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

the basis that members of each individual group have more or less similar
functions in the ecosystem.
Table 7 presents, for the seasonal surveys of 1977, the means, standard
errors, and numbers of observations of abundances of total algae and the nine
major groups of planktonic algae in the three depth zones and the inner and
outer station groups. These are graphed with the preceeding years in Figure 8.
Desmids (Fig. 8A) have shown almost no variation in abundance over the
entire eight years of the study.
Filamentous green algae (Fig. 8B), which in April 1976 had somewhat
increased in abundance in both station groups and in all three depth zones,
returned to preoperational levels in July of that year and have remained there
ever since.
Other algae (Fig. 8C), increased in abundance in all depth zones and both
station groups in 1976 and 1977, but similar abundances had been observed in
preoperational years. There is no clear evidence that the recent greater
abundances were plant-induced.
Filamentous blue-green algae (Fig. 8D) have been more abundant in all
depth zones and both sets of stations in the three operational years. In Zones
O and 1 increases at the outer stations equalled or exceeded those at the inner
stations in all three years. In 1976 and 1977 in Zone 2 July abundances at the
inner stations greatly exceeded those at the outer stations. Although these
inner stations are in front of the plant, they are offshore stations where the
plant's discharge plume is present little if any of the time; the increases at
these stations appear more apt to be effects of lake eutrophication than of
Cook Plant operation.
Coccoid blue-greens (Fig. 8E), which had been present in small amounts
during most of the preoperational surveys, increased notably in October of

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