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

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TABLE 6. The proportion of the multiple correlation coefficient: (R)
and the coefficient of determination, expressed as a percentage, (R2)
that each statistically significant variable contributes to the multiple
regression equation of all depths combined in Lake Michigan. The
dependent variable of the multiple regression equation (Y) is
represented by the numbers of Pontoporeia affinis/m2
Variable R R2
X10 Sphaeriidae.744 53.3
X3 Depth squared.018 2.8
X Chironomidae.008 1.2
X2 Depth.007 1.2
X7 Distance from shore.007 1.0
X1 Day of year.005.7
X6 Sediment type.005.8
X5 Bottom temperature.002.4
o796 63.4
Y= 12. 333 +.049X1 +.360X2 - 12. 174X3+.779X5 - 4. 193X6
- 3.476X + 2. 874X 10+ 2. 355X11
type, and distance from shore. Approximately 57 percent of the
variablilty in amphipod abundance was attributable to these six variables.
Only two parameters, sphaeriids and sediment type, were statistically significant in explaining the deviations in amphipod density of the
36-65 m depth zone. The sphaeriids accounted for 31 percent of the
changes in Pontoporeia abundance while the sediment type contributed
only 5 percent.
Within the 66-105 m depth zone the abundance of sphaeriids statistically represented the most important parameter, followed by depth