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

convincing evidence of plant operation selectively affecting any of the algal
categories.
Summarizing by years (with operational years underlined) gives: 1970
(2), 1971 (6), 1972 (5), 1973 (5), 1974 (2), 1975 (), 1776 (), 177 ).
The numbers of significant differences in operational years are within the
range of natural variation established during the preoperational years.
There is no evidence that plant operation has produced more significant
differences.
Summarized by depth zones, with the station group having the greatest
density of algae indicated and with operational years underlined, the cases
of significant differences become:
Zone 0 Zone 1 Zone 2
Inner greater 1 + Q Inner greater 0 +. Inner greater 6 +.11
Outer greater 1 + Q Outer greater 7 + 4 Outer greater 4 + Q
Cases of significant differences were equally divided in Zone O; in Zone
1 where the plant plume is located most of the time 11 of the 13 cases were
of greater abundances in the outer stations; in offshore Zone 2, 17 of the 21
cases involved higher abundances at the inner stations. In this situation
where the local currents move parallel to shore, an hypothesis that plant
operation inhibits phytoplankton abundances in Zone 1 inner while stimulating
them in Zone 2 inner is not supported by the abundance curves of Figure 8 and
does not seem tenable.
No convincing evidence of plant operation affecting local phytoplankton
numbers has surfaced from these analyses.
The Wilhm and Dorris diversity indices of Cook Plant phytoplankton
collections taken during the seasonal surveys of 1970 through 1977 have shown
an increasing trend since 1972. The increases have taken place in both inner

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