Ocean Dynamics

, Volume 54, Issue 2, pp 221–231 | Cite as

The age as a diagnostic of the dynamics of marine ecosystem models

  • Éric J.M. DelhezEmail author
  • Geneviève Lacroix
  • Éric Deleersnijder


The constituent-oriented age theory (CAT) worked out by Delhez et al. (1999) is a flexible tool that can be applied to diagnose complex models. It is shown here how this can be used to quantify the pace at which an ecosystem model works. At the cost of the introduction of one additional evolution equation for each compartment of the ecosystem model, the mean age of the biological material forming these compartments can be computed. The information obtained in this way complements the information provided by the concentration data; while the latter measures the standing stocks, the former provides an integrated assessment of the interaction rates and matter fluxes. The benefits of the method are demonstrated with a simple Lotka–Volterra system and a one-dimensional vertical model of the nitrogen cycle in the Ligurian Sea. The theory can be used to study the biological compartments individually or the ecosystem as a whole. In particular, the age is a valuable tool to quantify the overall cycling rate of nitrogen in the food web.


Age Diagnostic Ecosystem model Ligurian Sea 


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E. Deleersnijder is a Research Associate with the Belgian National Fund for Scientific Research (FNRS). This paper is MARE publication no. 21.

Copyright information

© Springer-Verlag Berlin Heidelberg 2004

Authors and Affiliations

  • Éric J.M. Delhez
    • 1
    Email author
  • Geneviève Lacroix
    • 2
  • Éric Deleersnijder
    • 3
  1. 1.Université de Liège, MAREModélisation et Méthodes MathématiquesLiègeBelgium
  2. 2.Management Unit of the North Sea Mathematical ModelsBrusselsBelgium
  3. 3.Université Catholique de LouvainInstitut d’Astronomie et de GéophysiqueLouvain-la-NeuveBelgium

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