Due to the constant thermal environment and lower carbonate saturation state of the Southern Ocean, Antarctic marine ectotherms are expected to be amongst the most sensitive to the combined stressors of warming and ocean acidification (OA).To investigate their long term acclimation capacity, adult Antarctic sea urchins, Sterechinus neumayeri, were incubated for 40 months under four treatments:

1) T cur - 0.3 deg C (present day) and pH 7.8 (moderate acidification)

2) pH cur 1.7 deg C (predicted temperature) and pH 8.1 (current pH)

3) pH-0.3 1.9 deg C and pH 7.8

4) pH-0.5 2.2 deg C and pH7.5 (high acidification)

The energy budget (energy absorbed, energy lost through respiration and as nitrogenous waste) and growth parameters (scope for growth, mass of somatic and gonad tissues and the CHN content of gonad) were measured through the duration of two 21 day feeding and food processing cycles.Energy budgets were fully acclimated to OA treatments but there was only partial acclimation to temperature. Although metabolic rate was lower in the ambient temperature treatment (-0.3 compared to 2 deg C) and more energy was absorbed from food, there was no significant difference in the scope for growth between treatments. S. neumayeri can acclimate to predicted near future OA and is resilient to predicted temperature conditions.