219
----..
Bacteria
I ----..
Phytopla~kton
Protozoa
'>0
\17
' ,
B
A
-- .~
-G
V
--- -(/
-G
'>@ ~ ~ ~
[51
~;~:~' "
'~
B
C
Figure 1. A) Diagram depicting competition between bacteria and phytoplankton for nitrogen and phosphorus at
low concentrations. Bactivory by flagellates increases the mineralization of Nand P. B) Uptake vs substrate
concentation diagram illustrating bacterial competitive advantage at low substate concentrations while
phytoplankton outcompete at higher substrate concentrations. C) Cartoon showing mineralization via
flagellate bactivory in the phytoplankton cell's microenvironment.
(Fuhrman et al., 1989; Cho and Azam, 1990); here most N will occur sequestered in bacteria.
This may be because bacteria have low K", - low V max (low flow) while phytoplankton have high
K", - high V max (high flow) uptake systems for ammonium; consequently, bacteria outcompete
phytoplankton for ammonium uptake at low ammonium levels but the opposite holds true at high
ammonium levels (Fig Ib). Thus, in low ammonium (micro)environments, using the energy
supplied by the phytoplankton, bacteria outcompete phytoplankton for N and thereby dominate
the biomass. Parenthetically, we note that high the relative biomass of bacteria in oligotrophic
waters (Fig. 2a) may explain the higher than expected diffuse attenuation coefficient on the basis
----..
Bacteria
I ----..
Phytopla~kton
Protozoa
'>0
\17
' ,
B
A
-- .~
-G
V
--- -(/
-G
'>@ ~ ~ ~
[51
~;~:~' "
'~
B
C
Figure 1. A) Diagram depicting competition between bacteria and phytoplankton for nitrogen and phosphorus at
low concentrations. Bactivory by flagellates increases the mineralization of Nand P. B) Uptake vs substrate
concentation diagram illustrating bacterial competitive advantage at low substate concentrations while
phytoplankton outcompete at higher substrate concentrations. C) Cartoon showing mineralization via
flagellate bactivory in the phytoplankton cell's microenvironment.
(Fuhrman et al., 1989; Cho and Azam, 1990); here most N will occur sequestered in bacteria.
This may be because bacteria have low K", - low V max (low flow) while phytoplankton have high
K", - high V max (high flow) uptake systems for ammonium; consequently, bacteria outcompete
phytoplankton for ammonium uptake at low ammonium levels but the opposite holds true at high
ammonium levels (Fig Ib). Thus, in low ammonium (micro)environments, using the energy
supplied by the phytoplankton, bacteria outcompete phytoplankton for N and thereby dominate
the biomass. Parenthetically, we note that high the relative biomass of bacteria in oligotrophic
waters (Fig. 2a) may explain the higher than expected diffuse attenuation coefficient on the basis