The Effects of
Temperature on the Incidence of
Fluorosis in Rainbow Trout
JOSEPH W. ANGELOVIC, Graduate Student
WILLIAM F. SIGLER, Head
JOHN M. NEUHOLD, Assistant Professor
Department of Wildlife Management
Utah State University
Logan, Utah
INTRODUCTION
The prevalence of pollution of our natural waters today makes it important to know the relations of fish to toxic amounts of the materials being
introduced into the aquatic environment.
The addition of fluoride to domestic water supplies for prevention of
dental caries has increased interest in the effects of.fluoride on the aquatic
environment. Fluorides have been studied extensively over the past 20 years,
but mostly concerning their effects on mammals. Fish have received minor
attention in research.
Fluorides occur naturally in many waters, especially in the western United
States. These waters generally contain low concentrations of fluoride except
in some instances such as the Firehole and Madison Rivers in Yellowstone
National Park which contain from one to 14 ppm and Walker and Pyramid
Lakes in Nevada which contain up to 13 ppm.
Fluorides also enter the aquatic environment by leaching from super phosphate fertilizers in the soil and from natural occurring deposits of such
minerals as fluorite, apatite, cryolite, and sedimentary phosphate rock. Other
sources of fluoride are the waste products from such industries as metal refining plants, fertilizer plants, and ceramic plants.
Another identity which can be lethal in the aquatic environment is temperature. Normally temperature increases speed-up or accentuates the toxic
effects of other substances in the aquatic environment. The purpose of this
study was to investigate the effects of temperature on the toxicity of fluorides
to rainbow trout as well as the effects of different temperature levels and
varying fluoride concentrations on rainbow trout.
Very little work has been done to date on the toxicities of fluorides to
fish. Lethal levels of sodium fluoride for goldfish were determined by Ellis (1).
Ellis indicates concentrations of 1,000 ppm fluoride killed goldfish in from 60
to 102 hrs in hard water. In soft water at 1,000 ppm the time to mortality
ranged from 12 to 29 hrs. In hard water at 100 ppm Ellis (1) found no mortality
in four days. DeRoos (2) attributes death of goldfish within four days to concentrations of 120 ppm fluoride. Neuhold and Sigler (3) state that in water
low in calcium and magnesium, the LD 50 for rainbow trout falls between 2. 7
and 4.7 ppm fluoride, while the LD 50 for carp lies between 75 and 91 ppm
of fluoride.
Ellis et al. (4) thought that sodium fluoride had no immediate severe adverse effects, since goldfish lived 10 days or longer in water containing 200
ppm fluoride.
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