Elevated CO2enhances nitrogen fixation and growth in the marine cyanobacterium Trichodesmium

Autor: J. Grigel, Ivan Šetlík, Eva Šetlíková, Ondřej Prášil, G. Rosenberg, Ilana Berman-Frank, Orly Levitan, J. Klepetar
Rok vydání: 2007
Předmět:
Zdroj: Global Change Biology. 13:531-538
ISSN: 1365-2486
1354-1013
Popis: The increases in atmospheric pCO₂ over the last century are accompanied by higher concentrations of CO₂(aq) in the surface oceans. This acidification of the surface ocean is expected to influence aquatic primary productivity and may also affect cyanobacterial nitrogen (N)-fixers (diazotrophs). No data is currently available showing the response of diazotrophs to enhanced oceanic CO₂(aq). We examined the influence of pCO₂ [preindustrial~250 ppmv (low), ambient~400, future~900 ppmv (high)] on the photosynthesis, N fixation, and growth of Trichodesmium IMS101. Trichodesmium spp. is a bloom-forming cyanobacterium contributing substantial inputs of 'new N' to the oligotrophic subtropical and tropical oceans. High pCO₂ enhanced N fixation, C : N ratios, filament length, and biomass of Trichodesmium in comparison with both ambient and low pCO₂ cultures. Photosynthesis and respiration did not change significantly between the treatments. We suggest that enhanced N fixation and growth in the high pCO₂ cultures occurs due to reallocation of energy and resources from carbon concentrating mechanisms (CCM) required under low and ambient pCO₂. Thus, in oceanic regions, where light and nutrients such as P and Fe are not limiting, we expect the projected concentrations of CO₂ to increase N fixation and growth of Trichodesmium. Other diazotrophs may be similarly affected, thereby enhancing inputs of new N and increasing primary productivity in the oceans.
Databáze: OpenAIRE
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