Ecoinformatics Problems of the World Ocean - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 301

accompanied by a decline in the total biomass of anchovy and predatory shes.

These effects were observed by Marti (1971) and Parin (1971).
To estimate the survivability of the PCE, Krapivin (1996) has introduced the
survivability function:

P i¼1 RRR u;k; z

B i u; k;

ð ; Þ d u k

z t d dz

ð Þ X

J ð t Þ ¼

ð 4 :

50 Þ P i¼1 RRR u;k; z

B i u; k; ð z ; t 0 Þ d k dz

ð Þ X

Figure 4.8 shows the survivability function ( 4.50 ) for various departures of
temperature from its model value. We will consider the system to be in a living state
if the condition J(t)> ʺ J(t 0 ) is carried out for t ≥ t 0 , where ʺ < 1 is the level of

survivability. It is obvious that temperature fl fluctuations by ± 7 K bring the system to

a ' dead state ' after 70 days for +7 K and after 190 days for − 7 K. Water temperature

fl 5 K turn out to be non-dangerous to the system, but they may

be the cause of its conversion into a different quasi-stationary state. This follows
from the comparison of the phase patterns of behaviour of the system trajectories
similar to these given in Fig. 4.9 where the PCE dynamics in the plane of B 5 ×

fluctuations within ±

B 7 is

given under different initial states.
It is supposed that fluctuations of solar radiation energy cause proportional vari-

ations of the water temperature. A climate block of GIMS is used for the calculation of
atmospheric temperature

fl

˃ A in ʩ . A temperature regime of PCE is described by the

Fig. 4.8 The estimation of
the PCE survivability under
the temperature variations.
The gures on the curves
show the water temperature
variations from the normal
conditions