Bente Edvardsen

Gran-Stadniczeñko, S., Šupraha, L., Egge, E. D., Edvardsen, B. Haptophyte diversity and vertical distribution explored by 18S and 28S ribosomal RNA gene metabarcoding and scanning electron microscopy. J. Euk. Microbiol. In press.

Eikrem, E., Medlin, L.K., Henderiks, J., Rokitta, S., Rost, B., Probert, I., Throndsen, J., Edvardsen, B. 2016. Haptophyta. In: Handbook of the Protists. Archibald, J. et al. (Eds.). p. 1-61.

Edvardsen, B., Egge, E.S., Vaulot, D. 2016. Diversity and distribution of haptophytes revealed by environmental sequencing and metabarcoding - a review. Perspectives in Phycology 3(2): 77-91.

Banguera-Hinestroza, E., Eikrem, W., Mansour, H., Solberg, I., Curdia, J., Holtermann, K., Edvardsen, B., Kaartvedt, S. 2016. Seasonality and toxin production of Pyrodinium bahamense in a Red Sea lagoon. Harmful Algae 55: 163–171.

Engesmo, A., Eikrem, W., Seoane, S., Smith, K., Edvardsen, B. Hofgaard, A and Tomas, C.R. 2016. New insights into the morphology and phylogeny of Heterosigma akashiwo (Raphidophyceae), with the description of Heterosigma minor sp. nov. Phycologia, 55: 279-294.

Forster, D., et al. 2016. Benthic protists: The under-charted majority. FEMS Microbiol. Ecol. 92:fiw120(8).

McNamee, S.E., Medlin, L.K., Kegel, J., McCoy G.R., Raine R., Barra L., Ruggiero, M.V., Kooistra W.H.C.F., Montresor, M., Hagstrom, J., Perez Blanc, E., Granéli, E., Rodríguez, F., Escalera, L., Reguera, B., Dittami, S., Edvardsen, B., Taylor, J., Lewis, J.M., Pazo, Y., Elliot, C.T., Campbell, K. 2016. Distribution, occurrence and biotoxin composition of the main shellfish toxin producing microalgae within European waters: A comparison of methods of analysis. Harmful Algae 55: 112-120.

Kopf, A. et al. 2015. The ocean sampling day. GigaScinece 4:27.

Massana R, et al. 2015. Marine protist diversity in European coastal waters and sediments as revealed by high-throughput sequencing. Env. Microbiol. 17(10):4035-4049

Gerecht, A., Šupraha, L., Edvardsen, B., Langer, G. Henderiks, J. 2015. Phosphorus availability modifies carbon production in Coccolithus pelagicus subsp. braarudii (Wallich) Schiller 1930. J. Exp. Mar. Biol. Ecol. 472: 24-31.

Egge, E. S., Johannessen, T. V., Andersen, T., Eikrem, W., Bittner, L., Larsen, A., Sandaa, R.-A. and Edvardsen, B. 2015. Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing. Mol. Ecol. 24:3026-3042.

Johannessen, T.V., Bratbak, G., Larsen, A., Ogata, H., Egge, E.S., Edvardsen, B., Eikrem, W., Sandaa, R.A. 2015. Characterisation of three novel giant viruses reveals huge diversity among viruses infecting Prymnesiales (Haptophyta). Virology. 476:180-188.

Egge, E.S. Eikrem, W., Edvardsen, B. 2015. Deep-branching novel lineages and high diversity of haptophytes in the Skagerrak (Norway) uncovered by 454 pyrosequencing. J. Euk. Microbiol. 62(1):121-140.

Duffield, C.J., Edvardsen, B., Eikrem, W., Alve, E. 2014. Effects of different potential food sources on upper-bathyal benthic foraminifera: an experiment with propagules. J. foram. Res., 44(4): 427–444.

Egge, E.S. Eikrem, W., Edvardsen, B. 2014. Deep-branching novel lineages and high diversity of haptophytes in the Skagerrak (Norway) uncovered by 454 pyrosequencing. J. Euk. Microbiol. 08/2014

Keeling, P.J. et al. 2014. The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): Illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing. PLoS Biology, 12(6): e1001889.

Logares, R. et al. 2014. Patterns of rare and abundant marine microbial eukaryotes. Curr. Biol. 24(8): 813-21.

Dunthorn et al. 2014. Placing environmental next generation sequencing amplicons from microbial eukaryotes into a phylogenetic context. Mol. Biol. Evol. 31(4): 993–1009.

Egge E, Bittner L, Andersen T, Audic S, de Vargas C, Edvardsen B. 2013. 454-pyrosequencing to describe microbial eukaryotic community composition, diversity and relative abundance: a test for marine haptophytes. PLOS One, 8(9): e74371.

Stüken, A, Dittami, S.M., Wenche, W., McNamee, S., Campbell, K., Jakobsen, K.S., Edvardsen, B. 2013. Novel hydrolysis-probe based qPCR assay to detect dinoflagellate saxitoxin transcripts in environmental samples, Harmful Algae, 28:108-117.

Dittami S.M., Hostyeva V., Egge E.S., Kegel J.U, W. Eikrem, Edvardsen, B. 2013. Seasonal dynamics of harmful algae in outer Oslofjorden monitored by microarray, qPCR, and microscopy. Environ. Sci. Pollut. Res., 20: 6719-6732.

Dittami, S.M., Riisberg, I., Edvardsen, B. 2013. Molecular probes for the detection and identification of ichthyotoxic marine flagellates of the genus Pseudochattonella (Dictyochophyceae, Heterokonta). Environ. Sci. Pollut. Res., 20: 6719-6732.

Edvardsen, B., Dittami, S.M., Chen, J., Groben, R., Brubak, S., Medlin, L.K. 2013. Molecular probes for the detection and identification of harmful algae in the genera Dinophysis and Phalacroma. 2012. Environ. Sci. Pollut. Res., 20: 6733-6750.

Guillou, L., Bachar, D., Audic, S., Bass, D., Berney, C., Bittner, L., Boutte, C., Burgaud, G., de Vargas, C., Decelle, J., del Campo, J., Dolan, J., Dunthorn, M., Edvardsen, B. Holzmann, M., Kooistra, W. H. C. F., Lara, E., Lebescot, N., Logares, R., Mahé, F., Massana, R., Montresor, M., Morard, R., Not, F., Pawlowski, J., Probert, I., Sauvadet, A.-L., Siano, R., Stoeck, T., Vaulot, D., Zimmermann, P. & Christen, R. submitted. The Protist Ribosomal Reference database (PR2): a catalog of unicellular eukaryote Small SubUnit rRNA sequences with curated taxonomy. Nucleic Acids Res. 41(DI): D597-D604.

Bittner L, Audic S, Gobet, A, Romac S, Egge ES, Edvardsen B, Santini S, Ogata H, Probert I, de Vargas C. 2013. Diversity patterns of uncultured haptophytes unravelled by pyrosequencing in Naples Bay. Mol. Ecol. 22:87-101.

Dittami, S.M. & B. Edvardsen 2013. GPR-Analyzer: a simple tool for quantitative analysis of hierarchical multispecies microarrays. Environ. Sci. Pollut. Res., 20: 6808-6815.

Skjelbred, B., Edvardsen, B., Andersen, T. 2013. Environmental optima for seven strains of Pseudochattonella (Dictyochophyceae, Heterokonta). J. Phycol., 49:54-60.

McCoy GR, Raine R, Medlin LK, Chen J, Kooistra W, Barra L, Ruggiero MV, Graneli E, Hagström J, Salomon PS, Reguera B, Rodríguez F, Escalera L, Edvardsen B, Dittami SM, Eikrem W, Lewis JM, Berzano M, Elliott CT, Campbel K & Pazos Y. 2012. Field testing for toxic algae with a microarray: initial results from the MIDTAL project, In Proceedings of the 14th International Conference on Harmful Algae. International Society for the Study of Harmful Algae and Intergovernmental Oceanographic Commission of UNESCO 2012, I.3. pp. 209-211.

Hostyeva, V., Eikrem, W., Edvardsen, B., Hasle G.R. 2012. Annual cycle of Pseudo-nitzschia species in Outer Oslofjorden, In Proceedings of the 14th International Conference on Harmful Algae. International Society for the Study of Harmful Algae and Intergovernmental Oceanographic Commission of UNESCO 2012, C. 6. pp. 81-83.

Dittami, S.M., Edvardsen, B. 2012. Culture conditions influence cellular RNA content in ichthyotoxic flagellates of the genus Pseudochattonella (Dictyochophyceae). J. Phycol. 48: 1050-1055.

Skjelbred, B., Edvardsen, B., Andersen, T. 2012. A high-throughput method for measuring growth and respiration in microalgal cultures, J. Appl. Phycol. 24:1589-1599.

Ota, S., Eikrem, W., Edvardsen, B. 2012. Ultrastructure and molecular phylogeny of thaumatomonads (Cercozoa) with emphasis on Thaumatomastix salina from Oslofjorden, Norway. Protist, 163:560-573.

Granéli, E., B. Edvardsen, D.L. Roelke and J.A. Hagström. 2012. The ecophysiology and bloom dynamics of Prymnesium spp. Harmful Algae 14:260-270.

Dittami S.M., Riisberg I., John U, Orr R.J.S., Jakobsen K.S., Edvardsen B. 2012. Analysis of expressed sequence tags from the marine microalga Pseudochattonella farcimen (Dictyochophyceae). Protist, 163:143-161.

Dittami SM, Aas HTN, Smestad Paulsen B, Boyen C, Edvardsen B, Tonon T. 2011. Mannitol in six autotrophic stramenopiles and Micromonas. Plant Signaling & Behavior 6: 1237-1239.

Sym, S. Pienaar, R., Edvardsen, B., Egge, E. 2011. Fine structure and systematics of Prymnesium radiatum sp. nov. (Prymnesiophyceae) from False Bay and Franskraal, South Africa. Eur. J. Phycol. 46: 229-248.

Edvardsen, B., Eikrem, W., Throndsen, J., Sáez, A.G., Probert, I., Medlin, L.K. 2011. Ribosomal DNA phylogenies and a morphological revision set the basis for a revised taxonomy of Prymnesiales (Haptophyta). Eur. J. Phycol. 46: 202-228.

Strand D.A., Holst-Jensen A., Viljugrein H., Edvardsen B., Klaveness D., Jussila J., Vrålstad T. 2011. Detection and quantification of the crayfish plague agent in natural waters – an approach for direct monitoring of aquatic environments. Dis. Aquat. Org. 95:9–17.

Skjelbred, B., Horsberg, T.E, Tollefsen, K.E., Andersen, T., Edvardsen, B. 2011. Toxicity of the ichthyotoxic marineflagellate Pseudochattonella (Dictyochophyceae, Heterokonta) assessed by six bioassays. Harmful Algae 10:144-154.

Oftedal, L., Skjærven, K.H., Coyne, R.T., Edvardsen, B, Rohrlack, T., Skulberg, O.M., Døskeland, S.O., Herfindal, L. 2010. The apoptosis-inducing activity towards leukemia and lymphoma cells in a cyanobacterial culture collection is not associated with mouse bioassay toxicity. J Ind Microbiol Biotechnol. 38:489–501.

Haande, S., Rohrlack, Semyalo, R.P., T., Brettum, P., Edvardsen, B., Solheim A.L., Sørensen, K. and Larsson, P. 2010. Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to environmental conditions. Limnologica 41(1): 20-29.

Rounge, T.B., Rohrlack, T., Decenciere, B., Edvardsen, B., Kristensen, T., K.S. Jakobsen. 2010. Subpopulation differentiation is associated with nonribosomal peptide gene cluster dynamics in Planktothrix. J. Phycol.46(4): 645-652.

Skjelbred, B., Horsberg, T.E, Tollefsen, K.E., Andersen, T. and Edvardsen, B. 2011. Toxicity of the ichthyotoxic marineflagellate Pseudochattonella (Dictyochophyceae, Heterokonta assessed by six bioassays. Harmful Algae 10(2): 144-154

Seoane, S,. Eikrem, W, Pienaar, R. and Edvardsen, B. 2009. Chrysochromulina palpebralis sp. nov. (Prymnesiophyceae): the description of a new haptophyte species, possessing two alternative morphologies. Phycologia 48:165-176.

Riisberg, I., Orr, R.J.S., Kluge, R., Shalchian-Tabrizi, K., Bowers H.A., Patil, V., Edvardsen, B. and Jakobsen, KS. 2009. Seven gene phylogeny of heterokonts. Protist. 160(2): 191-204

Riisberg, I. and Edvardsen, B. 2008. Genetic variation in bloom-forming ichthyotoxic Pseudochattonella species (Dictyochophyceae, Heterokonta) using nuclear, mitochondrial and plastid DNA sequence data. European J. Phycol. 43 (4): 413-422.

Halstvedt, C.B., Rohrlack, Ptacnik, R., Edvardsen, B. 2008. On the effect of abiotic environmental factors on production of bioactive oligopeptides in field populations of Planktothrix spp. (Cyanobacteria). J. Plankton Res. 30(5): 607-617.

Rohrlack, T., B. Edvardsen, R. Skulberg, C.B. Halstvedt, H.C. Utkilen, R. Ptacnik, and O.M. Skulberg. 2008. Oligopeptide chemotypes of the toxic freshwater cyanobacterium Planktothrix can form sub-populations with dissimilar ecological traits Limnology and Oceanography 53 (4): 1279-1293.

Edvardsen, B., Eikrem, W., Shalchian-Tabrizi, K., Riisberg, I., Johnsen, G., Naustvoll, L., Throndsen, J. 2007. Verrucophora farcimen gen. et sp. nov. (Dictyochophyceae, Heterokonta) - a bloom forming ichthyotoxic flagellate from the Skagerrak, Norway. J. Phycol. 43(5), 1054-1070.

Edvardsen, B. and Medlin, L.K. 2007. Molecular systematics of Haptophyta. In: Unravelling the algae – the past, present and future of algal molecular systematics. Lewis, J. and J. Brodie (eds.). The Systematics Association. pp. 183-196. Taylor and Francis, ISBN: 084937989X

Halstvedt, C.B., T. Rohrlack, T.Andersen, O. Skulberg, B. Edvardsen. 2007. Seasonal dynamics of Planktothrix spp. in Lake Steinsfjorden (Norway) related to environmental factors. J. Plankton Res. 29:471-482.

Haande, S., Ballot, A., Rohrlack, T., Wiedner, C., Fastner, J., and Edvardsen, B. 2007. Diversity of toxic and non-toxic Microcystis aeruginosa isolates (Chroococales, Cyanobacteria) from East-African water bodies. Arch. Microbiol. 188:15-25.

Lekve, K., Bagøien, E., Dahl, E., Edvardsen, B., Skogen, M. and Stenseth, N-C. 2006. Environmental forcing as a main determinant of bloom dynamics of the Chrysochromulina algae. Proc. Biol. Sci. 273(1605):3047-3055.

Edvardsen, B., Imai, I. 2006. The ecology of harmful flagellates within Prymnesiophyceae and Raphidophyceae. In: Granéli E., Turner J.T. (eds) Ecology of Harmful Algae, Ecological Studies, Vol. 189, Springer, Berlin, pp. 67-79.

Vestheim, H, B. Edvardsen, S. Kaartvedt. 2005. Assessing feeding of a carnivorous copepod using species-specific PCR. Mar. Biol. 147: 381-385.

Eschbach, E., Uwe J., M. Reckermann, A. D. Cembella, B. Edvardsen, L.K. Medlin 2005. Cell cycle dependent expression of toxicity by the ichthyotoxic prymnesiophyte Chrysochromulina polylepis. Aquat. Microb. Ecol. 39: 85-95.

Vestheim, H., S. Kaartvedt, B. Edvardsen. 2005. State-dependent vertical distribution of the carnivore copepod Pareuchaeta norvegica. J. Plankt. Res. 27: 19-26.

Dahl, E., Bagøien, E., Edvardsen, B., & Stenseth, N.-C 2005. The dynamics of Chrysochromulina species in the Skagerrak in relation to environmental conditions. J. Sea Res. 54:15-24.

Edvardsen, B., R. Skulberg, & O.M. Skulberg 2004. NIVA Culture Collection of Algae - microalgae for science and technology. Nova Hedwigia Beiheft 79: 99-114.

Sáez, A.G., Probert, I., Young, J.R., Edvardsen, B., Eikrem, W., & Medlin, L.K. 2004. A Review of the Phylogeny of the Haptophyta. In: H.R. Thierstein & J.R. Young (Eds.), Coccolithophores: from molecular processes to global impact. Springer Verlag, Berlin, pp 251-269.

Edvardsen, B., Shalchian-Tabrizi, K., Jakobsen, K.S., Medlin, L.K., Dahl, E. & Brubak, S., Paasche, E. 2003. Genetic variability and molecular phylogeny of Dinophysis species (Dinophyceae) from Norwegian waters inferred from single cell analyses of rDNA. J. Phycol. 39(2): 395-408.

Zapata, M., Edvardsen, B., Rodríguez, F., Maestro, M. & Garrido, J.L. 2001. Chlorophyll c2 monogalactosyldiacylglyceride ester (chl c2 -MGDG). A novel marker for Chrysochromulina species. Mar. Ecol. Prog. Ser. 219: 85-98.

