Phytoplankton of the seasonal surveys of 1977, and further pre- vs. post-operational comparisons at Cook Nuclear Plant / John C. Ayers, Susan J. Wiley.

TABLE 5. Means, standard errors, and numbers of observations of phytoplankton
diversity indices by seasons, depth zones, and inner or outer station groups in
Cook Plant major surveys during operational 1977. Previous years are reported
in Ayers, Southwick, and Robinson (1977) and Ayers (1978). The diversity index
used is that of Wilhm and Dorris (1968) based on log 2. Standard errors are
computed only when the number of observations is two or more.

1977

21 October

Zone 0, Inner
Mean
S. E.
N
Outer
Mean
S. E.
N
Zone 1, Inner
Mean
S. E.
N
Outer
Mean
S. E.
N
Zone 2, Inner
Mean
S. E.
N
Outer
Mean
S. E.
N

4.24
0.11
12
4.23
0.08
10
4.19
0.08
3
4.13
0.28
4
4.18
0.13
2
4.06
0.20
4

3.92
0.08
12
3.84
0.08
9
3.73
0.16
3
3.44
0.21
4
3.29
0.21
2
3.73
0.13
4

4.06
0.22
12
3.92
0.13
10
3.67
0.42
3
3.54
0.34
4
3.19
0.40
2
2.84
0.20
4

In Figure 6 the annual curves of mean diversity indices generally show
substantial degrees of parallelism between inner and outer station groups,
though parallelism was poor in all zones in 1971 and 1972, in Zone 0 in 1974,
and in Zone 1 in 1970 and 1973. Parallelism between the curves for inner
(treatment) and outer (control) stations indicates that changes in diversity

38