Record Details
Nitrogen uptake and phytoplankton growth in coastal upwelling regions
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Nitrogen uptake and phytoplankton growth in coastal upwelling regions |
| Names |
Kokkinakis, Steven A.
(creator) Wheeler, Patricia A. (creator) |
| Date Issued | 1987 (iso8601) |
| Note | Support for this rcscarch was provided by NSF grants OCE 82-08873 and OCE 83-08753 to P. Wheeler. |
| Abstract | Uptake of nitrogenous nutrients by microplankton off the Washington and Oregon coasts was measured during the 1985 upwelling period. Nitrogen uptake rates in low-NO3- waters (<5 μM) were 0.020–0.258 μmol N liter-1 h-1 and were primarily supported by regenerated nitrogen (71% of total uptake). Nitrogen uptake rates in high-NO3- waters (≥20 μM) were 0.281–1.480 μmol N liter-1 h-1 and new (NO3-) nitrogen supported 83% of total uptake. Phytoplankton N was estimated by assuming a constant Chl a : PN for phytoplankton and was used to calculate phytoplanktonspecific uptake rates. Despite differences in nutrient concentrations, PN and Chl a at three upwelling sites (Oregon, Benguela, and Peru), NO3- uptake normalized to Chl a, and estimates of NO-3-supported phytoplankton growth rates are remarkably similar. Nitrate uptake supports growth rates on the order of 1–2 d-1. Estimates of phytoplankton growth from rates of NH4+ + NO3- uptake range from 1.36 to 4.79 d-1 and are negatively correlated with concentrations of NO3- and phytoplankton N. The apparent increase in phytoplankton growth rates for waters with lower nitrogen availability may result from heterotrophic bacterial utilization of NH4+ nitrogen. |
| Genre | Article |
| Identifier | Limnol. Oceanogr., 32(5), 1987, 1112-1123 |