Edvardsen, B., Eikrem, W., Green, J.C., Andersen, R.A., Moon-van der Staay, S.Y. & Medlin, L.K. 2000. Phylogenetic reconstructions of the Haptophyta inferred from 18S ribosomal DNA sequences and available morphological data. Phycologia 39 (1): 19-35.

Eikrem, W. & Edvardsen, B. 1999.Chrysochromulina fragaria sp. nov. (Prymnesiophyceae) description of a new haptophyte flagellate from Norwegian waters. Phycologia 38(2): 149-155.

Dahl, E., Edvardsen, B. & Eikrem, W. 1998. ı blooms in the Skagerrak after 1988. In: Harmful Algae, Algas Nocivas. B. Reguera, J. Blanco, M. Fernández, T. Wyatt [Eds.]. UNESCO, Vigo, Spain, pp. 104-105.

Larsen, A. & Edvardsen, B. 1998. A study of relative ploidy levels in Prymnesium parvum and P. patelliferum (Haptophyta) analysed by flow cytometry. Phycologia 37(6): 412-424.

Edvardsen, B. & Medlin, L. 1998. Genetic analyses of authentic and alternate forms of Chysochromulina polylepis (Haptophyta). Phycologia 37(4): 275-283.

Edvardsen, B. & Paasche, E. 1998. Bloom dynamics and physiology of Prymnesium and Chrysochromulina. In: Physiological Ecology of Harmful Algal Blooms. NATO ASI Series G, vol. 41. Anderson, D.M., Cembella, A.D., Hallegraeff, G.M. [Eds.], Springer-Verlag, Heidelberg, pp. 193-208.

Simon, N., Brenner, J., Edvardsen, B. & Medlin, L. 1997. The identification of Chrysochromulina and Prymnesium (Haptophyta, Prymnesiophyceae) using fluorescent or chemiluminescent oligonucleotide probes: a means for improving studies on toxic algae. Eur. J. Phycol. 32: 393-401.

Edvardsen, B., Eikrem, W., Vaulot, D. & Paasche E. 1996. Comparison between authentic and alternate cells of Chrysochromulina polylepis: morphology, growth, toxicity and ploidy level. In: Yasumoto, T., Oshima, Y. [Eds.] Harmful and Toxic Algal Blooms. UNESCO, Japan, pp. 231-234.

Edvardsen, B. & Vaulot, D. 1996. Ploidy analysis of the two motile forms of Chrysochromulina polylepis (Prymnesiophyceae). J. Phycol. 32: 94-102.

Meldahl. A.-S., Kvernstuen, J., Grasbakken, G. J., Edvardsen, B. & Fonnum, F. 1995. Toxic activity of Prymnesium spp. and Chrysochromulina spp. tested by different methods. In: Harmful Marine Algal Blooms. Lassus, P., Arzul, G., Erard-Le Denn, E., Gentien, P., Marcaillou-Le Baut, C. [Eds.], Lavouisier, Paris, pp. 315-320.

Meldahl. A. -S., Edvardsen, B. & Fonnum, F.1994. The toxicity of four potentially ichthyotoxic marine phytoflagellates determined by four different test methods. J. Toxicol. Environ. Health 42: 289-301.

Meldahl. A. -S., Edvardsen, B. & Fonnum, F. 1993. The effect of Prymnesium-toxin on neurotransmitter transport mechanisms: the development of a sensitive test method. In: Smayda, T. J. & Shimizu, Y. [Eds.] Toxic Phytoplankton Blooms in the Sea. Elsevier, Amsterdam, pp. 895-900.

Edvardsen, B. 1993. Toxicity of Chrysochromulina species (Prymnesiophyceae) to the brine shrimp, Artemia salina. In: Smayda, T. J. & Shimizu, Y. [Eds.] Toxic Phytoplankton Blooms in the Sea. Elsevier, Amsterdam, pp. 681-86.

Edvardsen, B. & Paasche, E. 1992. Two motile stages of Chrysochromulina polylepis (Prymnesiophyceae): morphology, growth and toxicity. J. Phycol. 28: 104-114.

Paasche, E., Edvardsen, B. & Eikrem, W. 1990. A possible alternate stage in the life cycle of Chrysochromulina polylepis Manton et Parke (Prymnesiophyceae). Nova Hedwigia, Beiheft 100: 91-99.

Edvardsen, B., Moy, F. & Paasche, E. 1990. Hemolytic activity in extracts of Chrysochromulina polylepis grown at different levels of selenite and phosphate. In: Toxic Marine Phytoplankton. E. Granéli, B. Sundstrøm, L. Edler, D.M. Anderson [Eds.]. Elsevier, New York. pp. 284-289.

• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Aaboe, Signe & Down, Emily [Vis alle 12 forfattere av denne artikkelen] (2023). Sesongdynamikk til havis protister og meiofauna i det nordvestlige Barentshavet. Progress in Oceanography. ISSN 0079-6611. 218. doi: 10.1016/j.pocean.2023.103128. Fulltekst i vitenarkiv Vis sammendrag

  Rask reduksjon av havis i Arktis gjør behovet for økt forståelsen av det det is-assosierte økosystemet til en særlig presserende oppgave. I denne studien undersøker vi den forholdsvis dårlig kjente sesongvariasjonen i sammensetningen, mengden og biomasse av isbiotasamfunn bestående av encellete protister og meiofauna i de nederste 30 cm av havisen, i forhold til egenskaper i havisen og isdrift i det nordvestlige Barentshavet. Vi forventet lave mengder av isbiota om vinteren og de høyeste verdiene om våren, før issmelting. Våre resultater viser at havisforhold og biomassen av isalger varierer sterkt gjennom sesongen, mens konsentrasjonene av partikulært organisk karbon er relativt stabile gjennom alle årstidene. Lav biomasse av isbiota i mars synes å være relatert til sen start på isdannelsen og følgelig kort tidsperiode for etablering av isalger og meiofauna. Diatoméer, som Navicula spp. og Nitzschia spp., dominerte samfunnene av isalger gjennom alle årstidene. Med unntak fra mai måned, dominerte ciliater, dinoflagellater – spesielt av ordenen Gymnodiniales, og små flagellater. Meiofaunaen bestod hovedsakelig av is-assosierte hoppekreps, rotiferer og store ciliater, med dominans av omnivore arter gjennom alle årstidene. Store ciliater utgjorde den mest tallrike artsgruppen av meiofauna i alle isprøvene og årstider (50–90 %), men bidrar ikke nødvendigvis til den totale mengden av biomasse. Issmeltingen reduserer trolig biomasse av isalger i juli, mens biomassen av meiofauna holder seg høy – noe som indikerer ulike årssykluser for protister vs. meiofauna. Det tallrike isbiotasamfunnene som ble observert i desember styrker den økende oppfatningen av en aktiv isbiota om vinteren. Resultatene viser en sterk og delvis uventet sesongvariasjon i isbiotaen i Barentshavet, og indikerer at endringer i dannelsen av havis, drift og smelting, vil påvirke det is-assosierte økosystemet i betydelig grad.

• Bachmann, Lutz; Beermann, Jan; Brey, Thomas; de Boer, Hugo; Dannheim, Jennifer & Edvardsen, Bente [Vis alle 20 forfattere av denne artikkelen] (2023). The role of systematics for understanding ecosystem functions: Proceedings of the Zoologica Scripta Symposium, Oslo, Norway, 25 August 2022. Zoologica Scripta. ISSN 0300-3256. 52(3), s. 187–214. doi: 10.1111/zsc.12593. Fulltekst i vitenarkiv
• Kohlbach, Doreen; Goraguer, Lucie; Bodur, Yasemin V.; Müller, Oliver; Amargant Arumí, Martí & Blix, Katalin [Vis alle 23 forfattere av denne artikkelen] (2023). Tidligere havissmelting forlenger den oligotrofe sommerperioden i Barentshavet med lav algebiomasse og vertikal fluks. Progress in Oceanography. ISSN 0079-6611. 213. doi: 10.1016/j.pocean.2023.103018. Fulltekst i vitenarkiv Vis sammendrag

  Havisen i Arktis minker i utstrekning og tykkelse som et resultat av klimaoppvarming. Dette påvirker tidspunkt, lengde, størrelse og sammensetning av fytoplankton og planktonproduksjon med påfølgende effekter på det arktiske, marine næringsnettet, og på biogeokjemiske sykluser. I dette studie dokumenterer vi miljødrivere som påvirker sammensetning, tetthet, biomasse, trofisk nivå, og den vertikale strømmen av encellete eukaryoter (protister) og fytoplankton i Barentshavet, sent i august 2018 og 2019. Disse to årene var karakterisert av ulike havisforhold. I august 2018 hadde iskanten trukket seg bort fra sokkelkanten og inn i Nansen bassenget nord for 82 °N, mens det i 2019 var mye is i den nordvestre delen av Barentshavet nord for 79 °N. Våre resultater viser at de varierende isforholdene bidro til markerte forskjeller i strukturen i de pelagiske protistsamfunnene i disse havområdene. I august 2018 var protistsamfunnet i et avsluttet blomstringsstadium, karakterisert av næringsfattig overflatevann som på de fleste stasjonene var dominert av små fytoplanktonarter og protister, i første rekke flagellater og ciliater. I 2019 var det et større innslag av autotrofe arter med store celler, særlig diatoméer, som medførte at den totale protistbiomassen hadde høyrere innhold av klorofyll a, noe som indikerte at protistsamfunnet fremdeles var i en sen oppblomstringsfase. Diatoméer utgjorde en høyrere andel av protistbiomassen på isdekte stasjoner i begge årene sammenliknet med stasjoner i åpent vann. Dette mønsteret var også synlig ved å ha en større vertikalstrøm av protistbiomasse i 2019, dominert av dinoflagellater og diatoméer, sammenliknet med 2018. Resultatene indikerer at den forutsatte overgangen til det isfrie Barentshavet vil forlenge den næringsfattige sommerperioden, med en lav algebiomasse og redusert vertikal transport.

• Lundsør, Elisabeth; Lømsland, Evy Rigmor; Johnsen, Torbjørn Martin; Engesmo, Anette; King, Andrew Luke & Staalstrøm, Andre [Vis alle 11 forfattere av denne artikkelen] (2022). Marine phytoplankton community data and corresponding environmental properties from eastern Norway, 1896–2020. Scientific Data. ISSN 2052-4463. 9. doi: 10.1038/s41597-022-01869-3. Fulltekst i vitenarkiv
• Lundsør, Elisabeth; Eikrem, Wenche; Stige, Leif Christian; Engesmo, Anette; Gran-Stadniczeñko, Sandra & Edvardsen, Bente (2022). Changes in phytoplankton community structure over a century in relation to environmental factors. Journal of Plankton Research. ISSN 0142-7873. 44(6), s. 854–871. doi: 10.1093/plankt/fbac055. Fulltekst i vitenarkiv Vis sammendrag

  Changes in phytoplankton abundance and biomass during the period 1933–2020 were examined by statistical modeling using data from the Inner Oslofjorden phytoplankton database. The phytoplankton abundances increased with eutrophication from 1930s to 1970s, but with the implementation of sewage cleaning measures and a resulting reduction in nutrient releases, the phytoplankton abundance has since then decreased significantly. The onset of the seasonal blooms has started progressively later during the last 15 years, especially the spring bloom. The delayed spring bloom co-occurred with increasing temperature in winter and spring. The diatom biomass decreased more than that of dinoflagellates and other microeukaryotes. The diatom genus Skeletonema dominated the spring bloom and was found to be the key taxa in explaining these changes in abundance and phenology. Extensive summer blooms of the coccolithophore Emiliania huxleyi, which has been characteristic for the inner Oslofjorden, has also gradually decreased during the last decades, along with reducing eutrophication. Dinoflagellates have not had the same reduction in abundance as the other groups. Despite an increasing proportion of dinoflagellates compared with other taxa, there are no clear indications of increased occurrence of toxic algal blooms in inner Oslofjorden. However, the introduction of new “toxin-producing” species may cause concern.

• Supraha, Luka; Klemm, Kerstin; Gran-Stadniczeñko, Sandra; Hörstmann, Cora; Vaulot, Daniel & Edvardsen, Bente [Vis alle 7 forfattere av denne artikkelen] (2022). Diversity and biogeography of planktonic diatoms in Svalbard fjords: The role of dispersal and Arctic endemism in phytoplankton community structuring. Elementa: Science of the Anthropocene. ISSN 2325-1026. 10(1). doi: 10.1525/elementa.2021.00117. Fulltekst i vitenarkiv Vis sammendrag

  Understanding the processes that shape the community structure of Arctic phytoplankton is crucial for predicting responses of Arctic ecosystems to the ongoing ocean warming. In particular, little is known about the importance of phytoplankton dispersal by the North Atlantic Current and the prevalence and maintenance of Arctic endemism. We investigated the diversity and biogeography of diatoms from five Svalbard fjords and the Hausgarten observatory (Fram Strait) by combining diatom cultivation and 18S rRNA gene metabarcoding. In total, 50 diatom strains were isolated from the area during the HE492 cruise in August 2017. The strains were identified taxonomically using molecular and morphological approaches, and their biogeographic distribution was mapped using the local metabarcoding dataset and a global compilation of published metabarcoding datasets. Biogeographic analysis was also conducted for the locally most abundant diatom metabarcoding amplicon sequence variants. The biogeographic analyses demonstrated that Arctic diatoms exhibit three general biogeographic distribution types: Arctic, Arctic-temperate, and cosmopolitan. At Hausgarten and in outer Isfjorden on the west coast of Svalbard, the communities were dominated by genotypes with Arctic-temperate and cosmopolitan distribution. Diatom communities in nearby Van Mijenfjorden, inner Isfjorden and Kongsfjorden were dominated by genotypes with Arctic-temperate distribution, and cosmopolitan species were less abundant. The genotypes endemic to the Arctic had lower abundance on the west coast of Svalbard. The two northernmost fjords (Woodfjorden and Wijdefjorden) had a higher abundance of genotypes endemic to the Arctic. Our results demonstrate that the diatom communities in the Svalbard area consist of genotypes endemic to the Arctic, and genotypes with broader biogeographic distribution, all of which are further structured by local environmental gradients. Finer biogeographic patterns observed within Arctic-temperate and cosmopolitan genotypes suggest that certain genotypes can be used as indicators of increasing influence of Atlantic waters on the phytoplankton community structure in the Svalbard area.

• John, Uwe; Supraha, Luka; Gran-Stadniczeñko, Sandra; Bunse, Carina; Cembella, Allan & Eikrem, Wenche [Vis alle 13 forfattere av denne artikkelen] (2022). Spatial and biological oceanographic insights into the massive fish-killing bloom of the haptophyte Chrysochromulina leadbeateri in northern Norway. Harmful Algae. ISSN 1568-9883. 118. doi: 10.1016/j.hal.2022.102287. Fulltekst i vitenarkiv Vis sammendrag

  A bloom of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway during May and June 2019 was the most harmful algal event ever recorded in the region, causing massive mortalities of farmed salmon. Accordingly, oceanographic and biodiversity aspects of the bloom were studied in unprecedented detail, based on metabarcoding and physico-chemical and biotic factors related with the dynamics and distribution of the bloom. Light- and electron-microscopical observations of nanoplankton samples from diverse locations confirmed that C. leadbeateri was dominant in the bloom and the primary cause of associated fish mortalities. Cell counts by light microscopy and flow cytometry were obtained throughout the regional bloom within and adjacent to five fjord systems. Metabarcoding sequences of the V4 region of the 18S rRNA gene from field material collected during the bloom and a cultured isolate from offshore of Tromsøy island confirmed the species identification. Sequences from three genetic markers (18S, 28S rRNA gene and ITS region) verified the close if not identical genetic similarity to C. leadbeateri from a previous massive fish-killing bloom in 1991 in northern Norway. The distribution and cell abundance of C. leadbeateri and related Chrysochromulina species in the recent incident were tracked by integrating observations from metabarcoding sequences of the V4 region of the 18S rRNA gene. Metabarcoding revealed at least 14 distinct Chrysochromulina variants, including putative cryptic species. C. leadbeateri was by far the most abundant of these species, but with high intraspecific genetic variability. Highest cell abundance of up to 2.7 × 107 cells L 􀀀 1 of C. leadbeateri was found in Balsfjorden; the high cell densities were associated with stratification near the pycnocline (at ca. 12 m depth) within the fjord. The cell abundance of C. leadbeateri showed positive correlations with temperature, negative correlation with salinity, and a slightly positive correlation with ambient phosphate and nitrate concentrations. The spatio-temporal succession of the C. leadbeateri bloom suggests independent initiation from existing pre-bloom populations in local zones, perhaps sustained and supplemented over time by northeastward advection of the bloom from the fjords

• Egge, Elianne Dunthorn; Elferink, Stephanie; Vaulot, Daniel; John, Uwe; Bratbak, Gunnar & Larsen, Aud [Vis alle 7 forfattere av denne artikkelen] (2021). An 18S V4 rDNA metabarcoding dataset of protist diversity in the Atlantic inflow to the Arctic Ocean, through the year and down to 1000 m depth. Earth System Science Data. ISSN 1866-3591. 13, s. 4913–4928. doi: 10.5194/essd-13-4913-2021. Fulltekst i vitenarkiv
• Sandaa, Ruth-Anne; Saltvedt, Marius Rydningen; Dahle, Håkon; Wang, Haina; Våge, Selina & Blanc-Mathieu, Romain [Vis alle 11 forfattere av denne artikkelen] (2021). Adaptive evolution of viruses infecting marine microalgae (haptophytes), from acute infections to stable coexistence. Biological Reviews. ISSN 1464-7931. 97(1), s. 179–194. doi: 10.1111/brv.12795. Fulltekst i vitenarkiv
• Gérikas Ribeiro, Catherine; Lopes dos Santos, Adriana; Probert, Ian; Vaulot, Daniel & Edvardsen, Bente (2020). Taxonomic reassignment of Pseudohaptolina birgeri comb. nov. (Haptophyta). Phycologia. ISSN 0031-8884. 59(6), s. 606–615. doi: 10.1080/00318884.2020.1830255.
• Lundsør, Elisabeth; Stige, Leif Christian; Sørensen, Kai & Edvardsen, Bente (2020). Long-term coastal monitoring data show nutrient-driven reduction in chlorophyll. Journal of Sea Research. ISSN 1385-1101. 164. doi: 10.1016/j.seares.2020.101925. Fulltekst i vitenarkiv Vis sammendrag

  In this study we have compiled a long-term monitoring dataset from the inner Oslofjorden and supplemented it with short-term research data from the same station. Using generalized additive models analysing the data from this time series, we have examined how chlorophyll-a, hydrography, and various nutrient concentrations have changed during 1973–2017 and how they correlate. We describe the seasonality in chlorophyll-a, nitrogen, phosphorus, Secchi-depth, temperature and salinity and how the levels of each variable have changed the last forty years. The results show specifically how levels of chlorophyll-a have decreased significantly and how this correlates with decrease in nitrogen and phosphorus levels. Our results show a significantly positive correlation between chlorophyll-a and phosphorus during spring bloom and between chlorophyll-a and nitrogen during autumn bloom. However, phosphorus levels have increased again during the last 20 years, but chlorophyll-a levels are still low, indicating that the chlorophyll-a level currently may be controlled by the continuous decreasing trend in nitrogen. If nitrogen increase again, the chlorophyll-a level may also begin to increase. The impact of increasing temperature and possible change in starting point for the growing season should be studied further.

