 |
| Titel |
Latitudinal distribution of Trichodesmium spp. and N2 fixation in the Atlantic Ocean |
| VerfasserIn |
A. Fernández, B. Mouriño-Carballido, A. Bode, M. Varela, E. Marañón |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 10 ; Nr. 7, no. 10 (2010-10-15), S.3167-3176 |
| Datensatznummer |
250005016
|
| Publikation (Nr.) |
 copernicus.org/bg-7-3167-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| We have determined the latitudinal distribution of Trichodesmium spp. abundance and
community N2 fixation in the Atlantic Ocean along a meridional transect
from ca. 30° N to 30° S in November–December 2007 and April–May 2008.
The observations from both cruises were highly consistent in terms of
absolute magnitude and latitudinal distribution, showing a strong
association between Trichodesmium abundance and community N2 fixation. The highest
Trichodesmium abundances (mean = 220 trichomes L−1,) and community N2 fixation
rates (mean = 60 μmol m−2 d−1) occurred in the Equatorial
region between 5° S–15° N. In the South Atlantic gyre, Trichodesmium abundance was
very low (ca. 1 trichome L−1) but N2 fixation was always
measurable, averaging 3 and 10 μmol m2 d−1 in 2007 and 2008,
respectively. We suggest that N2 fixation in the South Atlantic was
sustained by other, presumably unicellular, diazotrophs. Comparing these
distributions with the geographical pattern in atmospheric dust deposition
points to iron supply as the main factor determining the large scale
latitudinal variability of Trichodesmium spp. abundance and N2 fixation in the
Atlantic Ocean. We observed a marked South to North decrease in surface
phosphate concentration, which argues against a role for phosphorus
availability in controlling the large scale distribution of N2
fixation. Scaling up from all our measurements (42 stations) results in
conservative estimates for total N2 fixation of ∼6 TgN yr−1
in the North Atlantic (0–40° N) and ~1.2 TgN yr−1 in the South
Atlantic (0–40° S). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|