations of fish fauna in two Zostera marina meadows in the inner Oslofjord.
• Christie, H.; Norderhaug, K.M.; Fredriksen, Stein & Kraufvelin, Patrik (2015). How can kelp and seagrass beds persist being both food and habitat?.
• Evankov, Ann Marie; Fredriksen, Stein; Christie, H.; Junge, Claudia & Brysting, Anne Krag (2015). Population genetic diversity and structure of two kelp species (Laminariales) in Norway.
• Evankow, Ann; Fredriksen, Stein; Christie, Hartvig C; Junge, Claudia & Brysting, Anne Krag (2015). Genetic tools reveal diversity and structure of kelp forests in Norway.
• Fredriksen, Stein; Moy, Frithjof Emil; Husa, Vivian; Sjøtun, Kjersti & Schneider, Susanne Claudia (2015). Alger Cyanophyta, Rhodophyta, Chlorophyta, Ochrophyta, I: Snorre Henriksen & Olga Hilmo (red.),  Norsk rødliste for arter 2015. Versjon 1.2.  Artsdatabanken.  ISBN 978-82-92838-41-9.  Alger.
• Fredriksen, Stein & Sjøtun, Kjersti (2015). Risikovurdering ved utseting av ikke-stedegen tare.
• Norderhaug, K.M.; Fagerli, Camilla; Andersen, Guri Sogn; Christie, H.; Moy, Frithjof Emil; Gundersen, Hege; Bekkby, Trine; Rinde, Eli; Fredriksen, Stein; Pedersen, Morten foldager & Dahl, Karsten (2015). Regime shifts in Norwegian kelp forests.
• Andersen, A; Thormar, Jonas; Norderhaug, KM & Fredriksen, Stein (2013). Benthic communities at the opera in Bjørvika.
• Brubak, Sissel Irene; Eikrem, Wenche; Fredriksen, Stein & Edvardsen, Bente (2013). Algal culture collection at the University of Oslo. Vis sammendrag

  Algekultursamlingen ved Universitetet i Oslo ble startet på 1950-tallet ved avdeling for Marin botanikk til bruk i eksperimentelle og taksonomiske studier. Samlingen har gjennomgått stadige forandringer og vært preget av pågående forskningsprosjekter. I dag består samlingen av mer enn 200 stammer av eukaryote og prokaryote marine mikroalger innen algedivisjonene Haptophyta, Dinophyta, Chlorophyta, Ochrophyta, Cryptophyta, Cyanophyta, Euglenozoa og Chloraracniophyta. De fleste stammene er isolert fra norske kystfarvann og ved fortynningsserier eller kapillærisolering av ansatte ved instituttet. De dyrkes i ulike sjøvannsmedier med saltholdighet fra 10 til 40 PSU, i 7 klimarom med temperaturer fra 3 til 25 °C. Nåværende samling har blitt utviklet blandt annet for forskning relatert til alger innen divisjonen Haptophyta, og inkluderer 85 stammer av denne gruppen. Samlingen inneholder flere "type-kulturer" som representerer en ny art beskrevet av UiO-forskere, og flere toksiske stammer. Algekulturene er en sentral del av forskningen og undervisningen om mikroalgers taksonomi, fylogeni, økologi, fysiologi, kjemi, genomikk og evolusjon ved instituttet. Kulturer sendes også til andre forskere i inn- og utland. Algekultursamlingen er en verdifull ressurs som også kan utnyttes innen bioprospektering og bioteknologi.

