dc.contributor.author |
Loick, Natalie |
|
dc.contributor.author |
Dippner, Joachim |
|
dc.contributor.author |
Doan, Nhu Hai |
|
dc.contributor.author |
Liskow, Iris |
|
dc.contributor.author |
Voss, Maren |
|
dc.date.accessioned |
2017-03-24T03:47:08Z |
|
dc.date.available |
2017-03-24T03:47:08Z |
|
dc.date.issued |
2007 |
|
dc.identifier.uri |
http://113.160.249.209:8080/xmlui/handle/123456789/19618 |
|
dc.description.abstract |
Upwelling and nitrogen (N) fixation provide new N for primary production off southern central Vietnam. Here we evaluate the roles of both N sources for zooplankton nutrition by comparing δ15N and δ13C values in nitrate, particulate organic matter (POM), and six net-plankton size fractions from monsoon and intermonsoon seasons. The δ13C values in POM and the net-plankton size fractions differed by 2–4‰ at any time. We assume that plankton from the POM filters was dominated by nano-and picoplankton as opposed to micro- and mesoplankton in the net-samples. The implications of this are discussed in terms of size differential pathways of C and N in the planktonic food web. We used δ15N to estimate the differences in N nutrition between the actual upwelling region and the oligotrophic area further offshore. The δ15N values of the net-plankton size fractions were depleted in δ15N by ca. 2‰ outside compared to inside the upwelling area during the monsoon season. We attribute these patterns to the additional utilization of N derived from N fixation. The concomitant findings of high N fixation rates reported earlier and low subthermocline nitrate (nitratesub) values of 2.9–3.6‰ support this conclusion. Net-plankton δ15N values increased with size, pointing to the dominance of higher trophic levels in the larger size fractions. According to a two source mixing model N fixation may have provided up to 13% of the N demand in higher trophic levels. |
vi,en |
dc.language.iso |
en |
vi,en |
dc.relation.ispartofseries |
Deep Sea Research Part I: Oceanographic Research Papers, Volume 54, Issue 4, April 2007, Pages 596–607;[http://www.sciencedirect.com/science/article/pii/S0967063706003281] [http://dx.doi.org/10.1016/j.dsr.2006.12.009] |
|
dc.subject |
Southern central Vietnam |
vi,en |
dc.subject |
Upwelling |
vi,en |
dc.subject |
Nitrogen fixation |
vi,en |
dc.subject |
Nitrogen isotopes |
vi,en |
dc.subject |
Carbon isotopes |
vi,en |
dc.subject |
Zooplankton |
vi,en |
dc.title |
Pelagic nitrogen dynamics in the Vietnamese upwelling area according to stable nitrogen and carbon isotope data |
vi,en |
dc.type |
Working Paper |
vi,en |