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aggregates exceeding 3
filtrates can feed on this biomass.
This fact must be taken into account when deriving a model of the ecosystem, since
in many regions of the World Ocean the bacteria production is comparable with the
production of phytoplankton (Kolber et al. 2001). Bacteria taking a special place in
the trophic pyramid, differ by a variable exchange, strongly decreasing with the
de
5
ʼ
in size, therefore the
-
cit of food, which is followed by the respective decrease of the rate of their
growth. The food for bacteria is mainly detritus d and dissolved organic matter
g emitted by phytoplankton (Hansell and Carlson 2002). As a result, the ration for
bacteria can be described by the Ivlev formula
;
R
b
¼ k
b
b½1
exp
k
1
;
d
d
k
1
;
g
g
ð
4
:
21
Þ
where k
b
, k
1,d
, and k
1,g
are the coef
cients determined experimentally.
The equation describing the dynamics of the bacterioplankton biomass is written
in the form:
@
b
=@
t
þ
V
u
@
b
=@u þ
V
k
@
b
=@k þ
V
z
@
b
=@
z ¼ R
b
T
b
M
b
X
s
2C
b
2
b
@u
2
b
@k
2
b
@
ð
4
:
22
Þ
2
2
z
2
C
bs
R
s
þ
k
2
;u
@
þ
k
2
;k
@
þ
k
2
;
z
@
;
where T
b
and M
b
are losses of the bacterioplankton biomass due to energy exchange
with the environment and the dying-off;
ʓ
b
is a set of the trophic subordination of
bacterioplankton (in a typical case
ʓ
b
is one element Z); C
b,s
is the share of bac-
terioplankton in the food ration of the s-th element of the ecosystem. The param-
eters T
b
and M
b
are described by the following relationships:
ð
4
:
23
Þ
T
b
¼ t
b
b
; l
b
ð
b
B
b
Þ
n
g;
M
b
¼ max
f
0
ð
4
:
24
Þ
ʼ
b
is the
where t
b
is the speci
c expenditure on the exchange with the environment;
'
ʾ
rate of
the bacteria
s dying-off;
B
b
and
are the constants that determine
the dependence of the intensity of the bacteria
'
s dying-off on their concentration.
The coef
cient k
2
=(k
2,
φ
, k
2,
ʻ
, k
2,z
) determines the process of the turbulent mixing
of the ocean waters.
The dynamic equation for the phytoplankton biomass is:
@
p
=@
t
þ
V
u
@
p
=@u þ
V
k
@
p
=@k þ
V
z
@
p
=@
z ¼ R
p
T
p
M
p
X
s
2C
p
2
p
@u
2
p
@k
2
p
@
ð
4
:
25
Þ
2
2
z
2
C
ps
R
s
þ
k
2
;u
@
þ
k
2
;k
@
þ
k
2
;
z
@
where
ʤ
p
is the set of the trophic subordination of phytoplankton, C
ps
is the share of
the phytoplankton biomass in the food ration of the elements of the s-th trophic
level of the ecosystem, T
p
is the expenditure on the energy exchange with the
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