Sensitivity of Atlantic salmon sac fry to acidity in the presence and absence of inorganic aluminum

The effect of pH on the toxicity of aluminum and its bioaccumulation by Atlantic salmon sac fry (Salmo salar) was studied under controlled conditions. We have developed an approach permitting us to verify the hypothesis of increasing aluminum bioavailability towards Salmo salar fry under physico-chemical condition (pH, T, [Al]) which simulate those present during periods of intermittent acidification in the spring. The experimental system consisted of three troughs in which pH and aluminum concentrations were specified. Each day a number of physico-chemical factors were measured. For a given treatment period of 17 days (pH 5 with or without Al) and a subsequent depuration of 18 days, we followed the survival of the salmon fry and the dynamics of their accumulation of aluminum. The biological results show a slightly elevated mortality (6%) in the acid solution (pH 5) containing the aluminum (135 μg/L) - cf. 1% in the absence of Al.