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Deployment: RR_EB05

Chief Scientist: 
David M. Nelson (Oregon State University, OSU)
Platform Type:
Start Date: 
End Date: 
equatorial Pacific Ocean; upwelling zone of the EEP (135 - 140 W)

This study was conducted in the eastern Equatorial Pacific along 110°W between 4°N and 3°S during the Equatorial Biocomplexity cruise (EB05) (September 2005) aboard R/V Revelle.

Kinetic experiments of two kinds were performed. The
first involved collecting seawater and immediately examining
the response of Si uptake to added Si(OH)4, as has been
done in several other systems described by investigators Brzezinski and Nelson. The second was designed to quantify the effect of the ambient [Fe] on the kinetics of Si uptake. In those experiments seawater was augmented with Fe and held for up to 4 days before examining the kinetics of Si uptake to allow time for the diatoms to
adjust to the addition of Fe. These two types of experiments are referred to as standard kinetic experiments and delayed kinetic experiments, respectively.
A total of 29 standard kinetic experiments were performed.
Fifteen were performed along 110°W and along the
equator between 09 and 29 December 2004 with
an additional 14 conducted between 08 and 24 September
2005 along 140°W and along a longitudinal transect at
0.5°N in the vicinity of a tropical instability wave.
Four delayed kinetic experiments were conducted in 2005.

This work was supported by National Science Foundation award OCE0322074, "Plankton dynamics and carbon cycling in the equatorial Pacific Ocean: Control by Fe, Si and grazing".


Brzezinski, Mark A., Cynthia Dumousseaud, Jeffrey W. Krause, Christopher I. Measures, and David M. Nelson. 2008. Iron and silicic acid concentrations together regulate Si uptake in the equatorial Pacific Ocean. Limnol. Oceanogr., 53(3), 2008, 875-889.