• Chambouvet, Aurélie; Monier, Adam; Maguire, Finlay; Itoiz, Sarah; del Campo, Javier & Elies, Philippe [Vis alle 9 forfattere av denne artikkelen] (2019). Intracellular Infection of Diverse Diatoms by an Evolutionary Distinct Relative of the Fungi. Current Biology. ISSN 0960-9822. 29(23), s. 4093–4101.e4. doi: 10.1016/j.cub.2019.09.074. Fulltekst i vitenarkiv
• Gran Stadniczeñko, Sandra; Krabberød, Anders Kristian; Sandaa, Ruth-Anne; Yau, Sheree; Egge, Elianne Dunthorn & Edvardsen, Bente (2019). Seasonal dynamics of algae-infecting viruses and their inferred interactions with protists. Viruses. ISSN 1999-4915. 11(11), s. 1–16. doi: 10.3390/v11111043. Fulltekst i vitenarkiv
• Adl, Sina M.; Bass, David; Lane, Christopher E.; Lukes, Julius; Schoch, Conrad L & Smirnov, Aleksey [Vis alle 47 forfattere av denne artikkelen] (2019). Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 66(1), s. 4–119. doi: 10.1111/jeu.12691. Fulltekst i vitenarkiv
• Mossige, Endre Joachim; Edvardsen, Bente; Jensen, Atle & Mielnik, Michal Marek (2019). A tunable, microfluidic filter for clog‑free concentration and separation of complex algal cells. Microfluidics and Nanofluidics. ISSN 1613-4982. 23(56). doi: 10.1007/s10404-019-2209-y. Fulltekst i vitenarkiv Vis sammendrag

  An inherent problem with microfluidic filters is the tendency to clog, especially when applied to cells due to their geometrical complexity, deformability, and tendency to adhere to surfaces. In this work, we handle live algal cells of high complexity without signs of clogging, achieved by exploiting hydrodynamic interactions around trilobite-shaped filtration units. To characterize the influence of cell complexity on the separation and concentration mechanisms, we compare the hydrodynamic interactions to those of synthetic, rigid microparticles. We discover that simple rolling along the filter structures, which prevents clogging for particles, cannot be applied to cells. Instead, we find that inertial effects must be employed to minimize the filter interactions and that this modification leads to only a minor reduction in device performance.

• Gran-Stadniczenko, Sandra; Egge, Elianne; Hostyeva, Vladyslava; Logares, Ramiro; Eikrem, Wenche & Edvardsen, Bente (2019). Protist Diversity and Seasonal Dynamics in Skagerrak Plankton Communities as Revealed by Metabarcoding and Microscopy. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 66(3), s. 494–513. doi: 10.1111/jeu.12700. Fulltekst i vitenarkiv
• Piredda, Roberta; Claverie, Jean-Michel; Decelle, Johan; de Vargas, Colomban; Dunthorn, Micah & Edvardsen, Bente [Vis alle 19 forfattere av denne artikkelen] (2018). Diatom diversity through HTS-metabarcoding in coastal European seas. Scientific Reports. ISSN 2045-2322. 8(1), s. 1–12. doi: 10.1038/s41598-018-36345-9. Fulltekst i vitenarkiv Vis sammendrag

  Diatoms constitute a diverse lineage of unicellular organisms abundant and ecologically important in aquatic ecosystems. Compared to other protists, their biology and taxonomy are well-studied, offering the opportunity to combine traditional approaches and new technologies. We examined a dataset of diatom 18S rRNA- and rDNA- (V4 region) reads from different plankton size-fractions and sediments from six European coastal marine sites, with the aim of identifying peculiarities and commonalities with respect to the whole protistan community. Almost all metabarcodes (99.6%) were assigned to known genera (121) and species (236), the most abundant of which were those already known from classic studies and coincided with those seen in light microscopy. rDNA and rRNA showed comparable patterns for the dominant taxa, but rRNA revealed a much higher diversity particularly in the sediment communities. Peculiar to diatoms is a tight bentho-pelagic coupling, with many benthic or planktonic species colonizing both water column and sediments and the dominance of planktonic species in both habitats. Overall metabarcoding results reflected the marked specificity of diatoms compared to other protistan groups in terms of morphological and ecological characteristics, at the same time confirming their great potential in the description of protist communities.

• Tillmann, Urban; Edvardsen, Bente; Krock, Bernd; Smith, Kirsty F; Paterson, Ruth F & Voss, Daniela H. (2018). Diversity, distribution, and azaspiracids of Amphidomataceae (Dinophyceae) along the Norwegian coast. Harmful Algae. ISSN 1568-9883. 80, s. 15–34. doi: 10.1016/j.hal.2018.08.011.
• Engesmo, Anette; Strand, David; Gran-Stadniczeñko, Sandra ; Edvardsen, Bente; Medlin, Linda K. & Eikrem, Wenche (2018). Development of a qPCR assay to detect and quantify ichthyotoxic flagellates along the Norwegian coast, and the first Norwegian record of Fibrocapsa japonica (Raphidophyceae). Harmful Algae. ISSN 1568-9883. 75, s. 105–117. doi: 10.1016/j.hal.2018.04.007. Fulltekst i vitenarkiv Vis sammendrag

  Blooms of ichthyotoxic microalgae pose a great challenge to the aquaculture industry world-wide, and there is a need for fast and specific methods for their detection and quantification in monitoring programs. In this study, quantitative real-time PCR (qPCR) assays for the detection and enumeration of three ichthyotoxic flagellates: the dinoflagellate Karenia mikimotoi (Miyake & Kominami ex Oda) Hansen & Moestrup and the two raphidophytes Heterosigma akashiwo (Hada) Hada ex Hara & Chihara and Fibrocapsa japonica Toriumi & Takano were developed. Further, a previously published qPCR assay for the dinoflagellate Karlodinium veneficum (Ballantine) Larsen was used. Monthly samples collected for three years (Aug 2009–Jun 2012) in outer Oslofjorden, Norway were analysed, and the results compared with light microscopy cell counts. The results indicate a higher sensitivity and a lower detection limit (down to 1 cell L−1) for both qPCR assays. Qualitative and semi-quantitative results were further compared with those obtained by environmental 454 high throughput sequencing (HTS, metabarcoding) and scanning electron microscopy (SEM) examination from the same samplings. All four species were detected by qPCR and HTS and/or SEM in outer Oslofjorden (Aug 2009–Jun 2012); Karlodinium veneficum was present year-round, whereas Karenia mikimotoi, Heterosigma akashiwo and Fibrocapsa japonica appeared mainly during the autumn in all three years. This is the first observation of Fibrocapsa japonica in Norwegian coastal waters. This species has previously been recorded off the Swedish west coast and German Bight, which may suggest a northward dispersal.

• Stadniczenko, Sandra Gran; Supraha, Luka; Egge, Elianne Dunthorn & Edvardsen, Bente (2017). Haptophyte Diversity and Vertical Distribution Explored by 18S and 28S Ribosomal RNA Gene Metabarcoding and Scanning Electron Microscopy. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 64(4), s. 514–532. doi: 10.1111/jeu.12388. Fulltekst i vitenarkiv Vis sammendrag

  Haptophyta encompasses more than 300 species of mostly marine pico‐ and nanoplanktonic flagellates. Our aims were to investigate the Oslofjorden haptophyte diversity and vertical distribution by metabarcoding, and to improve the approach to study haptophyte community composition, richness and proportional abundance by comparing two rRNA markers and scanning electron microscopy (SEM). Samples were collected in August 2013 at the Outer Oslofjorden, Norway. Total RNA/cDNA was amplified by haptophyte‐specific primers targeting the V4 region of the 18S, and the D1‐D2 region of the 28S rRNA. Taxonomy was assigned using curated haptophyte reference databases and phylogenetic analyses. Both marker genes showed Chrysochromulinaceae and Prymnesiaceae to be the families with highest number of Operational Taxonomic Units (OTUs), as well as proportional abundance. The 18S rRNA data set also contained OTUs assigned to eight supported and defined clades consisting of environmental sequences only, possibly representing novel lineages from family to class. We also recorded new species for the area. Comparing coccolithophores by SEM with metabarcoding shows a good correspondence with the 18S rRNA gene proportional abundances. Our results contribute to link morphological and molecular data and 28S to 18S rRNA gene sequences of haptophytes without cultured representatives, and to improve metabarcoding methodology.

• Johannessen, Torill Vik; Larsen, Aud; Bratbak, Gunnar; Pagarete, António; Edvardsen, Bente & Egge, Elianne Dunthorn [Vis alle 7 forfattere av denne artikkelen] (2017). Seasonal dynamics of haptophytes and dsDNA algal viruses suggest complex virus-host relationship. Viruses. ISSN 1999-4915. 9(4). doi: 10.3390/v9040084. Fulltekst i vitenarkiv
• Edvardsen, Bente; Egge, Elianne Dunthorn & Vaulot, Daniel (2016). Diversity and distribution of haptophytes revealed by environmental sequencing and metabarcoding – a review. Perspectives in Phycology. ISSN 2364-6993. 3(2), s. 77–91. doi: 10.1127/pip/2016/0052.
• Forster, Dominik; Dunthorn, Micah; Mahé, Frédéric; Dolan, John R.; Audic, Stéphane & Bass, David [Vis alle 35 forfattere av denne artikkelen] (2016). Benthic protists: The under-charted majority. FEMS Microbiology Ecology. ISSN 0168-6496. 92(8), s. 1–11. doi: 10.1093/femsec/fiw120.
• McNamee, Sara E.; Medlin, Linda K.; Kegel, Jessica; McCoy, Gary R.; Raine, Robin & Barra, Lucia [Vis alle 22 forfattere av denne artikkelen] (2016). Distribution, occurrence and biotoxin composition of the main shellfish toxin producing microalgae within European waters: A comparison of methods of analysis. Harmful Algae. ISSN 1568-9883. 55, s. 112–120. doi: 10.1016/j.hal.2016.02.008.
• Banguera-Hinestroza, E; Eikrem, W; Mansour, H; Solberg, I; Cúrdia, J & Holtermann, K [Vis alle 8 forfattere av denne artikkelen] (2016). Seasonality and toxin production of Pyrodinium bahamense in a Red Sea lagoon. Harmful Algae. ISSN 1568-9883. 55, s. 163–171. doi: 10.1016/j.hal.2016.03.002.
• Engesmo, Anette; Eikrem, Wenche; Seoane, Sergio; Smith, Kirsty; Edvardsen, Bente & Hofgaard, Antje [Vis alle 7 forfattere av denne artikkelen] (2016). New insights into the morphology and phylogeny of Heterosigma akashiwo (Raphidophyceae), with the description of Heterosigma minor sp. nov. Phycologia. ISSN 0031-8884. 55(3), s. 279–294. doi: 10.2216/15-115.1.
• Massana, Ramon; Gobet, Angelique; Audic, Stéphane; Bass, David; Bittner, Lucie & Boutte, Christophe [Vis alle 35 forfattere av denne artikkelen] (2015). Marine protist diversity in European coastal watersand sediments as revealed by high-throughputsequencing. Environmental Microbiology. ISSN 1462-2912. 17(10), s. 4035–4049. doi: 10.1111/1462-2920.12955.
• Egge, Elianne Sirnæs; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie & Larsen, Aud [Vis alle 8 forfattere av denne artikkelen] (2015). Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing. Molecular Ecology. ISSN 0962-1083. 24(12), s. 3026–3042. doi: 10.1111/mec.13160. Fulltekst i vitenarkiv
• Gerecht, Andrea Cornelia; Supraha, Luka; Edvardsen, Bente; Langer, Gerald & Henderiks, Jorijntje (2015). Phosphorus availability modifies carbon production in Coccolithus pelagicus (Haptophyta). Journal of Experimental Marine Biology and Ecology. ISSN 0022-0981. 472, s. 24–31. doi: 10.1016/j.jembe.2015.06.019.
• Johannessen, Torill Vik; Bratbak, Gunnar; Larsen, Aud; Ogata, Hirotaka; Egge, Elianne Sirnæs & Edvardsen, Bente [Vis alle 8 forfattere av denne artikkelen] (2015). Characterisation of three novel giant viruses reveals huge diversity among viruses infecting Prymnesiales (Haptophyta). Virology. ISSN 0042-6822. 476, s. 180–188. doi: 10.1016/j.virol.2014.12.014.
• Egge, Elianne Sirnæs; Eikrem, Wenche & Edvardsen, Bente (2015). Deep-branching novel lineages and high diversity of haptophytes in the Skagerrak (Norway) uncovered by 454 pyrosequencing. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 62(1), s. 121–140. doi: 10.1111/jeu.12157. Vis sammendrag

  Microalgae in the division Haptophyta may be difficult to identify to species by microscopy because they are small and fragile. Here, we used high-throughput sequencing to explore the diversity of haptophytes in outer Oslofjorden, Skagerrak, and supplemented this with electron microscopy. Nano- and picoplanktonic subsurface samples were collected monthly for 2 yr, and the haptophytes were targeted by amplification of RNA/cDNA with Haptophyta-specific 18S ribosomal DNA V4 primers. Pyrosequencing revealed higher species richness of haptophytes than previously observed in the Skagerrak by microscopy. From ca. 400,000 reads we obtained 156 haptophyte operational taxonomic units (OTUs) after rigorous filtering and 99.5% clustering. The majority (84%) of the OTUs matched environmental sequences not linked to a morphological species, most of which were affiliated with the order Prymnesiales. Phylogenetic analyses including Oslofjorden OTUs and available cultured and environmental haptophyte sequences showed that several of the OTUs matched sequences forming deep-branching lineages, potentially representing novel haptophyte classes. Pyrosequencing also retrieved cultured species not previously reported by microscopy in the Skagerrak. Electron microscopy revealed species not yet genetically characterised and some potentially novel taxa. This study contributes to linking genotype to phenotype within this ubiquitous and ecologically important protist group, and reveals great, unknown diversity.

