G. Crispi et al., A seasonal three-dimensional study of the nitrogen cycle in the Mediterranean Sea: Part II. Verification of the energy constrained trophic model, J MAR SYST, 20(1-4), 1999, pp. 357-379
In this study the lower trophic level variability induced by physical forci
ngs in the Mediterranean is investigated by means of a three-dimensional co
upled hydrodynamical-ecological model, when the lower trophic dynamics are
described using an NPD aggregated model. The seasonal cycle of the ecosyste
m response shows marked spatial differences according to the prevailing cyc
lonic or anticyclonic regimes and to the zonal and meridional permanent tro
phic gradients. The interplay between the mixed layer dynamics and the irra
diance penetration explains the gross ecosystem vertical dynamics while the
general circulation contributes to establish the prevailing trophic regime
in the sub-basins. Comparison of simulated chlorophyll concentrations with
corresponding CZCS images shows remarkable similarities both in gradients
and fields in different seasons. The main spatial characteristics of the se
asonal biochemical cycles are resolved with the proposed approach. Moreover
the orders of magnitude of obtained results, both for the inorganic nitrog
en evolution and for the phytoplankton growth, are in keeping with the data
considered. The main conclusion is that even a simplified trophodynamic mo
del coupled with open sea hydrodynamics can satisfactory reproduce the main
basin scale features and their seasonal evolution when the first trophic l
evel is energy limited. (C) 1999 Elsevier Science B.V. All rights reserved.