Some effects of life stage, temperature, pH and alkalinity on the acute toxicity of inorganic chloramines to young Coho salmon (Oncorhynchus kisutch)

by Lamperti, Larry Phillip

Acute toxicity bioassays (96-hr TL??) were employed to determine

the tolerance of coho salmon (Oncorhynchus kisutch) to inorganic

chloramines at the alevin (yolk sac fry), yolk absorption, and early

juvenile life stages. Any influence of changes in temperature, pH,

and total alkalinity on the tolerance of juvenile coho for chloramines

was also investigated.

The least tolerant stage occurred shortly after yolk absorption.

No change in juvenile coho was found when temperature was increased

from 10.8 to 15.0 C. Increasing alkalinity from 135 to 320 mg/l was

not shown to affect tolerance of the juvenile stage. Increasing pH

from 7.0 to 7.5 apparently did not change tolerance at this stage,

but an increase from 7.5 to 8.1 resulted in a significant decrease

in tolerance.