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  • E-mailMikal.Heldal@uib.no
  • Phone+47 55 58 46 75+47 480 96 673
  • Visitor Address
    Thormøhlensgt. 53 A/B
  • Postal Address
    Postboks 7803
    5020 Bergen
Books
  • Bratbak, Gunnar; Heldal, Mikal; Joint, Ian. 1995. Viruses - the new players in the game; their ecologial role and could they mediate genetic exchange by transduction? ISBN: 3-540-60134-1.
Journal articles
  • Våge, Selina; Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal; Larsen, Aud; Norland, Svein; Paulsen, Maria Lund; Pree, Bernadette; Sandaa, Ruth-Anne; Skjoldal, Evy Foss; Tsagaraki, Tatiana Margo; Øvreås, Lise; Thingstad, T. Frede. 2018. Simple models combining competition, defence and resource availability have broad implications in pelagic microbial food webs. Ecology Letters. 21: 1440-1452. doi: 10.1111/ele.13122
  • Erga, Svein Rune; Haugen, Stig Bjarte; Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal; Mork, Kjell Arne; Norland, Svein. 2017. Seasonal variations in C:N:Si:Ca:P:Mg:S:K:Fe relationships of seston from Norwegian coastal water: Impact of extreme offshore forcing during winter-spring 2010. Marine Chemistry. 196: 1-12. doi: 10.1016/j.marchem.2017.07.001
  • Romann, Julien Clement; Chauton, Mathilde Skogen; Hanetho, Sidsel Meli; Vebner, Marius Juelsrud; Heldal, Mikal; Thaulow, Christian; Vadstein, Olav; Tranell, Gabriella; Einarsrud, Mari-Ann. 2016. Diatom frustules as a biomaterial: effects of chemical treatment on organic material removal and mechanical properties in cleaned frustules from two Coscinodiscus species. Journal of porous materials. 23: 905-910. doi: 10.1007/s10934-016-0147-6
  • Thomsen, Helge A.; Østergaard, Jette B.; Heldal, Mikal. 2016. Coccolithophores in polar waters: Papposphaera sagittifera HET and HOL revisited. Acta Protozoologica. 55: 33-50. doi: 10.4467/16890027AP.16.005.4046
  • Thomsen, Helge Abildhauge; Egge, Jorun Karin; Heldal, Mikal. 2016. Papposphaera obpyramidalis (Haptophyta, Papposphaeraceae):New findings from both Polar Regions. Revue de Micropaleontologie. 59: 267-273. doi: 10.1016/j.revmic.2016.03.005
  • Carreira, Cátia; Heldal, Mikal; Bratbak, Gunnar. 2013. Effect of increased pCO(2) on phytoplankton-virus interactions. Biogeochemistry. 114: 391-397. doi: 10.1007/s10533-011-9692-x
  • Grob, Carolina; Ostrowski, Martin; Holland, Ross J.; Heldal, Mikal; Norland, Svein; Erichsen, Egil Severin; Blindauer, Claudia; Martin, Adrian P.; Zubkov, Mikhail V.; Scanlan, David J. 2013. Elemental composition of natural populations of key microbial groups in Atlantic waters. Environmental Microbiology. 15: 3054-3064. doi: 10.1111/1462-2920.12145
  • Paulino, Ana Isabel; Heldal, Mikal; Norland, Svein; Egge, Jorun Karin. 2013. Elemental stoichiometry of marine particulate matter measured by wavelength dispersive X-ray fluorescence (WDXRF) spectroscopy. Journal of the Marine Biological Association of the United Kingdom. 93: 2003-2014. doi: 10.1017/S0025315413000635
  • Steenbergh, A.K.; Bodelier, P.L.E.; Heldal, Mikal; Slomp, C.P.; Laanbroek, H.J. 2013. Does microbial stoichiometry modulate eutrophication of aquatic ecosystems? Environmental Microbiology. 15: 1572-1579. doi: 10.1111/1462-2920.12042
