Mortality and physiological stress of year-classes of landlocked and migratory Atlantic salmon, brown trout and brook trout in acidic aluminium-rich soft water (original) (raw)

1986, Water, Air, and Soil Pollution

Physiological stress, measured as changes in plasma chloride, and mortality were measured on different year-classes of landlocked and migratory Atlantic salmon, two strains of brown trout, and brook trout, in a flow-through system with acidic Al-rich soft water. The oldest year-classes of salmon were smolts. Water from Lake Byglandsfjord (pH = 5.9), was enriched with inorganic AI (as AICI3) ~nd H2SO 4 to pH = 5.1, total AI = 225 ug L-I, and labile AI = 135 ug L-~. As a reference, lake water was limed by means of a shellsan~ filter to pH = 6.2, increasing Ca-concentration from 1.0 to 1.5 mg L-~. During the 83 hr experiment, neither mortality nor physiological stress occurred in any species or year-class in the limed water. In the acid water, no mortality occurred on any stage of brown trout or brook trout. Among the migratory and landlocked salmon, however, 5% of the alevins died after 49 and 70 hr, respectively. All smolts of both the landlocked and the migratory salmon died after 83 and 35 hr, respectively, the co~responding loss rate of plasma chloride was-0.76 and-1.26 meq CI hr-~. Brook trout, however, increased plasma ion concentration during the experimental period, and hence showed no stress.