• Fredriksen, Stein & Wiencke, Christian (2013). RIGHT OR WRONG CONCLUSION? THE IMPORTANCE OF EQUAL PRECISIONS LEVEL IN BIODIVERSITY STUDIES.
• Norderhaug, Kjell Magnus; Fagerli, Camilla With; Moy, Frithjof Emil; Bekkby, Trine; Andersen, Guri Sogn; Gundersen, Hege; Rinde, Eli; Fredriksen, Stein; Pedersen, Morten F & Christie, Hartvig C (2013). Climate Change and Large Scale shifts in the Geographical Distribution of NE Atlantic Kelp Forests.
• Norderhaug, Kjell Magnus; Fagerli, Camilla With; Moy, Frithjof Emil; Bekkby, Trine; Andersen, Guri Sogn; Rinde, Eli; Fredriksen, Stein; Pedersen, Morten Foldager & Christie, Hartvig C (2013). Climate Change and Large Scale shifts in the Geographical Distribution of NE Atlantic Kelp Forests.
• Fagerli, C.W.; Norderhaug, K.M.; Christie, H.; Pedersen, M.F. & Fredriksen, Stein (2012). Importance of climate and predation for shifts between sea urchin dominated barren grounds and kelp forests.
• Fredriksen, Stein (2012). Bentosalgevegetasjonen på Svalbard.
• Fredriksen, Stein; Christie, H.; Nilsen, H.L & Sivertsen, L (2012). Spatial distribution of epiphytes and mobile fauna on Zostera marina (L.) and Fucus serratus (L.) from the Skagerrak area.
• Fredriksen, Stein; Husa, Vivian; Skjoldal, Hein Rune; Sjøtun, Kjersti; Christie, Hartvig C; Dale, Trine & Olsen, Yngvar (2012). Ingen regional overgjødsling på Vestlandet. Havforskningsrapporten.
• Pedersen, M.F.; Nejrup, L.B.; Pedersen, T.M. & Fredriksen, Stein (2012). Biomass & productivity of epiphytic algae on kelp Laminaria hyperborea.
• Fredriksen, Stein & Kile, Maia Røst (2011). The algal vegetation in the outer part of Isfjorden, Spitsbergen: a revisit of Per Svendsens sites after 50 years.
• Fredriksen, Stein; Skjoldal, HR; Husa, Vivian; Olsen, Yngvar; Christie, Hartvig C; Dale, Trine & Sjøtun, Kjersti (2011). Vurdering av eutrofisituasjonen i kystområder, med særlig fokus på Hardangerfjorden og Boknafjorden.
• Minchin, Tanya; Fredriksen, Stein & Norderhaug, K.M. (2011). What is replacing the sugar kelp in Skagerrak?.
• Silberberger, Marc & Fredriksen, Stein (2011). Effects of disturbance on the abundance and composition of infauna in Zosera marina L. communities.
• Fredriksen, Stein (2010). Biodiversitet i tareskog.
• Sjøtun, Kjersti; Fredriksen, Stein; Heggøy, Erling; Husa, Vivian; Langangen, Anders Vidar; Lindstrøm, Eli-Anne; Moy, Frithjof Emil; Rueness, Jan & Åsen, Per Arvid (2010). Alger: Cyanophyta, rhodophyta, chlorophyta, ochrophyta, I:  Norsk rødliste for arter 2010. The 2010 Norwegian Red List for Species.  Artsdatabanken.  ISBN 978-82-92838-26-6.  Alger.  s 79 - 86
• Fredriksen, Stein (2009). Stortare fra A til Å.
• S. Forsberg, Ida; Rustad, Ida & Fredriksen, Stein (2009). Manipuleringer i fjæra i indre Oslofjord.
• Steinhovden, Kristine & Fredriksen, Stein (2009). Temperaturtoleranser hos forskjellige isolater av sukkertare.
• Fredriksen, Stein (2008). Tang og tare i Nord.
• Heiaas, Harald; Thomas, Kevin; Fredriksen, Stein & Ketil, Hylland (2008). Overvåking av fotosyntetisk effektivitet i makroalger.
• Magnusson, Jan; Christie, H.; Fredriksen, Stein & Rueness, Jan (2008). "Grønne lunger" i byen en selvfølge - men hva med det marine nærmiljøet?. Fagrådet for vann og avløpsteknisk samarbeid i indre Oslofjord.  s 13- 15
• Fredriksen, Stein (2007). Alger som nyttevekster. Sopp og nyttevekster.  ISSN 1504-4165.  3(4), s 10- 13
• Sogn Andersen, Guri & Fredriksen, Stein (2007). Kelp associated epiphytes, their biomass production and community structure in relation to wave exposure and season.
• Christie, H.; Fredriksen, Stein; Magnusson, J. & Rueness, J. (2006). Marinbiologiske forbedringer av miljøet i Bjørvika/Bispervika. Vurderinger av muligheter.
• Sogn Andersen, Guri & Fredriksen, Stein (2006). Kelp associated epiphytes and their level of biomass production in relation to wave-exposure and season.
• Christie, H.; Fredriksen, Stein; Kraufvelin, Patrik & Norderhaug, K.M. (2005). Tang, tareskog og ålegras som leveområde og økosystem.
• Fredriksen, Stein (2005). Tareskogsforskningen i MARE.
• Sakshaug, Egil; Sjøtun, Kjersti; Fredriksen, Stein; Christie, Hartvig; Fosså, Jan Helge; Dale, Trine; Sivertsen, Knut & Hedlund, Nina (2002). Nedbeiting av tareskog i Norge. Rapport fra arbeidsgruppe nedsatt av Fiskeridepartementet og Miljøverndepartementet.
• Fredriksen, Stein (2002). Kelp forest in Western Norway.
• Fredriksen, Stein (2002). Produksjon av partikulært materiale fra stortare. Mulig næringskilde for krepsdyr i tareskogen?.
• Fredriksen, Stein & Christie, Hartvig (2002). Biodiversitet i makrofyttsamfunn. Variasjon i tid og rom.
• Fredriksen, Stein & Christie, Hartvig (2002, 01. september). Om tareskogen. [Radio].  NRK TV, Ut i naturen : NRK.
• Fredriksen, Stein; Christie, Hartvig & Boström, C. (2002). Nedbeiting av ålegras forårsaket av sneglen Rissoa membranacea.
• Sakshaug, Egil; Christie, Hartvig; Dale, Trine; Fosså, Jan Helge; Fredriksen, Stein; Hedlund, Nina; Sivertsen, Knut & Sjøtun, Kjersti (2002). Nedbeiting av tareskog i Norge. Rapport fra arbeidsgruppe nedsatt av Fiskeridepartementet og Miljøverndepartementet. Rapport til Fiskeridepartementet.
• Fredriksen, Stein (2000). Norwegian history.
• Fredriksen, Stein (2000). The coast of Norway.
• Sætre, Bjarte & Fredriksen, Stein (2000). Epifytter på ålegras og sagtang - en sammenligning mellom fire årstider. Vis sammendrag