  • Heldal, Mikal; Norland, Svein; Erichsen, Egil Severin; Sandaa, Ruth-Anne; Larsen, Aud; Thingstad, Tron Frede; Bratbak, Gunnar. 2012. Mg2+ as an indicator of nutritional status in marine bacteria. The ISME Journal. 6: 524-530. doi: 10.1038/ismej.2011.130
  • Heldal, Mikal; Norland, Svein; Erichsen, Egil Severin; Thingstad, Tron Frede; Bratbak, Gunnar. 2012. An unaccounted fraction of marine biogenic CaCO3 particles. PLoS ONE. 7. 6 pages. doi: 10.1371/journal.pone.0047887
  • Brussaard, Corina P.D.; Wilhelm, Steven W.; Thingstad, T. Frede; Weinbauer, Markus G.; Bratbak, Gunnar; Heldal, Mikal; Kimmance, Susan A.; Middelboe, Mathias; Nagasaki, Keizo; Paul, John H.; Schroeder, Declan C.; Suttle, Curtis A.; Vaqué, Dolors; Wommack, K. Eric. 2008. Global-scale processes with a nanoscale drive: the role of marine viruses. The ISME Journal. 2: 575-578. doi: 10.1038/ismej.2008.31
  • Løvdal, Trond Karsten; Skjoldal, Evy Foss; Heldal, Mikal; Norland, Svein; Thingstad, T. Frede. 2008. Changes in morphology and elemental composition of Vibrio splendidus along a gradient from carbon-limited to phosphate-limited growth. Microbial Ecology. 55: 152-161. doi: 10.1007/s00248-007-9262-x
  • Thingstad, T. Frede; Bellerby, Richard; Bratbak, Gunnar; Børsheim, Knut Yngve; Egge, Jorun Karin; Heldal, Mikal; Larsen, Aud; Neill, Craig Chandler; Nejstgaard, Jens Christian; Norland, Svein; Sandaa, Ruth-Anne; Skjoldal, Evy Foss; Tanaka, Tsuneo; Thyrhaug, Runar; Tøpper, Birte. 2008. Counterintuitive carbon-to-nutrient coupling in an Arctic pelagic ecosystem. Nature. 455: 387-391. Published 2008-09-18. doi: 10.1038/nature07235
  • Jacquet, Stephan; Domaizon, Isabelle; Personnic, Sébastien; Ram, Angia Sriram Pradeep; Heldal, Mikal; Duhamal, Solange; Sime-Ngando, Télesphore. 2005. Estimates of protozoan- and viral-mediated mortality of bacterioplankton in Lake Bourget (France). Freshwater Biology. 50: 627-645.
  • Thingstad, Tron Frede; Øvreås, Lise; Egge, Jorun Karin; Løvdal, Trond Karsten; Heldal, Mikal. 2005. Use of non-limiting substrates to increase size; a generic strategy to simultaneously optimize uptake and minimize predation in pelagic osmotrophs? Ecology Letters. 8.
  • Brussaard, Corina P.D.; Noordeloos, A.A.M.; Sandaa, Ruth-Anne; Heldal, Mikal; Bratbak, Gunnar. 2004. Discovery of a dsRNA virus infecting the marine photosynthetic protist Micromonas pusilla. Virology. 319: 280-291.
  • Landa, Harald; Bratbak, Gunnar; Heldal, Mikal. 2004. Abundance and dynamics of free flagellate scales in marine costal ecosystems. Aquatic Microbial Ecology. 37: 55-62.
  • Heldal, Mikal; Scanlan, Dave J.; Norland, Svein; Thingstad, Tron Frede; Mann, Nicholas H. 2003. Elemental composition of single cells of various strains of marine Prochlorococcus and Synechococcus using X-ray microanalysis. Limnology and Oceanography. 48: 1732-1743.
  • Øvreås, Lise; Bourne, David; Sandaa, Ruth-Anne; Casamayor, Emilio; Benlloch, Susana; Goddard, Victoria; Smerdon, Gary; Heldal, Mikal; Thingstad, Tron Frede. 2003. Response of bacterial and viral communities to nutrient manipulations in seawater mesocosms. Aquatic Microbial Ecology. 31: 109-212.
  • Castberg, Tonje; Thyrhaug, Runar; Larsen, Aud; Sandaa, Ruth-Anne; Heldal, Mikal; van Etten, J.L.; Bratbak, Gunnar. 2002. Isolation and characterization of a virus that infects Emiliania huxleyi (Haptophyceae). Journal of Phycology. 38: 767-774.
