Balance of nature: bacteria fix nitrogen in oceans (Introduction)

by David Turell , Sunday, February 23, 2025, 18:45 (11 days ago) @ dhw

Nitrogen vital for life is hard to come by:

https://www.sciencedaily.com/releases/2025/02/250219190827.htm

"...in the 1980s it was suggested that aggregates, so-called "marine snow particles," could possibly be suitable sites for N2fixation, and this was recently confirmed. Still, it has been an open question why the bacteria carrying out this N2fixation can be found worldwide in the ocean. Moreover, the global magnitude and the distribution of the activity have been unknown.

"Until now...

"In a new study, researchers... demonstrate, by use of mechanistic mathematical models, that bacteria attached to marine snow particles can fix N2 over a wide range of temperatures in the global oceans, from the tropics to the poles, and from the surface to the abyss. The study also shows that the activity of these bacteria accounts for about 10% of the overall N2 fixation in the global ocean.

***

"...Then he added "but it was definitely worth the effort, since the results are quite a breakthrough. Indeed our study disputes the long-standing paradigms that oceanic N2 fixation is exclusively restricted to surface waters of the tropical and subtropical oceans and that cyanobacteria are the only important diazotrophs."

"With their mechanistic models the researchers could also show a distinct latitudinal distribution of the bacteria fixing N2on marine snow particles, with highest rates in the oxygen minimum zones found in large regions of the global ocean. Moreover, it was shown that particle-associated bacteria can fix N2 at a much broader temperature range than cyanobacteria.

***

"'By fixing N2 mostly below the surface layers, the bacterial activity associated with particles is expected to have indirect and delayed impact on the oceanic nitrogen cycle compared to that of cyanobacteria. These insights may be particularly important when trying to predict plankton productivity in the future ocean impacted by global warming.'"

Comment: nature is balanced. Without cyanobacteria and nitrogen-fixing bacteria we would not exist.