English: A diagram showing the open ocean plankton ecosystem model developed by Michael Fasham and coauthors in:

Fasham, M. J. R.; Ducklow, H. W.; McKelvie, S. M. (1990). "A nitrogen-based model of plankton dynamics in the oceanic mixed layer". Journal of Marine Research 48: 591–639.

The diagram shows 7 ecosystem components: P, phytoplankton; Z, zooplankton; B, bacteria; D, detritus; Nn, nitrate; Nr, ammonium; Nd, dissolved organic nitrogen. The connecting arrows indicate flows of material between these components driven by processes such as primary production, grazing and remineralisation. Closed-headed arrows indicate flows of material that remain within the model ecosystem; open-headed arrows indicate flows of material out of the modelled domain, for instance below the ocean's upper mixed layer.

The image was originally generated in Encapsulated Postscript format using Xfig. This was converted into Scalable Vector Graphics format using Scribus (Microsoft Windows).