  • Gundersen, Kjell; Heldal, Mikal; Norland, Svein; Purdie, Duncan A.; Knap, Anthony H. 2002. Elemental C, N, and P cell content of individual bacteria collected at the Bermuda Atlantic Time-series Study (BATS) site. Limnology and Oceanography. 47: 1525-1530.
  • Jacquet, Stephan; Heldal, Mikal; Iglesias-Rodriguez, Debora; Larsen, Aud; Wilson, William; Bratbak, Gunnar. 2002. Flow cytometric Analysis of an E. Huxleyi bloom terminated by viral infection. Aquatic Microbial Ecology. 27: 110-124.
  • Oren, A.; Heldal, Mikal; Norland, Svein; Galinski, E.A. 2002. Intracellular ion and organic solute concentrations of the extremely halophilic bacterium Salinibacter ruber. Extremophiles. 6. 491-498.
  • Vrede, Katarina; Heldal, Mikal; Norland, Svein; Bratbak, Gunnar. 2002. Elemental composition (C,N,P)and cell volume of exponentially growing and nutrient limited bacterioplankton. Applied and Environmental Microbiology. 68: 2965-2971.
  • Castberg, Tonje; Larsen, Aud; Sandaa, Ruth-Anne; Brussaard, Corina P. D.; Egge, Jorun Karin; Heldal, Mikal; Thyrhaug, Runar; Van Hannen, Eric; Bratbak, Gunnar. 2001. Microbial population dynamics and diversity during a bloom of the marine coccolithophorid Emiliania huxleyi (Haptophyta). Marine Ecology Progress Series. 221: 39-46.
  • Heldal, Mikal. 2001. Mot vest med flatpakka båt. Sunnhordland Årbok. 82: 66-78.
  • Heldal, Mikal. 2001. Nokre hendingar frå krigsåra i Flakkavågen. Sunnhordland Årbok. 82: 109-113.
  • Larsen, Aud; Castberg, Tonje; Sandaa, Ruth-Anne; Brussaard, Corina P. D.; Egge, Jorun Karin; Heldal, Mikal; Paulino, Ana; Thyrhaug, Runar; Van Hannen, Eric; Bratbak, Gunnar. 2001. Population dynamics and diversity of phytoplankton, bacteria and viruses in a seawater enclosure. Marine Ecology Progress Series. 221: 47-57.
  • Sandaa, Ruth-Anne; Heldal, Mikal; Castberg, Tonje; Thyrhaug, Runar; Bratbak, Gunnar. 2001. Isolation and characterization of two viruses with large genome size infecting Chrysochromulina ericina (Prymneriophyceae) and Pyramimonas orientalis (Prasinophyceae). Virology. 290: 272-280.
  • Bratbak, Gunnar; Heldal, Mikal. 2000. Virus rule the waves - the smallest and most abundant members of marine ecosystems. Microbiology Today. 27: 171-173.
  • Rodriguez, F.; Fernandez, E.; Head, R.N.; Harbour, D.S.; Bratbak, Gunnar; Heldal, Mikal. 2000. Temporal variability of viruses, bacteria, phytoplankton and zooplankton in the western English Channel off Plymouth. MANGLER.
  • Fagerbakke, Kjell Magne; Norland, Svein; Heldal, Mikal. 1999. The inorganic ion content of native aquatic bacteria. Canadian journal of microbiology (Print). 304-311.
  • Heldal, Mikal. 1999. Minderne og Sangerhuen. Sunnhordland Årbok. 106-108.
  • Nesje, Ann Marie; Heldal, Mikal. 1999. Ei utvandrar-soge frå Tysnes. Sunnhordland Årbok. 51-70.
  • Bratbak, Gunnar; Jacobsen, Anita; Heldal, Mikal. 1998. Viral lysis of Phaeocystis pouchetii and bacterial secondary production. Aquatic Microbial Ecology. 16: 11-16.
  • Bratbak, Gunnar; Jacobsen, Anita; Heldal, Mikal. 1998. Viral lysis of Phaeocystis pouchetii and bacterial secondary production. Aquatic Microbial Ecology. 16: 11-16. Published 1998-10-15.