  Sæthre B. & Fredriksen S. Avdeling for marin botanikk, Biologisk Institutt, Universitetet i Oslo. Postboks 1069 Blindern, 0316 Oslo. Epifytter på ålegras (Zostera marina) og sagtang (Fucus serratus) ¿ en sammenligning gjennom 4 årstider. På verdensbasis finnes det rundt 50 arter sjøgress. I Norge finnes det to arter - vanlig ålegras (Zostera marina) og dvergålegras (Zostera noltii). Ålegras er utbredt langs hele kysten, dog sjelden funnet i Troms og Finnmark. Ett kjennetegn for sjøgrasarter, i motsetning til makroalger, er det underjordiske rotsystemet (rhizomet) som brukes både til å holde planten fast og til å ta opp næringssalter. Det tette bladlaget vil hos ålegras, som hos makroalger, skape voksested for epifyttiske alger og dyr og skjulested for svømmende dyr. Sjøgrasområder representerer på verdensbasis viktige marine økosystemer da de er svært produktive, i størrelsesorden 500 ¿ 1000 g karbon m-2 år-1. I Norge er slike områder regnet for å være viktige som oppvekstområder for fisk. Ålegras har spredte populasjoner og finnes langs hele kysten fra relativt eksponerte områder til mer beskyttede. En makroalge med lignende vid utbredelse er sagtang. Denne kan til en viss grad ligne ålegras i morfologi i det den er flattrykt og har en glatt overflate. Den har så vidt overlappende dybdeutbredelse med ålegras (utbredelsen er stort sett er grunnere). Særlig fordi sagtangen danner tette og i stor grad sammenhengende populasjoner, vil den være godt egnet for en sammenligning med ålegras som danner disjunkte populasjoner. Ålegras og sagtang har vært samlet gjennom 4 årstider, april, juni, september, november, på en beskyttet stasjon utenfor Flødevigen ved Arendal. Materialet ble fiksert og opparbeidet i lab ved UiO. Fra hver innsamling er det sett på 3 hele ålegrasplanter og på 5 biter av sagtang (fortrengningsvolum ca 400 ml). Sagtangsamfunnet er mest artsrikt sommer og høst, om våren er det særlig antall arter av dyr som er lavt (kun 5 arter fastsittende dyr). Ålegrassamfunnet på sin side er artsfattig i juni, noe som sannsynligvis skyldes plantenes raske vekst midtsommers. Flest arter fantes i ålegrassamfunnet i november. Det finnes arter som bare er knyttet til ett av de to undersøkte samfunnene. Både på ålegras og på sagtang ble det observert et kraftig nedslag av blåskjell i juni. Disse var imidlertid forsvunnet ved augustinnsamlingen. Konklusjon: Diversiteten i slike ålegras- og sagtangsamfunn er høy, med tydelige variasjoner gjennom året. Undersøkelsen inngår som en del av det NFR støttede prosjektet "Biodiversitet i makrofyttsamfunn. Variasjoner i tid og rom." Engelske stikkord: Macrophytes, epiphytes, temporal variation e-postadresse: bjartesa@bio.uio.no, stein.fredriksen@bio.uio.no

