Locomotor and physiological performances of striped bass relevant to Darwinian fitness under natural levels of hypoxia

Abstract

Due to climate change and anthropogenic influences, aquatic hypoxia is occurring more frequently, is more severe and it persist for longer periods of time. Juvenile striped bass being obligate aerobes and occupying an increasingly more hypoxic Chesapeake Bay, may be under additional pressures to meet their metabolic needs to support activities crucial for Darwinian fitness. The goals here were to investigate several such performances under hypoxia: sprint swimming, prey capture, escape response, hypoxia tolerance, and respiration rate under low and high flow conditions. Juvenile striped bass sprinted slower under hypoxia vs. normoxia in a repeatable manner. Kinematics of prey capture and escape response seemed to be unaffected when exposed to hypoxia, but motivation to escape and feed was reduced. Their hypoxia tolerance increased over time, but was not obviously related to their metabolic rates while swimming. Aerobic swimming metabolism was suppressed in hypoxic water. And lastly, all performances varied substantially between individuals.