Dinitrogen fixation and dissolved organic nitrogen fueled primary production and particulate export during the VAHINE mesocosm experiment (New Caledonia lagoon)

A significant finding from the VAHINE mesocosm experiment in New Caledonia's lagoons reveals that dinitrogen (N2) fixation and dissolved organic nitrogen (DON) play crucial roles in fueling primary production and particulate export, especially under nitrate-depleted conditions. The study demonstrated that while diazotrophic communities, such as diatom–diazotroph associations (DDAs) and unicellular cyanobacteria UCYN-C, both contribute to N2 fixation, UCYN-C-driven production was more efficient at promoting carbon export compared to DDAs. Additionally, DON consumption during the latter phase of the experiment suggested its importance as an additional nitrogen source, highlighting its potential significance in nitrogen-limited oceanic ecosystems.

Berthelot, H., Moutin, T., L’Helguen, S., Leblanc, K., Hélias, S., Grosso, O., Leblond, N., Charrière, B., & Bonnet, S. (2015). Dinitrogen fixation and dissolved organic nitrogen fueled primary production and particulate export during the VAHINE mesocosm experiment (New Caledonia lagoon). Biogeosciences, 12(13), 4099–4112. https://doi.org/10.5194/bg-12-4099-2015