Return to CIG

Search

View All Publications

Go To Publication by Year:

View Publications by Topic:

Adaptation

Agriculture

Air Quality

Aquatic Ecosystems and Fisheries

Background Papers

Climate: Atmospheric Modeling

Climate: Coupled Atmosphere-Ocean Modeling

Climate: Diagnostics

Climate: Global Climate

Climate: Ocean Modeling

Climate: PNW Climate

Climate: Regional Climate Modeling

Coastal Ecosystems

Coastal Environments

Conservation Biology

Data Analysis and Sharing

Energy

Fact Sheets

Forecasts and Applications

Forest Ecosystems

Human Health

Hydrology and Water Resources

Infrastructure

Integrated Assessment

Ocean Acidification

Oceanography

Program Documents

Science Advisory Reports

Societal Dimensions

Special Reports

Theses and Dissertations

View Publications by Author:

Search the Publication Abstracts:


Other CSES Links:

About CSES

CSES Personnel

Data / Links

Publications

Welcome to the publications directory for the Climate Impacts Group and the Climate Dynamics Group. Please contact the web administrator for assistance with any of these publications.


View: Abstract

An ecosystem model with iron limitation of primary and export production in the equatorial Pacific at 140W

Loukos, H., B. Frost, D.E. Harrison, and J. Murray. 1998. An ecosystem model with iron limitation of primary and export production in the equatorial Pacific at 140W. Deep Sea Research Part II: Topical Studies in Oceanography 44(9-10):2221-2250.

Abstract

We construct a one-dimensional ecosystem model (nitrate, ammonium, phytoplankton, zooplankton and detritus) with simple physics and biology in order to focus on the structural relations and intrinsic properties of the food web that characterizes the biological regime in the central equatorial Pacific at 140°W. When possible, data collected during the EgPac and other cruises were used to calibrate model parameters for two simulations that differ in the limiting nutrient, i.e. nitrogen or iron.

Both simulations show annual results in good agreement with the data, but phytoplankton biomass and primary production show a more pronounced annual variability when iron is used as the limiting nutrient. This more realistically reproduces the variability of biological production and illustrates the greater coupling between vertical physical processes and biological production when the limiting nutrient is iron rather than nitrogen. The iron simulation also illustrates how iron supply controls primary production variability, how grazing balances primary production and controls phytoplankton biomass, and how both iron supply and grazing control primary production. These results suggest that it is not possible to capture primary production variability in the central equatorial Pacific with biological models using nitrogen as the limiting nutrient.

Other indirect results of this modeling study were: (1) partitioning of export production between dissolved and particulate matter is almost equal, suggesting that the importance of DOC export may have been previously overestimated; (2) lateral export of live biomass has to be taken into account in order to balance the nitrogen budget on the equator at 140°W; and (3) preferential uptake of ammonium (i.e. nitrate uptake inhibition by ammonium) associated with high regeneration of nitrogen (low f ratio as a consequence of the food web structure imposed by iron limitation) largely accounts for the surface build-up of upwelled nitrate.