Geoscience Reference
In-Depth Information
The Okhotsk Sea ecosystem includes the following groups: phytoplankton,
bascterioplankton, protozoa, herbivorous zooplankton, predatory zooplankton,
nonpredatory zoobenthos, predatory zoobenthos, pelagic
shes,
demersal invertebrates, squids, seabirds, marine mammals. Fish community
includes the following species: pollock, herring, capelin, deep sea smelt, cyclop-
teriids, sakhalin plaice. Total
fishes, demersal
2013 was reduced from 8.9
mollion tonnes to 4.9 million tonnes. Fish biomass reducing process has different
anthropogenic forcings: water pollution and overexpluitation of biological
resources.
The Okhotsk Sea aquatory is divided into zones having speci
fish biomass during 1985
-
c ecological
features (Suzuki 1992). The spatial distribution of the
fish biomass depends on
seasonal conditions and to a great extent correlates with the layers outlined above.
The use of the sea biological resources is a function of this distribution. The
fishing
intensity essentially depends on the knowledge of the biomass distribution in the
zones with speci
c environmental conditions. Many authors (Plotnikov 1996; Aota
et al. 1992; Krapivin and Soldatov 2009a) have tried to solve this task by means of
models simulating the ecosystem dynamics. However, the modeling results do not
always turn out to be suf
cation of sea
zones by their productivity scale. The biocomplexity indicator is one such simple
form, which can identify these zones. In fact, it is shown by many investigators that
the Okhotsk Sea zones with high productivity, are characterized by complex many-
level trophic charts (Terziev et al. 1993). This effect is not universal to other seas.
For instance, the Peruvian current ecosystem has high productivity in zones where
the trophic chain is short (Krapivin 1996). These situations are distinguished by the
migration processes. That is why the biocomplexity of these ecosystems is formed
in various ways.
The following components of the Okhotsk Sea ecosystem are mentioned in
Table
6.20
: The trophical pyramid X ¼
ciently representative and re
fl
ect the classi
, where x
ij
is a binary value equal to
x
ij
“
under the existence or absence of a nutritive correlation between the i-th
and j-th components, respectively. De
1
”
or
“
0
”
ne the biocomplexity as function:
Þ
¼
X
20
X
19
nu; k;
ð
z
;
t
x
ij
C
ij
ð
6
:
30
Þ
i¼1
j¼1
where
are geographical latitude and longitude; t is the current time; z is the
depth; B
m,min
is the minimal biomass of the m-th component consumed by other
u
and
k
trophic levels; C
ij
¼ k
ij
B
i
;
R
j
þ
is the nutritive pressure of the j-th component on
the i-th component;
X
i
þ
¼
X
m
2
S
i
k
im
B
m
;
is the actual food storage which is available to the i-th component; k
im
= k
im
(t, T
W
,
S
W
)(i =1,
…
, 17) is the index of satisfaction of the nutritive requirements of the i-th
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