150
8. Impact of Dynamic Light and Nutrient Environments
of cells utilizing the nutrient. In the case of N, both dinoflagellate and diatom abundance influences the uptake rate. The uptake rate of nutrients
are also a function of the light level, where the maximum uptake for both
Nand Si occurs when light levels are greater than 20% surface irradiance
(Dugdale et al. 1981). The uptake of each group of each nutrient
(Group Uptake Nutrient) follows Michaelis-Menton kinetics, such that
Uptake Nutrient = V max Nutrient." ([Nutrient]/([Nutrient] + Ks Nutrients), (5)
where Vmax is the maximum uptake rate per cell of a given nutrient and Ks
is the half-saturation constant (the nutrient concentration [Nutrient] supporting half Vmax) . Because diatoms require both Nand Si, the maximum
uptake of Si by diatoms was scaled to the diatom uptake of nitrogen. The
dissolved nutrients (within the parcel of water) are taken up by phytoplankton cells, and there is a length of time before the nutrients are regenerated and returned to the dissolved form. The regeneration time for N is
assumed to be shorter than that for Si because regeneration of N is biologically mediated (Officer and Ryther 1980).
REGENSi3
REGENSi1
TOTALDIATOMS
Vmax Si
Ks Si
DIA UPTAKE N
SILICATE
FIGURE 8.7
8. Impact of Dynamic Light and Nutrient Environments
of cells utilizing the nutrient. In the case of N, both dinoflagellate and diatom abundance influences the uptake rate. The uptake rate of nutrients
are also a function of the light level, where the maximum uptake for both
Nand Si occurs when light levels are greater than 20% surface irradiance
(Dugdale et al. 1981). The uptake of each group of each nutrient
(Group Uptake Nutrient) follows Michaelis-Menton kinetics, such that
Uptake Nutrient = V max Nutrient." ([Nutrient]/([Nutrient] + Ks Nutrients), (5)
where Vmax is the maximum uptake rate per cell of a given nutrient and Ks
is the half-saturation constant (the nutrient concentration [Nutrient] supporting half Vmax) . Because diatoms require both Nand Si, the maximum
uptake of Si by diatoms was scaled to the diatom uptake of nitrogen. The
dissolved nutrients (within the parcel of water) are taken up by phytoplankton cells, and there is a length of time before the nutrients are regenerated and returned to the dissolved form. The regeneration time for N is
assumed to be shorter than that for Si because regeneration of N is biologically mediated (Officer and Ryther 1980).
REGENSi3
REGENSi1
TOTALDIATOMS
Vmax Si
Ks Si
DIA UPTAKE N
SILICATE
FIGURE 8.7