Thermal limits in native and alien freshwater peracarid Crustacea: the role of habitat use and oxygen limitation

1. In order to predict which species can successfully cope with global warming and how other environmental stressors modulate their vulnerability to climate related environmental factors, an understanding of the ecophysiology underpinning thermal limits is essential for both conservation biology a nd invasion biology. 2. Heat tolerance and the extent to which heat tolerance differed with oxygen availability were examined for four native and four alien freshwater peracarid crustacean species, with differences in habitat use across species. Three hypotheses were tested: 1) Heat and lack of oxygen synergistically reduce survival of species; 2) Patterns in heat tolerance and the modulation thereof by oxygen differs between alien and native species, and between species with different habitat use; 3) small animals can better tolerate heat than large animals and this difference is more pronounced under hypoxia. 3. To assess heat tolerances under different oxygen levels, animal survival was mon...