• Logares, Ramiro; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe & Christen, Richard [Vis alle 29 forfattere av denne artikkelen] (2014). Patterns of Rare and Abundant Marine Microbial Eukaryotes. Current Biology. ISSN 0960-9822. 24(8), s. 813–821. doi: 10.1016/j.cub.2014.02.050.
• Keeling, Patrick J.; Burki, Fabien; Wilcox, Heather M.; Allam, Bassem; Allen, Eric E. & Amaral-Zettler, Linda A. [Vis alle 81 forfattere av denne artikkelen] (2014). The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): Illuminating the Functional Diversity of Eukaryotic Life in the Oceans through Transcriptome Sequencing. PLoS Biology. ISSN 1544-9173. 12:e1001889(6). doi: 10.1371/journal.pbio.1001889. Fulltekst i vitenarkiv
• Dunthorn, Micah; Otto, Johannes; Berger, Simon A.; Stamatakis, Alexandros; Mahé, Frédéric & Romac, Sarah [Vis alle 16 forfattere av denne artikkelen] (2014). Placing environmental next-generation sequencing amplicons from microbial eukaryotes into a phylogenetic context. Molecular Biology and Evolution (MBE). ISSN 0737-4038. 31(4), s. 993–1009. doi: 10.1093/molbev/msu055.
• Gerecht, Andrea Cornelia; Supraha, Luka; Edvardsen, Bente; Probert, I. & Henderiks, Jorijntje (2014). High temperature decreases the PIC/POC ratio and increases phosphorus requirements in Coccolithus pelagicus (Haptophyta). Biogeosciences. ISSN 1726-4170. 11(13), s. 3531–3545. doi: 10.5194/bg-11-3531-2014.
• Duffield, Christopher James; Edvardsen, Bente; Eikrem, Wenche & Alve, Elisabeth (2014). Effects of different potential food sources on upper-bathyal benthic foraminifera: an experiment with propagules. Journal of Foraminiferal Research. ISSN 0096-1191. 44(4), s. 416–433. doi: 10.2113/gsjfr.44.4.416.
• Medlin, Linda K.; Montresor, Marina; Graneli, Edna; Reugera, Beatrix; Raine, Robin & Edvardsen, Bente [Vis alle 10 forfattere av denne artikkelen] (2013). MIDTAL (Microarrays for the Detection of toxic Algae). Phytotaxa. ISSN 1179-3155. 127(1), s. 201–210. doi: 10.11646/phytotaxa.127.1.19.
• Egge, Elianne Sirnæs; Bittner, Lucie; Andersen, Tom; Audic, Stéphane; de Vargas, Colomban & Edvardsen, Bente (2013). 454 Pyrosequencing to Describe Microbial Eukaryotic Community Composition, Diversity and Relative Abundance: A Test for Marine Haptophytes. PLOS ONE. ISSN 1932-6203. 8(9). doi: 10.1371/journal.pone.0074371. Fulltekst i vitenarkiv
• Stüken, Anke ; Dittami, Simon; Eikrem, Wenche; McNamee, Sara; Campbell, Katrina & Jakobsen, Kjetill Sigurd [Vis alle 7 forfattere av denne artikkelen] (2013). Novel hydrolysis-probe based qPCR assay to detect saxitoxin transcripts of dinoflagellates in environmental samples. Harmful Algae. ISSN 1568-9883. 28, s. 108–117. doi: 10.1016/j.hal.2013.06.003.
• Dittami, Simon; Riisberg, Ingvild & Edvardsen, Bente (2013). Molecular probes for the detection and identification of ichthyotoxic marine microalgae of the genus Pseudochattonella (Dictyochophyceae, Ochrophyta). Environmental Science and Pollution Research. ISSN 0944-1344. 20(10), s. 6824–6837. doi: 10.1007/s11356-012-1402-2.
• Dittami, Simon; Hostyeva, Vladyslava; Egge, Elianne Sirnæs; Kegel, Jessica U.; Eikrem, Wenche & Edvardsen, Bente (2013). Seasonal dynamics of harmful algae in outer Oslofjorden monitored by microarray, qPCR, and microscopy. Environmental Science and Pollution Research. ISSN 0944-1344. 20(10), s. 6719–6732. doi: 10.1007/s11356-012-1392-0.
• Dittami, Simon & Edvardsen, Bente (2013). GPR-Analyzer: a simple tool for quantitative analysis of hierarchical multispecies microarrays. Environmental Science and Pollution Research. ISSN 0944-1344. 20(10), s. 6808–6815. doi: 10.1007/s11356-012-1051-5.
• Skjelbred, Birger; Edvardsen, Bente & Andersen, Tom (2013). Environmental Optima for Seven Strains of Pseudochattonella (Dictyochophyceae, Heterokonta). Journal of Phycology. ISSN 0022-3646. 49(1), s. 54–60. doi: 10.1111/jpy.12008. Fulltekst i vitenarkiv
• Edvardsen, Bente; Dittami, Simon; Groben, René; Brubak, Sissel Irene; Escalera, Laura & Rodriguez, Francisco [Vis alle 9 forfattere av denne artikkelen] (2013). Molecular probes and microarrays for the detection of toxic algae in the genera Dinophysis and Phalacroma (Dinophyta). Environmental Science and Pollution Research. ISSN 0944-1344. 20(10), s. 6733–6750. doi: 10.1007/s11356-012-1403-1.
• Bittner, Lucie; Gobet, Angelique; Audic, Stéphane; Romac, Sarah; Egge, Elianne Sirnæs & Santini, Sebastien [Vis alle 10 forfattere av denne artikkelen] (2013). Diversity patterns of uncultured Haptophytes unravelled by pyrosequencing in Naples Bay. Molecular Ecology. ISSN 0962-1083. 22(1), s. 87–101. doi: 10.1111/mec.12108.
• Guillou, L; Bachar, Dipankar; Audic, Stéphane; Bass, David; Berney, Cedric & Bittner, Lucie [Vis alle 32 forfattere av denne artikkelen] (2013). The Protist Ribosomal Reference database (PR2): a catalog of unicellular eukaryote Small Sub-Unit rRNA sequences with curated taxonomy. Nucleic Acids Research (NAR). ISSN 0305-1048. 41(D1), s. D597–D604. doi: 10.1093/nar/gks1160.
• McCoy, Gary; Raine, Robin; Medlin, Linda K.; Chen, Jixin; Kooistra, Wiebe & Barra, Luciana [Vis alle 21 forfattere av denne artikkelen] (2012). Field testing for toxic algae with a microarray: initial results from the MIDTAL project. I Pagou, Kalliopi & Hallegraeff, Gustaaf (Red.), Proceedings of the 14th International Conference on Harmful Algae. International Society for the Study of Harmful Algae and Intergovernmental Oceanographic Commission of UNESCO. Unesco. ISSN 978-87-990827-3-5. s. 209–211. Fulltekst i vitenarkiv
• Hostyeva, Vladyslava; Eikrem, Wenche; Edvardsen, Bente & Hasle, Grethe Rytter (2012). Annual cycle of Pseudo-nitzschia species in Outer Oslofjorden, Norway. I Pagou, Kalliopi & Hallegraeff, Gustaaf (Red.), Proceedings of the 14th International Conference on Harmful Algae. International Society for the Study of Harmful Algae and Intergovernmental Oceanographic Commission of UNESCO. Unesco. ISSN 978-87-990827-3-5. s. 81–83. Fulltekst i vitenarkiv
• Skjelbred, Birger; Edvardsen, Bente & Andersen, Tom (2012). A high-throughput method for measuring growth and loss rates in microalgal cultures. Journal of Applied Phycology. ISSN 0921-8971. 24(6), s. 1589–1599. doi: 10.1007/s10811-012-9819-z.
• Dittami, Simon & Edvardsen, Bente (2012). CULTURE CONDITIONS INFLUENCE CELLULAR RNA CONTENT IN ICHTHYOTOXIC FLAGELLATES OF THE GENUS PSEUDOCHATTONELLA (DICTYOCHOPHYCEAE). Journal of Phycology. ISSN 0022-3646. 48(4), s. 1050–1055. doi: 10.1111/j.1529-8817.2012.01183.x.
• Graneli, Edna; Edvardsen, Bente; Roelke, Daniel & Hagström, Johannes A. (2012). The ecophysiology and bloom dynamics of Prymnesium spp. Harmful Algae. ISSN 1568-9883. 14(1), s. 260–270. doi: 10.1016/j.hal.2011.10.024. Vis sammendrag

  Members of Prymnesium belong to the division Haptophyta, class Prymnesiophyceae, order Prymnesiales and family Prymnesiaceae. As most haptophytes, members of the genus Prymnesium are unicellular and planktonic. The most known of these species is the ichthyotoxic P. parvum, which may form nearly monospecific dense blooms in coastal and inland waters. This species possesses extraordinary plasticity concerning life survival strategies, and is specifically addressed in this review. Toxins produced by P. parvum have hemolytic properties, that not only kill fish but also co-existing plankton. These substances are allelopathic (when other algae are killed) and grazer deterrent (when grazers are killed). Allelopathy enables P. parvum to utilize inorganic nutrients present in the surrounding water without competition from other algal species; and by eliminating its grazers P. parvum reduces cell losses. The paralized microalgae and/or zooplankton, are therefter ingested by the P. parvum cells, a process called phagotrophy. P. parvum is also able of osmotrophy, i.e. utilization of dissolved organic matter. In this review, the cellular characteristics, life cycles, bloom formation, and factors affecting toxicity, allelopathy, phagotrophy, and osmotrophy of P. parvum are discussed.

• Ota, Shuhei; Eikrem, Wenche & Edvardsen, Bente (2012). Ultrastructure and Molecular Phylogeny of Thaumatomonads (Cercozoa) with Emphasis on Thaumatomastix salina from Oslofjorden, Norway. Protist. ISSN 1434-4610. 163(4), s. 560–573. doi: 10.1016/j.protis.2011.10.007. Vis sammendrag

  A culture of Thaumatomastix was isolated from a sediment sample collected in Oslofjorden and established as a monospecific strain (UIO286). Based on this culture, light and transmission electron microscopy and phylogenetic analyses were carried out. Thaumatomastix species are confined within the order Thaumatomonadida of the class Imbricatea and phylum Cercozoa. They are heterotrophic and their cell bodies are covered with silica scales. Observations of thin sections as well as whole mounts indicate that the morphology and ultrastructure of UIO286 is identical to T. salina, which was initially described from salt pools in Denmark. Detailed examination revealed some new features such as the presence of pseudopodia and silica deposition vesicles producing spine scales. The phylogeny presented here includes ribosomal DNA sequences from both imbricatean cultures and environmental samples. The 18S rDNA phylogenetic tree suggests that (i) Thaumatomastix is paraphyletic within the Thaumatomonadida clade, (ii) there is no close affinity between T. salina and other cultured and sequenced strains, but it is closely related to a sequence obtained from environmental DNA; we propose the present strain to serve as a reference culture of Thaumatomastix species and T. salina. Further, we discuss the distribution, habitats, and evolution of scale formation among euglyphids and thaumatomonads.

• Dittami, Simon; Riisberg, Ingvild; John, Uwe; Orr, Russell; Jakobsen, Kjetill Sigurd & Edvardsen, Bente (2012). Analysis of Expressed Sequence Tags from the Marine Microalga Pseudochattonella farcimen (Dictyochophyceae). Protist. ISSN 1434-4610. 163(1), s. 143–161. doi: 10.1016/j.protis.2011.07.004.
• Sym, Stuart; Pienaar, Richard; Edvardsen, Bente & Egge, Elianne Sirnæs (2011). Fine structure and systematics of Prymnesium radiatum sp. nov. (Prymnesiophyceae) from False Bay and Franskraal, South Africa. European journal of phycology. ISSN 0967-0262. 46(3), s. 229–248. doi: 10.1080/09670262.2011.554886. Vis sammendrag

  A novel colonial prymnesiophyte from the inshore waters of South Africa, which is reminiscent of the genus Corymbellus, is described at light and electron microscope levels. It differs from the only species of this genus, Corymbellus aureus, in scale structure, cell shape and colony morphology and has a complement of unusual morphological features that link it most with members of the Prymnesiales. Phylogenetic analyses of the nuclear-encoded SSU and LSU ribosomal DNA sequences indicate that this organism is closely related to members of the genus Prymnesium sensu lato and it is thus considered as a novel species, here named P. radiatum. The closest relative to P. radiatum in the SSU rDNA phylogenetic tree was Prymnesium neolepis (formerly Hyalolithus neolepis). The reconfiguration of the cytoskeleton during cell division in this organism is also novel, with a progressive elaboration of existing elements, rather than the massive reorganization expected in the prymnesiophytes.

• Edvardsen, Bente; Eikrem, Wenche; Throndsen, Jahn; Sáez, Alberto; Probert, Ian & Medlin, Linda K. (2011). Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of Prymnesiales (Haptophyta). European journal of phycology. ISSN 0967-0262. 46(3), s. 202–228. doi: 10.1080/09670262.2011.594095. Vis sammendrag

  Nucleotide sequences of the nuclear-encoded small subunit (18S rDNA) and partial large subunit (28S rDNA) ribosomal DNA were determined in 30 different species of the haptophyte genera Prymnesium, Chrysocampanula, Chrysochromulina, Imantonia and Platychrysis, all belonging to the order Prymnesiales. Phylogenies based on these and other available haptophyte 18S, 28S and plastid 16S rDNA sequences were reconstructed, and compared with available morphological and ultrastructural data. The rDNA phylogenies indicate that the genus Chrysochromulina is paraphyletic and is divided into two major clades. This is supported by ultrastructural and morphological data. There is a major split between Chrysochromulina species with a saddle-shaped cell form (clade B2) and the remaining species in the genus (clade B1). Clade B2 includes the type species C. parva and taxa belonging to this clade thus retain the name Chrysochromulina. The non-saddle-shaped Chrysochromulina species analysed are closely related to Hyalolithus, Prymnesium and Platychrysis species. Imantonia species are sister taxa to these species within clade B1. An amendment to the classification of the order Prymnesiales and the genera Prymnesium, Platychrysis and Chrysochromulina is proposed with one new and one emended family (Chrysochromulinaceae and Prymnesiaceae, respectively), two new genera (Haptolina and Pseudohaptolina), and one new species (Pseudohaptolina arctica). We suggest a revision of the taxonomy of the Prymnesiales that is in accordance with available molecular evidence and supported by morphological data.

• Dittami, Simon; Aas, Hoai Thi Nguyen; Paulsen, Berit Smestad; Boyen, Catherine; Edvardsen, Bente & Tonon, Thierry (2011). Mannitol in six autitrophic stramenopiles and micromonas. Plant Signalling & Behavior. ISSN 1559-2316. 6(8), s. 1–3. doi: 10.4161/psb.6.8.16404.

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• Eikrem, Wenche; Vader, Anna; Hofgaard, Antje & Edvardsen, Bente (2023). Phytoplankton in the Arctic Ocean - Species Composition and Biomass during the Nansen Legacy Arctic basin cruise, 24 Aug-26 Sep 202. Vis sammendrag

  At the southern-most station along the S-N transect, P7, the pelagic protist community was characterized by both high diversity and abundance. Large diatom species dominated the community, and large dinoflagellates and Phaeocystis pouchetii were also abundant. Moving north and into the ice, the protist community in the water column changed. Smaller organisms and heterotrophic species became more prominent. The larger diatom species became much scarcer but were still present. The community in the ice cores was dominated by pennate diatoms, but dinoflagellates and in particular the heterotrophic species were also abundant. In addition, green flagellates, cryptomonads, chrysophytes, and haptophytes were frequent. The sea-ice showed the highest chlorophyll-a values and had larger cells. In the melt ponds the salinity was low, but variable (2.8-5.7). The chlorophyll-a values there were low, and the species composition varied, and the taxa present were associated with brackish and freshwater as well as a benthic lifestyle.

• Saubrekka, Karoline; Vader, Anna; Supraha, Luka & Edvardsen, Bente (2023). Diversity and distribution of Arctic protists in pelagic and sympagic habitats in the northern Barents Sea as revealed by metabarcoding. Vis sammendrag

  Protists play crucial roles in the marine ecosystems and in a rapidly changing Arctic it is important to reveal who are there, when and where, for future research and management. The aim of this study was to describe and compare the composition of protist communities in sea ice and pelagic habitats from samples collected in the northern Barents Sea along a transect in August 2018 with low sea-ice extent and 2019 with high sea-ice extent. Metabarcoding targeting the 18S rRNA gene revealed 3682 unique amplicon sequence variants (ASVs), a proxy for species, and clear difference in ASV composition in ice and pelagic habitats. The pelagic community showed interannual differences. In 2018 the community was dominated by dinoflagellates and nano- and pico-plankton such as Micromonas polaris. In 2019 a community with more centric diatoms was observed at ice edge stations. Members of the class Chrysophyceae dominated in melt ponds, whereas communities within the ice were dominated by dinoflagellates and pennate diatoms. The community changed from top to bottom of the ice cores and the diversity was higher in thick than thin ice. Just below the ice, dinoflagellate ASVs dominated together with Phaeocystis. Our results indicate that protist communities are distinct and specialized by habitat. With further ocean warming, pelagic communities may shift towards smaller flagellates, and thinning of the sea ice may lead to a loss of habitats and diversity.

• Edvardsen, Bente; Supraha, Luka; Egge, Elianne Dunthorn & Saubrekka, Karoline (2023). Diversity and distribution of marine protists in the Arctic explored by a polyphasic approach.
• Edvardsen, Bente (2023). Biodiversity of microalgae in Scandinavian marine waters.
• Saubrekka, Karoline; Vader, Anna; Supraha, Luka; Andersen, Tom & Edvardsen, Bente (2023). Diversity and Distribution of Arctic Protists in Pelagic and Sympagic Habitats in the Northern Barents Sea as Revealed by Metabarcoding.
• Edvardsen, Bente (2023). On the track of causes for fish-killing algal blooms. Vis sammendrag

  Harmful algal blooms (HABs) in marine, brackish and fresh waters resulting in fish-kills occur worldwide and may lead to great economic and ecological losses, as well as suffering for the fish. Farmed fish in pens and ponds are especially prone as they cannot escape from the blooms. Many ichthyotoxic blooms are sporadic events and the causes and triggering factors of these HABs are often poorly understood. Knowledge on the responsible algae and their physiology, ecology and environmental factors promoting their growth are required to understand these events. Bloom formation may also be linked to their toxicity through a relaxation of the top-down control from grazers, pathogens or competitors. We thus also need to understand how toxin production or toxicity are affected by various environmental factors to be able to understand causes of HABs. Knowledge about the responsible toxin(s) and their mode of action may however be limited and difficult to quantify. In this presentation I will compare ichthyotoxic haptophytes and look at similarities and differences in their bloom formation, ecology, physiology and toxicity in order to better understand causes for some of these blooms, especially of the little studied species Chrysochromulina leadbeateri.

