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

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crop of P. affinis in the lake to be approximately 1, 700 individuals/m2,
and that 70 percent of the total wet volume of the macrobenthos consisted
of Pontoporeia. Henson and Chandler (unpublished data), cited by Henson
(1966), found approximately 1,500 individuals/m2 in the Straits of
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Mackinac. Marzolf (1965) noted more than 14, 000 amphipods/m at one
station in the Grand Traverse Bay region. Powers et al. (1967) recorded
one station in the lake where P. affinis exceeded 23, 000 individuals /m2.
Powers and Alley (1967) showed that the average standing crop of this
amphipod exceeded more than 2, 700 individuals/m2 and that it comprised
64 percent of the total macrobenthos. In a comparative study, Robertson
and Alley (1966) showed that the average abundance of P. affinis,
oligochaetes, and sphaeriids was significantly greater in 1964 than in
1 931.
RESEARCH PLAN
With the present interest concerning the rates of eutrophication
and increase in pollution, and because this amphipod is the first macrobenthic organism to be driven out by increased pollution, it is reasonable
to study it. The objective of this investigation was to gain information
on the ecology of the amphipod Pontoporeia affinis in Lake Michigan and
to evaluate its normal patterns of reproduction, normal changes in seasonal abundance, and normal patterns of spatial distribution. When
these are known, pollution-caused deviations can be recognized.
The data presented here were collected during comprehensive