Carbon, nitrogen and O(2) fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea
2011 (English)In: The ISME Journal, ISSN 1751-7362, Vol. 5, no 9, 1549-1558 p.Article in journal (Refereed) Published
Photosynthesis, respiration, N(2) fixation and ammonium release were studied directly in Nodularia spumigena during a bloom in the Baltic Sea using a combination of microsensors, stable isotope tracer experiments combined with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorometry. Cell-specific net C-and N(2)-fixation rates by N. spumigena were 81.6 +/- 6.7 and 11.4 +/- 0.9 fmol N per cell per h, respectively. During light, the net C: N fixation ratio was 8.0 +/- 0.8. During darkness, carbon fixation was not detectable, but N(2) fixation was 5.4 +/- 0.4 fmol N per cell per h. Net photosynthesis varied between 0.34 and 250 nmol O(2) h(-1) in colonies with diameters ranging between 0.13 and 5.0 mm, and it reached the theoretical upper limit set by diffusion of dissolved inorganic carbon to colonies (>1 mm). Dark respiration of the same colonies varied between 0.038 and 87 nmol O(2) h (1), and it reached the limit set by O(2) diffusion from the surrounding water to colonies (>1 mm). N(2) fixation associated with N. spumigena colonies (41mm) comprised on average 18% of the total N(2) fixation in the bulk water. Net NH(4)(+) release in colonies equaled 8-33% of the estimated gross N(2) fixation during photosynthesis. NH(4)(+) concentrations within light-exposed colonies, modeled from measured net NH(4)(+) release rates, were 60-fold higher than that of the bulk. Hence, N. spumigena colonies comprise highly productive microenvironments and an attractive NH(4)(+) microenvironment to be utilized by other (micro) organisms in the Baltic Sea where dissolved inorganic nitrogen is limiting growth.
Place, publisher, year, edition, pages
2011. Vol. 5, no 9, 1549-1558 p.
stable isotopes, microsensors, N(2) fixation, photosynthesis, respiration, ammonium release
IdentifiersURN: urn:nbn:se:su:diva-67287DOI: 10.1038/ismej.2011.20ISI: 000295782900015OAI: oai:DiVA.org:su-67287DiVA: diva2:470912
authorCount :72011-12-302011-12-272011-12-30Bibliographically approved