• Edvardsen, Bente; Fon, Mathias; Reitzel, Helene; Šupraha, Luka; Andersen, Tom & Uhlig, Silvio (2023). Growth preferences of the haptophyte Chrysochromulina leadbeateri forming ichthyotoxic blooms in fjords in N Norway. Vis sammendrag

  Microalgal flagellates of the genera Chrysochromulina and Prymnesium may form extensive blooms in marine and brackish waters causing fish kills. Chrysochromulina leadbeateri blooms caused massive fish kills in fish farms in Northern Norway in May 1991 and 2019. More than 14 500 tons of farmed salmon died in 2019. Cultures from both blooms were used in physiological experiments to investigate possible causes for the blooms. Growth experiments with varying salinity, temperature and irradiance in a facultative design were performed. Highest growth rates were obtained at temperatures 11-15 oC and salinities 25-30, and the tolerance range for growth were between 4-15 oC and salinities 20-34. Under optimal conditions, growth rates increased with irradiance (up to 100 µmol photons m-2 s-1). During the bloom in 2019, highest C. leadbeateri concentrations were found in waters with slightly reduced salinity (32-33) and sea surface temperatures around 7oC. Strains from the blooms in 1991 and 2019 were identical in the 18S rRNA gene. This ribotype appears to have a cold water-Arctic geographical distribution based on the metaPR2 metabarcoding datasets, whereas other ribotypes of C. leadbeateri in this dataset show a cosmopolitan or temperate-warm water distribution. We suggest that C. leadbeateri consists of several ribotypes with different growth preferences and that the toxic blooms in Northern Norway were formed by a ribotype adapted to cold waters with slightly reduced salinity and can tolerate rather high irradiances. Possible causes for the ichthyotoxic blooms will be discussed.

• Larsen, Thomas ostenfeld; Wang, Xinhui; Fon, Mathias; Andersen, Aaron John Christian; Hansen, Per Juel & Uhlig, Silvio [Vis alle 8 forfattere av denne artikkelen] (2023). Insights into the chemistry of microalgal toxins involved in recent northern European fish killing events.
• Fon, Mathias; Supraha, Luka; Andersen, Tom; Uhlig, Silvio & Edvardsen, Bente (2023). Using high-throughput techniques to understand the growth of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway.
• Samdal, Ingunn Anita; Uhlig, Silvio; Solhaug, Anita; Fon, Mathias; Gilbert, Dorothea & Ivanova, Lada [Vis alle 15 forfattere av denne artikkelen] (2023). Toxic microalgae in Norwegian waters - Uncovering fish-killing mechanisms of phytoplankton from Scandinavian waters.
• Kwasniewski, Slawomir; Altenburger, Andreas; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Dabrowska, Anna Maria & Edvardsen, Bente [Vis alle 25 forfattere av denne artikkelen] (2023). Biodiversity in the northern Barents Sea and adjacent Nansen Basin – towards an updated inventory. Vis sammendrag

  Biodiversity patterns shape and drive ecosystem processes and functions in the global ocean. Given the changing climate and recent agreements to protect ocean regions, current estimates of biodiversity must be assembled. Here, we present new estimates and spatial patters of taxon richness from microbes to mammals from a shelf-to-basin transect in the northern Barents Sea and southern Nansen Basin from seasonal sampling in 2018-2022 by the Nansen Legacy project. We find that estimates of taxon richness are higher on the shelf than in the basin for pelagic protists, zooplankton, and benthic macrobenthos, nematodes, and prokaryotes, but not for sympagic protists. Taxon richness varied seasonally for pelagic prokaryotes, protists, and zooplankton, but little for sympagic meiofauna, benthic prokaryotes and macrobenthos. Unsurprisingly, taxon richness was generally highest for single-celled taxa. Taxon-rich groups included: sympagic diatoms; pelagic prokaryotes (e.g., Alphaproteobacteria), diatoms, dinoflagellates, copepods; and benthic prokaryotes (with abundant taxa, e.g., Candidatus nitrosopumilus and Woesia), nematodes, and polychaetes. Unexpectedly absent - though known from earlier studies - were, for example, nematodes in sea ice. Ironically, at top (and perhaps other) trophic levels species richness is likely to be enhanced regionally for some time, while losses of Arctic (endemic) species will impact global biodiversity, and potentially Arctic ecosystem functioning

• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Patrohay, Evan & Aaboe, Signe [Vis alle 12 forfattere av denne artikkelen] (2023). Seasonal dynamics of sea ice protists and meiofauna in the northwestern Barents Sea in relation to sea ice properties . Vis sammendrag

  The rapid decline of Arctic sea-ice including that in the Barents Sea makes understanding sympagic biology an urgent task. Seasonal ice sampling (2019-2022) as part of the Nansen Legacy project focused on ice biota composition and abundance in the bottom 30cm of Barents Sea ice in relation to ice properties. In December and May we sampled growing first-year ice, while in July and August melting, older sea ice dominated, overall agreeing with ice trajectories. Abiotic ice conditions and Chla varied strongly seasonally, while POC values were unexpectedly homogenous. Low ice biota abundances in March could be related to late ice formation resulting in a short time for biota to build up biomass. Pennate diatoms dominated the bottom ice algal communities in all seasons, with highest biomass in May. Outside May, small-sized flagellates were co-dominant. Overall, ice meiofauna was comprised of harpacticoid copepods, copepod nauplii and rotifers, foraminiferans and highly abundant ciliates. While melting ice had released ice algal biomass in July, abundance of secondary producers remained high, indicating different life history traits. Unexpectedly abundant communities occurred in December, further strengthened the notion of an active biota in the dark Arctic winter. The data demonstrated a strong and partly unexpected seasonality in the ice biota, indicating that changing timing of ice formation and melt will significantly impact composition and phenology of sympagic communities.

• Marquardt, Miriam; Assmy, Philipp; Edvardsen, Bente; Goraguer, Lucie Hélène Marie; Gradinger, Rolf Rudolf & Patrohay, Evan [Vis alle 9 forfattere av denne artikkelen] (2023). Seasonal dynamics of sea ice protists and meiofauna in the northern Barents Sea. Vis sammendrag

  The declining Arctic sea ice makes understanding sympagic biology a urgent task, including the Northern Barents Sea, which is highly influenced by ice loss and increased Atlantic inflow. A seasonal ice sampling effort (2019-2022) as part of the Nansen Legacy project focused on the poorly known ice biota composition and abundance in the bottom 30cm of Barents Sea ice in relation to season, hydrography and ice properties. We expected low abundances during the polar night and highest values during the spring prior to ice melt. From December and March, ice thickness increased while melting dominated in summer. Pennate diatoms, such as Navicula and Nitzschia spp., were dominating the bottom ice protist communities during all periods, while small-sized dinoflagellates were co-dominant. Ice meiofauna was comprised of harpacticoid copepods, copepod nauplii, rotifers, occasional visitors such as acoels and foraminiferans and highly abundant ciliates (50-90 %; total abundances). Surprisingly, active December communities occurred in higher than expected abundances. Low abundances in March could be related to later on-set of ice formation and reduced time for biota to establish. Maximum meiofauna abundances in May reflect a late spring bloom development. In August despite ice melting meiofauna abundances were still high. The data demonstrated a strong and partially unexpected seasonality in the ice biota, indicating that changing timing of ice formation and decay will significantly impact the current sea ice biology.

• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp; Bluhm, Bodil; Aaboe, Signe & Down, Emily [Vis alle 12 forfattere av denne artikkelen] (2023). Seasonal dynamics of sea ice protists and meiofauna in the Northern Barents Sea. .
• Chen, An; Fon, Mathias; Edvardsen, Bente; Uhlig, Silvio & Solhaug, Anita (2023). Evaluation of toxicity of the microagla Chrysochromulina leadbeateri using the Atlantis salmon gill epithelial cell line ASG-10.
• Edvardsen, Bente (2022). Mikroalger i Arktis - hvor unike er de?
• Edvardsen, Bente (2022). DNA-strekkoding – et verktøy for gjennkjenning av arter.
• Edvardsen, Bente (2022). Planteplankton i Oslofjorden, endringer og mulige årsaker.
• Edvardsen, Bente; Supraha, Luka & Egge, Elianne Dunthorn (2022). Diversity and distribution of marine protists in the Arctic explored by a polyphasic approach.
• Edvardsen, Bente (2022). Metabarcoding and Systematics of Protists in the Ocean to Understand Ecosystem Functioning.
• Edvardsen, Bente (2022). Exploration of protist diversity and distribution in the ocean by a polyphasic approach.
• Edvardsen, Bente & Eikrem, Wenche (2022). Haptophyte taxonomy.
• Edvardsen, Bente; Supraha, Luka; Egge, Elianne Dunthorn & John, Uwe (2022). Harmful haptophyte blooms in Norway - bloom dynamics and ecology, with special focus on the Chrysochromulina leadbeateri blooms.
• Vogt, Yngve & Edvardsen, Bente (2020). Varmere hav endrer algesamfunnet i Arktis. Apollon : Forskningsmagasin for Universitetet i Oslo. ISSN 0803-6926.
• Edvardsen, Bente; Supraha, Luka; Gran-Stadniczeñko, Sandra; Eikrem, Wenche & John, Uwe (2020). An in-depth study of Chrysochromulina leadbeateri bloom in northern Norway during spring 2019. Vis sammendrag

  The toxic algal bloom of the haptophyte Chrysochromulina leadbeateri in spring 2019 was the largest bloom of this species in Norwegian waters and worldwide ever recorded. Starting in the Vestfjorden area in northern Norway during early May and expanding north to Balsfjorden and Tromsø area, the bloom caused a major mortality of farmed salmon, with over 13 000 tonns of fish reported as lost during the outbreak. The C. leadbeateri bloom in northern Norway was studied in-depth in frame of a research cruise led by Alfred Wegener Institute (Germany) and in collaboration with the University of Oslo. The cruise focused on studies of phytoplankton diversity, distribution and functional ecology in several fjord systems along the northern Norwegian coast (Lofoten-Vesterålen area, Balsfjorden, Lyngen, Porsangerfjorden, Laksefjorden, Tanafjorden). Biological and environmental data collected during the cruise allowed for detailed analyses of the blooming organism, its distribution patterns in northern Norway, and its ecology. Cultures of C. leadbeateri isolated from the bloom were used to determine the morphology, taxonomic identity, and phylogenetic placement of the organism, and to compare it with a C. leadbeateri strain isolated from the previous major bloom in 1991. Metabarcoding data, light microscopy counts and flow cytometry data were used to map the distribution and abundance of the species along the coast of northern Norway, and correlate its distribution with biotic and abiotic parameters. Preliminary results show that the blooming organism is genetically identical in marker genes to the strain from the bloom in Vestfjorden in 1991. However, both strains and C. leadbeateri in field material exhibit significant intraspecific genetic variability. Biogeographic mapping shows that the bloom was most pronounced in the Balsfjorden area, with maximum cell concentration of over 27 million cells L-1. From an ecological perspective, C. leadbeateri abundance showed positive correlation with phosphate and nitrate, negative correlation with salinity and a slightly positive correlation with temperature. The results of our work provide a unique, in-depth insight into C. leadbeateri blooms, which may help in the monitoring, modelling and predicting similar events in the future. Ongoing work in our group focus on physiological and genetic profiling of the isolated C. leadbeateri strains with the aim to improve our understanding of factors triggering toxicity and bloom formation.

• Edvardsen, Bente (2020). Norsk algekultursamling (NORCCA) - en verdifull ressurs for innovasjon.
• Samdal, Ingunn Anita & Edvardsen, Bente (2020). Massive salmon mortalities during a Chrysochromulina leadbeateri bloom in Northern Norway. Harmful Algae News. ISSN 0020-7918. s. 4–5.
• Edvardsen, Bente; Lundholm, Nina & Medlin, Linda K. (2018). Tribute to Professor Grethe Ryther Hasle. Diatom Research. ISSN 0269-249X. 33(1), s. 117–122. doi: 10.1080/0269249X.2018.1451392.
• Edvardsen, Bente (2018). Endosymbiose hos alger i havet. Biolog. ISSN 0801-0722. 1, s. 14–20.
• Edvardsen, Bente (2017). Algal cultures for biotechnological innovation.
• Edvardsen, Bente (2017). Discovery of unknown microalgae and protozoa in the Ocean. Vis sammendrag

  http://oiw.no/speakers/bente-edvardsen

• Edvardsen, Bente (2017). Symbiose og alger i havet.
• Edvardsen, Bente (2017). Klimaendringer og effekter på planteplanktonet i havet.
• Edvardsen, Bente (2017). Planteplanktonet i havet og effekter av klimaforandringer. Vis sammendrag

  Planteplanktonet i havet står for nesten halvparten av all fotosyntese og oksygenproduksjon på jorda, og er næringsgrunnlaget for det meste av livet i havet. Planteplanktonets sammensetning har betydelse for høyere trofiske nivåer. Et viktig spørsmål er derfor hvordan klimaforandringer vil påvirke produksjonen og sammensetningen av planteplanktonet i havet, og dermed produksjon av dyreplankton og fisk. Og vil endringer i planteplanktonsamfunnet kunne påvirke klimaet? For å kunne besvare disse spørsmålene trenger vi å kjenne artene som er til stede og hvordan planktonsammensetningen varierer i tid og rom. Og hvordan styrer ulike miljøfaktorer deres forekomst? I mitt foredrag vil jeg belyse disse spørsmålene og fortelle om vår forskning hvor vi undersøker planktonets mangfold og forekomst i Oslofjorden og Arktis med DNA-analyser av typen dypsekvensering, og med lys- og elektron-mikroskopi. Med dypsekvensering har vi oppdaget et stort mangfold av små encellede eukaryoter. Mange er nye registreringer for Norge og flere taksonomiske grupper er nye for vitenskapen. Noen er til stede året rundt, andre kun deler av året, noen har vid utbredelse, andre er kun funnet i Arktis. Kunnskap om deres sesongmessige og romlige forekomst, størrelse og taksonomiske tilhørighet bidrar til å forstå deres betydning i næringsnettet.

• Edvardsen, Bente; Egge, Elianne Dunthorn; Vaulot, Daniel; Larsen, Aud; Bratbak, Gunnar & Moreau, Hervé [Vis alle 7 forfattere av denne artikkelen] (2017). Protist community structure in Atlantic Arctic through the year as revealed by high throughput sequencing.
• Egge, Elianne Dunthorn; Vaulot, Daniel; Larsen, Aud; Bratbak, Gunnar; Uwe, John & Edvardsen, Bente (2017). Protist community structure in Atlantic Arctic through the year as revealed by high throughput sequencing. Vis sammendrag

  Unicellular protists, including microalgae are main suppliers of photosynthetic products that higher trophic levels depend upon. Yet, the Arctic protist community contains a vast unknown diversity and many of the described species are poorly known. Diversity and dynamics throughout the polar night and at great depths remains particularly understudied due to limited access. In the MicroPolar project we asked “Who are present and when during the year?”, “How is the community structured by depth and geography?” and “What are the environmental driving forces for the observed distribution?” Sampling cruises to North and West of Svalbard were carried out five times during 2014 (January, March, May, August and November). Samples were collected at 3-6 stations and four depths (1-1000m). Fifty litres were divided into four size fractions from micro- to picoplankton. The 18S V4 region of nuclear rDNA and the 16S V9 region of chloroplast rDNA and rRNA were high throughput sequenced with Illumina. We obtained c. 35 000 Operational Taxonomic Units (OTUs) clustered at 98% similarity. The protist community composition differed significantly between the dark and light seasons, and between surface water and beyond the photic zone. Also OTU richness varied significantly with depth and season. OTU richness was significantly higher in the deeper layers all months except March. The May samples had lowest richness, whereas August had highest. Both in terms of OTU richness and proportional read abundance Dinophyta was dominating in most samples, except in the May samples representing the spring bloom, where diatoms dominated. The 200 most frequent OTUs were detected all seasons and in both surface and deeper layers. The majority of these were assigned to defined clades consisting of environmental sequences only, such as MAST-clades and Dino-Group clades. This highlights the need for more reference DNA sequences from cultures. Several abundant and frequent OTUs matched well-known Arctic species, such as Chaetoceros gelidus (socialis), Phaeocystis pouchetii, Gyrodinium fusiforme and Micromonas pusilla. Interestingly, OTUs assigned to Picobiliphyta were also among the most ubiquitous OTUs. Picobiliphyta were first described in 2007 in particular from samples from the Arctic Ocean, and all are thought to be heterotrophic. As global climate change is expected to be most severe in the Arctic and may affect microbial communities and biogeochemical cycles more seriously in this region than anywhere else, this study is important to be able to assess the impact of climate change in the Arctic at the microbial level.

