Effects of temperature and hypoxia on the metabolic performance of juvenile striped bass (Morone saxatilis)

Striped bass (Moron saxatilis) found in estuaries and rivers of North America face many environmental challenges. These challenges may have led to local extirpations of striped bass, as has been observed in the Ashley River in South Carolina. The link between environmental challenges and extirpation may be physiological capacities, such as standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic metabolic scope (AMS). The objective of this study was to determine the effect of temperature and oxygen availability on the metabolic capacities of striped bass, thereby assessing the physiological capability for survival under varying environmental conditions. After being acclimated to water temperatures of 20 degrees C, 25 degrees C, and 32 degrees C, striped bass swam at their acclimation temperature while being acutely exposed to dissolved oxygen (DO) levels of 2.5, 3.0, and 4.0 mg/L. The highest values of SMR, MMR, and AMS were observed at 32 degrees C, a temperature approaching the upper lethal limit. The MMR, AMS, and exhaustion time were significantly reduced at DO concentrations below 4.0 mg/L. These results indicate that juvenile striped bass are metabolically limited as DO concentrations fall below 4.0 mg/L. However, juvenile striped bass in the Ashley River may be minimally affected by this potential challenge because these conditions are rarely observed.