Fig. 2. Activation energy of aerobic respiration in North Sea and White Sea Littorina saxatilis acclimated to 13° and 4°C. Arrhenius breakpoint temperatures (ABTs) are given above the respective columns. Activation energy (E_a) values below and above the respective ABTs were determined in the temperature range 0-28°C. E_a values beyond ABT were significantly lower than E_a values above the ABT in all experimental groups (P<0.05). On the x-axis, the population of origin (North Sea vs White Sea) and acclimation temperatures (4°C vs 13°C) are indicated.