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

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used in the statistical treatment of the data collected at the stations of
the long-term study area.
INTERSPECIFIC AND INTRASPECIFIC ASSOCIATIONS
The associations between Pontoporeia and the other macrobenthic
groups of the short-term study area were determined by the correlation
coefficients. The two size categories of this amphipod were treated
independently of each other in the association analysis. Figure 24 indicates a significant association between small and large Pontoporeia;
while figures 25 and 26 indicate that both small and large Pontoporeia
exhibit a significant inverse relationship with the oligochaetes. Figure
27 shows a significant inverse relationship between large amphipods and
the Sphaeriidae. Correlation analysis did not show significant associations between small amphipods and sphaeriids nor did it reveal significant relationship between this amphipod and the Chironomidae.
The associations between total Pontoporeia and the other macrobenthic groups of the long-term study area were also determined by
correlation coefficients. Figures 28-30 indicate that total Pontoporeia
were positively associated with oligochaetes, sphaerids, and chiromonids,
ENVIRONMENTAL RELATIONSHIPS
For this investigation it was assumed that Pontoporeia responds
to changes in its environment and that these changes are reflected by
increases or decreases in abundance. A low density indicates response