The elemental stoichiometry of dissolved and particulate matter in the sea,
especially the nitrogen-to-phosphorus ratio, is an important parameter for
studies of the nutrient control of plankton growth and for modeling biogeo
chemical processes, including carbon sequestration. Nitrogen (N) and phosph
orus (P) pools have been measured on approximately monthly intervals for a
9-yr period at a deep-ocean station in the North Pacific subtropical gyre (
Sta. ALOHA; 22 degrees 45'N, 158 degreesW). These data sets reveal complex
interactions between N and P pools, and several unexpected secular trends.
Models based on steady-state assumptions will not capture these temporal va
riations, especially the apparently rapid response of the microbial assembl
ages to stochastic nutrient intrusion events and the time-varying (seasonal
, interannual and decadal scale) changes in dissolved matter N:P ratios. Ba
sed on an analysis of these data, we hypothesize that the gyre is presently
in a period of net fixed N sequestration and P control of plankton rate pr
ocesses. (C) 2001 Elsevier Science Ltd. All rights reserved.