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

instead the increases in form numbers at the inner and outer station groups
appear to be an effect of the lake's eutrophication process.
Inner-Outer Graphical Comparisons: Diversity Indices
Cook Plant species diversity data for the years 1971 through 1976 have
been presented and discussed by Ayers, Southwick, and Robinson (1977) and Ayers
(1978). The tabulated data in those reports are for the most part not repeated
here. This section is concerned with extending the previous discussions,
tabulations, and figures to include the major surveys carried out in 1977.
As was done in the report cited above, the diversity index data have
been stratified by three depth zones and by inner treatment stations (near
the plant) and outer control or reference stations groups. The diversity
index used is, as previously, that of Wilhm and Dorris (1968):
S
d = - (ni/n) log2 (ni/n)
i=1
where S is the number of species, n is the total number of phytoplankton in
cells/ml, n1 is the number of phytoplankton of the i species.
Mean diversity indices and associated standard errors for each
depth-zone-station-group combination in 1977 have been computed and are
presented in Table 5. In Figure 6 the surveys of 1977 have been added at the
end of the time plots of diversity indices and standard errors which were
presented by Ayers (1978).

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