Effects of Long-Term Preexposure to Sublethal Concentrations of Acid and Aluminum on the Ventilatory Response to Aluminum Challenge in Brook Trout (Salvelinus fontinalis)

Abstract

Adult brook trout (Salvelinus fontinalis; 200–300 g) were preexposed for 10 wk to 75 μg Al3+∙L−1, pH = 5.2, in soft water (25 μequiv Ca2+∙L−1) and controls to the same conditions without Al3+. When challenged with a lethal dose of Al3+(333 μg∙L−1) at the same pH (5.2) and Ca2+(25 μequiv∙L−1), the control fish demonstrated a twofold increase in ventilation volume and ventilatory stroke volume within the first two hours, an increase in [Formula: see text], and a decrease in pHa and hemoglobin O2saturation. These effects were not seen in the group chronically preexposed to sublethal Al, indicating that some acclimation had occurred. Although the prechallenge [Formula: see text] and [Formula: see text] were the same in the two groups, the arterial pH, plasma [HCO3−], and hemoglobin O2saturation of the Al-preexposed fish were significantly below those of the control fish, suggesting that the acclimation was achieved at some cost. Possible mechanisms are discussed.