Acclimation to warming but not hypoxia alters thermal tolerance and metabolic sensitivity in an estuarine crustacean

Coastal species are challenged by multiple anthropogenic stressors. Plasticity may buffer the effects of environmental change, but investigation has largely been restricted to single-stressor performance. Multistressor studies have often been short-term and relatively less is known about the consequences of plasticity under one stressor for performance under another. Here, we aimed to test for the effects of thermal or hypoxic acclimation on thermal tolerance in the amphipod Gammarus chevreuxi. Animals were chronically exposed to raised temperature or hypoxia prior to determination of upper thermal limits and routine metabolic rate (RMR). Warm acclimation increased all metrics of thermal tolerance, but hypoxic acclimation had no effect. Different responses to the two stressors was also observed for the thermal sensitivity of RMR. Consequently, this species possesses the ability to increase thermal tolerance via plasticity in response to chronic warming but increasing duration of hypoxic episodes will not confer cross-tolerance to a warming environment.