• Eikrem, Wenche; Medlin, Linda K.; Henderiks, Jorijntje; Rokitta, Sebastian; Rost, Björn & Throndsen, Jahn [Vis alle 8 forfattere av denne artikkelen] (2017). Haptophyta. I Archibald, John M.; Simpson, Alastair G B & Slamovits, Claudio H (Red.), Handbook of the Protists. Springer Publishing Company. ISSN 978-3-319-28148-3. s. 1–61. doi: 10.1007/978-3-319-32669-6_38-1. Vis sammendrag

  Haptophyta are predominantly planktonic and phototrophic organisms that have their main distribution in marine environments worldwide. They are a major component of the microbial ecosystem, some form massive blooms and some are toxic. Haptophytes are significant players in the global carbonate cycle through photosynthesis and calcification. They are characterized by the haptonema, a third appendage used for attachment and food handling, two similar flagella, two golden-brown chloroplasts, and organic body scales that serve in species identification. Coccolithophores have calcified scales termed coccoliths. Phylogenetically Haptophyta form a well-defined group and are divided into two classes Pavlovophyceae and Coccolithophyceae (Prymnesiophyceae). Currently, about 330 species are described. Environmental DNA sequencing shows high haptophyte diversity in the marine pico- and nanoplankton, of which many likely represent novel species and lineages. Haptophyte diversity is believed to have peaked in the past and their presence is documented in the fossil record back to the Triassic, approximately 225 million years ago. Some biomolecules of haptophyte origin are extraordinarily resistant to decay and are thus used by geologists as sedimentary proxies of past climatic conditions.

• Edvardsen, Bente; Egge, Elianne Dunthorn; John, Uwe & Vaulot, Daniel (2016). Protist diversity revealed by metabarcoding in Kongsfjorden, Svalbard mesocosm experiment. Vis sammendrag

  As a part of the MicroPolar project a mesocosm experiment was conducted in Kongsfjorden, Svalbard in July 2015. The aim was to assess the effect of grazing pressure and levels of organic carbon on the microbial composition and relative abundance over time. In this part of the project we studied how the protist community composition and relative abundance were affected by these two factors. Water samples (2L) were harvested 5 times during a 10 days incubation, and DNA from the size fractions 0.2-3 and 3-50 µm were PCR amplified by eukaryote general V4 18 rRNA gene primers and tag sequenced by Illumina. Both composition and relative abundance differed significantly in response to the two factors.

• Edvardsen, Bente; Vaulot, Daniel & Egge, Elianne Sirnæs (2016). A global haptophyte 18S rRNA gene phylogeny including potentially novel lineages, and a curated reference sequence database for taxonomic assignment of metabarcodes. Vis sammendrag

  Microalgae of the division Haptophyta are a major component of the marine nanoplankton and present in all seas. They are important primary producers and grazers of picoplankton in the ocean, and their metabolic products can have an impact on global climate. Due to their small size, species are mostly difficult to distinguish by microscopy. Environmental sequencing studies have revealed a high marine haptophyte diversity. We have constructed a curated haptophyte 18S rRNA-gene reference database comprising c. 970 sequences, mostly >800 bp for taxonomic assignment of environmental sequences and metabarcoding reads. We have taxonomically assigned all sequences by phylogenetic analyses, removed chimeras, updated the taxonomy according to recent revisions, and defined clades without cultured and sequenced representatives. Haptophyta embrace numerous clades potentially representing novel lineages from genus to class level. Here we present current knowledge on their distribution based on available 18S rRNA gene sequences.

• Edvardsen, Bente; Egge, Elianne Sirnæs; Stadniczenko, Sandra Gran; Johannessen, Torill Vik; Eikrem, Wenche & Sandaa, Ruth-Anne [Vis alle 10 forfattere av denne artikkelen] (2015). Diversity and seasonal dynamics of marine haptophytes and their viruses and the role of biotic interactions. Vis sammendrag

  Members of the phytoplankton division Haptophyta are a major component in marine pico- and nanoplankton communities. They often occur in bloom concentrations that may have a major impact on the global carbon balance, on climate forcing and sometimes cause fish-kills. Because haptophytes are tiny and difficult to identify in the microscope little is known about their seasonal dynamics and ecological role at the species level. Virus may terminate haptophyte blooms and, according to the “killing the winner” concept, possibly prevent blooms by keeping them under constant control. The aim of this study within the HAPTODIV project was to reveal the diversity and dynamics of marine haptophytes to species level and how this relates to abiotic factors and viruses. We assessed the haptophyte and Phycodnaviridae/ Mimiviridae (algal viruses) taxonomic composition, OTU richness and relative abundance over time by high-throughput amplicon sequencing (metabarcoding) of monthly samples over 2 years from the outer Oslofjorden, Skagerrak, Southern Norway. Metabarcoding revealed higher haptophyte diversity (156 OTUs estimating species) than previously observed in the area with electron and light microscopy (85 spp), and most (84%) of this diversity remains to be cultured and sequenced. Many may represent novel lineages at the class to genus level, or species new for science. More than half of the OTUs (93) were affiliated with the order Prymnesiales such as members of e.g. Chrysochromulina and Prymnesium. Haptophyte richness and community composition showed high temporal variation and significant yearly periodicity correlating with light and temperature, with highest richness in autumn (Sep-Nov) and lowest in the spring (Apr-May). Our results indicated, however, that the abiotic factors only accounted for about 30% of the variation, and suggest that biotic factors explain some of the residual variation. Also algal virus diversity was high and showed temporal variations with highest richness in Sept-Oct. Biotic interactions between haptophytes and algal viruses were assessed by co-occurrence analyses. We detected 56 haptophyte-virus pairs with significant co-occurrence, of 49 000 possible pairs. The distribution patterns of these pairs may shed light on the role of virus infection on phytoplankton community composition and dynamics. We suggest that this approach may be a first step to test the “killing-the-winner” concept on haptophyte diversity and distribution.

• Edvardsen, Bente; Egge, Elianne Sirnæs; Stadniczenko, Sandra Gran; Johannessen, Torill Vik; Larsen, Aud & Sandaa, Ruth-Anne [Vis alle 7 forfattere av denne artikkelen] (2015). Diversity, seasonal dynamics and biotic interactions in marine phytoplankton and virus communities. Vis sammendrag

  The taxonomic composition of phytoplankton communities and relative abundance of taxa in oceanic ecosystems undergo continuous change. This community reorganization is of major importance to higher trophic levels and biogeochemical cycles. This succession is partly accounted for by hydrographical and meteorological variations that select for different traits in time and space, but also by biological processes, such as pathogens. Virus may terminate haptophyte blooms and, according to the “killing the winner” concept, possibly prevent blooms by keeping them under constant control. We assessed the haptophyte (algal host) and Phycodnaviridae/Mimiviridae (virus) taxonomic composition and relative abundance by high-throughput amplicon sequencing of monthly samples over 2 years from the outer Oslofjorden. Haptophyte richness and community composition exhibited high temporal variation and significant yearly periodicity, with highest richness in autumn (Sept-Oct) and lowest in the spring (April-May). Also, algal virus diversity showed seasonal variations with highest richness in September-October and lowest in August. Biotic interactions between haptophytes and viruses and among haptophytes were evaluated to provide new insight in the role of biotic processes for phytoplankton community composition and dynamics.

• Edvardsen, Bente & Hessen, Dag Olav (2015). Genome size variation in microalgae”. Vis sammendrag

  Genome size among eukaryotic microalgae vary with a factor of more than 17 000. The rRNA gene copy number similarly vary more than 12 000 times. The lowest genome size and rRNA gene copy number has been found in picoplanktonic chlorophytes (Ostreococcus, 12 Mb) and ochrophytes (Nannochloropsis, 25 Mb) and the highest in large dinoflagellate cells (e.g. c. 450 Gb in Prorocentrum micans and 12000 rDNA copies in Akashiwo sanguinea). For taxa analysed so far, the genome size is correlated with cell size and carbon-content both between and within species. Cell size is also generally positively correlated with growth rate within a taxonomic group, and smaller genome size thus corresponds to higher growth rate. A great diversity of life cycles is found among microalgae including diploid (diatoms), haplo-diploid (haptophytes), or haploid (dinoflagellates, many chlorophytes). The nutrient-sparing hypothesis implies selection for small cells and genomes under nutrient limited conditions, and may explain why some groups have retained a haploid or a haplo-diploid life cycle. A biphasic life cycle may be favorable under variable environmental conditions through niche partitioning or provide escape from biotic pressures such as pathogens and grazers, but may get lost under stable conditions. Nutrient scarcity may however also promote smaller cells due to their larger surface : volume ratio. Here we have compiled published data on eukaryotic microalgal genome size, cell size and growth rate and added own data for haptophytes to compare patterns among taxonomic groups, reveal driving forces and relate this to life cycle strategies.

• Le, Nhat Hao Tran; Tadesse, Margey; Edvardsen, Bente; Paulsen, Berit Smestad; Walker, S & Stokka, Anne Jorunn [Vis alle 7 forfattere av denne artikkelen] (2015). Marine bioprospecting of marine microalgae.
• Edvardsen, Bente (2014). The diversity and dynamics of marine haptophytes. Projects Journal. 37, s. 39–41.
• Edvardsen, Bente (2014). Minnetale over professor Grethe Rytter Hasle. Årbok / Det norske videnskaps-akademi. ISSN 0332-6209.
• Edvardsen, Bente; Stadniczenko, Sandra Gran; Eikrem, Wenche; Hostyeva, Vladyslava; Logares, Ramiro & Egge, Elianne Sirnæs (2014). Diversity and seasonal dynamics of small dinoflagellates in the Skagerrak, Norway revealed by 454 pyrosequencing and microscopy. Vis sammendrag

  Some dinoflagellates are small and difficult to identify under the light microscope and thus little is known about their seasonal dynamics at the species level. Here we combined high-throughput sequencing and microscopy to explore their diversity and seasonal dynamics, and relate this to environmental factors. We collected 21 monthly samples of nanoplankton (3-45 μm size fraction) from outer Oslofjorden, southern Norway over two years. The 18S V4 ribosomal DNA was amplified from RNA/cDNA and 454-pyrosequenced. The reads were cleaned, denoised and clustered to 99% in Qiime and assigned to taxon. From 46250 reads assigned to Dinoflagellata we detected 367 unique operational taxonomic units (OTUs) assessed to represent species or genera. The most OTU-rich orders were Gymnodiniales (32%), Syndiniales (22%), and Peridiniales (17%), followed by Dinophysiales (8%), Gonyaulacales (7%) and Suessiales (4%). Reads assigned to Gymnodiniales dominated in all samples except June and August 2010 when reads assigned to Suessiales dominated. We observed strong seasonal variation and significant yearly periodicity in dinoflagellate richness and species composition. OTU richness was highest in late autumn and lowest in winter-spring. Seasonal dynamics of potentially toxic taxa were examined. We also assess and discuss the ability to detect potentially toxic dinoflagellate species with 18S V4 high throughput sequencing and compare this with standard microscopical methods and electron microscopy. Potentially toxic species <45 μm observed under the microscope included e.g. Alexandrium pseudogonyaulax, A. ostenfeldii, Azadinium spinosum, Karenia mikimotoi, Karlodinium veneficum and Prorocentrum minimum.

• Edvardsen, Bente; Egge, Elianne Sirnæs; Johannessen, Torill Vik; Eikrem, Wenche; Sandaa, Ruth-Anne & Bittner, Lucie [Vis alle 10 forfattere av denne artikkelen] (2014). Diversity and seasonal dynamics of marine haptophytes and their viruses. Vis sammendrag

  Members of the division Haptophyta are phytoplankton and a major component in marine pico- and nanoplankton communities. They often occur in bloom concentrations that may have a major impact on the global carbon balance, on climate forcing and sometimes cause fish-kills. Because haptophytes are small and difficult to identify in the microscope little is known about their seasonal dynamics and ecological role at the species level. We have studied the diversity and seasonal dynamics of marine haptophytes and their viruses, and how species composition and diversity are related to environmental factors using 454 pyrosequencing, complemented with electron microscopy and flow cytometry. This study revealed higher species richness of haptophytes than previously observed in the area with electron and light microscopy. The majority of the OTUs matched genetically uncharacterised taxa, most of which were affiliated with the order Prymnesiales. Several of the OTUs matched sequences forming deep-branching lineages, potentially representing novel classes of haptophytes. Haptophyte richness and community composition exhibited high temporal variation and significant yearly periodicity, with highest richness in autumn and lowest in the spring. Some taxa, such as some bloom forming species were present all year round, whereas most coccolithophores only appeared from summer to early winter. Also the algal virus (Phycodnaviridae) diversity was high and showed seasonal variations. Our results indicated that the abiotic factors only accounted for about 30% of the variation, and suggests that biotic factors may explain some of the residual variation.

• Henderiks, Jorijntje; Gerecht, Andrea; Hannisdal, Bjarte; Liow, Lee Hsiang; Reitan, Tore & Schweder, Tore [Vis alle 7 forfattere av denne artikkelen] (2013). PhytoSCALE project: calibrating phytoplankton cell size as a proxy for climatic adaptation.
• Engesmo, Anette; Hostyeva, Vladyslava; Strand, David; Naustvoll, Lars Johan; Vrålstad, Trude & Edvardsen, Bente [Vis alle 7 forfattere av denne artikkelen] (2013). Assessing the abundance of the ichthyotoxic Karenia mikimotoi by quantitative PCR and microscopy. Vis sammendrag

  The dinoflagellate Karenia mikimotoi may form blooms causing fish kills in coastal waters of the North East Atlantic region, including Norway and Sweden. A K. mikimotoi specific quantitative PCR (qPCR) assay was developed, based on the use of SYBR Green 1. The abundance of Karenia was assessed in samples from Outer Oslofjorden (Station OF2) collected monthly from August 2011 to June 2012, and 10 stations in Skagerrak collected during a cruise in April/May 2012. According to the qPCR assay, Karenia was present in all samples at station OF2, with a peak in August and September and with very low numbers in February, March, April and May. Karenia was also identified by light microscopy of net hauls (20 μm mesh) in both August and September. Cell counts were performed on the same samples and Karenia was only recorded in September (180 000 cells L-1). At the stations of the 2012 April/May Skagerrak cruise the abundance of Karenia was either very low or below the detection limit of our qPCR assay and Karenia was not observed by microscopy in any of the corresponding cell counts or net hauls. These results demonstrate that the qPCR assay was more sensitive than traditional counting methods using light microscopy in the detection of Karenia. In addition to traditional microscopy based methods, qPCR assays can be a powerful tool in the identification and quantification of Karenia and other harmful algae and may prove especially useful if applied in early warning programs.

• Brubak, Sissel Irene; Eikrem, Wenche; Fredriksen, Stein & Edvardsen, Bente (2013). Algekultursamlingen ved Universitetet i 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.

• Edvardsen, Bente; Egge, Elianne Sirnæs & Eikrem, Wenche (2013). Morphology, phylogeny and diversity of haptophytes.
• Edvardsen, Bente (2013). Toxigenic marine microalgae in Norway and their toxins.
• Edvardsen, Bente; Egge, Elianne Sirnæs; Torill Vik, Johannessen; Sandaa, Ruth-Anne; Eikrem, Wenche & Larsen, Aud [Vis alle 12 forfattere av denne artikkelen] (2013). Diversity and dynamics of marine haptophytes and their viruses. Vis sammendrag

  Haptophytes are nano- and picoplanktonic microalgae and important primary producers in the sea. They often form blooms that may impact on global carbon balance and climate forcing, and at times cause fish kills. Viruses may terminate these blooms. Knowledge on haptophyte diversity, quantitative distribution and dynamics at species level is limited because they are small and fragile, and species identification usually requires electron microscopy or molecular methods. In the project HAPTODIV we have developed methods to explore the diversity and dynamics of haptophytes and their viruses, using 454-pyrosequencing, environmental clone libraries, DNA-sequencing of new isolates, pulsed field gel electrophoresis, quantitative PCR, flow cytometry and microscopy. Plankton samples and environmental data were collected monthly from the Oslofjorden and Raunefjorden for two years. A high diversity of haptophytes was revealed, and a majority of the sequences represent unknown or uncultured species. Several taxa are recorded for the first time in Norwegian and North European waters and some may represent new taxonomic lineages (orders and class). In Oslofjorden and Raunefjorden, some taxa are present at all times, such as bloom-formers in the genera Emiliania, Phaeocystis, Chrysochromulina and Prymnesium, whereas the calcifying coccolithophorids were found mainly in summer-autumn, the period with highest diversity and temperature. The diversity of virus infecting algae (Phycodnaviridae), including haptophyte specific viruses, differed over time and with locality and was highest in spring and lowest in winter. We have isolated and characterised four new haptophyte specific viruses that differ more in genome size, DNA sequence or infection cycle than previously shown. Genetic characterisation of viruses and their haptophyte hosts have revealed their diversity, and also improved our understanding of virus-host interactions and fundamental biological processes in the ocean.

