Temperature Selection of Atlantic Salmon (Salmo salar) and Brook Trout (Salvelinus fontinalis) as Influenced by Various Chlorinated Hydrocarbons
The effects of previous exposure to p,p′-DDT, o,p′-DDT, p,p′-DDD, p,p′-DDE, and methoxychlor on temperature selection by juvenile Atlantic salmon (Salmo salar) in a horizontal temperature gradient were similar. Exposure to low concentrations resulted in no change or a decrease in selected temperatures as compared to control values of about 16 C. Exposure to higher concentrations raised selected temperatures. The concentrations of the substances required to produce a given effect varied as: p,p′-DDT≥p,p′-DDD> methoxychlor >o,p′-DDT>p,p′-DDE. Exposure levels of p,p′-DDA≤ 8 ppm did not alter temperature selection nor did exposure to Aroclor® 1254, a polychlorinated biphenyl (PCB) preparation at 2 ppm. Aldrin lowered temperature selection at 0.1–0.15 ppm. In a vertical gradient, brook trout (Salvelinus fontinalis) previously exposed to p,p′-DDT and p,p′-DDD selected higher temperatures than controls.