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at the time interval [t
0
, t
1
] if the biomass of its elements is within limits Di
i
≥
D
i,min
.
Correlations between the trophic levels and nonliving elements give summary
conditions for survivability criteria: ΣDi.
min
≤ ʣ
D
i
. Finally, survivability criteria for the
OSE can be written in the form: J(t)
≥ ʱ
J(t
0
), where J = U(t)/U(t
0
),
U
ðÞ
¼
P
k¼1
R
ðu;k;
z
Þ
B
k
ð
t
; u; k;
x
Þ
dx;
t
0
is a moment of time when value of
function A(t) is considered as known;
< 1 is the level of survivability. Really, we
consider the OSE to be in a living state if the condition J(t)>
ʱ
J(t
0
) is carried out for
t > t
0
. Calculations of J(t) for t > t
0
demonstrate how the OSE reaction depends on
the variability of various environmental conditions. For example,
ʱ
fluctuations in the
oxygen saturation of water may be of anthropogenic origin (oil pollution, large
discharge of sewage waters, temperature increase, etc.). The J(t) shows that the
OSE displays a high degree of stability with respect to the initial saturation of water
with oxygen, then how the OSE proceeds rapidly to a quasi-stationary regime of
functioning at D
9
(t
0
,
fl
1.8 ml/l and how long it takes to overcome the initial
shortage of oxygen in the case of D
9
(t
0
,
ˆ
,
ʻ
, z)
≥
ˆ
,
ʻ
, z) = 1.1 ml/l. For D
9
(t
0
,
ˆ
,
ʻ
,
z)
0.8 ml/l, the OSE is unable to proceed to the stationary regime of functioning.
The OSE is observed to be more sensitive to dynamic effects when the water is
saturated with oxygen. A reduction of the oxygen production by 12 % does not
in
≤
uence the OSE dynamics. However, the OSE does not survive when the oxygen
production is decreased as much as 20 %.
Calculations of J(t) offer the possibility for detecting the capability in searching
zones at risk for survivability in
fl
Ω
. For instance, one of particularly dangerous
anthropogenic in
uences is the change in nutrient concentration. Simulation
experiments enable us to determine the variations in the vertical uprising velocity of
water within the same range.
To estimate the turbulent escape of nutrients into layers, overlying the maximal
depth of photosynthetic layer (z
fl
h
*
), it is assumed in the SMOSE that the velocity
of water uprise is equal to 10
−
3
cm/s. The obtained data point to the fact that, on the
average, the integrated pattern of the distribution of community elements is not a
subject to any signi
≤
10
−
4
to
10
−
2
and even 10
−
1
cm/s, but it is observed to be drastically distorted under a
higher, which is the most important under a lower (<10
−
4
cm/s) vertical advection
of water.
Table
6.22
gives some of the results obtained in the case of a variation of the
concentration of nutrients at the initial moment of time t
0
. From the comparison of
the results contained herein, it seems that a variation of the nutrients concentration
within a wide range at the moment t=t
0
does not practically affect the behaviour of
OSE at the moments t
cant variations within the velocity range from 3.5
×
≫
t
0
. The system, so to speak,
'
healts
'
with time from the
'
, has suffered and proceeds to the same functioning level. When initial
nutrient conditions is limiting, the OSE teaches the stable state during 50 days only.
If the nutrient concentration at the time t
0
has unlimited level the OSE had reached
the stable state on the 30th day after beginning of simulation experiment.
The OSE model allows to realize other various simulation experiments. Clearly,
there exist some problems with parametrical descriptions of OSE functions.
blows
'
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