EFFECTS OF ACUTE TEMPERATURE-CHANGE ON RESPIRATION AND TOXICANT UPTAKE BY RAINBOW-TROUT, SALMO-GAIRDNERI (RICHARDSON)

The effects of an acute reduction in temperature (from 17-degrees to 18-degrees-C) on respiration and the uptake of benzo[a]pyrene, 2,2',5,5'-tetrachlorobiphenyl, and naphthalene by the gills of rainbow trout (Salmo gairdneri Richardson) were investigated with a fish metabolic chamber. As the temperature was lowered, decreased respiratory functions coupled with decreased O2 and toxicant uptake efficiencies resulted in reduced O2 consumption and toxicant uptake. Changes in trout respiration had no consistent effect on either O2 or toxicant uptake efficiencies. Linear correlations were observed between O2 and toxicant uptake efficiencies and between O2 consumption and toxicant uptake. The reductions in O2 and toxicant uptake are attributed to the combined effects of temperature change on gill membrane permeability and on trout O2 demand. A framework for predicting changes in toxicant uptake on the basis of changes in O2 consumption is proposed based on quantitative relationships observed between O2 and toxicant uptake.