G. Crispi et al., Nutrients cycling in Mediterranean basins: the role of the biological pumpin the trophic regime, ECOL MODEL, 138(1-3), 2001, pp. 101-114
The Mediterranean Sea is generally characterized by the presence of oligotr
ophic conditions, which are more pronounced in its eastern part. The effect
s of physical and biological fluxes on the nitrogen and phosphorus distribu
tions are here addressed by means of a box model. Numerical simulations obt
ained with realistic fluxes, as well as the analysis of the asymptotic beha
vior of the model support the hypothesis that inverse estuarine circulation
is not sufficient to explain the oligotrophic regime. Conversely, it appea
rs that the downward fluxes of organic matter play a major role in sustaini
ng and stabilizing the oligotrophy as found in the observations. Indeed the
trophic gradients between the western and the eastern Mediterranean arise
as a consequence of the unbalance of the loads emitted in the basins, with
greater inputs into the western, but, in any case, they are maintained in t
he long run by the biological pump. (C) 2001 Elsevier Science B.V. All righ
ts reserved.