Back to Search
Start Over
High cell-specific rates of nitrogen and carbon fixation by the cyanobacterium Aphanizomenon sp. at low temperatures in the Baltic Sea.
- Source :
- FEMS Microbiology Ecology; Dec2015, Vol. 91 Issue 12, p1-10, 10p, 1 Color Photograph, 3 Charts, 5 Graphs
- Publication Year :
- 2015
-
Abstract
- Aphanizomenon is a widespread genus of nitrogen (N<subscript>2</subscript>)-fixing cyanobacteria in lakes and estuaries, accounting for a large fraction of the summer N<subscript>2</subscript>-fixation in the Baltic Sea. However, information about its cell-specific carbon (C)- and N<subscript>2</subscript>-fixation rates in the early growth season has not previously been reported. We combined various methods to study N<subscript>2</subscript>-fixation, photosynthesis and respiration in field-sampled Baltic Sea Aphanizomenon sp. during early summer at 10°C. Stable isotope incubations at in situ light intensities during 24 h combined with cell-specific secondary ion mass spectrometry showed an average net N<subscript>2</subscript>-fixation rate of 55 fmol N cell<superscript>-1</superscript> day<superscript>-1</superscript>. Dark net N<subscript>2</subscript>-fixation rates over a course of 12 h were 20% of those measured in light. C-fixation, but not N<subscript>2</subscript>-fixation, was inhibited by high ambient light intensities during daytime. Consequently, the C:N fixation ratio varied substantially over the diel cycle. C- and N<subscript>2</subscript>-fixation rates were comparable to those reported for Aphanizomenon sp. in August at 19°C, using the same methods. High respiration rates (23% of gross photosynthesis) were measured with 14C-incubations and O<subscript>2</subscript>-microsensors, and presumably reflect the energy needed for high N<subscript>2</subscript>-fixation rates. Hence, Aphanizomenon sp. is an important contributor to N<subscript>2</subscript>-fixation at low in situ temperatures in the early growth season. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01686496
- Volume :
- 91
- Issue :
- 12
- Database :
- Complementary Index
- Journal :
- FEMS Microbiology Ecology
- Publication Type :
- Academic Journal
- Accession number :
- 113488786
- Full Text :
- https://doi.org/10.1093/femsec/fiv131