Significant N-2 fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries

Research output: Contribution to journalJournal article – Annual report year: 2015Researchpeer-review

Without internal affiliation

  • Author: Bentzon-Tilia, Mikkel

    University of Copenhagen

  • Author: Traving, Sachia J.

    University of Copenhagen, Denmark

  • Author: Mantikci, Mustafa

    Aarhus University, Denmark

  • Author: Knudsen-Leerbeck, Helle

    Aarhus University, Denmark

  • Author: Hansen, Jorgen L. S.

    Aarhus University, Denmark

  • Author: Markager, Stiig

    Aarhus University, Denmark

  • Author: Riemann, Lasse

    University of Copenhagen, Denmark

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Nitrogen (N) fixation is fueling planktonic production in a multitude of aquatic environments. In meso-and poly-haline estuaries, however, the contribution of N by pelagic N2 fixation is believed to be insignificant due to the high input of N from land and the presumed absence of active N2-fixing organisms. Here we report N2 fixation rates, nifH gene composition and nifH gene transcript abundance for key diazotrophic groups over 1 year in two contrasting, temperate, estuarine systems: Roskilde Fjord (RF) and the Great Belt (GB) strait. Annual pelagic N2 fixation rates averaged 17 and 61 mmol Nm-2 per year at the two sites, respectively. In RF, N2 fixation was mainly accompanied by transcripts related to heterotrophic (for example, Pseudomonas sp.) and photoheterotrophic bacteria (for example, unicellular diazotrophic cyanobacteria group A). In the GB, the first of two N2 fixation peaks coincided with a similar nifH-expressing community as in RF, whereas the second peak was synchronous with increased nifH expression by an array of diazotrophs, including heterotrophic organisms as well as the heterocystous cyanobacterium Anabaena. Thus, we show for the first time that significant planktonic N2 fixation takes place in mesohaline, temperate estuaries and that the importance of heterotrophic, photoheterotrophic and photosynthetic diazotrophs is clearly variable in space and time.
Original languageEnglish
JournalI S M E Journal
Issue number2
Pages (from-to)273-285
Number of pages13
Publication statusPublished - 2014
Externally publishedYes
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Great Belt Denmark, Europe Palearctic region, Roskilde Fjord Denmark, Europe Palearctic region, Gram-Negative Aerobic Rods and Cocci Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Pseudomonadaceae [06508] Pseudomonas genus, Nostocales Cyanobacteria Oxygenic Photosynthetic Bacteria Eubacteria Bacteria Microorganisms (Bacteria, Cyanobacteria, Eubacteria, Microorganisms) - Nostocaceae [09241] Anabaena genus, Oxygenic Photosynthetic Bacteria Eubacteria Bacteria Microorganisms (Bacteria, Cyanobacteria, Eubacteria, Microorganisms) - Cyanobacteria [09200] cyanobacteria common, Anabaena nifH gene [Nostocaceae] expression, transcription, cyanobacteria nifH gene [Cyanobacteria] expression, transcription, Pseudomonas nifH gene [Pseudomonadaceae] expression, transcription, RNA transcript, 03502, Genetics - General, 07502, Ecology: environmental biology - General and methods, 07510, Ecology: environmental biology - Oceanography and limnology, 30000, Bacteriology, general and systematic, 31000, Physiology and biochemistry of bacteria, 31500, Genetics of bacteria and viruses, Biodiversity, Estuarine Ecology, Molecular Genetics, environmental parameter, nitrogen fixation, species abundance, temperate estuary, Biochemistry and Molecular Biophysics, Ecology, Environmental Sciences, Illumina amplicon sequencing laboratory techniques, genetic techniques, quantitative PCR qPCR laboratory techniques, genetic techniques, reverse-transcription quantitative PCR RT-qPCR laboratory techniques, genetic techniques, Ecology, Microbiology, Central Baltic Sea, Nitrogen fixation, Marine ecosystems, Pacific Ocean, NIFH gene, Planktonic cyanobacteria, SUBOXIC WATERS, Surface waters

ID: 110642942