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5 - Zooplankton Volume - Time Series
The annual averages of zooplankton volume and fish egg abundance were calculated from log-normalized data for the CalCOFI Standard Grid and for
subareas as defined above. These averages were plotted against time (Figures below). Numbers next to data points indicate the year. Regression lines (see below) for the time periods 1951 - 1985 and 1986 - 1998
are included in the graphs of zooplankton volume. The average sample month and its standard deviation was plotted for each year as an aid to gauge sampling coverage over the year.
Regressions were
performed on these annual averages and results of these analyses are given in Table 5.1 for the time period 1951 - 1998, Table 5.2 for the time period 1951 - 1985 and Table 5.3 for the time period 1986 - 1998.
The
decline in zooplankton throughout the CalCOFI study domain over the last 20 years (Roemmich and McGowan, 1995) is evident from all plots of annually averaged zooplankton volumes (see below). The 1985 - 1998 time period is
characterized by lower zooplankton volume and lower variability, even if the latter is normalized by the average zooplankton volume. For example, for the Standard Grid the standard deviations of trend residuals of
zooplankton volumes are 36% and 16% of the means for the time periods 1951 - 1985 and 1986 - 1998, respectively.
|
|
Figure 1 - CalCOFI Standard Grid
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
Figure 2 - Southern California Bight Coastal
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
|
Figure 3 - Southern California Bight
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
Figure 4 - California Current
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
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Figure 5 - California Current Offshore
Sta 90-120
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
Figure 6 - Santa Barbara Basin
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
|
Figure 7 - Point Conception
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
Figure 8 - Central California Coastal
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
|
Figure 9 - Central California Offshore
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
Figure 10 - Monterey Bay Coastal
Zooplankton vs Year
Fish Eggs
Sample Coverage
|
|
|
Figure 11 - Monterey Bay Offshore
Zooplankton vs Year
Fish Eggs
Sample Coverage
Sample Coverage
|
|
|
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Table 5.1 - Time series analysis of the CalCOFI zooplankton displacement volumes.
See above for the definition of the subareas. Listed are the average zooplankton displacement volume (average),
its standard deviation (St. Dev.). For the regression analysis are listed the number of years that were used for the regression analysis (observations), the r-square of the regression, the significance level of the regression, the
value of the intercept (to = 1900), the standard error associated with the intercept (St-Error), the value of the slope, the standard error associated with the slope(St-Error) and the probability that the slope is not significantly
different from zero (p-value).
|
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
|
1951 - 1998
|
Whole
|
Coastal
|
S-Cal Bight
|
Cal Current
|
Offshore
|
SB Basin
|
|
Average
|
115
|
108
|
126
|
120
|
72
|
149
|
|
St. Dev.
|
59
|
49
|
70
|
69
|
54
|
93
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
44
|
44
|
44
|
44
|
43
|
32
|
|
r-square
|
0.436
|
0.211
|
0.378
|
0.443
|
0.376
|
0.191
|
|
significance
|
0.000
|
0.002
|
0.000
|
0.000
|
0.000
|
0.012
|
|
Intercept (a)
|
314
|
224
|
346
|
356
|
238
|
356
|
|
St-Error
|
36
|
35
|
44
|
42
|
34
|
79
|
|
Slope (s)
|
-2.660
|
-1.554
|
-2.954
|
-3.157
|
-2.230
|
-2.728
|
|
St-Error
|
0.467
|
0.464
|
0.584
|
0.546
|
0.449
|
1.025
|
|
P-value
|
0.000
|
0.002
|
0.000
|
0.000
|
0.000
|
0.012
|
|
|
|
|
|
|
|
|
|
|
St-Grid
|
Central Cal
|
Central Cal
|
|
|
|
|
1951 -1998
|
Pt Conception
|
Coastal
|
Offshore
|
|
|
|
|
Average
|
183
|
231
|
170
|
|
|
|
|
St. Dev.
|
93
|
125
|
120
|
|
|
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
43
|
42
|
42
|
|
|
|
|
r-square
|
0.229
|
0.278
|
0.548
|
|
|
|
|
significance
|
0.001
|
0.000
|
0.000
|
|
|
|
|
Intercept (a)
|
406
|
562
|
618
|
|
|
|
|
St-Error
|
65
|
86
|
65
|
|
|
|
|
Slope (s)
|
-2.999
|
-4.435
|
-5.985
|
|
|
|
|
St-Error
|
0.860
|
1.129
|
0.859
|
|
|
|
|
P-value
|
0.001
|
0.000
|
0.000
|
|
|
|
|
Table 5.2 - As table X.4.1 but for the time interval 1951 - 1985.
