Fig. 1.

The response of maximum heart rate (ƒ_Hmax) to acute warming in rainbow trout before (0d) and for 28d following transfer from 10 to 18 °C. Trout were acutely warmed from an initial temperature of 10 °C (a) until their heartbeat became arrhythmic. The ƒ_Hmax at 10 and 18 °C over the acclimation period are shown relative to that at 0d (b), along with the incremental Q₁₀ (c), and the temperatures at which the Q₁₀ fell below 2.0 (T_Q10<2), the peak ƒ_Hmax occurred (T_peak), and the heartbeat became arrhythmic (T_arr). Dissimilar letters in panels b. and d. indicate significant differences between timepoints. Dashed lines (a. and c.) indicate temperatures at which individuals were removed after exhibiting arrhythmias.