Ecology of the burrowing amphipod, Pontoporeia affinis, in Lake Michigan / by Wayne Paul Alley.

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of freedom for the small and total Pontoporeia are 11. Only the mean
was estimated in calculating the Poisson distribution so the degrees of
freedom for this curve are k - 2. The degrees of freedom for large
Pontoporeia are 5. In every case the chi square test was not significant,
indicating that the observed histograms did not deviate significantly from
the expected distribution.
Long Term Study Area
The mean and variance of the replicated samples taken at the 35
stations of the long-term study area were plotted against each other for
total Pontoporeia per square meter (r =.417, d. f. = 575) (Fig.. 22).
The correlation coefficient computed for this plot implied a significant
interaction between the mean and variance. The square root transformnation was calculated for the data from every station stop. The mean
and variance of these transformed data were plotted against each other
(r =. 076, d. f. = 573) (Fig. 23) and the mean appeared to be independent of the variance. The cube root and logarithmic transformations
were also calculated for these data but the resulting correlation coefficients of the mean-variance relationship were significant. These results
indicated that the square root transformation best removed the interaction that existed between the mean and variance.
On the other hands the cube root transformation best removed the
interaction that existed between the means and variances of the oligochaetes, sphaeriids, and chironomids. Transformed data have been