• Edvardsen, Bente (2013). Biodiversity of microalgae -screening the potential. Vis sammendrag

  Microalgae are a very diverse group of organisms, embracing single celled, filamentous or colony forming prokaryotic and eukaryotic microorganisms able to perform photosynthesis. Some lineages have however lost this ability, such as about half of the dinoflagellate species, and a number of heterokonts, which are heterotrophic. More than 20000 micro algal species have been described from marine and fresh waters. The application of molecular methods to environmental seawater samples show that there is a great hidden diversity, especially of the smallest nano- and pico-algae. It has been estimated that no more than 10% of the marine microalgal diversity is known and brought into culture. Microalgae produce a range of bioactive compounds, which are a potential resource for various applied purposes. They are the primary source of omega-3 long-chain polyunsaturated amino acids (LC-PUFA) in the marine food web, and fish obtain omega-3 LC-PUFA from microalgae through their diet. They are also a source of genes that regulate the biosynthetic pathways of these PUFAs. Members of kingdom Chromista and divisions Haptophyta, Ochrophyta and Dinophyta often show high content of fatty acids and a high proportion of the valuable LC-PUFA eicosapentaenoic (EPA) and/or docosahexaenoic acids (DHA). Members of Cyanophyta rarely contain these LC-PUFAs and members of Chlorophyta (green algae) usually contain no or low levels of DHA. However, there are large differences within groups and growth conditions are also of great importance. Only a small number of species are presently used as feed in aquaculture. In the search for new, potentially valuable micro-algal strains culture collections should be screened, and new strains isolated from habitats similar to the desired growth conditions. Dilution series may be the most efficient isolation technique for small, abundant and competitive microalgae, whereas capillary isolation may be the preferred method for isolation of larger and more rare organisms.

• Egge, Elianne Sirnæs; Eikrem, Wenche; Hostyeva, Vladyslava; Andersen, Tom; Bittner, Lucie & Johannesen, Torill [Vis alle 9 forfattere av denne artikkelen] (2012). Diversity and seasonal dynamics of haptophytes in outer Oslofjorden revealed by 454 pyrosequencing.
• Egge, Elianne Sirnæs; Eikrem, Wenche; Andersen, Tom & Edvardsen, Bente (2012). HAPTODIV-Diversity and dynamics of marine haptophytes.
• Egge, Elianne Sirnæs; Eikrem, Wenche; Hostyeva, Vladyslava; Andersen, Tom; Bittner, Lucie & Johannesen, Torill [Vis alle 9 forfattere av denne artikkelen] (2012). Diversity and seasonal dynamics of haptophytes in outer Oslofjorden revealed by 454 pyrosequencing.
• Edvardsen, Bente (2012). Diversity and dynamics of marine haptophytes and their viruses (HAPTODIV). Vis sammendrag

  Haptophytes are microalgae and a major component in marine pico- and nanoplankton communities. They often occur in bloom concentrations that may have a major impact on the global carbon balance and climate forcing ,besides sometimes causing fish-kills. Because haptophytes are small and difficult to identify under the light microscope little is known about their seasonal dynamics and ecological role below the genus level. In the ongoing project HAPTODIV we aim at providing new knowledge about the diversity and dynamics of haptophytes, and how species composition, diversity and their abundances are affected by their viruses and environmental factors. We have developed, tested and applied a strategy for analysing diversity using 454-pyrosequencing, and combine this with environmental clone libraries, electron microscopy, qPCR and flow cytometry. We have used an artificial haptophyte community consisting of 11 cultured species to investigate the ability of 454-pyrosequencing in detection and assessment of the number of species present, and the assessment of relative abundance in terms of cell numbers and biomass. We compared DNA to RNA/cDNA, and 454-pyrosequencing to Sanger sequencing of clone libraries using two different V4-SSU rDNA haptophyte-specific primer pairs, and five different strategies to clean the sequence data from errors. I will further present some results on the diversity and dynamics of haptophytes and their viruses using this strategy.

• Gerecht, Andrea Cornelia; Hostyeva, Vladyslava; Edvardsen, Bente; Probert, Ian & Henderiks, Jorijntje (2012). How does phosphorus limitation impact coccolith size and morphology?
• Gerecht, Andrea Cornelia; Hostyeva, Vladyslava; Edvardsen, Bente; Probert, Ian & Henderiks, Jorijntje (2012). How does phosphorus limitation impact coccolith size and morphology?
• Edvardsen, Bente; Egge, Elianne Sirnæs; Bittner, Lucie; Eikrem, Wenche; Audic, Stéphane & Andersen, Tom [Vis alle 9 forfattere av denne artikkelen] (2012). Diversity and dynamics of marine haptophytes as revealed by 454 pyrosequencing. Vis sammendrag

  Haptophytes are microalgae and a major component of marine plankton communities. Our aim is to provide new knowledge on the diversity and distribution of haptophytes below the genus-level, and how this is affected by environmental factors. We have developed and tested methods for analysing diversity using 454-pyrosequencing, We designed haptophyte-specific rDNA primers and constructed haptophyte databases and phylogenies for taxonomic assignation. We sequenced an artificial haptophyte community and compared the diversity and relative abundances from DNA and RNA/cDNA using various rDNA primers, and different programs to 18 remove errors from sequence data. We applied 454-pyrosequencing to samples from six European coastal sites and seasonal samples from Oslofjorden, and combined this with electron microscopy. We propose a strategy to more accurately depict the haptophyte diversity using 454-pyrosequencing and present results using this strategy.

• Hostyeva, Vladyslava; Dittami, Simon; Skylstad, Viljar Alain; Eikrem, Wenche & Edvardsen, Bente (2012). Seasonal dynamics of harmful algae in the outer Oslofjord monitored using microarrays, qPCR, and microscopy.
• Edvardsen, Bente; Egge, Elianne Sirnæs; Bittner, Lucie; Audic, Stéphane & de Vargas, Colomban (2012). A strategy for 454-pyrosequencing of ribosomal SSU DNA and RNA to more accurately assess protist diversity and relative abundance. Vis sammendrag

  Next generation sequencing of ribosomal DNA is increasingly used to assess the biodiversity and structure in microbial communities. Our aim was to develop a method to depict the diversity and community structure of marine planktonic haptophytes to species level. We used a mock community consisting of equal number of cells of 11 species representing all known haptophyte orders to investigate the ability to detect and assess the number of species present, and assess the relative abundance in terms of cell numbers and biomass by 454-pyrosequencing. We compared DNA to RNA/cDNA, 454-pyrosequencing to Sanger sequencing of clone libraries, and two different V4-SSU rDNA haptophyte biased primer pairs. Further, we tested 5 different strategies to clean the sequence data from errors. Up to 6000 unique tags per sample (with avg. 16500 reads) were obtained before sequence cleaning and clustering, and higher diversity was obtained from cDNA than DNA. The distribution of reads assigned to a species was significantly different from the initial proportions of cells or biomass in the culture mix, but cell numbers were better reflected by proportion of cDNA than DNA reads. Here we propose a strategy to more accurately depict the haptophyte diversity and assess relative abundance using 454-pyrosequencing.

• Vrålstad, Trude; Strand, David; Edsman, Lennart; Edvardsen, Bente; Engdahl, Fredrik & Fristad, Rosa Ferreira [Vis alle 14 forfattere av denne artikkelen] (2012). Hunting the crayfish plague disease agent in water sources – challenges and possibilities. Vis sammendrag

  The specialized North American crayfish parasite and oomycete Aphanomyces astaci causes crayfish plague in European crayfish. Infectious A. astaci zoospores are released from American carrier crayfish and from diseased or dead European crayfish. The A. astaci spore quantity in the ambient water of crayfish will therefore largely reflect disease outbreaks in European crayfish or carrier status in American crayfish. During the past few years, molecular methods detecting A. astaci directly from crayfish tissues has become widely accepted. Now, the first studies employing A. astaci specific qPCR directly from water samples are approaching. Monitoring waterways could facilitate early warning of A. astaci infections, improve risk assessments, and reveal of infection reservoirs. It might also serve as a supplementary tool for declaring crayfish stocks and water bodies infection free in nature and aquaculture. Over the past three years, we have worked on this topic in a Nordic collaborative project. Here, we present methodological experiences e.g. sampling volumes, filtration methods, and subsequent molecular analyses. Possibilities and challenges connected to the transition from laboratory, via aquaria models, to natural environments are discussed. Furthermore, unknown diversity of oomycetes resembling A. astaci in the target DNA motif challenges the reliability of qPCR results, both from crayfish and natural environmental samples. We have therefore identified means that increase the probability of distinguishing between possibly true and false positives. These include qPCR optimizations, and use of a decision support tool that evaluates the qPCR result reliability on the basis of linearity (R2) and amplification efficiency of the PCRs.

• Edvardsen, Bente & Eikrem, Wenche (2011). Species committee for microalgae in the Norwegian Artsdatabanken.
• Bittner, Lucie; Gobet, Angelique; Egge, Elianne Sirnæs; Audic, Stéphane; Santini, Sebastien & Ogata, Hiroyuki [Vis alle 10 forfattere av denne artikkelen] (2011). Diversity of Haptophyta in the Bay of Naples as revealed by next generation sequencing (NGS): "anything new under the sea"?
• Edvardsen, Bente & Egge, Elianne Sirnæs (2011). QUANTIFICATION OF HAPTOPHYTE SPECIES BY PYROSEQUENCING: IS READ ABUNDANCE PROPORTIONAL TO SPECIES BIOVOLUME? Vis sammendrag

  Amplicon-sequencing of ribosomal RNA genes has become a standard for assessing microbial diversity in environmental samples. Abundance is of interest in addition to presence/absence of species to assess their ecological importance. The proportion of DNA sequences/reads from a particular species may, however, not reflect the proportion of the species in a sample in terms of cell number. We investigated the relationship between cell number and biovolume in an artificial community of haptophyte species, and the number of DNA sequences/reads appearing in libraries produced by cloning and 454-pyrosequencing nucleic acids extracted from this community. One million cells from each of 11 haptophyte species were pooled, and DNA and RNA extracted, and the V4 region of the small subunit ribosomal gene was amplified using haptophyte specific primers. The amplicons were sequenced by 454-pyrosequencing or Sanger sequencing. Pyrosequencing with 17000 reads per sample recovered all species in the culture mix, whereas clone libraries with 50-80 sequences per sample only recovered <50% of the species. Our results show that the proportion of reads from the different species in the 454-libraries were significantly different from the proportion of cells in the pool. There was a positive correlation between cell volume and read abundance, and thus cell size should be taken into account when interpreting 454-sequence data quantitatively.

• Edvardsen, Bente & Eikrem, Wenche (2011). Fish-killing algal problems in Norway. Vis sammendrag

  The aquaculture industry in Norway produced 940 000 metric tons salmon and trout to a value of 22 billion NOK in 2009 and is the world’s largest producer of farmed salmon. Ichthyotoxic algae may however cause large economic losses for fish farmers in Norway. Harmful algal blooms has been a threat to fish farms in Norway ever since its early era in the early70-ies. In the period 1974-1991 the dinoflagellate Karenia mikimotoi (=Gyrodinium aureolum) formed blooms almost yearly that at times discolored the water brown and caused recurrent fish kills in fish farms along the Skagerrak coast. In 1988 the haptophyte Chrysochromulina polylepis formed the possibly most extensive and toxic bloom ever recorded, killing not only farmed fish but also feral fauna and flora in the Skagerrak and Kattegat off the coasts of Norway, Sweden and Denmark. While this bloom appeared to be a unique event, the related haptophyte Prymnesium parvum formed recurrent blooms in a brackish-water fjord system in Ryfylke, W Norway that caused fish kills in the period 1989-1995. The fish farms were then moved from the most affected fjord arms and when they started up again in 2006 Prymnesium parvum again formed ichthyotoxic blooms. The haptophyte Chrysochromulina leadbeateri similarly killed farmed fish during several years (1991, 2000, 2003, and 2010) in the Lofoten area in N Norway. During the last decade another algal group has caused problems for fish farmers in Norwegian waters, the dictyochophytes, represented by Pseudochattonella and recently Dictyocha species. Pseudochattonella was for the first time recorded in bloom concentrations in N European waters in 1998, and it has been speculated whether it may have been introduced from Asia by ballast water. In 2001, Pseudochattonella formed a massive ichthyotoxic bloom in the Skagerrak and Kattegat, this time in cold waters (2-6 °C). Cultures were isolated, examined and found to represent a new species, Pseudochattonella farcimen, differing in rDNA sequence, ultrastructure and growth preferences from the previously known P. verruculosa (=Chattonella verruculosa), first reported from Japan. Since then Pseudochattonella has been recorded in the Kattegat and Skagerrak yearly and some years in bloom concentrations (e.g. 2006, 2011). The most recent ichthyotoxic algal flagellate to be recorded in Norwegian waters is the silicoflagellate Dictyocha fibula. It may occur in a naked form without the typical silica-skeleton (speculated to be identical to ‘Chattonella globosa’), in bloom concentrations together with the skeleton-bearing form. Fish-kills have occurred since 2007 along the W and S coast of Norway in waters dominated by this species. All these ichthyotoxic species have several features in common. They are nanoplanktonic (size range approx. 5-30 µm in diameter) flagellates with yellow-brown plastids of a haptophyte origin. They usually form blooms after the diatom spring bloom in stratified waters. Some have been shown to be mixotrophic. The toxin structure, production and toxicity are not well understood. Despite ample studies to elucidate factors influencing toxin production and growth we do still not fully understand what triggers the toxicity and bloom formation. Functional genomics may contribute to fill some of these gaps.

• Edvardsen, Bente; Nersveen, Lars; Torgrimsby, Tonie Leonora; Engesmo, Anette; Egge, Elianne Sirnæs & Eikrem, Wenche (2011). Diversity and distribution of nano- and picoeukaryotes in the Southern Ocean as revealed by 454-pyrosequencing, clone libraries and microscopy. Vis sammendrag

  In this study we explored the diversity and distribution of planktonic nano- and picoeukaryotes in Antarctic waters by combining 454-pyrosequencing, clone libraries and electron microscopy. Water samples were collected and physico-chemical parameters measured during summer 2008 with the Norwegian R/V G.O. Sars in the Atlantic sector of the Southern Ocean, at stations along a transect (15°E) between 45-67o S. Ribosomal DNA of plankton in the size range 0.8-35µm was amplified with universal eukaryotic and haptophyte specific primers followed by pyro- and Sanger sequencing. Most rDNA sequences could not be assigned to a cultured and sequenced species (at ≥99,3% identity level) indicating that a large fraction of the plankton community remains to be genetically characterized. Electron microscopy revealed some of this diversity, but more cultured strains are needed as reference for a precise identification. The taxonomic groups represented with highest number of clones/reads were dinoflagellates, stramenopiles and haptophytes. The species composition was significantly different at the northernmost station compared to further south, suggesting that nano- and picoeukaryote species composition and distribution may serve as indicators of climate change in polar waters.

• Egge, Elianne Sirnæs & Edvardsen, Bente (2011). HAPTODIV - Diversity and dynamics of marine haptophytes.
• Egge, Elianne Sirnæs & Edvardsen, Bente (2011). QUANTIFICATION OF HAPTOPHYTE SPECIES BY PYROSEQUENCING: IS READ ABUNDANCE PROPORTIONAL TO SPECIES BIOVOLUME?
• Miles, Christopher; Rundberget, Thomas; Egaas, Eliann; Johansen, Renate & Edvardsen, Bente (2011). Fish-killing algae—a chemical perspective.
• Johansen, Renate; Miles, Christopher; Egaas, Eliann; Rundberget, Thomas & Edvardsen, Bente (2011). Are fish-killing algae a problem in Norwegian fish farming?
• Dankel, Eli; Supraha, Luka; Edvardsen, Bente; Eikrem, Wenche & Saubrekka, Karoline (2023). Arktiske kalkflagellater: et morfologisk og molekylært dypdykk i det nordlige Barentshavet. Universitetet i Oslo. Vis sammendrag

  Oppblomstringer av kalkflagellater utgjør et viktig fundament for næringskjeden i Barentshavet. Fjernanalyse med satellittbilder har de siste tiårene dokumentert at denne oppblomstringen beveger seg nordover i takt med økende klimaendringer. Det er likevel fortsatt uvisst hva som skjer på artsnivå. Å forstå hvordan forekomsten til den enkelte art forandrer seg i møte med endrede miljøbetingelser, som redusert is og økende temperatur, gjør at man enklere kan forutse hvordan fytoplanktonsamfunnet vil respondere på et fremtidig, varmere Arktis. For denne oppgaven ble det hentet inn vannprøver fra syv stasjoner på et sør-nord-transekt i Barentshavet i august 2018 og 2019 under tokt i regi av forskningsprosjektet Arven etter Nansen (AeN). 2018 var globalt et av de varmeste årene på mange tiår, og Barentshavet var dermed isfritt den sommeren. I 2019 derimot var større deler av Barentshavet dekket av is. Prøver tatt for både svepeelektronmikroskopi (scanning electron microscopy, forkortet «SEM») og metastrekkoding (metabarcoding) ble brukt i oppgaven slik at resultatene fra metodene kunne sammenlignes. Formålet med SEM var å utføre både en kvalitativ og kvantitativ analyse av kalkflagellater. Metastrekkoding ble brukt til sekvensering av 18S rRNA-genet. I SEM fant jeg i prøvene fra 2018 Emiliania huxleyi, Coccolithus pelagicus, Papposphaera sarion, Papposphaera arctica, Wigwamma annulifera og Porsildia acerviphora. Utenom Coccolithus pelagicus og Wigwamma annulifera, ble de samme artene funnet i 2019. I tillegg ble Syracosphaera Marginiporata funnet i prøver fra et AeN-tokt i november-desember 2019. Artene fra 2018 var hovedsakelig til stede på den sørligste stasjonen i transektet, mens artene fra 2019 generelt ble funnet på flere forskjellige stasjoner. Fra metastrekkoding ble det registrert 13 OTUer (Operational Taxonomic Units) som er bestemt til kalkflagellat-taksa. Ettersom det stort sett mangler referansesekvenser for arktiske kalkflagellater, ble de fleste OTUene kun klassifisert til klasse eller orden. OTUene var for det meste til stede i prøvene fra den sørligste, og de to nordligste stasjonene. Det ble ikke observert et nevneverdig mønster i sammenheng med isdekket. Det ble derimot både for SEM og metastrekkoding observert at de fleste artene var til stede på stasjoner som i ulik grad ble påvirket av Den nordatlantiske havstrømmen. Resultatene er likevel ikke holdbare nok til å trekke en konklusjon om hvordan kalkflagellatsamfunnet i Barentshavet vil se ut i fremtiden. Ettersom de fleste OTUene viste lav taksonomisk oppløsning, og alle celler funnet i SEM ble bestemt til artsnivå, anbefaler jeg at SEM forblir den foretrukne metoden for kvalitativ og kvantitativ analyse av kalkflagellater.

