 |
| Titel |
Heterotrophic prokaryote distribution along a 2300 km transect in the North Pacific subtropical gyre during a strong La Niña conditions: relationship between distribution and hydrological conditions |
| VerfasserIn |
M. Girault, H. Arakawa, A. Barani, H. J. Ceccaldi, F. Hashihama, G. Grégori |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 11 ; Nr. 12, no. 11 (2015-06-10), S.3607-3621 |
| Datensatznummer |
250117981
|
| Publikation (Nr.) |
 copernicus.org/bg-12-3607-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| The spatial distribution of heterotrophic prokaryotes was investigated
during the Tokyo–Palau cruise in the western part of the North Pacific
subtropical gyre (NPSG) along a north–south transect between 33.60 and
13.25° N. The cruise was conducted in three different hydrological
areas identified as the Kuroshio region, the subtropical gyre area and the
transition zone. Two eddies were crossed along the transect: one cold-core
cyclonic eddy and one warm-core anticyclonic eddy and distributions of the
heterotrophic prokaryotes were recorded. By using analytical flow cytometry
and a nucleic acid staining protocol, heterotrophic prokaryotes were
discriminated into three subgroups depending on their nucleic acid content
(low, high and very high nucleic acid contents labelled LNA, HNA and VHNA,
respectively). Statistical analyses performed on the data set showed that
LNA, mainly associated with low temperature and low salinity, were dominant
in all the hydrological regions. In contrast, HNA distribution seemed to be
associated with temperature, salinity, Chl a and silicic acid. A latitudinal
increase in the HNA / LNA ratio was observed along the north–south transect
and was related to higher phosphate and nitrate concentrations. However, the
opposite relationship observed for the VHNA / HNA ratio suggested that the
link between nucleic acid content and oligotrophic conditions is not linear,
underlying the complexity of the biodiversity in the VHNA, HNA and LNA
subgroups. In the Kuroshio Current, it is suggested that the high
concentration of heterotrophic prokaryotes observed at station 4 was linked
to the path of the cold cyclonic eddy core. In contrast, it is thought that
low concentrations of heterotrophic prokaryotes in the warm core of the
anticyclonic gyre (Sta. 9) are related to the low nutrient concentrations
measured in the seawater column. Our results showed that the high
variability between the various heterotrophic prokaryote cluster abundances
depend both on the mesoscale structures and the oligotrophic gradient. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|