  • Bratbak, Gunnar; Jacobsen, Anita; Heldal, Mikal; Nagasaki, Keizo; Thingstad, Frede. 1998. Virus production in Phaeocystis pouchetii and its relation to host cell growth and nutrition. Aquatic Microbial Ecology. 16: 1-9.
  • Bratbak, Gunnar; Jacobsen, Anita; Heldal, Mikal; Nagasaki, Keizo; Thingstad, Frede. 1998. Virus production in Phaeocystis pouchetii and its relation to host cell growth and nutrition. Aquatic Microbial Ecology. 16: 1-9. Published 1998-10-15.
  • Mostajir, B.; Fagerbakke, Kjell Magne; Heldal, Mikal; Thingstad, Tron Frede. 1998. Elemental composition of individual pico- and nano-sized marine detrital particles in the northwestern Mediterranean Sea. Oceanologica Acta. 21: 589-596.
  • Mostajir, Behzad; Fagerbakke, Kjell Magne; Heldal, Mikal; Thingstad, Tron Frede; Rassoulzadegan, Fereidoun. 1998. Elemental composition of individual pico- and nano- sized marine detrital particles in the northwestern Medeteranian Sea. Oceanologica Acta. 21: 589-596.
  • Nesje, Anne Marie Skriveseth; Heldal, Mikal. 1998. Ei utvandrar-soge frå Tysnes. Sunnhordland Årbok. 79: 66-76.
  • Oren, Aharon; Bratbak, Gunnar; Heldal, Mikal. 1997. Occurrence of virus-like particles in the Dead Sea. Extremophies. 1: 143-149.
  • Oren, Aharon; Heldal, Mikal; Norland, Svein. 1997. X-ray microanalysis of intracellular ions in the anaerobic halophilic eubacterium <i>Haloanaerobium praevalens</i>. Canadian journal of microbiology (Print). 43: 588-592.
  • Tuomi, P.; Torsvik, Terje; Heldal, Mikal; Bratbak, Gunnar. 1997. Bacterial population dynamics in a meromictic lake. Applied and Environmental Microbiology. 63: 2181-2188.
  • Bratbak, Gunnar; Heldal, Mikal; Thingstad, Tron Frede; Tuomi, Pirjo. 1996. Dynamics of virus abundance in coastal seawater. FEMS Microbiology Ecology. 19: 263-269.
  • Bratbak, Gunnar; Willson, William; Heldal, Mikal. 1996. Viral control of Emiliania huxleyi blooms? Journal of Marine Systems. 9: 75-81.
  • Brussard, Corina P. D.; Kempers, Rob S.; Kop, Arjen J.; Riegman, Roel; Heldal, Mikal. 1996. Virus-like particles in a summer bloom of Emiliania huxleyi in the North Sea. Aquatic Microbial Ecology. 10: 105-113.
  • Fagerbakke, Kjell Magne; Heldal, Mikal; Norland, Svein. 1996. Content of carbon, nitrogen, oxygen, sulfur and phosphorus in native aquatic and cultured bacteria. Aquatic Microbial Ecology. 10: 15-27. Published 1996-03-14.
  • Gundersen, Kjell; Bratbak, Gunnar; Heldal, Mikal. 1996. Factors influencing the loss of bacteria in preserved seawater samples. Marine Ecology Progress Series. 137: 305-310. Published 1996-06-27.
  • Heldal, Mikal. 1996. Poluphosphate bodies aligned along the anterior axoneme of the cryptomonad Rhodomonas lacustris: Possible relevance to symbiotic origin of Undulipodia. Symbiosis. 21: 1-7.
  • Heldal, Mikal; Norland, Svein; Fagerbakke, Kjell Magne; Thingstad, Tron Frede; Bratbak, Gunnar. 1996. The elemental composition of bacteria: a signature of growth conditions? Marine Pollution Bulletin. 33: 3-9.
  • Jacobsen, Anita; Bratbak, Gunnar; Heldal, Mikal. 1996. Isolation and characterisation of a virus infecting Phaeocystis pouchetii (Haptophyceae). Journal of Phycology. 32: 923-927.
