Spatial variation in N₂-fixation rate and diazotroph activity in the Tropical Atlantic

J. P. Montoya (1) , M. Voss (2) , D. G. Capone (3)

1 Georgia Institute of Technology [Atlanta]
2 IOW - Leibniz-Institut für Ostseeforschung Warnemünde
3 USC - University of Southern California

A variety of N₂-fixers occur in the tropical Atlantic and these diazotrophs make a substantial contribution to the nitrogen budget of the upper water column. A synthesis of previously published and novel rate measurements for the Tropical North Atlantic provides insight into the role of two different diazotroph groups in supporting N₂ fixation in the tropical Atlantic. The overall rate of N₂-fixation by the two groups of diazotrophs was similar in the eastern and western parts of the basin, but N₂-fixation by \textit{Trichodesmium} was strongly dominant in the western part of the basin while small diazotrophs played a much larger role to the east of 40° W. The reasons for this shift in dominance are unclear, as is the identity of the small organisms fixing N₂ in the water column.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

J. P. Montoya, M. Voss, D. G. Capone. Spatial variation in N₂-fixation rate and diazotroph activity in the Tropical Atlantic. Biogeosciences Discussions, 2006, 3 (6), pp.1739-1761. ⟨hal-00297855⟩