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

line from 1971 through 1972 to 1974. Trends of abundance increase in the
flagellates, pennate diatoms, and blue-green algae have been commented upon; it
appears that these algal categories are probably responsible for the trends in
total algae.
In depth Zone 0, parallelism between the annual curves of total algae
abundance has been generally excellent and it is necessary to go back to 1970
and 1972 to find surveys wherein the standard errors of the means for inner and
iter station groups do not overlap. Parallelism between the curves for inner
and outer stations has been if anything, better in the operational years than
during preoperation. The increasing ablndances in both station groups must be
attributed to changes in the lake, not to Cook Plant operation.
In Zone 1, parallelism between the annual curves of abundances has been
better in the operational years than it was in preoperational years. Except
for April 1975, abundances in this zone have been consistently higher in the
outer station group. If plant operation results in heat stimulation of
phytoplankton reproduction, as has been postulated, and with the plant's waste
heat plume in the inner stations of Zone 1 most or all of the time, the higher
abundances should have been at these stations; in eight of the nine operational
surveys, however, the highest abundances were in the stations of the outer
group. If plans operation results in phytoplankton inhibition at the inner
stations of Zone 1, then inhibition should have been less (abundances higher)
at these stations during 1975 when the plant was in the testing and power
ascension phase than during 1976 and 1977 when the plant operated at higher
levels and more consistently than in 1975; abundances at the inner stations,
however, have continued to increase from 1975 through 1977. With the trends
toward increasing abundances beginning at least as early as preoperational
1974, there is no clear evidence that operation of the plant has affected the

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