T. Legovic et A. Cruzado, A MODEL OF PHYTOPLANKTON GROWTH ON MULTIPLE NUTRIENTS BASED ON THE MICHAELIS-MENTEN-MONOD UPTAKE, DROOPS GROWTH AND LIEBIGS-LAW, Ecological modelling, 99(1), 1997, pp. 19-31
A model of phytoplankton population growing on more than one potential
ly limiting nutrient is formulated and investigated. The model is base
d on the Michaelis-Menten-Monod uptake function for each nutrient, the
Droop's function for growth of phytoplankton and Liebig's law for gro
wth on different nutrients. The model is analyzed in a simple set up o
f phytoplankton culture reactor. Conditions are specified for which st
eady phytoplankton existence state is stable. Since growth depends on
internal nutrient content, the limiting nutrient may be recognized as
the one having the smallest content in phytoplankton relative to the s
ubsistence quota. According to the model, in steady state during equal
limitation by several nutrients, the Redfield ratio is equal to the r
atio of subsistence quotas and to the ratio of uptake rates. Contrary
to wide spread use, the ratio of nutrients in water is not the Redfiel
d ratio but a function of the growth rate. In oligotrophic waters, how
ever, nutrients are in another ratio that may be used as an analog to
the Redfield ratio in phytoplankton. The model may be used as a submod
el of larger ecosystem models. (C) 1997 Elsevier Science B.V.