Fig. 1. Changes in plasma Na⁺, Cl^–, K⁺ (A–C) and cortisol (D–F) concentrations, and gill Na⁺/K⁺-ATPase activity (G–I) in lake trout (A,D,G), brook trout (B,E,H) and Atlantic salmon (C,F,I) following direct transfer from 0 p.p.t. to 30 p.p.t. Each value represents the mean ± s.e.m., N=10 (except for 7 days in A,D,G: N=8; in B,E,H: N=5). Symbols in A–C: circles, Na⁺; triangles, Cl^–; squares, K⁺. Values with different lowercase letters are significantly different (e.g. a significant difference is observed between `a' and `b', but not between `a' and `a,b', or between `b' and `a,b', P<0.05, Tukey–Kramer test).