• Walbækken, Hanna Myhre; Eikrem, Wenche; Edvardsen, Bente; Saubrekka, Karoline & Hofgaard, Antje (2023). Dinoflagellate diversity in the Barents Sea: a comparative identification analysis. Universitetet i Oslo. Vis sammendrag

  An important group in the protist community in marine habitats are dinoflagellates. In this study the diversity of dinoflagellates in a transect of seven pelagic sea stations in the Northern Barents Sea in August 2018 and August 2019 was assessed. The two sampling periods were characterized with low and high sea-ice extent, respectively. I have studied the diversity and presence of dinoflagellate species in the sample transect using the molecular method DNA metabarcoding, and the morphological methods light microscopy (LM), and scanning electron microscopy (SEM). The results from species identification were used to observe and compare potential differences in the two sampling years. It was shown that the morphological methods were limited in identification success by little amount of material in several of the vertical net haul samples, resulting in some bias when these results were compared with DNA metabarcoding that revealed a high number of OTU (operational taxonomic unit) reads assigned to division Dinoflagellata. Species classification by DNA metabarcoding was shown to be limited by the availability of reference sequences in the curated protist ribosomal database PR2. It yielded a rough overview of the composition of dinoflagellate species in the sampling transect that could be closer examined with more time to study single OTUs. Identification done by LM and SEM revealed the presence of genera in certain stations that was not revealed in metabarcoding, and vice versa. I also found that Lugol’s solution functioned well for the preservation of cell structure for sample analysis in SEM. Climate change is shown to cause more and rapid alterations in the Arctic, and the loss of sea-ice is an important consequence of a warmer climate. Regarding interannual differences in 2018 and 2019, the morphological methods showed some differences in species composition with genus Protoperidinium more often identified in 2018 than other species, and the same for Gymnodiniales species in 2019. This could potentially show a shift in phytoplankton communities in a changing environment, although time-series are necessary to predict the future compositions of dinoflagellate species. As phytoplankton makes up the fundament for the Arctic food chain, studies of changing environmental conditions are valuable for ecological reasons.

• Edvardsen, Bente; Gryn, Khrystyna; Šupraha, Luka; Eikrem, Wenche & Saubrekka, Karoline (2023). Biodiversity and distribution of Arctic phytoplankton and ice algae. Universitetet i Oslo. Vis sammendrag

  The project aims to enhance our understanding of Arctic marine ecosystems by researching the diversity, distribution, and functioning of phytoplankton and ice algae in response to rapid environmental changes. The diversity and biogeography of phytoplankton and ice algae from the Barents Sea were studied by combining algal cultivation and 18S and 28S rRNA gene sequencing. During the Nansen legacy project cruise in August 2019 (AeN706), a total of 46 algal strains were isolated from stations along a S-N transect in the Barents Sea into the Arctic Ocean. The identifications obtained from DNA sequencing, phylogenetic analysis and morphological examination indicated the presence of common Arctic algal species, such as Attheya septentrionalis, Thalassiosira gravida, and Chaetoceros neogracilis, among the identified genotypes. Additionally, this study has also characterised potentially novel species or species that have not been adequately described before. Taxonomic identification of the strains was performed using molecular and morphological approaches, and the biogeographic distribution was mapped using a global compilation of published metabarcoding datasets. It was demonstrated by the biogeographic analyses that four general biogeographic distribution types exist for arctic phytoplankton and ice algae: polar, arctic, arctic-temperate, and cosmopolitan. Genotypes with arctic-temperate distribution was most common among the characterised strains, and genotypes endemic to the arctic was also found. Only two genotypes with cosmopolitan distribution and one genotype with polar distribution were discovered. The results highlight that the phytoplankton and ice algal communities in the Barents Sea and Arctic Ocean consist of genotypes endemic to the Arctic and genotypes with broader biogeographic distributions.

• Røsbak, Silje K.; Edvardsen, Bente; Eiler, Alexander; Saubrekka, Karoline & Fon, Mathias (2023). Mikrobielt samfunn i kulturer av Chrysochromulina leadbeateri og relaterte svepeflagellater undersøkt med metastrekkoding. Universitetet i Oslo. Vis sammendrag

  Skadelige marine algeoppblomstringer er et tilbakevendende problem over hele verden, der skadene har en påvirkning på økosystemer og lokal økonomi. Chrysochromulina leadbeateri var årsak til en massiv fiskedød i 2019, men mekanismene bak denne oppblomstringen er fortsatt ukjent. Målet med oppgaven var å undersøke bakteriediversiteten i kulturer av den fiske-giftige Chrysochromulina leadbeateri, og sammenligne denne mot andre beslektede svepeflagellater, både hos potensielt giftige og ikke-giftige arter. I tillegg til dette ble bakteriediversiteten av mikrobiomet mellom fastsittende bakterier på algecellene og frittlevende bakterier i kultur undersøkt. I denne oppgaven ble det prokaryote mikrobiomet i kulturer av tre stammer av Chryochromulina leadbeateri og 6 stammer av beslektede svepeflagellatarter analysert. Dette ble gjort ved metastrekkoding av det ribosomale 16S rRNA-genet. Det ble påvist et mangfoldig mikrobiom der hele bakteriedatasettet inneholdt 3 rekker, 14 ordener og 53 slekter. Bakteriesamfunnets sammensetning bestod hovedsakelig av medlemmer i rekken Proteobacteria etterfulgt av medlemmer av rekken Bacteroidota, og kun noen få ASVer i rekken Actinobacteria. Av de 14 ordenene var Rhodobacterales, Flavobacteriales, Caulobacterales, Rhiszobiales og Cytophagales de mest vanlige. Av de 53 slektene var Marivita (Rhodobacterales) den mest abundante, etterfulgt av Roseovarius (Rhodobacterales), Jannaschia (Rhodobacterales), Hoefla (Rhizobiales), Seohaeicola (Rhodobacterales), Hyphomonas (Rhodobacterales) og Sulfitobacter (Rhodobacterales). Taksonomisk fordeling av bakterieslekter mellom de potensielt giftige og ikke-giftige svepeflagellatene viste forskjeller, der de potensielt giftige hadde flest unike identifiserte bakterieslekter. Når det gjelder alfadiversitet (forskjeller innad i et samfunn) viser de to gruppene derimot ingen store forskjeller i mikrobiomet. Det ble funnet en svak signifikant sammenheng i mikrobiomets betadiversitet (forskjeller mellom samfunn) mellom kulturer av potensielt giftige og ikke-giftige svepeflagellater, der svepeflagellatens giftighet innen slekt hadde en svak effekt i denne studien. I tillegg viste slekten til svepeflagellaten til å ha en signifikant betydning for hvilke bakteriearter som ble funnet i algekulturer. Ved en sammenligning av fordelingen av bakterieslekter som er fastsittende til algecellen og frittlevende i algekultur, deler de to gruppene 80 % av bakterieslektene, og har dermed høy likhet. De frittlevende bakteriene har høyest antall ASVer, noe som indikerer at de fleste bakterie-typene lever fritt i kultur. Dette vises også ved de statistiske analysene, der alfadiversiteten for de IV frittlevende bakteriene i kultur har et signifikant rikere mikrobiom i forhold til fastsittende bakterier til algecellen. Betadiversiteten mellom fastsittende og frittlevende bakterier viser derimot ingen signifikante forskjeller, som vil si at mikrobiom-sammensetningen ikke kan forklares ut ifra om det er fastsittende på algecellene eller frittlevende i kultur.

• Tran, Jacquelynn Phuong-Vy; Edvardsen, Bente; Fon, Mathias; Heuschele, Jan David & Titelman, Josefin (2023). When hungry meets harmful: investigating the toxic relationship between haptophytes and copepods. Predatory induced defenses in Chrysochromulina leadbeateri. . Universitetet i Oslo. Vis sammendrag

  Harmful algal blooms are a recurring phenomenon all around the world, causing devastating effects including massive fish kills. A bloom of the toxic haptophyte, Chrysochromulina leadbeateri, in Northern Norway during May-June 2019 was the largest bloom ever recorded in that area causing massive mortalities of farmed salmon. While past C. leadbeateri blooms are known to cause such damage, relatively little is known about this toxic haptophyte, compared to other species. Some studies have investigated the bloom dynamics and abiotic factors influencing its toxicity, but little is known about the biotic influences. In particular, the predator-prey interactions with copepods. Past studies have found that when other species are directly exposed to predation threats (e.g. herbivorous copepods), the algae will respond by inducing and/or increasing toxicity potential as a defense mechanism. Those studies have focused on toxic diatoms and dinoflagellates producing shellfish toxins, but the potential for fish-killing algae to be influenced by predation pressure remains to be explored. In this thesis, I examined the biotic interactions between the toxic C. leadbeateri and the grazing Acartia sp. copepods. I first conducted a series of 3-day tolerance experiments, exposing Acartia sp. to different C. leadbeateri concentrations to answer: What is the threshold C. leadbeateri concentration that Acartia sp. can maintain survival and grazing? Then I conducted 3-day induction experiments, exposing C. leadbeateri to varying levels of grazing pressure, and in vitro tests using two fish cell lines to measure this potential grazing-induced toxicity to answer: Does the presence of copepod grazers affect toxicity in the ichthyotoxic haptophyte C. leadbeateri? Through the initial tolerance experiments, I determined that ca. 5 x 104 cells ml-1 of C. leadbeateri was the threshold concentration that enough Acartia sp. could survive and maintain feeding for the later toxicity induction experiments. Acartia sp. short-term tolerance to direct exposure to C. leadbeateri appeared to be concentration and time-dependent since the toxins need to be taken up by Acartia sp. to cause mortalities. Copepod grazing habits observed during the induction experiment appeared unaffected when C. leadbeateri was the only food source, as evidenced by fecal pellet production. However to accurately determine the effects of grazing on C. leadbeateri, future studies should observe grazing periodically with Acartia sp. exposed to different C. leadbeateri concentrations and non-toxic food alternatives. I examined whether the toxicity of C. leadbeateri was influenced by the presence of grazing copepods using in vitro tests on two fish (Rainbow trout and Atlantic salmon) cell lines to measure cell viability and light microscopy to look at morphological changes. I created different concentrations of algal extracts from crude C. leadbeateri material exposed to varying grazing levels. The different extracts were exposed to the gill cells in a microplate-based assay for 24 hours and at the endpoint, cell viability was measured using Alamar blue as an indicator dye. It seems that while increasing algal extract concentration decreases cell viability, extract made from C. leadbeateri exposed to increasing grazing pressure does not increase the negative effects on cell viability. The light micrographs of the gill cells suggest the same, but with some inclination that grazing pressure does affect some toxicity potential in C. leadbeateri. Unfortunately, with the lack of more independent trials, there is no statistical analyses to back up these claims. More experiments would allow for proper analyses and a potentially more conclusive statement about the relationship between copepod grazing and the toxicity potential of C. leadbeateri. This thesis can be used as a starting point for future research on the dynamics between toxic haptophytes and their copepod grazers.

• Reitzel, Helene; Edvardsen, Bente; Šupraha, Luka & Heuschele, Jan David (2023). The ichthyotoxic algae Chrysochromulina leadbeateri – an investigation into favorable conditions for growth and toxicity. . Universitetet i Oslo. Vis sammendrag

  Harmful algal blooms can be devastating to local ecosystems as well as have major impacts on economy and aquaculture. Chrysochromulina leadbeateri caused the death of an estimated seven and a half million farmed salmon in 2019, and the cause of this bloom is still unknown. While the growth and toxicity of other toxic prymnesiophytes have been examined, we still know little about optimal conditions for growth and toxicity of Chrysochromulina leadbeateri. In this thesis I have examined the growth of C. leadbeateri in controlled conditions, and how different salinities and temperatures affects the growth rate. I also examined the toxicity and whether or not I could induce it in a laboratory setting, and whether phosphorous limitation or other temperatures or salinities could play a role. I conducted three growth experiments. The first to establish a relationship between cell density and chlorophyll a fluorescence measurements. The second and third growth experiments were used to establish how different temperatures and salinities affected the strains of C. leadbeateri and how the different conditions affected growth rate as well as establish tolerance limits. Low temperatures and low salinities seemed to affect growth negatively, while optimum growth conditions were at 15°C and a salinity between 25 and 30. I recommend that the growth experiments are replicated with the inclusion of higher temperatures to establish where the upper temperature limit is, as well as repeat the temperatures used to get a better understanding of growth at 11°C as the equipment here had some flaws. I performed three Artemia bioassay experiments. The first showed that the cultures did not become more toxic after growing in phosphorous limited conditions compared to those that hadn’t. The second and third Artemia bioassay experiments were performed to see whether temperature or salinity played a role in inducing toxicity, as well as where in the growth phase the cultures were. Cultures that were in their stationary stage were toxic to Artemia nauplii, and this seemed to play a larger role in inducing toxicity than temperature or salinity.

• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 7 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy Q4. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 7 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy Q3. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 8 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy Q1. Norwegian Polar Institute.
• Assmy, Philipp; Wold, Anette; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wiktor, Jozef & Tatarek, Agnieszka [Vis alle 7 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy JC2-2. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Goraguer, Lucie Hélène Marie; Wiktor, Józef & Tatarek, Agnieszka [Vis alle 7 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy JC2-1. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 7 forfattere av denne artikkelen] (2022). Ice algae biodiversity Nansen Legacy JC1. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wiktor, Józef; Tatarek, Agnieszka & Dabrowska, Anna Maria (2022). Phytoplankton biodiversity Nansen Legacy Q4. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Józef [Vis alle 8 forfattere av denne artikkelen] (2022). Phytoplankton biodiversity Nansen Legacy Q3. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Józef [Vis alle 8 forfattere av denne artikkelen] (2022). Phytoplankton biodiversity Nansen Legacy Q2. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef (2022). Phytoplankton biodiversity Nansen Legacy Q1. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Wiktor, Jozef & Tatarek, Agnieszka [Vis alle 8 forfattere av denne artikkelen] (2022). Phytoplankton biodiversity Nansen Legacy JC2-2. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 8 forfattere av denne artikkelen] (2022). Phytoplankton biodiversity Nansen Legacy JC2-1. Norwegian Polar Institute.
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Jozef [Vis alle 7 forfattere av denne artikkelen] (2022). Phytoplankton biodiversity Nansen Legacy JC1. Norwegian Polar Institute.
• Reigstad, Marit; Gabrielsen, Tove M.; Amargant-Arumi, Marti; Amundsen, Rita; Bluhm, Bodil & Bodur, Yasemin V. [Vis alle 37 forfattere av denne artikkelen] (2022). Seasonal Cruise Q3: Cruise Report . Septentrio Academic Publishing. ISSN 2703-7525. Vis sammendrag

  The Nansen Legacy Q3 cruise, 5-27 August 2019, initiated the seasonal investigations of the Nansen Legacy transect. The transect represent an environmental gradient going through the northern Barents Sea, and included 7 process stations (P1-P7) lasting 6-53 hrs. CTD stations were taken to increase the hydrographic resolution on the transect. The program included measurements and sampling from the atmosphere, sea ice, ocean and sea floor. Data collected ranged from physical observations, chemical, biological and geological data collection, and the aim was to link observations and measurements to improve our understanding of the systems involving both climate, human impacts and the ecosystems. Deployment of moorings and gliders extended the observational capacity in time and space, outside the cruise period.

• Strand, David; Vrålstad, Trude; Edvardsen, Bente & Klaveness, Dag (2013). Environmental DNA monitoring of the alien crayfish plague pathogen Aphanomyces astaci in freshwater systems - Sporulation dynamics, alternative hosts and improved management tools. Faculty of Mathematics and Natural Sciences. ISSN 1501-7710.

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