  • Jacobsen, Anita; Bratbak, Gunnar; Heldal, Mikal. 1996. Isolation and characterization of a virus infecting Phaeocystis pouchetii (Prymnesiophyceae). Journal of Phycology. 32: 923-927.
  • Bratbak, Gunnar; Levasseur, M.; Michaud, M.; Cantin, G.; Fernandez, E.; Heimdal, B.R.; Heldal, Mikal. 1995. Viral activity in relation to Emiliania huxleyi blooms: a possible mechanism of DMSP release? Marine Ecology Progress Series. 128: 133-142.
  • Bratbak, Gunnar; Levasseur, M.; Michaud, M.; Cantin, G.; Fernández, E.; Heimdal, B.R.; Heldal, Mikal. 1995. Viral activity in relation to Emiliania huxleyi blooms: a possible mechanism of DMSP release? Marine Ecology Progress Series. 128: 133-142.
  • Norland, Svein; Fagerbakke, Kjell Magne; Heldal, Mikal. 1995. Light element analysis of individual bacteria by X-ray microanalysis. Applied and Environmental Microbiology. 61: 1357-1362.
  • Tuomi, Pirjo; Fagerbakke, Kjell Magne; Bratbak, Gunnar; Heldal, Mikal. 1995. Nutritional enrichment of a microbial community: The effects on activity, elemental composition, community structure and virus production. FEMS Microbiology Ecology. 16: 123-134.
  • Fagerbakke, K. M.; Heldal, Mikal; Norland, Svein; Heimdal, B. R.; Båtvik, H. 1994. Emiliania huxleyi. Chemical compositiln and size of coccoliths from enclosure experiments and a Norwegian fjord. Sarsia. 79: 349-355.
  • Fagerbakke, K. M.; Heldal, Mikal; Norland, Svein; Heimdal, B. R; Båtvik, H. 1994. Emiliania huxleyi: Chemical composition and size of coccoliths from enclosure experiments and a Norwegian fjord. Sarsia. 79: 349-355.
  • Heldal, Mikal. 1994. Blodiglar brukte i folkemedisin. Sunnhordland Årbok.
  • Heldal, Mikal; Norland, Svein; Bratbak, Gunnar; Riemann, B. 1994. Determination of bacterial cell number and cell volume by means of flow cytometer, transmission electron microscopy, and epifluorescene microscopy. Journal of Microbiological Methods.
  • Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal. 1993. Viral mortality of the marine algae Emiliania huxleyi (Haptophyceae) and termination of algal blooms. Marine Ecology Progress Series. 93: 39-48.
  • Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal. 1993. Viral mortality of the marine alga Emiliania huxleyi (Haptophyceae) and termination of algal blooms. Marine Ecology Progress Series. 93: 39-48.
  • Thingstad, Tron Frede; Heldal, Mikal; Bratbak, Gunnar; Dundas, Ingrid. 1993. Are viruses important partners in pelagic food webs? Trends in Ecology & Evolution. 8: 209-213.
  • Bratbak, Gunnar; Heldal, Mikal; Thingstad, T.F; Riemann, B; Haslund, O.H. 1992. Incorporation of viruses into the budget of microbial C-transfer. A first approach. Mar.Ecol.Prog.. 83: 273-280.
  • Dundas, Ingrid; Bratbak, Gunnar; Heldal, Mikal. 1992. Roles of virus/phage in marine microbial ECOSYSTEMS. Short Communications of the 1991 International Biotechnology Conferense. 1: 146-150.
  • Thorseth, Ingunn Hindenes; Furnes, Harald; Heldal, Mikal. 1992. The importance of microbiological activity in the alteration of natura l basaltic glass. Geochimica et Cosmochimica Acta. 56: 445-450.
  • Thorseth, Ingunn Hindenes; Furnes, Harald; Heldal, Mikal. 1992. The importance of microbiological activity in the alteration of natural basaltic glass. Geochimica et Cosmochimica Acta. 56: 845-850.
  • Fagerbakke, K. M.; Heldal, Mikal; Norland, Svein. 1991. Variation in elemental content among and within trichomes in Nostoc calcicola 79WA01 measured by x-ray micro-analysis. FEMS Microbiology Letters. 227-232.
