Lake Baikal is a unique ecosystem being the oldest and deepest freshwater lake on earth. Due to stable conditions over millions of years it is suggested that Baikal endemic amphipods are vulnerable to climate change, pollutants and invading species. In this study we investigated the effects of elevated temperature and cadmium levels on the physiological performances of the Baikal endemic amphipods Eulimnogammarus verrucosus and Eulimnogammarus cyaneus and the ubiquitous Palearctic amphipod Gammarus lacustris. This amphipod is regularly introduced into Lake Baikal and a potential invader. We focused on ion and acid/base regulation, oxygen consumption and ventilatory rates as performance parameters. First results showed that magnesium levels in hemolymph decreased during temperature increase (6-30°C, 1°C h-1) in all species investigated while cadmium did not have any effect. Furthermore, Baikal amphipods are not particularly sensitive to cadmium compared to other amphipod species as demonstrated by mortality experiments. The study revealed that E. verrucosus is living under stress conditions when temperatures exceeded 12-14°C while E. cyaneus is able to compensate for the increased oxygen demand up to 27°C (6-30°C, 0.8°C d-1). Given that E. cyaneus and G. lacustris showed similar resting metabolic rates this cannot explain why G. lacustris is not able to establish in Lake Baikal. Differences in the physiological performance under stress conditions between the two studied Baikal species are large. Hence it is supposed to be species-specific to what extent global change will affect Baikal endemics.