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

18

bottom. The corer was then tipped to one side, closed off by a metal
plate, and inverted, resulting in transfer of the contents to the jar. A
numbered lid was placed on the jar after the coring tube had been
removed. Divers were able to observe and report any organisms that
excaped when the corer was removed from the mason jar. Such losses
were rare. Formalin was added as a preservative after the samples
were returned to the surface.
In study area 1 a systematic sampling procedure was utilized.
Forty-five samples were taken at 1-ft intervals along 6 transects each
7 1/2 feet long that radiated in a spoke-fashion from the center of the
sampling frame (Fig. 8). Two samples were lost. Study area 2 was
situated adjacent to study area 1. Forty-five samples, representing
triplicates, were taken in 15 randomly chosen quadrats selected from
36 quadrats located within the boundaries of the 15 x 15 ft sampling
frame (Fig. 8). The area of each quadrat was 6. 25 ft 2
LABORATORY PROCEDURES
Long-Term Study Area
In the laboratory the organisms and residual sediment of a sample
were placed in a white porcelain pan. Each organism was counted and
placed in its respective taxonomic group. Pontoporeia affinis,
Oligochaeta, Sphaeriidae, and Chironomidae constituted the entire
sample. Occasionally additional organisms such as leeches, snails,