• Bjærke, Marit Ruge & Fredriksen, Stein (1999). Epifytter på Sargassum muticum.
• Christie, Hartvig & Fredriksen, Stein (1999). Where have all the kelp plants gone?.
• Fredriksen, Stein & Christie, Hartvig (1999). Biodiversitet i makrofyttsamfunn. Variasjon i tid og rom.
• Fredriksen, Stein & Rueness, Jan (1999). Food chain studies in a Norwegian kelp forest based on stable carbon isotope analysis. Vis sammendrag

  FOOD CHAIN STUDIES IN A NORWEGIAN KELP FOREST BASED ON STABLE CARBON ISOTOPE ANALYSIS S. FREDRIKSEN & J. RUENESS University of Oslo, Department of Biology, Section for Marine Botany, P.O. Box 1069 Blindern, N-0316 Oslo, Norway. Email: stein.fredriksen@bio.uio.no, jan.rueness@bio.uio.no Laminaria hyperborea is the dominant and canopy forming kelp species along the Norwegian coast. It creates a three dimentional forest which is habitat for numerous other algae and animals. Food chain studies have been carried out in the kelp forest by using stable isotopes. The young kelp plants have a more negative carbon (13C/12C) ratio (- 21¿ to -24¿) than the old plants (- 15¿ to 17¿). No significant annual variation was found. Some red algae (RED ALGAE I, fig. 1, e.g. Palmaria palmata, Polysiphonia elongata, Rhodomela confervoides) had ratios equal to the old kelp plants, while others (RED ALGAE II, fig. 1, e.g. Delesseria sanguinea, Phycodrys rubens, Ptilota gunneri) had ratios in the range - 32¿ to -35¿. Phytoplankton ratios were in the range from - 23¿ to - 27¿. Most of the animals analyzed, both invertebrates (grazers and filter feeders) and vertebrates (fish), had 13C/12C ratios from - 15¿ to - 23¿ suggesting that these animals have kelp as their primary carbon source. The nudibranch Aplysia punctata had a 13C/12C ratio from -29 to - 33¿, and is an example of a species feeding on mostly red algae. The only group for which the isotopic ratio was close to that of phytoplankton was the amphipods. We interpret this as the result of a mixed diet of kelp and red algae rather than phytoplankton. This is supported by the fact that phytoplankton abundance is at a minimum, in early autum, when the amphipods are most abundant.

• Gustad, E.C. & Fredriksen, Stein (1999). Bruk av stabile karbonisotoper til å spore tareskogens influensområde.
• Sivertsen, L. & Fredriksen, Stein (1999). Epifytter på Zostera marina (ålegras).

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