Growth, mineral uptake and skeletal calcium deposition in brown trout, Salmo trutta L., yolk-sac fry exposed to aluminium and manganese in soft acid water

In 30-day exposures in artificial soft water medium, survival of brown trout alevins was not affected by low pH (4.5,4.8, 5.4), by low calcium concentration (10.25 μmol l^?1) or by manganese (≤20 μmol l^?1), but was impaired by aluminium (6–8 μmol l^?1) at low calcium concentration (10 μmol l^?1) irrespective of pH (4.5 or 5.4). Manganese (6.6, 20 μmol l^?1) impaired net calcium uptake and calcium deposition in the skeleton at low calcium concentration (25 μmol l^?1) irrespective of pH. Aluminium (2–8 μmol l^?1) impaired gross development, net uptake of calcium, potassium and sodium, and calcium deposition in the skeleton, and slightly increased the net loss of magnesium, some of these effects being more severe at calcium concentration 10 μmol l^?1 than 50 μmol l^?1, and some more severe at pH 5.4 than pH 4.5. Net uptake of calcium and sodium were impaired at low pH (4.5, 4.8), and skeletal calcium deposition was impaired at low calcium concentration (10 μmol l^?1), but these effects of low pH and low calcium concentration were slight compared with those of the trace metals. The possible role of trace metals in reports of the deleterious effects on fish of low pH levels is discussed.