, Volume 37, Issue 3, pp 237–252

Marine nitrogen: Phosphorus stoichiometry and the global N:P cycle


DOI: 10.1023/A:1005712322036

Cite this article as:
DOWNING, J.A. Biogeochemistry (1997) 37: 237. doi:10.1023/A:1005712322036


Nitrogen supply is often assumed to limitmarine primary production. A global analysis of totalnitrogen (N) to phosphorus (P) molar ratios shows thattotal N:P is low (<16:1) in some estuarine andcoastal ecosystems, but up to 100:1 in open oceans.This implies that elements other than N may limitmarine production, except in human impacted, estuarineor coastal ecosystems. This pattern may reconcileconflicting enrichment studies, because N additionfrequently increases phytoplankton growth where totalN:P is expected to be low, but P, Fe, or Si augmentphytoplankton growth in waters where total N:P ishigh. Comparison of total N:P stoichiometry betweenmarine and freshwaters yields a model of the form ofthe aquatic N:P cycle.

freshwaterlimitationmarinenitrogenphosphorusratiostoichiometrytrace elements

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

    • 1
  1. 1.Department of Animal EcologyIowa State UniversityAmesUSA