Seasonal Studies of a Pelagic Ecosystem (Meridian 110 ° E)
503
Is is clear, even from this preliminary analysis, that there are basic biological
differences between the tropical and subtropical zones. However, the correlations that
were obtained, based as they are on concurrent pairs of values, are not easy to interpret.
in terms of cause and effect. Some allowance needs to be made for natural time lags
between one cycle and another. Serial correlations are required. In calculating these,
we have been limited by the sampling frequency.
Table 6a. Correlation matrices for various biological properties by day and night in the tropical zone
(** significant at 99% level; * significant at 95% level; N.S. not significant)
t::
0
~
t::
"l
Zooplankton
os
Day Tropical
0..
>-.
0
..c
(n = 33-36)
0
0N
0
C
...
Chlorophyll a
0.26
0
'>
::2
'0
U
v
::>
Productivity
0.54*'
0.23
"
<1)
0
...
...
os
A-.
..c
0Phosphate
0.48**
0.23
0.26
'" 0
2l
..c
os
A-.
...
Nitrate
0.40'
0.46**
0.16
0.49**
i
t::
0
~
t::
Zooplankton
os
Night Tropical
0..
"l
0
(n = 35)
0
>-.
N
..c
Chlorphyll a
0.33
0c
0
...
0
c
0
~
B
::2
c
..:.:
MWT
U
os
c
i5::
os
t::
Plankton
0.36*
0.29
f-<
0..
0
~
0
~
...
<1)
v
c
:.:E
eo
MWT
::E
0
...
Macroplankton
u
0.24
0.24
0.36'
I~
~
::E
IMWT
~
Micronekton
0.14
-0.15
0.29
0.57**
::E
Three trophic levels were chosen for the first approach viz, phytoplankton, zooplankton, and micronekton. Although zooplankton is not an homogeneous entity, at
least there is no overlap with the other trophic levels that have been selected. Observations
at each position (station) were associated with others on the same occasion (normal
correlations) and also with observations prior and subsequent (serial correlations). This
was done for 2 time intervals: that between consecutive cruises (N, N + 1), and that
between consecutive legs of the same cruise (n, n + 1). The results are shown in Table 7.
The table shows that, for the data as a whole, these 3 biological characteristics varied
with space and time in a fashion consistent with the concept of trophic succession. There
were high correlations between the phytoplankton of one cruise (PN) and the zooplankton
503
Is is clear, even from this preliminary analysis, that there are basic biological
differences between the tropical and subtropical zones. However, the correlations that
were obtained, based as they are on concurrent pairs of values, are not easy to interpret.
in terms of cause and effect. Some allowance needs to be made for natural time lags
between one cycle and another. Serial correlations are required. In calculating these,
we have been limited by the sampling frequency.
Table 6a. Correlation matrices for various biological properties by day and night in the tropical zone
(** significant at 99% level; * significant at 95% level; N.S. not significant)
t::
0
~
t::
"l
Zooplankton
os
Day Tropical
0..
>-.
0
..c
(n = 33-36)
0
0N
0
C
...
Chlorophyll a
0.26
0
'>
::2
'0
U
v
::>
Productivity
0.54*'
0.23
"
<1)
0
...
...
os
A-.
..c
0Phosphate
0.48**
0.23
0.26
'" 0
2l
..c
os
A-.
...
Nitrate
0.40'
0.46**
0.16
0.49**
i
t::
0
~
t::
Zooplankton
os
Night Tropical
0..
"l
0
(n = 35)
0
>-.
N
..c
Chlorphyll a
0.33
0c
0
...
0
c
0
~
B
::2
c
..:.:
MWT
U
os
c
i5::
os
t::
Plankton
0.36*
0.29
f-<
0..
0
~
0
~
...
<1)
v
c
:.:E
eo
MWT
::E
0
...
Macroplankton
u
0.24
0.24
0.36'
I~
~
::E
IMWT
~
Micronekton
0.14
-0.15
0.29
0.57**
::E
Three trophic levels were chosen for the first approach viz, phytoplankton, zooplankton, and micronekton. Although zooplankton is not an homogeneous entity, at
least there is no overlap with the other trophic levels that have been selected. Observations
at each position (station) were associated with others on the same occasion (normal
correlations) and also with observations prior and subsequent (serial correlations). This
was done for 2 time intervals: that between consecutive cruises (N, N + 1), and that
between consecutive legs of the same cruise (n, n + 1). The results are shown in Table 7.
The table shows that, for the data as a whole, these 3 biological characteristics varied
with space and time in a fashion consistent with the concept of trophic succession. There
were high correlations between the phytoplankton of one cruise (PN) and the zooplankton