Na+/K+-ATPase (NKA) and V-type H+-ATPase (VHA) enzyme activities in gill homogenates. Branchial NKA (A) and VHA (B) maximum activities were determined along the time course of 168 h exposure to control (pH 8.1) and acidified conditions (pH 7.7 and pH 7.3). The exposure period was separated into a short-term (grey) and medium-term (white) acclimation period. No statistical differences were observed between the three different pH treatments using two-way ANOVA (p < 0.05). Bars represent mean ± SE (n = 3 replicate tanks, with six biological replicates per time point and treatment).