The seasonal biological surveys of 1971 / John C. Ayers, Samuel C. Mozley, John A. Stewart.

1972) was used consistently.
When samples contained major proportions of sand grains more than 0.5 mm
in diameter, the samples were stirred vigorously in a funnel-shaped tub and
animals and fine sediments were decanted onto a 0.5-mm mesh screen. Coarser
material remained in the tub and was discarded after it had been rinsed to
remove all animals. When little or no medium or coarser sand grains were
present, the entire sample washed through the sieve. Sieve residues were
preserved in buffered formalin.
In the laboratory, animals were picked from the residue, counted by
major taxa and transferred to fresh, buffered formalin. For species identification, all animals were recounted. Greater skill and more painstaking
procedure resulted in modifications of the original counts, usually by minor
fractions of the total. In particular, a revised procedure involving the use
of compound microscopes led to changes in estimates of numbers of oligochaetes
in the samples. Oligochaetes and chironomid larvae were mounted on microscope
slides for species identification. Only representative specimens of each type
have been retained for future reference, but unmounted amphipods, fingernail
clams (Sphaeriidae) and other animals have been kept in storage.
In the April and July surveys the transects 6.4 km (4 miles) north and
south of the plant site were not analyzed because they were of only minor
interest in view of the time and effort required for species-level analysis.
They are beyond the likely extent of plume effects. The November 1971 samples
from these transects were analyzed, however, since bad weather forced abandonment of the more distant (11 km, or 7 miles along shore from the plant) reference transects in that month. No samples were available for stations DC-1
or DC-6 in July. Samples from NDC-4-4 and SDC-4-4 were always analyzed because they added significant information about the deepest part of the survey
area, which was otherwise sparsely sampled.
Taxonomy of Oligochaeta follows J. K. Hiltunen's unpublished keys (personal communication; Great Lakes Fishery Laboratory, U.S. Department of the
Interior, Ann Arbor, Mich.) and Brinkhurst and Jamieson (1971). Taxonomy of
5phaerium follows Herrington (1962). Taxonomy of Chironomidae derives from
scattered literature, primarily Roback (1957), Cernovskii (1949) and Mason
(1973), with nomenclature adjusted in conformity with Hamilton et al. (1969).
Pennak (1953) was the basis of other identifications.

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