Maximum rates of N-2 fixation and primary production are out of phase in a developing cyanobacterial bloom in the Baltic Sea

: Gallon JR, Evans AM, Jones DA, Albertano P, Congestri R, Bergman B, Gundersen K, Orcutt KM, von Brockel K, Fritsche P, Meyerhofer M, Nachtigall K, Ohlendieck U, Hekkert STL, Sivonen K, Repka S, Stal LJ, Staal M

Publisher: AMER SOC LIMNOLOGY OCEANOGRAPHY

: 2002

Limnology and Oceanography

: LIMNOLOGY AND OCEANOGRAPHY

: LIMNOL OCEANOGR

: 47

: 5

: 1514

: 1521

: 8

: 0024-3590

DOI: https://doi.org/10.4319/lo.2002.47.5.1514

Although N-2-fixing cyanobacteria contribute significantly to oceanic sequestration of atmospheric CO2, little is known about how N-2, fixation and carbon fixation (primary production) interact in natural populations of marine cyanobacteria. In a developing cyanobacterial bloom in the Baltic Sea, rates of N-2, fixation (acetylene reduction) showed both diurnal and longer-term fluctuations. The latter reflected fluctuations in the nitrogen status of the cyanobacterial population and could be correlated with variations in the ratio of acetylene reduced to N-15(2), assimilated. The value of this ratio may provide useful information about the release of newly fixed nitrogen by a cyanobacterial population. However, although the diurnal fluctuations in N-2, fixation broadly paralleled diurnal fluctuations in carbon fixation, the longer-term fluctuations in these two processes were out of phase.