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Research article - Peer-reviewed, 2015

Nitrogen fixation by cyanobacteria stimulates production in Baltic food-webs

Karlson, Agnes M. L.; Duberg, Jon; Motwani, Nisha H.; Hogfors, Hedvig; Klawonn, Isabell; Ploug, Helle; Sveden, Jennie Barthel; Garbaras, Andrius; Sundelin, Brita; Hajdu, Susanna; Larsson, Ulf; Elmgren, Ragnar; Gorokhova, Elena


Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N-2 allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.


Diazotrophic cyanobacteria; Food webs; Zooplankton grazing; Secondary production; Fish

Published in

AMBIO: A Journal of the Human Environment
2015, volume: 44, number: Suppl 3, pages: S413-S426

Authors' information

Karlson, Agnes M. L.
Stockholm University
Duberg, Jon
Stockholm University
Motwani, Nisha H
Stockholm University
Hogfors, Hedvig
AquaBiota Water Research
Klawonn, Isabell
Stockholm University
Ploug, Helle
University of Gothenburg
Barthel Svedén, Jennie
Stockholm University
Garbaras, Andrius
Center for Physical Sciences and Technology (FTMC)
Sundelin, Brita
Stockholm University
Hajdu, Susanna
Stockholm University
Larsson, Ulf
Stockholm University
Elmgren, Ragnar
Stockholm University
Gorokhova, Elena
Stockholm University

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