|
1949 - 85
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
|
|
Whole
|
Coastal
|
S-Cal Bight
|
Cal Current
|
Offshore
|
SB Basin
|
|
Mean
|
140
|
124
|
153
|
149
|
91
|
189
|
|
St. Deviation
|
53
|
49
|
67
|
64
|
54
|
99
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
31
|
31
|
31
|
31
|
30
|
19
|
|
r-square
|
0.095
|
0.003
|
0.084
|
0.120
|
0.133
|
0.026
|
|
significance
|
0.091
|
0.760
|
0.115
|
0.057
|
0.048
|
0.506
|
|
Intercept (a)
|
242
|
142
|
274
|
286
|
214
|
53
|
|
St-Error
|
59
|
58
|
75
|
70
|
60
|
200
|
|
Slope (s)
|
-1.515
|
-0.261
|
-1.794
|
-2.036
|
-1.829
|
2.076
|
|
St-Error
|
0.868
|
0.846
|
1.104
|
1.025
|
0.884
|
3.056
|
|
P-value
|
0.091
|
0.760
|
0.115
|
0.057
|
0.048
|
0.506
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1949 - 85
|
St-Grid
|
Central Cal
|
Central Cal
|
Monterey Bay
|
Monterey Bay
|
d
|
|
|
Pt Conception
|
Coastal
|
Offshore
|
Line 67 St <52
|
Line 67 St > 50
|
d
|
|
Mean
|
214
|
281
|
221
|
369
|
289
|
|
|
St. Deviation
|
93
|
117
|
111
|
307
|
133
|
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
30
|
29
|
29
|
14
|
29
|
|
|
r-square
|
0.014
|
0.009
|
0.254
|
0.005
|
0.147
|
|
|
significance
|
0.534
|
0.628
|
0.005
|
0.808
|
0.040
|
|
|
Intercept (a)
|
282
|
348
|
564
|
566
|
601
|
|
|
St-Error
|
110
|
138
|
114
|
798
|
147
|
|
|
Slope (s)
|
-1.018
|
-0.998
|
-5.100
|
-2.659
|
-4.652
|
|
|
St-Error
|
1.616
|
2.037
|
1.684
|
10.725
|
2.157
|
|
|
P-value
|
0.534
|
0.628
|
0.005
|
0.808
|
0.040
|
|
|
Table 5.3 - As table 5.1 but for the time interval 1986 - 1998
|
1986 - 98
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
St-Grid
|
|
|
Whole
|
Coastal
|
S-Cal Bight
|
Cal Current
|
Offshore
|
SB Basin
|
|
Mean
|
56
|
68
|
62
|
53
|
28
|
91
|
|
St. Deviation
|
12
|
18
|
14
|
14
|
6
|
37
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
13
|
13
|
13
|
13
|
13
|
13
|
|
r-square
|
0.450
|
0.554
|
0.379
|
0.240
|
0.067
|
0.099
|
|
significance
|
0.012
|
0.004
|
0.025
|
0.089
|
0.392
|
0.295
|
|
Intercept (a)
|
251
|
379
|
271
|
210
|
67
|
365
|
|
St-Error
|
65
|
84
|
81
|
85
|
44
|
250
|
|
Slope (s)
|
-2.116
|
-3.382
|
-2.275
|
-1.714
|
-0.425
|
-2.985
|
|
St-Error
|
0.706
|
0.914
|
0.878
|
0.920
|
0.476
|
2.714
|
|
P-value
|
0.012
|
0.004
|
0.025
|
0.089
|
0.392
|
0.295
|
|
|
|
|
|
|
|
|
|
1986 - 98
|
St-Grid
|
Central Cal
|
Central Cal
|
Monterey Bay
|
Monterey Bay
|
|
|
|
Pt Conception
|
Coastal
|
Offshore
|
Line 67 St <52
|
Line 67 St > 50
|
|
|
Mean
|
111
|
118
|
55
|
n.d.
|
58
|
|
|
St. Deviation
|
35
|
44
|
13
|
n.d.
|
17
|
|
|
Regression
|
|
|
|
|
|
|
|
observations
|
13
|
13
|
13
|
n.d.
|
n.d.
|
|
|
r-square
|
0.234
|
0.065
|
0.125
|
n.d.
|
n.d.
|
|
|
significance
|
0.094
|
0.402
|
0.237
|
n.d.
|
n.d.
|
|
|
Intercept (a)
|
514
|
384
|
160
|
n.d.
|
n.d.
|
|
|
St-Error
|
220
|
306
|
84
|
n.d.
|
n.d.
|
|
|
Slope (s)
|
-4.386
|
-2.893
|
-1.137
|
n.d.
|
n.d.
|
|
|
St-Error
|
2.391
|
3.319
|
0.909
|
n.d.
|
n.d.
|
|
|
P-value
|
0.094
|
0.402
|
0.237
|
n.d.
|
n.d.
|
|
|
|
