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

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South Bay, Lake Huron. Green (1965) found a maturation period of 2
years in Cayuga Lake, New York, and SegerstrRle (1950) reported that
P. affinis matured in one year at a depth of 3 m and required 3 years to
mature at a depth of 35 m in the Baltic Sea. Summer breeding, which
appears to be common in North American oligotrophic lakes, was first
recorded in the Baltic Sea in 1967 by SegerstrRle and represents the only
record of summer breeding in Eurasia.
Observed variations in the duration of the breeding season and
development are likely attributable to corresponding variations in water
temperature. In Lake Michigan, the average bottom temperature of the
10-15 m depth zone, from March to October, is approximately 9~C. The
average bottom temperature at 20-35 and 36-86 m depth zones for the
same time interval is approximately 7~C and 5~C respectively. Depths
beyond 86 m have an average bottom temperature that is slightly less
than 4 C from March to October. An examination of bottom temperature
records of the present study indicated that Pontoporeia did not breed at
any depth when the bottom temperature exceeded 70Co Samter and
Weltner (1904) observed that temperatures greater than 7 C prevented
egg production and concluded that the type and locality of a lake determined to a large extent the time and duration of the reproductive period.
PATTERNS OF SPATIAL DISTRIBUTION
Short- Term Study Area
Living organisms are subject to a multitude of variable factors,