The Acute Toxicity of
Some Heavy Metals to Different Species of
Warm Water Fishes
QUENTIN H. PICKERING, Fisheries Research Biologist
Taft Sanitary Engineering Center
Cincinnati, Ohio
CROSWELL HENDERSON, Fisheries Research Biologist
U.S. Fish and Wildlife Service
Ft. Collins, Colorado
INTRODUCTION
Despite progress in the treatment of metallic wastes, the discharge of heavy-
metal wastes by metal finishing industries and others is still a serious water pollution problem because of the toxic properties of these metals and their other adverse effects on water quality. McKee and Wolf (1) have summarized the sources
of individual heavy metals and their salts. Information on the toxicity of metals
has been summarized by Doudoroff and Katz (2) and McKee and Wolf (1).
The need for water quality criteria that will make it possible to establish
water pollution parameters is critical to the conservation of aquatic life. As a
first consideration in the development of criteria for heavy metals, this comparative study was undertaken to determine the acute toxicity of the salts of copper,
zinc, nickel, trivalent chromium, lead, and hexavalent chromium to four species
of warmwater fishes and the dependence of this toxicity on certain other water
quality characteristics.
METHODS
To evaluate and compare the acute toxicity of the heavy metals, 24-, 48-,
and 96-hr TLm (Median Tolerance Limit) values were determined. The TLm is
the concentration of a toxic material in water that kills 50 per cent of the test
animals under experimental conditions during a specified time interval. The
TLm was used because the concentration required to effect a response in 50 per
cent of the test fish is more reproducible than any other value. Toxicities were
not characterized with respect to the slope of concentration-mortality curves.
The TLm is not an estimate for the species under test unless a random sample
is used. Unfortunately, in the present study it was impossible to obtain a random
sample of the total population of the species. In a random sample, every member of the species must have an equal chance of being in the sample. In tests
such as these, however, there is no method of meeting this condition of equal
chance for all individuals of a species. We can, therefore, only say that if the
samples used in this study were random, then the results obtained (i.e., the TLjt,
values) are estimates for the species under test.
Static bioassays for determining acute toxicity were conducted according to
the methods recommended by the American Public Health Association (3).
Laboratory facilities and equipment were the same as those described by Henderson and Tarzwell (4).
Because different species of fish may have widely different sensitivities to
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