  • Heldal, Mikal; Bratbak, Gunnar. 1991. Production and decay of viruses in aquatic environments. Marine Ecology Progress Series. 72: 205-212.
  • Kjeldstad, B.; Heldal, Mikal; Nissen, H.; Bergan, A. S.; Evjen, K. 1991. Changes in polyphosphate composition and localization in Propionebacterium acnes after near-ultraviolet irradiation. Canadian journal of microbiology (Print). 562-567.
  • Bratbak, Gunnar; Heldal, Mikal; Norland, Svein; Thingstad, Tron Frede. 1990. Viruses as Partners in Spring Bloom Microbial Trophodynamics. Applied and Environmental Microbiology. 1400-1405.
  • Børsheim, K. Y.; Bratbak, Gunnar; Heldal, Mikal. 1990. Enumeration and biomass estimation on planktonic bacteria and viruses by transmission electron microscopy. Applied and Environmental Microbiology. 56: 352-356.
  • Bergh, Ø; Børsheim, K. Y.; Bratbak, Gunnar; Heldal, Mikal. 1989. High abundance of viruses found in aquatic environments. Nature. 340: 467-468.
Reports and theses
  • Bratbak, Gunnar; Heldal, Mikal. 1997. Program and group reports from course in Microbial activity and diversity in aquatic interphases. Institutt for mikrobiologi, Universitetet i Bergen.
  • Vadstein, O; Heldal, Mikal. 1992. Occurence of dissolved and particulate nutrients. [Mangler utgivernavn].
  • Heldal, Mikal; Knutsen, G. 1989. Sluttrapport til Direktoratet for naturforvaltning for prosjektet "Chr ysochromulina. Algenes fyiologiske egenskaper". [Mangler utgivernavn].
Book sections
  • Thingstad, T. Frede; Bratbak, Gunnar; Heldal, Mikal. 2008. Aquatic phage ecology. Kapittel. In:
    • Abedon, Stephen T. 2008. Bacteriphage ecology - population growth, evolution, and impact of bacterial viruses. Advances in molecular and cellular microbiology No. 15. Cambridge University Press. 526 pages. ISBN: 9780521858458.
  • Heldal, Mikal; Bratbak, Gunnar; Erichsen, Egil S.; Norland, Svein. 2003. X-ray microanalysis of native aquatic bacteria. 836-842. In:
    • Mendes-Vilas, A. 2003. Science, Technology and Education of Microscopy; an Overview.
  • Heldal, Mikal. 2001. Mirakelbakterien. 153-165. In:
    • Hartenstein, Tilman. 2001. P2 Akademiet U. ISBN: 82-7118-277-3.
  • Heldal, Mikal. 2000. Morphology as a parameter for diversity in bacterial populations. In:
    • Seckbach, Joseph. 2000. Journey to Diverse Microbial Worlds: Adaptation to Exotic Environments.
  • Heldal, Mikal. 1997. Klubba-Adno og fola hennar. 172-174. In:
    • [Mangler etternavn], [Mangler fornavn]. 1997. Sunnhordland : Årbok frå Sunnhordland folkemuseum og sogela g.
  • Heldal, Mikal. 1997. Kalkbrenning. 85-99. In:
    • [Mangler etternavn], [Mangler fornavn]. 1997. Sunnhordland : Årbok frå Sunnhordland folkemuseum og sogela g.
  • Heldal, Mikal. 1996. "Med den slemme spedalched... angreben". 69-79. In:
    • [Mangler etternavn], [Mangler fornavn]. 1996. Sunnhordland. Årbok 1996.
  • Bratbak, Gunnar; Heldal, Mikal. 1993. Total Counts of Viruses in Aquatic Environments. In:
    • [Mangler etternavn], [Mangler fornavn]. 1993. Handbook of methods in Aquatic Microbial ecology. (Red.: Kemp, P. F., Sherr, B. F., Sherr, E. B., Cole, J. J.).
  • Heldal, Mikal. 1993. Measurements of elemental content and dry weight of single cells: X-ray microanalysis. In:
    • [Mangler etternavn], [Mangler fornavn]. 1993. Handbook of methods in Aquatic Microbial ecology. (Red.: Kemp, P. F., Sherr, B. F., Sherr, E. B., Cole, J. J.).

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